eHam.net - Amateur Radio (Ham Radio) Community

Call Search
     

New to Ham Radio?
My Profile

Community
Articles
Forums
News
Reviews
Friends Remembered
Strays
Survey Question

Operating
Contesting
DX Cluster Spots
Propagation

Resources
Calendar
Classifieds
Ham Exams
Ham Links
List Archives
News Articles
Product Reviews
QSL Managers

Site Info
eHam Help (FAQ)
Support the site
The eHam Team
Advertising Info
Vision Statement
About eHam.net



[Articles Home]  [Add Article]  

Mythical Antennas

Alan Applegate (K0BG) on February 4, 2010
View comments about this article!

Mythical Antennas

Experimentation is a major aspect of amateur radio. In fact, the innate learning style some of us are endowed with at birth, requires a hands-on approach, or we just don't get it! Others do very well with nothing more than reading books, while others excel in classroom-based learning. In the real world, the average person's learned intelligence is a combination of all three. Looking at this another way; if you're not endowed with at least a modicum of knowledge (book or classroom based) about the subject at hand, the results from your experimentation will be suspect at best. With that in mind...

Without doubt, the most prevalent experimental theme in amateur radio, and the most controversial, is the ubiquitous antenna. Everyone has to have one is some form another, and God knows there are more forms of it than any one person can imagine. There are dipoles, monopoles, yagis, off-center fed ones, verticals, wires, aluminum ones, mobiles, HF, VHF, inverted Vs, slopers, quads, and even dummy ones. And every single one of them must adhere to principles set forth by Kirchoff and Maxwell. There are no mythical antennas which can violate, defy, circumvent, ignore, or modify these principles.

It's agreed that not everyone is endowed with the capability to understand the aforementioned principles. However, you should have some basic knowledge about antennas just to install a store-bought one. When you don't have the knowledge, you could easily end up dead! At the least, you end up throwing your money away and/or be stuck with a less than stellar sky wire.

The following antenna examples all have a great following. Some users are so enamored with their choice, they ignore the inherent problems associated with them. A few even re-propagate the mythical attributes they're supposedly endowed with, even though they defy the aforementioned principles.

Nowadays, with the aid of modeling software like EZNEC, the masses can learn a lot more about antennas, what their radiation patterns look like, and even their approximate efficiency. Yet the myths about some of them just won't go away! Seemingly, once myths get into print, they obtain gospel status, as if commanded by the almighty. Well, let's look a little closer at some of the more popular antennas, with supposedly mythical properties.

Digressing. EZNEC, and some of the other numeric electromagnetic coding engines, are marvelous programs. They allow expert, and neophyte alike, to model all-manner of antenna parameters. However, the results are dependent on the data provided. For example, leaving out the feed line when doing an analysis will skew the results. Another common error is miscalculating ground losses. Therefore, assuming and quoting the results verbatim, without a basic understanding of how antennas behave, often leads users astray. In other words, they're a tool, not a panacea!

Case One: The End-Fed Dipole

If you just stop and think about the phrase end-fed dipole, the idea just falls apart. If it is end-fed, then it can't a dipole! A dipole is also a balanced antenna, and will technically have equal currents flowing in both poles. In the real world, the balance is not perfect, but is easily handled (using a balun perhaps) so that common mode current on its feed line will be at a minimum.

In the case of the proposed end-fed dipole, the return current must flow back down the outside of the coax feed line, as common mode. Some proponents argue that these unwanted currents can be choked off with a proper ferrite-based choke or balun. Others claim the common mode currents are an asset, allowing the antenna to work better; whatever that means.

One manufacturer openly claims the antenna is multibanded, with a low SWR, even though the fine print says you need an antenna tuner. However, no matter how you cut it, the end-fed dipole is a lousy antenna, fraught with common mode (both ingress and egress), and claiming otherwise reeks in the face of reality. After all, you can't negate the aforementioned principles, no matter what you do.

Case Two: The Off-Center-Fed Dipole (?)

Almost universally, off-center-fed antennas are referred to as Windoms, albeit they have no resemblance to Loren Windom's, W8GZ (sk) original, single wire feed design. Some manufacturers prefix them with the name of a state, assumedly to set them apart from all of the rest of the modified designs.

Remembering that a dipole is an antenna consisting of two equal length elements with a connecting feed at its center, then how can it be off-center-fed, and still be a dipole? Like the misnamed end-fed dipole, the level of common mode current is inordinate. Proponents often espouse the use of a voltage balun in some unorthodox ratio. That might be 1:4, 1:6 or even 1:9, depending on the anecdotal proof of the pudding. About all that happens is, the balun saturates which adds loss, and uncertainty to its already poor performance. Allow me to digress once again.

I have a pet peeve with respect to how ratio baluns are represented in popular text. You often see 4:1 when in reality they mean 1:4. For example; If the feed line is 50 ohm, and we have a 4:1 ratio, then technically the output of the balun is 12.5 ohms. Expressed as 1:4, the input is 50 ohms, and the output is 200 ohms. The situation gets even uglier when you see ratios of 9:1 (5.5 ohm output), when they really mean 1:9 (450 ohms). While a nit perhaps, it is more defining than adding the universally missing verbiage—step up or step down as the case may be—after the expressed ratio.

The actual length of the two elements vary with the designer. To be sure, each one has his/her pet lengths and balun ratio, assumedly designed to negate common mode current and/or enhance some other presumed attribute. Whether or not problems arise due to common mode current (the design notwithstanding), has more to do with the installation parameters, which for all practical purposes are beyond anyone's control. This makes the off-center-fed antenna a true conundrum.

Just for the record, we're not talking about input SWR, which can be mediated to some extent by carefully choosing the lengths of the elements. And, there may be some designs which exhibit low common mode on some bands, but certainly not all, an included balun notwithstanding.

Case Three: The G5RV As An All-band Antenna

There are as many variations of the G5RV as there are variations of Windoms. There are shortened ones, elongated ones, juniors, seniors, and (no lie) off-center-fed ones! Fact is, Louis Varney, G5RV (sk) published several versions himself, both with and without baluns. Someplace along the line, the notion got started that the G5RV was an all-band antenna. Here is a sentence (a verbatim cut and paste) from the web page of one of the companies which makes and sells a version of it: The G5RV is an excellent all-band (3.5-30 MHz) 102 Ft. dipole. The 102 Ft. dipole with 31 Ft. feeder of 450 ohm transmission line achieves a resonance on all bands from 80 to 10 meters with only one antenna without any loss in traps and coils. The impedance at the end of the 450 ohm feed line is 50-60 ohms. No wonder folks are confused!

If you really want to know what kind of antenna the G5RV really is, then here's the nitty gritty, complements of Tom Rauch, W8JI. If you read the data, you'll notice the high input impedance on 30, 17, and 10 meters. Unless you have a very good quality antenna tuner, you might not be able to find a match on these bands. Even then, the overall losses would be rather high. Realizing this, some all-band proponents of the G5RV, suggest removing the coax, and just feed the ladder line directly. When you do this, can it still be called a G5RV?

Case Four: Why 43 Feet?

Within the last few years, the 43 foot vertical has become popular, and available from several manufacturers. Proponents would have you believe the length is special. The truth is, it isn't. The length doesn't assure a good match except where it's resonant. Speaking of which, it isn't resonant across the HF spectrum as one company asserts. Contrary to some advertisements, it does indeed need radials (ground plane), as any vertical monopole does. Further, just because it doesn't have traps, doesn't mean much either. In fact, I suspect a properly installed Hustler 6 BTV will out perform it in any respect.

There's a dirty little secret about the requisite (?) matching balun you don't see in print very often. Most 43 foot vertical antenna sellers recommend a 1:4 voltage balun (always expressed as 4:1). Little if any thought is put into the fact a voltage balun can become a very lossy lump of ferrite when subjected to high reactive loads; almost a given no matter the band of operation.

If you're using a shack-mounted tuner, feed line losses vary all over the board. While tolerable on some frequencies, it certainly isn't tolerable over the whole HF spectrum, balun or no balun, as some pundits claim. Here's a discussion about the 43 foot wonder which appeared in these very pages about 15 months ago. It begs reading if you use a 43 foot vertical, or thinking about buying one.

Case Five: The Quad

Some years back, an article appeared in a popular amateur radio magazine extolling the virtues of the quad antenna, and how much better it was than a yagi, especially at low mounting heights. It further stated the gain was 2 dB better than a comparable yagi; they were less prone to noise reception; and the take off angle was lower. The truth lies elsewhere.

It really doesn't make much difference what the supporting structure is comprised of, be it fiberglass or aluminum. Nor does it make a difference if the elements are DC grounded, used with balun or without a balun, or whether they're in a diamond or square orientation. Their gain isn't any better than a comparable yagi; they're not any quieter than a yagi; and their take off angle isn't any lower.

The only true attribute a quad has (other than they're less susceptible to corona discharge), is their inability to withstand icing conditions.

A Truth

Common threads in the reviews of antennas universally contain references to DX stations worked, and statements like this antenna just works, or this antenna rocks, and, the SWR is low clear across the band! These statements are nothing more than jabberwocky.

Here's a real-world truth many amateurs will openly argue about: When it comes to simplicity, ease of building, ease of erecting, and ease of tuning, it's very difficult to beat a simple resonant dipole fed with coax. If you mount it correctly, you can actually achieve about 8 dBi of gain. Not too shabby for two chunks of wire, and few miscellaneous pieces of hardware. And you know what? No experimenting needs to be done! Oh. And they really do work!

Conclusion

The best way to combat the misinformation highway, is to spend the requisite effort to learn basic antenna theory, using whatever method is best for you. While experimenting is part of the effort perhaps, it should be based on truths, and not on myths.

When it comes to the printed word, I think Joseph Pulitzer said it best; A cynical, mercenary, demagogic press will in time produce a people as base as itself. To paraphrase; Basing your experimental efforts on myths, and then repeating them ad nauseam, only places you in the same criticizable position as the myth itself.

 

Alan, KØBG
http://www.k0bg.com

Member Comments:
This article has expired. No more comments may be added.
 
Mythical Antennas  
by WW5AA on February 4, 2010 Mail this to a friend!
Let the flames begin! A quote from the net this week, “My G5RV is the best antenna I have ever had. At 25’ I work everything I hear on all bands. Can anyone tell me if setting it up facing EU will help working some DX?” Most of those reading this article that have one of the mentioned antennas will not have a clue Alan.

Tnx es 73 de Lindy
 
Mythical Antennas  
by K9ZF on February 4, 2010 Mail this to a friend!
Nice article Alan.

I used to spend hours going through Cebik's pages of antenna tests. Fun stuff!


73
Dan
--
Amateur Radio Emergency Service, Clark County Indiana. EM78el
K9ZF /R no budget Rover ***QRP-l #1269 Check out the Rover Resource Page at:
<http://www.qsl.net/n9rla> List Administrator for: InHam+grid-loc+ham-books
Ask me how to join the Indiana Ham Mailing list!
 
Mythical Antennas  
by W9CPI on February 4, 2010 Mail this to a friend!
Great work Alan. I always enjoy your articles. After many, many years of being told that simple verticals and/or dipoles wouldn't work well, I have been amazed at the results I've had with these basic designs -- even when installed in unpromising locations! W9CPI/ZP9EH
 
Mythical Antennas  
by KB4WEC on February 4, 2010 Mail this to a friend!
I will never understand why some guy's will spend several thousand dollars in gear, and then tie it to a G5RV at 25ft throw in a 2.5kw amp and get on 75 meters and talk to there friend in the next town down the road !!
I will get on 75 with them , run my 703 at ten watts and have no issue with every body hearing me until I tell them I'm running ten watts, with a good antenna.
Guess , some people just want to spend the big bucks and throw a wire out the window.
Maybe some body needs to start making some old wire antennas with ladder line feed, a instruction mannual about 300 pages , and put a price tag on it for about $1,500.00 and I bet you would get some interest in it, you know, just so they could spend some dollars and talk about it.
Throw up 120 ft of 14ga wire as high as you can, connect one side of it to one end of 450 ohm ladder line, and connect the other side to the other leg of the latter line, run the ladder line to your radio (have to say this) room, connect it to a small tuner 300 watts or less, use a short section of coax to connect the radio to the tuner, and read the book on the tuner, tune the antenna, and be surprised at how well you get out !!
73
KB4WEC
 
Mythical Antennas  
by N1OU on February 4, 2010 Mail this to a friend!
Very enjoyable article with good points made. Makes sense. However, science will never take away the "magic" of a QSO conducted on a piece of metal that accidentally worked. For some reason this seems especially true on 6 and 10 meters where propagation effects can be spectacular at times.

I do recall that one aerodynamic scientist conclusively proved that, due to poor design, bumble bees can't fly. Maybe some of our less sensible skyhooks should be renamed "bumble bee antennas".

73

Gordon, N1OU
 
Mythical Antennas  
by K4LJA on February 4, 2010 Mail this to a friend!
Alan;
What a well written, easy to understand article.
Thank you. It is up to your usual high standards.
Randy K4LJA in Monroe, Louisiana
 
RE: Mythical Antennas  
by NY4D on February 4, 2010 Mail this to a friend!
New - and some seasoned - hams buy a rig that transmits from 1.8 to 432 Mhz. They think there must be some antenna that will do the same. So the antenna advertising flim-flam starts as it is an easy way to make a sale.

Most hams don't understand resonance, and they have learned a myth that a 1:1 swr at 50 ohms is resonance. Reactance, what's that?

And how about baluns, which term for advertising and marketing purposes now includes simple rf chokes that do no transforming or balancing.

Modeling programs are great learning tools but I find them a starting point for real world results.
 
RE: Mythical Antennas  
by AD4U on February 4, 2010 Mail this to a friend!
Thanks for a very interesting article. I especially liked the paragraph about the quad vs the yagi. I have used both since becoming a HAM in the 1960's. Quad VS Yagi is a debate that will rage for many years.

For no particular reason I prefer a quad, everything else being equal. But the yagi is much easier to build, to put up, and keep up. Large homebrew monoband yagis are all that I have used for the past 10 years.

The quad concept was "conceived" by the engineers (Moore)at a commercial shortwave broadcast station HCJB in Quito Equador SA. As you stated the ONLY reason they started to investigate alternatives to their yagi was the corona from the high power at the high altitudes was literally eroding (eg: melting) the ends of their yagi.

Dick AD4U
 
Mythical Antennas  
by W2NVD on February 4, 2010 Mail this to a friend!
In lighthearted response, would the high impedance side of a balun be the input on Rx?

To be fair, at my present QTH I don't have a lot of room. I've used a 135' doublet, 135' "OCF", G5RV, all about 35' at the highest point. All have served well as a single multiband antenna for my purposes, though none of them I would classify as a 'super' antenna. I guess I try to do the best with what I've got.

I have a house I'm fixing up and I put up an 80m horizontal loop, about the same height, fed with twinlead, a homebrew balun and a tuner. With the power turned all the way down on my old 735 I manage S9 on 80m fairly consistently a good distance up into Ontario from the 'southern tier' of NY.

I agree, it's worth every bit of time that you spend on studying. I may never have a high gain beam on a tower but I'm sure having fun seeing what I can do throwing some wire up in the air, according to some proven designs. I plan on trying a few different types after I get up there, and yes, there'll be at least a couple dipoles!

Thanks for a great article!

Bill W2NVD
 
Mythical Antennas  
by N0SAP on February 4, 2010 Mail this to a friend!
Nothing like having a can of antenna wax to get the signals to just slide off the wires and reduce wind resistance. "SAP"
 
RE: Mythical Antennas  
by N1DVJ on February 4, 2010 Mail this to a friend!
I always thought that K0BG was an arrogant little... Well, you get the idea.

But the bottom line is that he's right. And I find myself constantly going back to anything he writes to check things out and start from that point as my point of reference. And almost every time I find myself in the end right back where I was when I first went to his writings. In fact, the only real faults I ever found was a tendency to not be fully in tune with reality that compromise sometimes dictates that 'The best tool and the best tool for the job' are not always the same.

But as I said, I still find myself right back at what he writes as the 'gold standard'.

Maybe he comes off a bit brusque from dealing with all the self-appointed experts that in reality know knowing, and regualarly show that fact off!
 
Mythical Antennas  
by W4LWZ on February 4, 2010 Mail this to a friend!
Thank you Alan, for another reasoned well thought out article. Antennas have to obey the same laws of physics that us mortals do. There is no magic. I teach tech and general classes all the time and I use your articles to explain away the myths found in antenna advertisements.
 
Mythical Antennas  
by KB2DHG on February 4, 2010 Mail this to a friend!
A very well written article.
I have experamented with many wire antenna designs.
Living in a restricted CONDO, I had to be very crafty.
I purchased several commercial antennas all with poor performance. I was about to through in the towel but I decided to try one more thing. Building my own antenna.
I needed a multi band antenna so the best choice would be the G5RV...
I used bear copper wire cut it to 51 feet a side then cut 31 feet of 450 ohm ladderline. I directly attached the coax to the ladderline NO BALUN.
I could only get it up 21 feet but it is on top of the roof which is 80 feet up. Anyway, This home brew G5RV workes GREAT! I can't believe that a simple home built antenna worked better than a comercial built one. I mean with the exception of directivity, I am working DX and all stateside! Can't wait till the sun cycle comes!
so getting bac to this great article, I truly am a fan of experamenting with antennas!
Thank you...
 
RE: Mythical Antennas  
by N0YXB on February 4, 2010 Mail this to a friend!
I agree that one should learn the basics of antenna theory, but don't be discouraged from experimenting with antennas, even the ones listed in this article. If you're enjoying yourself, and learning, then you're on the right track.
 
RE: Mythical Antennas  
by AD4U on February 4, 2010 Mail this to a friend!
Anybody who says a G5RV at 25 feet is the best antenna they every had, means a G5RV at 25 feet is probably the only antenna they every had.

Seriously a G5RV is good for what it is. Just don't try to make it something that it is not.

Dick AD4U
 
Mythical Antennas  
by N5TGL on February 4, 2010 Mail this to a friend!
Regarding cubical quads:

"how much better it was than a yagi, especially at low mounting heights"

Personally, I can't see how this is not true? Once you get a loop one diameter from the ground, going higher really doesn't make any difference. Not so with a yagi. If you don't get a yagi up high, you're turning it into a cloudwarmer. Last field day I made a simple 9.5' magnetic loop, (obviously not a quad but the loop concept still holds true) mounted it about 2' (yes, two feet) off the ground and made a contact from Houston, TX to Hawaii on 100w, and he came back to me on the first attempt. I don't think a yagi would have worked in that situation.

"they're not any quieter than a yagi"

Since they are based on a loop antenna, (which rejects E) I don't see how they can't be quieter than a yagi, which is based on a dipole. (which sucks in both E and M) It's further compounded by not being mounted high enough, which has the main lobe pointed upward and picking up all the E interference from atmospherics.

Regarding dipoles:

"If you mount it correctly, you can actually achieve about 8 dBi of gain"

Really? This sounds very interesting. What would be that correct mounting method, and what is the angle of radiation?

"If you're using a shack-mounted tuner, feed line losses vary all over the board. While tolerable on some frequencies, it certainly isn't tolerable over the whole HF spectrum"

All I got to say to that is this: http://w2du.com/Chapter01.pdf

G5RV
Yep, once people realize it's a 20m antenna that acts like a random wire on the other bands, life will be good! Really good analysis on it on page 20-10 here: http://w2du.com/Chapter20.pdf
 
Mythical Antennas  
by K8SOR on February 4, 2010 Mail this to a friend!
Alan,
As usual, a very informative article. In my almost 50 years as a ham, I've used almost everything imaginable for an antenna, some worked very well, some very poorly. I regularly work a gent in Montana that loads his rain gutters. I guess one could say that any antenna beats no antenna.
Good article.
73,
Skip K8SOR
 
Mythical Antennas  
by N3QE on February 4, 2010 Mail this to a friend!
I think that some of the newbie adoration for a particular antenna has more to do with the fact that they can use it to work QSO's that make them happy.

That's not a minor point. After all, having QSO's that make you happy is IMHO the best part of being a ham.

But realistically, 100W into a light bulb will let you work a good amount of stuff on 40M, especially if the other guy has a good ear and the band is open to somewhere. When 20M and 15M are open I'm sure it'll let you work DX. I'm sure it'd work for some of the easy Euro DX on 40M too. Does that mean a light bulb is the best antenna ever? Of course not. But don't blame the newbie for thinking it's the best thing since sliced bread - the fact that it works, no matter how incredibly inefficient it is, is enough to make a lot of people happy. And I'm glad it makes them happy.

Incidentally, I'm not making any suppositions in the above paragraph. When I was a kid, and my dummy load was just a light bulb, I had several DX QSO's on 40M and 15M working into the light bulb when I was under a mistaken impression that paralleling the light bulb with my antenna somehow was fixing my SWR. (I was a misguided youth... compare me with misquided adults who think that good SWR is any kind of measure of an entanne). Isn't radio just magic?
 
Mythical Antennas  
by NX7U on February 4, 2010 Mail this to a friend!
Mythical!
I thought the Unicorn was the first mobile station, just look at that built-in whip antenna on the forehead. I bet that busts pile-ups!
 
RE: Mythical Antennas  
by AJ8MH on February 4, 2010 Mail this to a friend!
Great article. I coat my wire antennas with Vaseline and notice a 2 db improvement on receive. Antennas are so much fun to play with!

http://webpages.charter.net/aj8mh-radio/notebookind5.html

Joe ( AJ8MH )
 
RE: Mythical Antennas  
by N2RRA on February 4, 2010 Mail this to a friend!
Great article Alan! You reeled me in! :)

Agree on all your text and very well said. Especially when you suggested and I quote:

"The best way to combat the misinformation highway, is to spend the requisite effort to learn basic antenna theory, using whatever method is best for you. While experimenting is part of the effort perhaps, it should be based on truths, and not on myths."

Quads! Here we go again, LOL!

To use as an example there are people with four towers that have both Quads and Yagis on them. These Hams that have been around over 30 years experience Dx'ing will prove the supposed myths through "Experiments and Experience" that are in favor of the, Quad! Of course there are folks that are in favor of the Yagi, but again there's a reason why this subject can not be debunked when the proof is in the pudding.

There's just no denying that there's something more about the Quad than some program is telling, but to call them Narcissistic, or nothing else short of an exploited imagainative miscreed is harsh. Not saying you said this but it has been said before by other people in other articles that will take offense their intelligence is being questioned.

Experiment, Experiment, Experiment!

To the general Ham,

If you have a small lot and are forced to use multi banded dipoles experiment with other multibanded dipoles before making such an ignorant post and commented of how the only one dipole you have ever owned is the "Best antenna ever". Srii!

If you want to debate over what beam concept is better than the other make sure you have at least two towers and each beam at the same height before even making a suggested analysis amungst other possible variables of course. The help of antenna software will be handy, but real world test need to be worked in there based on your terrain.

Experience, Experience, Experience and go with what best works for you after your experimental analysis based on truth, not myths, and not what other people try telling you other wise. Don't easily be mislead by possible agenda's that are trying to make names for themselves by debunking, the many greats like Varney, Cebik and alike.

73,

Thanks Alan for the article!
 
RE: Mythical Antennas  
by K4AHO on February 4, 2010 Mail this to a friend!
Alan, congratulations!! I have been reading your stuff for quite some time and this article has been your very best subtle humor piece so far. Although the article is several months premature, no one has caught on... Shades of Larson E. Rapp.. LOL...

73

Jim
K4AHO
 
RE: Mythical Antennas  
by W6CAW on February 4, 2010 Mail this to a friend!
I bet you also believe in man made global warming? I talk all over the world on my 160 meter Carolina Windom, with 100 watts, from 160M th 20M. Junk science lives.
 
Mythical Antennas  
by K0FF on February 4, 2010 Mail this to a friend!
"Balun" means "BAlanced to UNbalanced" and is a bi directional device. There is no "input" or "output", the ports are interchangeable in that sense.

The ratio of a Bal-Un should be the ratio of the BALanced impedance to the UNbalanced impedance.

Geo>K0FF
 
Mythical Antennas  
by N1LQ on February 4, 2010 Mail this to a friend!
I have used a homemade G5RV, a 133 ft. Carolina Windom and a Par End-Fedz half-wave antenna over the past 32 years of Dx'ing.
According to Alan my 342 DXCC confirmed countries, all done with 100 watts, no tower, no beam and no linear must all be 'mythical QSO's'.
Funny... I got all the cards. Hmmm...
 
RE: Mythical Antennas  
by N4KZ on February 4, 2010 Mail this to a friend!
Thanks for setting the record straight on so many antennas. The antenna manufacturers' marketing types have created so many myths out there that it's sad, very sad. I have sat here for a couple years now wondering how in my four decades of ham radio did I miss the fact that the 43-foot tall vertical is the best thing since sliced bread? Or that a G5RV - regardless of its version -- is an all-band antenna? How could I not know these things?

P.T. Barnum must have been a ham.

73, N4KZ
 
Reductio ad absurdum  
by K5END on February 4, 2010 Mail this to a friend!

"The best way to combat the misinformation highway..."

Eo ipso reductio ad absurdum.

This serendipitous yet logical concession means that the content of articles and on websites on the "misinformation highway" (in the absence of professional credentials, critical review or proof) is not credible.
 
Mythical Antennas demistified  
by KJ4ADN on February 4, 2010 Mail this to a friend!
Interesting read - and equally interesting comments.

AIM 4170b was the best investment I've made in HAM radio. One of my favorite pastimes is plugging into these all-band wonders and comparing bandwidth, noting the type of ground, feedline... it makes the hobby interesting.

Equally interesting, listening to these fantastic stories about the latest (fad) antenna, and trying to figure out why some of them transmit anything at all. Personally, I find all the BS kinda funny - and the prices appalling - but, even laziness has a price.

For me, I'm blessed with very conductive ground "perfect" - so my resonate verticals open up to the EU with nice reception and good reports, weekend, after weekend. Tuner? Once I got the antenna system worked out, the tuner was turned off/removed. The little extra work pays off in better DX reception, and my 100 watts ain't much, but it's not warming coils of wire. I see no point in trying to match a poor antenna to an expensive radio.

When I started reading the article with real skepticism (it lacks HARD data, I thought)... most of it I've either encountered, or probably will encounter. Just the other day, I heard a station calling CQ... and did a double take, I was still hooked up to a dummy load. "must be running some REAL power... hmmmm...." I bet someone's already capitalized on that "perfect match, all-band, tuner-less, antenna" idea.

Thanks for the article and the comments worth reading, refreshing... for a change.

Bill
KJ4ADN
 
RE: Mythical Antennas demistified  
by AE6RO on February 4, 2010 Mail this to a friend!
In defense of the 43 foot vertical, it is close to a 5/8 wave vert on 20 (42 feet). Properly executed (with radials of course), it should give 2 to 3 dB gain over isotropic. This means a proper high Q loading coil at the base, not a lossy balun. Unless you want your signal to contribute to global warming ...

Of course if you really want gain put up a single band dipole and get your 8 dbi. <sigh>. 73, John
 
RE: Mythical Antennas demistified  
by K0FF on February 4, 2010 Mail this to a friend!
Bill said: "When I started reading the article with real skepticism (it lacks HARD data, I thought)... most of it I've either encountered, or probably will encounter. Just the other day, I heard a station calling CQ... and did a double take, I was still hooked up to a dummy load. "must be running some REAL power... hmmmm...." I bet someone's already capitalized on that "perfect match, all-band, tuner-less, antenna" idea.

Bill
KJ4ADN "

Yes Bill, there was (is?) an antenna that has a "matching device" across the feedpoint. Someone X-Rayed the "device" and learned that is is a 50 Ohm resistor! Yet the antenna does work, sort of, and it makes the radio happy.

Geo>K0FF
 
RE: Mythical Antennas  
by AE5JU on February 4, 2010 Mail this to a friend!
"If you just stop and think about the phrase end-fed dipole, the idea just falls apart. If it is end-fed, then it can't a dipole!"


Exactly!!!


73
Paul
AE5JU
 
RE: Mythical Antennas demistified  
by N1DVJ on February 4, 2010 Mail this to a friend!
On dummy loads... When I lived in Texas, one of the clubs sponsored a contest that involved transmitting using a standard filiment light bulb. Then they had to add rules on what socket you could use, and even how to hook to the socket. Performance was just too good!

As to the resistor in the potted box, I saw the original article years ago, with a picture of the X-Ray. Wasn't it in QST?
 
Mythical Antennas  
by N0AH on February 4, 2010 Mail this to a friend!
I agree on the 43 foot vertical.......

The modern day YUGO of antennas-

Nice write up Alan-
 
RE: Mythical Antennas  
by K0FF on February 4, 2010 Mail this to a friend!
Joe said: "I coat my wire antennas with Vaseline and notice a 2 db improvement on receive.
Joe ( AJ8MH ) "

Vaseline will errode rubber components, rubber covered wire etc. Use instead Antenna Wax!

http://www.qsl.net/k0ff/Antenna%20Wax%20by%20K%d8FF/


(not actually for sale any more, sorry)

Geo>K0FF
 
RE: Mythical Antennas  
by K5LXP on February 4, 2010 Mail this to a friend!
I could probably cite an exception to every one of Alan's generalities but in the context of which it was written it's tough to disagree.

I think what it comes down to is not the merits of a particular topology, rather the execution of them.

You *can* get an end fed half wave to behave, and get good performance from a 43ft vertical. But, it *matters* how you do it.

A lot of hams seem oblivious to the idea that it matters how and where you put an antenna up. You can take any given antenna and make or break it with the installation. You just can't take a G5RV, install it 10ft high in your yard with six bends in it with the feedline laying on the ground, and expect it to perform anything like how an optimally installed one would. But this is exactly what you hear in the help forums from guys having issues with performance, tuning and EMI problems. Or, you hear the ubiquitous "I can work everything I hear", but of course they are missing so much more they could be hearing with a properly deployed antenna.

This isn't an abstract concept. A light bulb lights a room better from the ceiling than the floor. A loudspeaker up on a shelf is heard more clearly than one behind the couch. So why do hams insist on taking well understood antenna configurations, mutating them to fit their particular (sometimes arbitrary) physical constraints, then blame the antenna *type* for the compromised results?

Yes, I understand the idea that not everyone has room to deploy antennas optimally. But what seems to be missing is the understanding that a key feature to any antenna is its' deployment, and when you alter that, you've altered a fundamental component of the design. A G5RV is no more a G5RV when it's 10' up, with six bends and the feedline on the ground than it is still rolled up in the package it comes in. It's no longer an OCF, or "windom" or what have you when it's stapled under the eaves of your house or run through your attic. A 43' vertical is just a metal stick in the ground without an optimal groundplane. An antenna can only reach its potential when due consideration is given to its installation.

The "myth" comes from when you take a well understood design, altering it into something it's not, then calling it a bad antenna when it doesn't meet the expectation.


Mark K5LXP
Albuquerque, NM
 
RE: Mythical Antennas  
by KE3HO on February 4, 2010 Mail this to a friend!
K0BG - "I have a pet peeve with respect to how ratio baluns are represented in popular text. You often see 4:1 when in reality they mean 1:4. For example; If the feed line is 50 ohm, and we have a 4:1 ratio, then technically the output of the balun is 12.5 ohms. Expressed as 1:4, the input is 50 ohms, and the output is 200 ohms. The situation gets even uglier when you see ratios of 9:1 (5.5 ohm output), when they really mean 1:9 (450 ohms). While a nit perhaps, it is more defining than adding the universally missing verbiage—step up or step down as the case may be—after the expressed ratio."

No, actually 4:1 is correct. It is a BALUN. *** BAL-UN *** BALanced to UNbalanced. For example, if the 50 ohm side is the UNbalanced side and the 200 ohm is the BALanced side, then you would use a 200 ohm BALanced to 50 ohm UNbalanced balun, which is a 4:1 BALUN.
 
Mythical Antennas  
by KC8LTL on February 4, 2010 Mail this to a friend!
I agree with most of your statements. However, even if calling it a "dipole" is indeed accurate, I fail to understand why voltage feeding a half wave antenna would be less efficient than current feeding one, assuming an appropriate feeding device. Granted that current feeding is trivial while voltage feeding is more complex, but assuming the feed works, a 1/2 wave antenna is a 1/2 wave antenna.

Ken McGuire
KC8LTL
 
RE: Mythical Antennas  
by K0BG on February 4, 2010 Mail this to a friend!
There is a minor typo Bruce found; Everyone has to have one is some form another... that should be 'in' not 'is'. Thanks Bruce.

On the balun ratio; I was taught in engineering classes that both block and flow diagrams always have their inputs on the left, and outputs on the right. I still follow that premise as it is logical for several reasons.

As I said, it is a pet peeve. If folks would just put the (always) missing descriptor after the ratio, it wouldn't matter, but that's not the case. In fact, to my knowledge, only one Elmer on this web site has ever done that, and that's Owen, VK1OD.

Even the ARRL Handbook doesn't have a standard convention, but that fact doesn't mean, there shouldn't be one. I'm just trying to do my part.

Alan, KØBG
www.k0bg.com
 
RE: Mythical Antennas  
by K0BG on February 4, 2010 Mail this to a friend!
Clark, you posted before I got mine up. In my opinion, the fact it is BAL-UN doesn't mean much either. I can easily have a balanced outgoing feed (400 ohm ladder line), converted back to unbalance (50 ohm) coax.

Again, without the descriptor, it's technically questionable.

Alan, KØBG
www.k0bg.com
 
Mythical Antennas  
by N9BH on February 4, 2010 Mail this to a friend!
Alan,

Great job!!

73
Bruce - n9bh
 
RE: Mythical Antennas  
by WD8T on February 4, 2010 Mail this to a friend!
Amen brother Alan. Even though you didn't comment on the most most mystical antenna of them all.. No what I mean eh?
 
RE: Mythical Antennas  
by K0FF on February 4, 2010 Mail this to a friend!
"If you just stop and think about the phrase end-fed dipole, the idea just falls apart. If it is end-fed, then it can't a dipole!"

Correct it is not a dipole but it is still the same antenna. A half wave radiator, but end fed. The Voltages and currents will be the exact same as a center fed dipole.

Voltage fed antennas have been common over the years, and are just as valid as current fed (center fed dipole) designs.

Usually the end fed or Voltage fed half wave antenna is used as a vertical, fed in a variety of ways. The J Pole is an example of a half wave fed via a quarter wave stub. LC networks work well too. All such "tuned" matches work only at the tuned frequency.
A toroid transformer can be used to cover more frequencies, i.e. harmonics.

I like to simply add an additional quarter wave of wire to the end of a half wave, then feed it direct.
The 5/8 vertical is a fine tuned version of this, the extra 1/8 wave being used to tune the angle of radiation instead of the feedpoint impedance. Try using a 2 meter 1/4 wave on 440. Works fine. I tweak the antenna for the 440 band, let it fall where it may in the 2 meter band (Marconi Radiator: an antenna where ground is an integral part of the system, resonant on any odd number of quarter waves).
The traditional dipole formulas fall apart a bit when stacking wires end to end because there are less "end insulators" used, therefore the "end effect" does not apply to the ends that are connected.

When the end fed half wave is used horizontally, it is referred to as a Zepp, for Zeppelin. Used as a trailing antenna, they worked well.

Another end fed antenna is the Flat Top as used on large ships. The antenna starts AT THE RADIO, goes through an insulator in the bulkhead, up to the flat top. One wire, all of which is the antenna. This is the only instance I have ever seen that the "tuner" inside the radio IS an antenna tuner. All "tuners" in ham radio rigs are "line flatteners", not antenna tuner.

Shown here is an example of a shipboard transmitter;
http://www.qsl.net/k0ff/Radioroom/K0FF-MM.jpeg

notice the high Voltage feedthough at the top of the radio. Here is another installation, where there is a large neon bulb clipped to the antenna wire:
http://www.qsl.net/k0ff/Radioroom/K0FF-MM.jpeg

I've used these "flat tops" from 500 KHz to 10 Meters with fantastic results.

The real "MYTH" in ham radio is that coax cable is the only way or even the best way to feed an antenna!

Just my opinion of course.

Geo>K0FF
 
RE: Mythical Antennas  
by KE3HO on February 4, 2010 Mail this to a friend!
Case 1: The End-Fed Dipole

I don’t recall ever seeing anyone refer to an end-fed wire as a dipole, but that doesn’t matter – the fact that I don’t recall seeing it does not mean that it hasn’t happened :-)

The problem with the end-fed monopole is not that it is an end-fed monopole. The problems related to this antenna are in execution.

There is this idea that an end-fed antenna does not need any counterpoise. This is just plain wrong. Even a half-wave wire end-fed at its resonant frequency requires a counterpoise. Kirchhoff’s Current Law applies at the feedpoint of the antenna. Any current that flows in the antenna must also flow in the ground system. Without a counterpoise, this current flows down the feedline. Some will say (incorrectly,as Alan pointed out) that you can simply choke this off with a current balun. Kirchhoff’s Current Law still applies. Without the counterpoise, anything you do to choke off the common mode current will give an equal reduction in the antenna current. All you are doing is adding impedance to the system and therefore additional losses. If you make the losses in that impedance high enough, you can get very small common mode current. Unfortunately, you also get an equally small current in the radiating element.

Feeding this antenna requires two things (at a minimum). First, the above mentioned counterpoise. Second, an appropriate impedance matching network AT THE FEEDPOINT. An additional item that is worthwhile, but not absolutely required (assuming the first two items are PROPERLY done) is a 1:1 current balun (or common mode choke) in the feedline between the impedance matching network and the shack.

Does this mean that an end-fed monopole is a junk antenna? Not at all. Why would anyone choose, for example, a half-wavelength end fed wire over a half-wavelength center-fed dipole? Here are some reasons. There are certainly others that I have not thought of.

1) Size/geometry of available space and/or support structures.
2)Given a support for a half-wave vertical, having it base-fed (end-fed) has some mechanical advantages over center-fed. It is easy to lay coax on the ground to the feedpoint. Having that coax come off of the antenna at its midpoint means that you have to bring the coax away from the antenna a significant distance in a horizontal (or nearly horizontal) run to minimize the coupling between the lower section of the antenna and the outside of the coax.
3)Given a sufficiently long length of wire, a proper counterpoise, and a proper variable impedance matching network at the feedpoint, it can be a useful multi-band antenna. Keep in mind that the voltages present in the matching network can be substantial and the matching network has to be designed for the application.

It is very easy to build a half-wavelength center-fed dipole and hang it between two trees. Hams have been hanging up half-wavelength wires center-fed with 50 ohm coax and no balun and having pretty good results for decades. Building an end-fed monopole (half-wavelength or arbitrary length) requires a lot of care and a lot more equipment. Just laying out the counterpoise for the end-fed monopole is more work than building an entire half-wavelength center fed dipole. Losses in the matching network are a factor that is not present in the center-fed dipole. Still, with proper care and good execution, an end-fed monopole can be a useful antenna *IF* its advantages are to YOUR advantage.

73 - Jim
 
RE: Mythical Antennas  
by WB2WIK on February 4, 2010 Mail this to a friend!
Nice article, Alan!

Now I have to get back to injecting the dB grease into my new run of coax.

Man, this is time consuming.
 
Another truth  
by KA4KOE on February 4, 2010 Mail this to a friend!
Ground mounted verticals MUST have radials!!

...the more the better!

A lot of short ones are better than a few long long ones!

Philip
KA4KOE
 
RE: Another truth  
by K0FF on February 4, 2010 Mail this to a friend!
Phillip said: "Ground mounted verticals MUST have radials!!
Philip
KA4KOE "

Ground mounted end fed half wave verticals actually don't require radials.

Ground mounted 1/4 wave radiators do require a counterpoise, it is the other half of tha antenna.

Geo>K0FF
 
Mythical Antennas  
by KJ6ETL on February 4, 2010 Mail this to a friend!
Great article!
How about vertical antenna’s ?
 
Mythical Antennas  
by KL7AJ on February 4, 2010 Mail this to a friend!
Very nice article, Alan. You said a lot of things I've been saying for years. :)

I would like to make a comment on the quad, however. It's fairly easy to show that a quad responds to circular polarized signals arriving off axis. This could account for a lot of the observed performance, especially at low angles. Why is this important? All ionospherically refracted signals are circularly polarized! I have an upcoming QST article, hopefully in September that describes this in great detail. "Gimme an X, Gimme an O, what's that spell? RADIO." This article is the culmination of years of ionospheric research by myself and others. See references to Digisonde and other ionosondes.

Eric
 
RE: Mythical Antennas  
by NN2X on February 4, 2010 Mail this to a friend!
About the Quad..

Well, I don't know about the software programs, but I did spend able of money, and leased top end test equipment comparing Quads and Yagis

I put up 2 65 Towers, and place a 32 FT Boom (Yagi Mono Bander), 20 meters, and 32 Foot Quad (20 Meters)..Went down range, and measure the F/B and foward Gain, both were computered modeled, and were name brand mnufactured..Well, there was that 2db difference, between the Quad and Yagi, however, when we compared multiband, to multband, there was much larger differences, favoring the Quad..The Yagi was using interlace system

My test equipment back then was 8566 Spec An from HP..I did the antenna plots, and the rest of it! About quiter antenna, yep, the Quad was more quite..(Due o the G/T)..Sorry my real tests did not agree with the orginal post..! Best Tom Wright, NN2X
 
Mythical Antennas  
by N8RGQ on February 4, 2010 Mail this to a friend!
Mythical Antennas

"THE DIPOLE"

The "DIPOLE" is the worlds best Antenna !
The Gain is " 8 DBI " !
You should never EVER use A BALUN/UNUN , Direct FEED only !



THE FACTS !

The "DIPOLE" is the standard reference antenna it has O db gain !

Unless you use A BALUN you can have current flow down the shield of your coax !

The "DIPOLE" has NULLS , DEAD spots off of each end !



Go run Alan's CALL K0BG !

USA
K0BG

Alan R Applegate

3202 Notting Hill

Roswell, NM 88201-0403

USA



Check out his "ROSWELL OFFICIAL ALLEN VEHICLE!"

Check out the LOOP on the passenger side rear of his truck !

Check out the three loops he uses for A CAP HAT on his vertical !

Don't forget to look at his GREEN ALIEN picture on the side of his truck !



The only thing I can agree to is that the HUSTLER BTV series ANTENNAS are very good !

IF BALUN/UNUN are sooooooooooooooo bad why does just about every major Antenna manufacture use them /

CUSHCRAFT , HYGAIN , PAR , MFJ , KLM and I can go on and on !

Currently I have the following Antennas up !

Cushcraft X7 , Cushcraft R8 , KLM-14 Element 6 m beam , Hustler 5BTV "FOUR SQUARE" fed with A UNUN , A home brew Loop ruining around my ceiling fed with 16 to 1 BALUN and 180 Degrees from the feed point A 800 ohm terminating Resistor , A radio Shack 102 in whip with the tip sliped out of top of my roof next to PVC vent pipe fed with A 6 to 1 UNUN and I could go on and on but I think you get the point !

My main HF rig is the ICOM IC-7800 , the amp here is the ICOM PW-1 and I have BALUN/UNUN's every where and have let to have damage or failure out of any of them !

I Finaly have A use for A simply DIPOLE I will point one of the ends towards "ROSWELL NEW MEXICO!"

73 ,

Terry

N8RGQ

PS- Alan "APPLEGATE" AKA "AL BUNDY" say hi to Christina "APPLEGATE" AKA "KELLY BUNDY" at the next Family Reunion for me ! :)
 
RE: Another truth  
by KE3HO on February 4, 2010 Mail this to a friend!
"Ground mounted end fed half wave verticals actually don't require radials. "

They do if you want current to flow in the antenna, or are willing to accept a common mode current that is equal to the current in the antenna.

Granted, the end-fed half-wave wire is fed at a high voltage low current point, so you can get away with a less ambitious counterpoise, but any current that flows in the antenna must also flow in the ground system somewhere, either in your counterpoise or back down your feedline to the shack.

73 - Jim
 
RE: Mythical Antennas  
by EX_AA5JG on February 4, 2010 Mail this to a friend!
"The 'DIPOLE' has NULLS , DEAD spots off of each end"

Only if it is a 1/2 wavelength or more above ground. Below that the pattern is pretty circular with few nulls.

73s John AA5JG
 
RE: Mythical Antennas  
by KL7AJ on February 4, 2010 Mail this to a friend!
The fact that so many hams for so many years have gotten by with so many mythical/lame antennas, simply proves that QRP works. :)

Eric
 
RE: Another truth  
by K0FF on February 4, 2010 Mail this to a friend!
Jim said:""Ground mounted end fed half wave verticals actually don't require radials. "
They do if you want current to flow in the antenna, or are willing to accept a common mode current that is equal to the current in the antenna.

Granted, the end-fed half-wave wire is fed at a high voltage low current point, so you can get away with a less ambitious counterpoise, but any current that flows in the antenna must also flow in the ground system somewhere, either in your counterpoise or back down your feedline to the shack.

73 - Jim "


A) how much current is flowing at the feedpoint of a Voltage fed antenna? Theoretically zero. Actually, not much.

B) If using an LC match a GROUND connection is adequate. Not a counter poise or radial. If a counterpoise is used, it would be small ( a few feet for 20M antenna)

E) If using a quarter wave stub feed, we are back to no ground, no counterpoise.

F) One can't make generalizations about antennas, generally. Never say never. Never say always.

The max current flowing in a half wave wire is in the middle of the wire, no matter where it is fed.

Geo>K0FF
 
RE: Mythical Antennas  
by KG6YV on February 4, 2010 Mail this to a friend!
Intersting article, some things make sense others do not to me.

If you think that a windom antenna doesn't work then go model my Carolina Windom with EZNEC. I did. It says it works with radiation patterns providing much better low angle radiation on 75/40 meters at 40 ft. height.

True I don't proclaim low SWR on 7 bands like some of the manufacturers, I use a tuner. On that account I agree that some folks are over-marketing things a bit.

But sir, I had plain old dipoles at the same height (40ft) and was never able to work the 75 and 48M DX I can work on SSB with my Carolina Windom. Yes, I did A/B comparisons. The Windom got thru when the dipoles couldn't

So, I respectfully disagree on the subject of the windom. The other items you write about make sense to me.


Greg
KG6YV
 
Mythical Antennas  
by G0GQK on February 4, 2010 Mail this to a friend!
Alan, you'll be arrested and end up in court accused and found guilty of saying some nasty things about antenna's if you're not careful !

Mind you there have been blokes like you saying those things for years but STILL they take no notice ! I remember a fella named Kurt N. Sturba, I'm sure you must know of him, who used to write regularly about all the myths surrounding lengths of wire bent one way or another, and he was always right. You're not Kurt N.Sturba are you ?

Something else that's been doing the rounds in recent years,by people who should know better, is the suggestion that a 1:1 balun is used with open wire feeders on an all band dipole. As I often comment, if you don't use a 4:1 balun with open wire feeder on a dipole what the hell DO you use a 4:1 balun for ?

Mel G0GQK
 
RE: Another truth  
by KG6MZS on February 4, 2010 Mail this to a friend!
Allan;

I loved it, thanks. I am a graphic designer with an art background and I don't come to the hobby with much knowledge or aptitude in electrical engineering. This kind of article is very helpful for the electrically challenged folks like myself in pointing us in the right direction.

I will say that although a full sized G5RV is not an "all band" antenna, it is a pretty good starter antenna if one is going to put up just one modest antenna. I used one at first and as long as it was up 35' or higher (50' in my case) it got me on a lot of bands even if it wasn't so great on 10m, 17m and 30m.

I've since gone to two doublets - a 80m and a 30m fed with homemade 600 ohm ladder line and between the two of them I seem to get everything pretty well. It is fun to see which performs better on any given band and I am still experimenting with optimizing my feedline lengths.

All the fun is in the pursuit of perfection - which is good because nobody ever gets there.

73 de Eric, KG6MZS
 
Mythical Antennas in Black & White  
by DL4NO on February 4, 2010 Mail this to a friend!
Hell Alan,


you see a few things a litte one-sided:


Case One: The End-Fed Dipole

True: This is no dipole, but nevertheless a resonant antenna. Here in Europe this antenna has been quite pupular since it was patented by Josef Fuchs, OE1JF, in 1927. This design lives from the fact that the antenna is fed in a current knot with very little current. If the ground system has an impedance of a few 100 Ohms - who cares?


Case Two: The Off-Center-Fed Dipole

Is it important whether you call it a dipole or not? The idea of this antenna is to feed it at a point where you have similar impedances on different bands which happens to be "a little" above 50 Ohms. OK, Windom fed it with a single wire what we should not do these days...


Case Four: Why 43 Feet?

Normally you build verticals because of their low elevation angles. Keeping this in mind you should not make them longer than 5/8 of the shortest wavelength you intend to use - perhaps a bit less, but not exactly a half wavelength because of the matching problems. You can then use them for perhaps a 3:1 or 4:1 frequency range, read: 40 to 10 m if you use an antenna tuner directly at the base of the antenna.


Case Five: The Quad

Quads were mostly built because they were easier to home-brew than trap yagis. I know there were nearly religious discussions of quad vs. yagi. But these have been many years ago.
 
Mythical Antennas  
by N7NSL on February 4, 2010 Mail this to a friend!
An excellent article. At present I use a Windom with 4:1, whoops 1:4 balum with fair to good results - I thought. But during field day a friend put up just a plain 40 meter dipole next to my Windom. There was a noticeable receive gain increase. That opened alot of eyes.
Thanks again for your thoughtful article.
73
Ted, N7NSL
 
Mythical Antennas  
by K3LUE on February 4, 2010 Mail this to a friend!
Now that we've debunked a lot of antennas, what is the "BEST" antenna. Of course, this topic will have to be broken down to situations such as cost, size, what restrictions are you up against, size restrictions such as height or HOA regs, etc but under the various categories, what is the best that can be done?
THis has been dealt with over the years but it's a new year. What's the update?
 
Mythical Antennas  
by WW3K on February 4, 2010 Mail this to a friend!
Alan,

The writer who said: "let the flames begin..." was a pretty good prognosticator <spelling?>. hihi

Your article, while well executed, fails to address the merits / virtues of the antennas you obviously disdain.

1. End fed (voltage-fed) half wave: While somewhat difficult to match, might be an obvious solution for certain mounting situations where a center-fed half wave would be inappropriate. Surely, all the 5.0 eHam Product Review ratings for items such as the PAR End Fed Half Wave antennas couldn't be wrong, could they? (Yes, I am quite aware that most reviews are SUBJECTIVE.)

2. OCD (Off-Center<fed>-Dipole), aka: Windom: It's merit lies in it's multibanding capability. There has been quite sufficient modeling of this antenna to prove it's worth. Is it a compromise? Certainly.... but what antenna isn't?

3. G5RV (and derivatives): This much misaligned antenna has certainly withstood the test of time. When properly constructed (and mounted), it is a wonderful multibander, perhaps superior to OCD designs. It's strength lies in the fact that it uses it's twinlead to match/multiband the antenna. It offers a more symmetrical radiation pattern on higher freqs than an OCD design does (OCD's tend to distort their patterns toward the longer elements on the higher frequencies.)

4. 43' Monopole: Again, this antenna's virtue is that it can be multibanded. Also, when mounted over a good radial field and properly matched, should outperform other methods of multibanding (i.e.: trap verticals) especially on lower bands like 40/60/75/80 meters. It is also close to 5/8 wavelength on 20 meters, is omnidirectional, and offers a low angle of radiation (for DXing) that one could only obtain by mounting your beloved 1/2 wave center fed 8 dbi of gain dipole at 5/8 wavelength or above. Does it radiate some unwanted high angles on frequencies above 14 MHz? Yes. Are they overcome by the PREDOMINATELY low wave angles? YES again. So, if PROPERLY matched over a GOOD RADIAL FIELD, what's not to like? I hate to sound like a broken record, but check for yourself what other hams are using by checking the product reviews. Your will find the 43' vertical, (regardless of manufacturer) seems to get rave reviews.

5. The QUAD: Are you for real? You've really got me scratching my head on this one. Are we to believe that because SOME quads have experienced SOME ice loading issues that your are gonna come here and bash quads? There are probably dozens, if not HUNDREDS of hames here in New England who would challenge you on this one! First off, with a 2 ele quad, you get at LEAST 2 db gain from driven element alone, and then (at least) another 3 db gain from either the director or reflector (depending upon how you configure) alone, not to mention the SUPERIOR F/B RATIO as compared to other 2 element designs (1/4 wave spacing 90 degree out of phase dual-driven designs notwithstanding). All I can say on this one is: GET REAL.

The truth is: EVERY ANTENNA IS A COMPROMISE. And, what works for SOME, in SOME locations / configurations / over SOME earth's, may or may NOT work for others.

The old ham who said: "Get as much wire up there as high as you can" really knew HIS stuff. Even the late-GREAT L.B. Cebik was a proponent of multibanding a Horizontally Oriented, Horizontally Polarized Full wave loop.

Please understand that my intent is NOT to criticize or contradict your post, rather expand upon your <apparent> critical viewpoint of the above antenna designs, by offering some additional information.

Thank you so much for your opinion, I herein have offered mine.

73 and God Bless!

Dominick Tuzzo - WW3K
Derby, CT

P.S.: I too am not a big fan of end fed half wave designs..... but hey, they do indeed work!
 
RE: Mythical Antennas  
by WB2WIK on February 4, 2010 Mail this to a friend!
>Mythical Antennas Reply
by N5TGL on February 4, 2010 Mail this to a friend!
Regarding dipoles:

"If you mount it correctly, you can actually achieve about 8 dBi of gain"

Really? This sounds very interesting. What would be that correct mounting method, and what is the angle of radiation?<

Installing it 1WL above earth yields about 8.5 dBi gain for any dipole, at a radiation angle of 25 degrees.

You might want to see the actual plot with gain and elevation angle. A good place to view it is here:

http://w8ji.com/antennas.htm
 
RE: Mythical Antennas  
by WB2WIK on February 4, 2010 Mail this to a friend!
>RE: Mythical Antennas Reply
by KG6YV on February 4, 2010 Mail this to a friend!
If you think that a windom antenna doesn't work then go model my Carolina Windom with EZNEC. I did. It says it works with radiation patterns providing much better low angle radiation on 75/40 meters at 40 ft. height.

True I don't proclaim low SWR on 7 bands like some of the manufacturers, I use a tuner. On that account I agree that some folks are over-marketing things a bit.

But sir, I had plain old dipoles at the same height (40ft) and was never able to work the 75 and 48M DX I can work on SSB with my Carolina Windom. Yes, I did A/B comparisons. The Windom got thru when the dipoles couldn't<

::This is pretty irrelevant, and quite believable. The "Carolina Windom" is actually a top-loaded vertical (Marconi) that uses the section of coax above the balun to do the radiating, so it has a lower radiation angle than a normal dipole or OCF dipole (which is what most people call a "Windom" nowadays).

So, it's not really "any" kind of Windom. They just call it that.
 
RE: Mythical Antennas  
by WB2WIK on February 4, 2010 Mail this to a friend!
Re "Quads vs. Yagis," I'd recommend anyone interested in this get a copy of the May 1979 Ham Radio magazine and see the article by N6NB.

He touches on the subject here:

http://commfaculty.fullerton.edu/woverbeck/antgain.htm

But I remember the real, live, on-the-air, side-by-side tests run prior to the article. They were great, and sometimes quite funny.

Under NO condition was any sized quad found to outperform a portable Yagi on a tower trailer pulled up to the same property and set to the same height, on any HF band (and used to contact the same stations, at various distances). He tried and tried (and tried!) to find an example where the Quad outperformed the smaller yagi but just couldn't find one. The results, with lots of photographs and data, were all in the magazine article. A few snapshots from the same article are on the website link provided above.
 
Mythical Antennas  
by K0RGR on February 4, 2010 Mail this to a friend!
I think the discussion you cite is a bit hard on the 43' vertical.

I put one up last year, frankly not expecting much, and I've been pleasantly surprised.

The main critics in the discussion you cite assume losses on some bands of 3-5 dB. Well, I'd go along with that on 160 meters. But on the other bands, my SWR is less than 4:1 and I'm feeding it with LMR-400 low loss cable, so there isn't anything close to 3 dB loss. Above 80 meters, the SWR is around 3:1 and my rig's built-in tuners can handle it.

I currently have only 20 radials on it - more to follow. I think this is as good as any vertical I've used on 40 and 20 meters, with 30 meters as a bonus, and that includes the HyGain HyTower. On 80, it's mediocre, but I can work both coasts with it fairly well. On 160, it radiates, but not that much. It works OK on 15 - about as well as the HyTower, and I haven't used it much on 10, but worked a little DX there last fall.

No, this won't be my main antenna for the higher bands. But with the addition of the matchbox design from the current ARRL Handbook to let me remotely resonate it on 80 and 160, I think it will be my main lowband DX antenna for a long time to come.
 
Mythical Antennas  
by G6NJR on February 4, 2010 Mail this to a friend!
I will never understand why certain people insist on attempting to prove they may know a whisker more than the average ham it is pure oneupmanship nothing more nothing less and certain people are extremely guilty of it time and time again and quite frankly it gets a little monotonous

Pete G6NJR YMMV mine does not
 
RE: Mythical Antennas  
by K0FF on February 4, 2010 Mail this to a friend!
Alan said: "On the balun ratio; I was taught in engineering classes that both block and flow diagrams always have their inputs on the left, and outputs on the right. I still follow that premise as it is logical for several reasons.

Alan, KØBG
www.k0bg.com "

But Alan what do you do when in receive mode and the input IS the antenna?

Geo>K0FF
 
End fed PAR antennas  
by KC8CXZ on February 4, 2010 Mail this to a friend!
How do you explain the extremely high ratings, and rather enthusiastic reviews for the PAR 'End Fedz' end fed antennas? How would they compare to a dipole? Just curious. Thanks.
 
Mythical Antennas  
by VE2JL on February 4, 2010 Mail this to a friend!
Great read!!! Myth versus reality exposed. Comments have been great also.

How about a follow up on propagation myths? Seems a lot of hams could use a refresher course.( and I should probably include myself in there)HI HI
 
RE: Mythical Antennas  
by K0FF on February 4, 2010 Mail this to a friend!
VE2JL said:"How about a follow up on propagation myths?"

OK.

Geo>K0FF
 
RE: Mythical Antennas  
by K0BG on February 4, 2010 Mail this to a friend!
Geo, the truth is, it doesn't matter, lexical semantics aside. As I said earlier, only one Elmer here ever added the descriptive wording necessary for a complete understanding of the in vs. the out.

And, there is another, perhaps cloudier reason, I think the way I do about the subject.

For some reason which escapes me, amateurs assume the receiver's input impedance is always the same as the transmitter's, when in reality it seldom is. In fact, in a lot of cases the receive S+N/N ratio would improve if the transmit balun was bypassed on receive.

We could carry this on and on, but I do believe I made my reasoning clear, moot or not.

Alan, KØBG
www.k0bg.com
 
RE: Mythical Antennas  
by K0FF on February 4, 2010 Mail this to a friend!
Posted By K0BG:

"Geo, the truth is, it doesn't matter"

OH....... Never mind.


Geo>K0FF
 
Mythical Antennas  
by N0AH on February 4, 2010 Mail this to a friend!
Let me get this right....your 43 foot vertical rocks on 10-20M, is ok on 40M, and stinks on 80 and is a dummy load on 160M....ok, fb

But read the antenna "flame thrower" ad that perhaps suggested you but it in the first place, performance on the low bands, and reread your comments....-Ironic statements eh? Hah hah..... (trust me, I've been there...sure it works, I spent money on it, the bolt's don't rust, it has to work.....it is not working....)

It reminds me so much of the MFJ-1026 noise cancelling unit that wipes out static crashes, blah blah blah with a putzy 18 inch active antenna....., they left that out of the ad....oh yeah, if you want it to work, just add another outdoor vertical like the one that can't hear with static crashes.....

It is all smoke and mirrors and the two big advertisors of the "wonder 43 foot vertical antenna" are past business partners acting they are in a divorce....lately, it has been like watching a Manopoly game seeing which company is going to buy which company out next....then jacking the prices on the new goods- ugghhh-

My guess is that they use the same ad agency- the apple does not fall far from the tree- (-: at least one of the companies is making some very decent stuff, or at least it looks cool- - the other, the same old trash- mighty fine trash at that- but the ads read with a lot of the same hype- "I got more bolts for you and these don't rust!!!!" These ads are all very entertaining until you have to deal with the defects- or it may not do half of what is advertised after it is in concrete....

Forget these cousins.....Personally, I'm keeping my Alpha Delta 1/4 wave multiband sloper for the low bands, that is if that is what it is.....(the title sure is cool beans) I worked every state but MS (ironic, must of been all of those home grown 43 foot verticals), LA and KH6 in last week's 160M CQWW....not bad for a 55 foot chunk of wire- total investment, under $100.00, reaching KL7 twice, and working both Dakota's, priceless-

Gee Alan, you never write much that ever creates controversy- hi
 
RE: Mythical Antennas  
by ZENKI on February 4, 2010 Mail this to a friend!
Oh you dont know,,, those 43 foot verticals change the pseudo Brewster angle. Its something in the 5KW UNUN that does it.

The longer the vertical, the taller the DX tales!
 
RE: Mythical Antennas  
by WB2WIK on February 4, 2010 Mail this to a friend!
Nothing wrong with a 43' vertical.

I built one from wire, two insulators, and rope (total cost about $15) and hung it from a tree limb that was about 45' above ground. With only 24 radials under it (all about 43' long) it worked fine and exactly as well as a $500 43' tall self-supporting vertical that doesn't need the tree limb.

If anyone expects the self-supporting version to work 1 dB better than the $15 wire version, I have oceanfront property in Phoenix I'd like to sell; please call.
 
RE: Mythical Antennas  
by KZ5A on February 4, 2010 Mail this to a friend!
Pretty funky article.

Let's see..... the only antennas that actually work are yagis and CF dipoles, and dipoles get 8 dbi gain if you install them properly. Right......

Apparently, "properly" in this context means situated between a reflector and several directors.

I thought this sort of article was traditionally reserved for April 1.

73 Jack KZ5A
 
RE: Mythical Antennas  
by K1BQT on February 4, 2010 Mail this to a friend!
Good lord, Alan, you sure pried opened the worm can with that one! As someone who's designed a bunch of matched-in OCFDs that actually work and don't talk back down the feed line, I applaud your recognition that some people haven't been as compulsive. But don't give the OCFD a universal black eye or suggest it's not a "real" dipole because the sides aren't the same length. Fact is, a properly designed OCFD will have pretty much the same current distribution and radiation characteristics as a center-fed dipole. If it walks like a duck.....?
 
Mythical Antennas  
by K9ZF on February 4, 2010 Mail this to a friend!
So what compromise do you guys see in the "Windom"? Assuming full size for the lowest band, and erected as a "flat top" at decent height?

I've considered "building" one. Mainly because I was under the impression it would perform the same as a normal dipole, and present an easier load to match with a simple tuner.

How would you compare the Windom [or OCF dipole, if you prefer] to a horizontal full wave loop at the same height? [full wave at the lowest band...]

I think I would prefer the loop, however, I have lots of real estate, but no trees or other supports. So I think it would be easier to support the dipole with one or two supports than the loop with 3 or 4...

I'm not much of a DX'er, state side performance is the main objective.


73
Dan
--
Amateur Radio Emergency Service, Clark County Indiana. EM78el
K9ZF /R no budget Rover ***QRP-l #1269 Check out the Rover Resource Page at:
<http://www.qsl.net/n9rla> List Administrator for: InHam+grid-loc+ham-books
Ask me how to join the Indiana Ham Mailing list!
 
RE: Mythical Antennas  
by K3AN on February 4, 2010 Mail this to a friend!
It's good to know that the concept of an end-fed Zepp as an efficient antenna can be laid to rest. All those old ARRL handbooks and antenna books were wrong. Thanks Alan!
 
RE: Mythical Antennas  
by WB2WIK on February 4, 2010 Mail this to a friend!
K9ZF a loop works better, and the more "round" it is in shape (circular, then maybe octagonal, hexagonal, square...3-sided is not as good) the better it works.

Two advantages of a full-wave loop (FW for the lowest frequency used, using the ~1005/f formula) are it's more omnidirectional than any sort of doublet, and it's resonant on all harmonics, both odd and even. A single 80m loop can cover most of the HF ham bands (except 160m) in a single swipe if it's cut for the low end of the band.
 
RE: Mythical Antennas  
by WB2WIK on February 4, 2010 Mail this to a friend!
Alan, it's a shame that even the Extra exam proves zero proficiency in any kind of electromagnetic theory. :-p

Guys actually don't seem to know that a 1/2 wave dipole over earth produces 8+ dBi gain, routinely, which is the whole advantage of using horizontal antennas.

I'm astonished. And maybe a bit embarrassed.

Good article, and keep up the good work.
 
RE: Mythical Antennas  
by W9AC on February 4, 2010 Mail this to a friend!
> "When it comes to simplicity, ease of building, ease of erecting, and ease of tuning, it's very difficult to beat a simple resonant dipole fed with coax."

However, eight resonant dipoles needed to cover 3.5 MHz to 30 MHz isn't my idea of "simplicity, ease of building, and ease of erecting." Arguably, 15m can be used with the 40m dipole. Fine, call it seven dipoles.

Also, the amount of coaxial line loss and incremental losses associated with higher SWR at the band edges of the resonant antenna need to be evaluated. There's more loss associated with coaxial-fed resonant dipoles than one typically thinks.

A much better method of feeding a monoband, half-wave dipole involves feeding it with a half-wave multiple of 600-ohm line at a line current maximum point, trimmed to achieve a 50-ohm VSWR of less than 1.5:1 at the transmitter end and optionally, slightly altering the apex of the feed -- again to achieve a 50-ohm VSWR at the end of the 600-ohm line. The overall system loss with this dipole is substantially less than typical coax-fed dipoles.

My own idea of "simplicity, ease of building, ease of erecting, and ease of tuning" of the half-wave dipole? I would focus on all-band operation and not depend on erecting seven or eight dipoles for good 80-10m performance.

If I had to use a fixed line length, I would start with a half-wave dipole at the lowest operating frequency. Next, I would choose an odd electrical multiple of 1/8-wave of 600-ohm transmission line at the lowest operating frequency. The odd 1/8-wave multiples brings the 50-ohm VSWR into very reasonable matching range for a tuner while minimizing tuner loss.

If I could change the feed-line length? I would use W5DXP's method of starting with a half-wave dipole cut for the lowest frequency, then alter the length (via RF relays) of 600-ohm line fed at a current maximum point to achieve less than a 1.5:1 50-ohm VSWR -- and achieve it without a tuner.

When I mention "50-ohm VSWR," I'm discussing the VSWR seen by the transmitter at the input to the 600-ohm line -- not the VSWR on the 600-ohm line. The VSWR on the 600-ohm line does not change as its length is changed. But, the VSWR at the 50/600-ohm junction and all points of the 50-ohm line section back to the transmitter does indeed change, but only as the load and/or 600-ohm line length changes. The 600-ohm section creates a variable RF transformer for the 50-ohm section. Transpositions like these between two unequal line impedances create interesting opportunities.

In either case, two highly efficient dipoles, each achieving very high efficiency by two different methods. And, I would put either one of them up against a resonant dipole fed by coax.

Paul, W9AC
 
RE: Mythical Antennas  
by W9PMZ on February 4, 2010 Mail this to a friend!
if the user is happy with the results that they obtain, so be it.

ham radio is no different than any other endeavor in life; "mine is better than yours"; and with all the pontification that ensues........

73,

carl - w9pmz
 
RE: Mythical Antennas  
by WB2WIK on February 4, 2010 Mail this to a friend!
W9AC, no one could disagree with that!

It's all true.

However parallel dipoles fed with coax are very easy to install and also work very well without the need for trimming line lengths and such.

I've used 80-40-30-20-17-12-10m parallel dipoles with about 12" separation between them lots of times at many locations. Single feedline, SWR never above 2:1 except at the edges of 80 meters (band's just too wide!), and although there's some element interaction, use of an analyzer and site-tuning makes this fairly simple work.

Lots of advantages to coax, like you can bury it and run it almost anywhere. Its downfall occurs when it's mismatched, but the parallel resonant dipole design resolves that.
 
RE: Mythical Antennas  
by K9MHZ on February 4, 2010 Mail this to a friend!
Alan's post is good, but a couple of things stick out....

- Lots of junk science in the world of antennas, no doubt

- BUT, we operate on lots of bandwidth on lots of bands. Just posting how silly we all are when we're trying to get a few more bands out of a wire, or how stupid we all are in thinking that our antenna tuners somehow make a bad antenna good really gets old.

YES, full-sized dipoles for each and every band, mounted way way up high, coupled with nice baluns is the way to go....WE GET IT, ALAN. It's just not practical for everyone, so that's when compromises happen. Not everyone's saying "this antenna really gets out"....many of us know we're using a Rube Goldberg setup, but don't have any other choice.

Good grief.

Brad, K9MHZ
 
RE: Mythical Antennas  
by W5ESE on February 4, 2010 Mail this to a friend!
> If you just stop and think about the phrase
> end-fed dipole, the idea just falls apart. If it
> is end-fed, then it can't a dipole!

Why not?

If it's field strength radiation pattern has two
major lobes, it's a dipole.

Whether it's fed at the end, in the middle, or
somewhere else.

I agree that a EFHW 40m antenna will no longer
be a "dipole" on 15m or 10m, because the pattern
will have broken up into a larger number of lobes.

73
Scott W5ESE
 
RE: Mythical Antennas  
by KT4WO on February 4, 2010 Mail this to a friend!
Gota love the guy who said he worked 450,000,000 DX stations.. so his antenna must be good....

And...just think..he is someones Elmer...FM

KT4WO
 
Mythical Antennas  
by K5ML on February 4, 2010 Mail this to a friend!
...and speaking of antenna myths:

"Here's a real-world truth many amateurs will openly argue about: When it comes to simplicity, ease of building, ease of erecting, and ease of tuning, it's very difficult to beat a simple resonant dipole fed with coax. If you mount it correctly, you can actually achieve about 8 dBi of gain. Not too shabby for two chunks of wire, and few miscellaneous pieces of hardware. And you know what? No experimenting needs to be done! Oh. And they really do work!"

Pray tell, how does one mount a dipole to get an 8 db gain? From what I recall, the gain of a dipole was about 2.1 db over an isotropic antenna. I eagerly await learning how to pick up almost 6 db of gain through proper mounting.
 
RE: Mythical Antennas  
by N3OX on February 4, 2010 Mail this to a friend!
The more time goes on, the more I am convinced that the most important antenna building, installation, and advising skill is self-skepticism.

This is especially true when you're dealing with a couple types of antennas:

1) Antennas you hate

2) Antennas you love

The physics of antennas are completely known. However, *I* do not completely know them, and I recognize that. What I do know is that the answer exists. And what I also know is that emotion and discussion have absolutely, positively NOTHING to do with that answer. And there's also only *one* answer if the question is specific enough.

But we never get one answer from the community. We get big clouds of "information" consisting of a mixture of strong opinion, reason, fact, falsehood, truth, and plausible-sounding folklore, and we often pluck antenna decisions out of that.

That's an important shortcut, because few of us intend primarily to be antenna engineers. And even antenna engineers make mistakes. Nevertheless, the answer is somewhere in the math. It is somewhere in a solution to Maxwell's equations with proper boundary conditions.

Too many words just get in the way and lead to answers that are both right and wrong depending on interpretation. That's not how antenna theory works. There's no opinion, no interpretation that can match quantitative prediction.

It's really important to keep self-skepticism, because that drags you back to the math, or to the realization that you can't do the math. That can be a frustrating thing. But it's important, because without it, a lot of opinion, over-generalization, and even love and hate slips in to the discussion and poses as quantitative reasoning.

I've been guilty of that. It's very easy to know the things you know. What's hard is to challenge yourself to check to make sure you know the things you know, and to remind yourself what you don't know. I hear a lot of certain words coming from people who I know are wrong.

Sometimes I hear those certain, but incorrect, words coming from me, a few years ago, in the archives.

The problem often turns out to be too many words, not enough math. These days, sometimes I type out a few hundred words of response, catch myself saying something I'm not sure I can justify, going and running an EZNEC model or something, and wiping out
everything I wrote...

73
Dan





 
RE: Mythical Antennas  
by N3OX on February 4, 2010 Mail this to a friend!
"I eagerly await learning how to pick up almost 6 db of gain through proper mounting."

Put it at a great height over a large reflecting plane.

A dipole in free space has around 2.1dBi gain. A dipole above the earth is not in free space.
 
RE: Mythical Antennas  
by W7ETA on February 4, 2010 Mail this to a friend!
Great prose!
Concise, easy to follow.

When I was a Novice, one of gods who walked upon water, someone in a radio club using a Bash book to pass Extra, WOWED me with the tail of an end fed dipole using an atmospheric stub. One could actually use the atmosphere to replace the missing portion of a dipole. I think that was around 1980?

I dunno know about yagi having the same gain, or it being as quiet on receive as a quad? NO. I really mean, I don't know? I heard the myth so long, and can't test the assertion, so I don't know.

Since I can't do the math, lack the background to understand the physics, I find I use rules of thumb to understand antennas and simple things like electron flow.

73
Bob
 
RE: Mythical Antennas  
by K5END on February 4, 2010 Mail this to a friend!
>

"The problem often turns out to be too many words, not enough math..."


That is the most accurate and relevant comment in this entire thread.
 
RE: Mythical Antennas  
by K5END on February 4, 2010 Mail this to a friend!
"attempting to prove they may know a whisker more than the average ham it is pure oneupmanship nothing more nothing less and certain people are extremely guilty of it time and time again and quite frankly it gets a little monotonous"

Sir, you have discovered the man behind the curtain.
 
Mythical Antennas  
by NO6L on February 4, 2010 Mail this to a friend!
Well, yet another amateur who likes to take swipes at the "Hornets Nest of Myths", like me. I shall begin with my "Stick of Logic" and take a few swipes myself.

First:

No, you are not nit picking when you discuss balun ratios, you're being technically correct. Aren't we, as "Amateur Scientists" who pride ourselves in deductive reasoning, logic and investigations, not supposed to screw up something as simple as ratios? Look in any automotive repair manual and you will see transmission gear ratios listed as, for example, ...3d gear 2:1, 4th gear 1:1, 5th gear(overdrive) 1:1.1. Not 1.1:1 for 5th.

Windoms, Windoms, Windoms.

I'm friggen' tired of hearing licensed radio amateurs on the air, or in print, calling an off center (more properly, "asymmetrical") dipole a Windom. If you can't use the correct terminology, go into stamp collecting. Why am I "sick and tired" of it? Simple, the same reason I'm tired of the same people using country and city names for phonetics. When you describe your antenna as a Windom, I picture in my mind a, well, a Windom, not an asymmetrical dipole. Yes, I know it's technically not a dipole, but what else can I call it at this time?

"I worked the world with X antenna".

Big... fat... hairy deal. I can work the world with a somewhat straitened out wire coat hanger, without the varnish scraped off. ;-) If the propagation is right and noise low enough, anything conductive will serve as an antenna.

The two you missed:

There's two other mythical antennas, and I use the term "antenna" loosely here. They are (drum roll), the Iso-Tron and EH antennas. Actually, the real antenna is the outside of the shield of the coaxial cable that feeds them. How do I know? Simple, put a line isolator/W2DU balun at the feed and the the VSWR goes berserk and you no longer get a signal radiated, or received for that matter. The typical idiotic reply is that the line isolator chokes off the current within the coaxial cable. Uh, wrong. If that were the case, it would do the same for my inverted "V", and it doesn't. Still don't think so? Bury the feed line a foot and see how far you get, if you can tame the VSWR. Good luck with that. Also, the "engineers" that design these things say to use more than 1/4 wave of feed line so you don't get a "hot shack". Uh, think about that, there genius. It seems to me if you feed a "real" dipole antenna with coax and no balun you have to do the same thing to *alleviate* a hot shack. That right there is the first clue as to what is happening. In fact, the performance of these "antennas" is so abismal you'd have better luck grounding the end of the shield real well and extending the center conductor 1/4 wave and leave it laying on the ground. And you won't have a hot shack, to boot. Oh, by the way, their explanation for shack RF is that these antennas radiate so efficiently that the outside of the shield picks up the signal and "pipes" it into the shack. Yeah, whatever. You know, the explanations the Iso-Tron and EH antenna fanboys give for what you see is every bit as entertaining as the explanations Flat-Earthers give for what we see in the *real* world. And just as wrong.

VSWR Myths.

"Oh, man, ya' got to keep them SWRs down to 1:1. It's very important to keep down them SWRs because if'n ya' don't, ya' won't get out and they'll get into yer radio and burn it out." That was not heard on CB, it and many other similar "epiphanies" regarding VSWR are heard across the amateur bands as well. Look, I'm not even going to get into it, just read the first two sections of this if you're clueless about reflection mechanics:
homepages.ipact.nl/~pa1are/tuner/reflections.pdf

Of 43 feet and men

43 feet, eh? Well, I may be paying that thread a visit, too. This ought to be fun.
 
RE: Mythical Antennas  
by HAMMYGUY on February 4, 2010 Mail this to a friend!
I think Allen got irritated by the recent Slinky antenna article having so many "it works for me!" comments that it made him get his nose to the keyboard to respond to them all indirectly.

Allen, nice article, well written (you have a good style), but I certainly don't share your observations. You've managed to poo-poo several COMPROMISE antennas that work quite well for most. No their not the best, but some don't have the real estate to put up numerous resonant single band dipoles.

Real world observations are valid. Working the world on 5 watts into a compromise antenna doesn't mean the antenna is a piece of rubbish. The software will prove that it could be improved, but the proof is in the pudding. Does the antenna radiate well enough for the ham using it to make reliable contacts? That to me is the best way to tell if an antenna is working well.
 
RE: Mythical Antennas  
by N3OX on February 4, 2010 Mail this to a friend!
"Does the antenna radiate well enough for the ham using it to make reliable contacts? That to me is the best way to tell if an antenna is working well."

I agree with you that we shouldn't be going around trying to dismiss people's working stations and their happy results just because their antenna sucks, but the test you propose above is not really a test of the antenna!

"Real world observations are valid"

The problem with "real world observations" in this context is that anecdotal DX-and-contacts pragmatism, while it is very useful for any given ham, doesn't translate at all into objective advice or recommendation. Our QRP-operating friends prove every day that a signal 13dB down from a typical barefoot 100W rig can work the world. Does that in any way mean that an antenna that, for *no good reason,* wastes 13dB of the input power is a "good antenna?"

No way. If there is some other antenna that is a dozen dB better and has similar complexity, cost, size, and frequency range, then it's absurd for anyone to *recommend* the lossier one. The lossy one is not a compromise, it is a bad antenna, and should be called a bad antenna.

The problem is that hams have a lot of emotional investment in their antennas. DX-and-contacts pragmatists don't want to hear that their antenna is terrible and has little to recommend it in an objective sense.

- - - - - - -

Now, that said, I think some of the people who are interested in theoretical prediction need to learn to be less dismissive of low-precision but real measurements, like A/B testing two antennas and reporting the difference in "S-units" or in "I can hear this or that DX on antenna 1 and not on antenna 2." There is a huge difference between these and the logbook page. An A/B test, even on changing signals, even on skywave, even with the poor ruler mark of the "S-unit" has one very important difference vs. a logbook page.

Since the antennas are switched quickly in succession, they eliminate the day to day propagation variations that make our logbooks so interesting. 20m today could be 50dB 100dB worse than 20m yesterday, but 20m sampled every two seconds for five minutes, even using the S-unit, is probably going to be within 6 or 8dB of the right answer.

I've seen this sort of report being entirely dismissed, and that doesn't make sense. I hate S-units. They don't mean a fixed size thing. But if you report six S-units difference between two antennas, there's still a substantial difference. It could be 6dB or 36dB, but it's something (and it's not 36dB) ;-)

Even worse is dismissing the "I can't hear this guy on antenna 1 and I can on antenna 2." That points to a profound difference between those two antenna systems, and if I dismiss that I'm just calling you a liar.

This is a major political and scientific mistake. Yes, the NEC-2 model *I just ran* can't predict what you just said. But I didn't model your exact situation complete with feedlines, baluns or lack thereof, nearby confounding conductors. I might not have even put both antennas in the same model. I didn't ponder how my models suggest the two antennas would pick up noise from your house. Largely, this is because I didn't have the information. If the model were constructed properly with all the information, we should be able to work together to figure it out, and learn something in the process.

Sometimes it seems like hams report antenna differences and are greeted with a response like "this doesn't fit neatly in the subset of antenna theory that I know, and it doesn't fit neatly with my simple model." When you tell that to someone who doesn't do modeling after they reported a result that was profound, you've just called them a liar and given them a reason to doubt modeling, period.

That's bad. It makes people mad. It spawns wacky theories about modeling "not being able to handle" the antenna in question. And worst of all, it prevents us from getting to the root of the disconnect, which is always the most interesting thing and where the learning happens.

I think not enough people appreciate that modeling and antenna theory can be essentially perfect if you have antenna types and installations where you aren't forced to leave something important out or put in a really strong assumption, and also that finally figuring out and reproducing a weird, "wrong seeming" empirical result in the model can give great insight into a whole broad class of weird antenna observations.

To work toward this best, though, we have to be able to have honest discussions about bad antennas vs. good antennas, we need to recognize that a logbook is a horrifically low precision measurement, yet also recognize that an A/B test, even a sloppy one, may be a hundred thousand times better than a logbook full of nice contacts, and simple low precision A/B tests are likely to be available in great abundance.

That's not going to work if we all get mad at each other because of hard-headed opinions on theory vs. "real world experience," and unfortunately, that seems to be quite common.

73
Dan






 
Mythical Antennas  
by IZ4KBS on February 5, 2010 Mail this to a friend!
While a share that an antenna cannot have magical properties, I do not see how a so-called end fed dipole (or EFHWA):

1) cannot be seen as a dipole.

2) is a lousy antenna.

3) tries to defy Kirchhoff's law.

First, anything having two poles is a dipole by definition, and the fact that a dipole is voltage-fed rather than current-fed does not change that fact.

Second, why should an EFHWA be a lousy antenna ? If properly fed, i.e. through a suitable matching network, I think it can be a rather effective antenna, especially for /P and QRP work. Being voltage-fed does not mean defeating Kirchhoff's law, it just means that the second "pole" does not need to be very extensive, due to the small amount of current that flows through it. Losses are usually due to unmatched lossy feedlines, like long runs of coax, but in /P ops there's often no need for a feedline at all, with the EFHWA wire connecting directly to the rig, and if RF power is low then the body of the rig, the operator, the extra wiring (earphones, etc.) and the vicinity to ground can provide all of the "second pole" that is needed.

This is not to say that coax-fed "standard" dipoles do not work, but in typical /P setups, where the dipole is not so high, the fact that it needs two supports and a (more or less) bulky feedline hanging from the middle make it a less convenient antenna, and probably not all that efficient either. And the little more efficiency it may theoretically provide over an EFHWA is likely to go lost in the required feedline if it is coax, or in the tuner/balun needed at the rig end if using a balanced feeder.

What is certainly true is that an antenna really works only if it is:

1) extensive, with respect to wavelength

2) high up

with the second factor being more important. And, of course, low SWR is not an indications of effciency, in fact it is often an indication of the contrary, but I think most of us already know that.

Caveat emptor: I'm speaking mostly about /P and QRP here. With a base station and QRO I agree that RF in the shack may occur with an EFHWA, depending on a number of factors.
 
Mythical Antennas  
by AD5VM on February 5, 2010 Mail this to a friend!
'the end-fed dipole is a lousy antenna'

I'm not going to disagree with Alan, he obviously knows more about this stuff than I do but for him to say that the highest rated antenna on eham.net and maybe the highest rated item of any type with 296 reviews and a score of 5.0/5.0 seems strange. I understand that with some compromise (small) antennas the reviews can be misleading because an 80 meter Isotron maybe the only thing some guy can get on the balcony of his apartment, and to him, it's the best antenna in the world because it let him get on 80 meters with an antenna he could fit on his balcony. However, the end fed dipole is the same size as a regular dipole and is roughly the same price so this can not be the case. I believe just like so many other aspects of physics, there are just some things we don't fully understand yet.
 
RE: Mythical Antennas  
by KH6AQ on February 5, 2010 Mail this to a friend!
How BALUNS are represented:

We say a balun is 4:1 when we refer to a 200 ohm balanced to 50 ohm unbalanced. Like so:

BAL (200 ohm balanced), UN (50 ohm unbalanced)

If it is designed for 50 ohms unbalanced to 12.5 ohm balanced we might call it a 1:4 BALUN.

But the convention is to call any RF common-mode choke a balun. Go to Mini-circuits for an example. Nothing there is called a common-mode choke although that is what some of their BALUNS really are.
 
RE: Mythical Antennas  
by AA4PB on February 5, 2010 Mail this to a friend!
"no matter how you cut it, the end-fed dipole is a lousy antenna"

This is too broad of a statement. End-fed half waves can be a very effective antenna if installed and fed properly. Very often they are not and mfgs sometimes mislead about how they work (or maybe they don't know themselves).

The end fed half wave does have the advantage of minimal current in the counterpoise allowing you to get away with less of a counterpoise. The current is never zero however so its got to flow somewhere. If you don't provide a counterpoise then the current is going to flow in the coax shield, the radio case, and other station wiring and accessories. In some cases, like QRP, this may be acceptable - in other cases it may be unacceptable. One thing is for sure - there is something acting as a counterpoise and it has exactly the same amount of current in it as in the feed point of the antenna.

Regarding the definition of dipole: If dipole means the number of lobes, then why is it a dipole? Dipoles typically have many more than two lobes. If an antenna is a dipole because it has two major lobes then why isn't a yagi a monopole? Why is a monopole (a vertical) omni directional? Traditionally a dipole is a center fed half wave and an end fed half wave is an "end fed half wave". I guess it really doesn't matter what you call it as long as you understand how it works.
 
RE: Mythical Antennas  
by W5ZIT on February 5, 2010 Mail this to a friend!
"Case Four: Why 43 Feet?

Within the last few years, the 43 foot vertical has become popular, and available from several
manufacturers. Proponents would have you believe the length is special. The truth is, it isn't. The length
doesn't assure a good match except where it's resonant. Speaking of which, it isn't resonant across
the HF spectrum as one company asserts. Contrary to some advertisements, it does indeed need radials
(ground plane), as any vertical monopole does. Further, just because it doesn't have traps, doesn't
mean much either. In fact, I suspect a properly installed Hustler 6 BTV will out perform it in any
respect.

There's a dirty little secret about the requisite (?) matching balun you don't see in print very often. Most
43 foot vertical antenna sellers recommend a 1:4 voltage balun (always expressed as 4:1). Little if any
thought is put into the fact a voltage balun can become a very lossy lump of ferrite when subjected to
high reactive loads; almost a given no matter the band of operation.

If you're using a shack-mounted tuner, feed line losses vary all over the board. While tolerable on
some frequencies, it certainly isn't tolerable over the whole HF spectrum, balun or no balun, as some
pundits claim. Here's a discussion about the 43 foot wonder which appeared in these very pages about 15
months ago. It begs reading if you use a 43 foot vertical, or thinking about buying one."

Actually the 43, or in those days the 44 foot vertical appeared in the 1950s and was fairly popular for a
while. The chief advantage that I saw in building one of those verticals was the method of construction.
Beer was sold in 'tin' cans at the time which could easily be soldered together to form the radiator.
Sticks 4 or 5 feet in length were fabricated and then the individual sticks were soldered together to make
up the 44 foot length. As far as I could tell, the main advantage in this vertical was the emptying of
the cans in preparation for soldering them together.

When downspout material was suggested to make up the 44 foot length, some folks grudgingly used the new
material and copper downspout antennas took some of the 'glory' from the beer can verticals. I used
common galvanized downspout material to fabricate two such verticals and mounted them about 15 feet apart.
One antenna was fed with a matching network and was tuned for 20 or 40 meters. The other antenna used a
series tuned circuit to resonate it on either 20 or 40 meters. A field strength meter sitting on a step
ladder about 50 feet away was used (using binoculars) to set the parasitic element as either a director or
reflector as the parasitic element was tuned. The field strength meter showed an S curve as the
resonance was approached, with the dip indicating that the element was a reflector and a peak showing it was
tuned as a director. (The field strength meter was located beyond the parasitic element)

The recent attention given the 43 foot vertical is interesting since the thing was first visited back in the '50s' and was
well received back then. I found it to be an excellent performer with my converted diathermy machine on 20 meter CW.

73 - Jim W5ZIT
 
A few observations.  
by K0FF on February 5, 2010 Mail this to a friend!
I am reading a lot about "modeling" this and "modeling" that. I am not reading much about LC networks, quarter
wave stubs, tuned feeders, height above ground in degrees of wavelength, angle of radiation, single point grounding, field strength meters, antenna current meters.

I am reading a lot about "this antenna works DX". I am not reading about " this antenna works DX through a world
class pileup". Working DX has little to do with distance.

Where in the modeling program does it show that a stacked pair of 6 element 20 meter mono banders on a rotating tower can be skunked into the Caribbean from the Midwest US by a smaller, lower beam, but into VU it leaves the small antenna in the dust?

Someone asked "what is the BEST antenna?". No one answered. The answer is another question: "Best for what?".

A 20 meter monobander at 90 feet with infinite front to back ratio, infinite front to side ratio, a 3 degree angle of takeoff and a one degree front lobe, sounds perfect......unless you are working a roundtable or a net. Then a Mosley TA-33 seems to be the perfect antenna all of a sudden.

Geo>K0FF
 
RE: Mythical Antennas  
by N5TGL on February 5, 2010 Mail this to a friend!
43 feet? Genius!

If you have a 43' antenna that you feed against ground and tune it with an antenna coupler such as a AH-4 or AH-2, or even as a longwire it should work just fine. That length avoids every multiple of every band -- just what a tuner like that would like to see. Personally, I think it would work great if used that way.
 
RE: Mythical Antennas  
by WMCO on February 5, 2010 Mail this to a friend!
More junk from a self proclaimed antenna guru.
Dipole means 2 identical lengths? Since when? Di/pole means 2 pole it does not mean 2 identical pols. I can have a dipole with one side being 50ft and the other being 200ft. It is still a DI (2) pole antenna. This article like a lot of the nonsense on his website is typical for the self made guru that thinks his crap don't stink and nobody else but him knows anything.
 
RE: Mythical Antennas  
by W2RI on February 5, 2010 Mail this to a friend!
This thread is hilarious.

So a 43' vertical sucks, as does a PAR END-FEDZ ? Well, that may be true - except that they work for folks who, for one reason or another, can't or won't use a monobander on a 300' tower.

I used to think it was politics. Then, after I found a wife, I suspected it is matrimony that is. But now I am learning that it is ham radio that truly is the art of the compromise.

There's nothing special about a 43' vertical, except that it's a compromise antenna that provides reasonable performance on a number of bands. The end-fed dipole works surprisingly well, despite what the models may say. Sure stacked Optibeams are perhaps the ideal configuration. But a Zero-Five works DX. Maybe not ideally, but who cares ?

And incidentally, while NEC may be a very useful tool, it is only a model and, as such, an approximation of reality. I understand that the real world performance of the Hex-Beam, for example, in terms of gain and F/B is better than modeled. As too is the Optibeam wire beam, to pick just two examples.
 
RE: Mythical Antennas  
by AD6KA on February 5, 2010 Mail this to a friend!
"if the user is happy with the results that they obtain, so be it."

Yup, I agree. If someone is pleased as punch with the QSO's he's making with his G5RV, what purpose does it serve to drop a steamer (turd) on his choice of antenna and call him a fool?

Could he make a beter antenna? Sure. But many people aren't retired, ***have lives outside of ham radio*** and don't have the extra time, money, space, etc for some super duper 900 foot loop at 60 feet.

Live and let live.
 
RE: Mythical Antennas  
by K1BXI on February 5, 2010 Mail this to a friend!
WMCO....."Dipole means 2 identical lengths? Since when?"

Since about 1886 when Hertz described the half wave dipole.

When we talk about a 1/2 wave dipole we are talking about its electrical length, not its physical length, which has to be two equal lengths left and right of the feed point.

John
 
RE: Mythical Antennas  
by K1BXI on February 5, 2010 Mail this to a friend!
Perhaps I should have said "When we talk about a 1/2 wave dipole we are talking about its electrical properties."

John
 
RE: Mythical Antennas  
by K0FF on February 5, 2010 Mail this to a friend!
John said: WMCO....."Dipole means 2 identical lengths? Since when?"

Since about 1886 when Hertz described the half wave dipole.

When we talk about a 1/2 wave dipole we are talking about its electrical length, not its physical length, which has to be two equal lengths left and right of the feed point.

John "

OK, I'll go along with that. Let's call all the others that are not equal Bipoles.

Geo>K0FF
 
Mythical Antennas  
by KL7AJ on February 5, 2010 Mail this to a friend!
One of the best (and totally forgotten) multiband antennas is the half-wave Hertz antenna (unbroken) fed with a DELTA Match and 600 ohm ladder line. With the correct ratio of the Delta length and width, this can work on four even harmonic bands with a close match to 600 ohms.

eric
 
Mythical Antennas  
by N8QBY on February 5, 2010 Mail this to a friend!
G6NJR Pete said: "I will never understand why certain people insist on attempting to prove they may know a whisker more than the average ham it is pure oneupmanship nothing more nothing less and certain people are extremely guilty of it time and time again and quite frankly it gets a little monotonous". This is the most accurate statement made so far on this post. It's simple, throw the wire in the air, if it works, great, if it doesn't....go fishing. Nuff said.
 
RE: Mythical Antennas  
by N6AJR on February 5, 2010 Mail this to a friend!
What, no Fan Dipole??
 
RE: Mythical Antennas  
by W9OY on February 5, 2010 Mail this to a friend!
This article is silly

I have a 135 ft flat top open wire fed to a Matchbox, works good.

I have a 40M 1/2 wave end fed vertical, works good

I have a inv-L, works good

I have a 45ft wire vertical with a tuner at the base, works good

I have a T for 160, works good

I have a full size 80M 1/4 wave vert, works good

I have a 20M 5/8 vert, works good

I have a second center loaded 80M 1/4 vert wave with a 40M 1/4 wave hanging off the side (like a fan dipole), works good

Sometimes I run the 135ft flat top on 6M into a 6M balanced tuner, works good

I've run quads and triangles and phased arrays and beams all of them worked good

There is no mythology here. All of these antennas meet some criteria. Some have slightly higher gain on some band of interest, some are kind of equally compromised across all frequencies so they work pretty good everywhere. Some fit the lot size of the average ham. Some allow for stealth etc etc each has its own advantage.

What is the weakness of the so called dipole that the author so beloves? It's resonant on only one freq other wise is it just as much of a compromise as any of the above antennas. Just try running your 80M coax fed resonant dipole on 40 or 20 and see what a stellar performer it is.

73 W9OY
 
Mythical Antennas  
by AE9L on February 5, 2010 Mail this to a friend!
Alan,

Good article..
There actually is, as you know, a end fed dipole. It's called a Sleeve Dipole.
Just to add to the mix.
Jerry
 
RE: Mythical Antennas  
by ZENKI on February 5, 2010 Mail this to a friend!
"Mythical Antennas"

Mythical low angle takeoff. Where most people live the brewster angle will determine the takeoff angle not the length of the antenna.

The only advantage of the 43 ft vertical would be slightly better performance on 80 and 160 meters over the typical loaded trap vertical antenna, or some other other low dipole.

If you going to invest your money in a 5/8th or 1/2 wave vertical antenna, you would be smarter if you first invested some time and money measuring your soil conductivity.

On the bands where most people use these 43ft verticals its a waste of good aluminum. I would rather put a simple hex beam on the top of one these 43 verticals. You cant beat a simple quarter wave vertical with as many radials as practicable.

If you live on the salt flats or near the sea, long verticals and end fed zepp's might be worth the investment.

Low angle takeoff does not come in the box!

I sell low angle grease if you need some. I need some money for the deposit on my saltwater island.
 
RE: Mythical Antennas  
by WB2WIK on February 5, 2010 Mail this to a friend!
>RE: Mythical Antennas Reply
by ZENKI on February 5, 2010 Mail this to a friend!
I sell low angle grease if you need some.<

::Does it come in easy to use dispensers?

I've been applying dB grease to my coax lines and it requires a syringe-like injector; makes this a time consuming task.
 
RE: Mythical Antennas  
by WB2WIK on February 5, 2010 Mail this to a friend!
>RE: Mythical Antennas Reply
by N6AJR on February 5, 2010 Mail this to a friend!
What, no Fan Dipole??<

It's "Fanned Eyepole," I tell you.
 
Mythical Antennas  
by KB3IYM on February 5, 2010 Mail this to a friend!
Thank you for this well written article. I am interested in loop antennas, which were conspicuous by their absence. It is my conjecture that they would work every bit as well as a "real" resonant dipole.
Any thoughts on this?
 
RE: Mythical Antennas  
by K1DA on February 5, 2010 Mail this to a friend!
IZ4KBS is EXACTLY RIGHT. I must admit, though, that K0BG had me going until he started in on "resonant" dipoles. Yeah, sure, BG, and how far away from "resonance" (in cycles) must we go before it ain't "resonant" any more?? Define that for the masses. "Resonance" is a handy way to a predictable feed point impedance, which is useful, but if you are prepared to take on the task of matching something more complex, have at it. If you look at the current and voltage on a half wave, which doesn't change no matter where is is fed as a half wave you might figure it out.

There are some very sound engineering reasons to use 43 feet as a vertical, I am sure 8JI might explain it to you.
 
RE: Mythical Antennas demistified  
by N5YPJ on February 5, 2010 Mail this to a friend!
Alan thanks for the nice informative article. I'm very glad to have read it because I was seriously considering what I considered to be an upgrade a 43 ft monopole with a tuner at the base to replace my 6BTV. Now I'll put my money into something more effective.
 
RE: Mythical Antennas demistified  
by N5YPJ on February 5, 2010 Mail this to a friend!
Alan thanks for the nice informative article. I'm very glad to have read it because I was seriously considering what I considered to be an upgrade a 43 ft monopole with a tuner at the base to replace my 6BTV. Now I'll put my money into something more effective.
 
Mythical Antennas  
by N8QBY on February 5, 2010 Mail this to a friend!
Where is Vito when you don't need him? Anyone heard from Vito? Is he still on the top side of the grass?
 
Mythical Antennas  
by AF6IT on February 5, 2010 Mail this to a friend!
Amusing thread given some of the reactions. The icing comment about quads leads me to a fun recollection of a story I saw in print- A ham was using a loop antenna of some sort (probably a HOHPL) which iced up. He measured the DC resistance then did a calculation. Hooked his 12v battery charger to it and within a couple minutes the antenna was deiced! Not sure that would be quite as helpful with a quad though it might be scaled down to some extent. (Don't blame me if you fry something trying this :-) Fortunately not every ham lives where everything ices up. From L.B. Cebik's website I understand the comparison is that Yagi antennas & quads- if properly constructed & mounted- are generally pretty equivalent. Whatever minor advantages the Yagi has are not usually deal breakers. Nice thing about any antenna which uses any form of loop is there is less tendency to build up a static charge- although this does not negate the need for proper impulse suppression if using a quad or loop.

K0FF said "Try using a 2 meter 1/4 wave on 440. Works fine." Define fine! Loads well, yes absolutely. But radiation angle? Most (not all) of your 70cm signal will be sent skyward or into the ground. Try modeling it! Sounds a bit less than "fine" to me. I know many do it anyway with little thought to efficiency. Many (even vendors) also call a 2m J-pole a dual band antenna. Loading alone does not make it dual band. Ed Fong designed a nice J-pole made mostly of tv twin lead which really does qualify as an honest dual band antenna. Plans available online- complete with good explanation of how it keeps the radiation angle where desired for 70cm. I haven't done any real testing yet on mine, though it does nicely work 50 mile distant repeaters on 100mw. More testimony of the repeater than the antenna, but anything less would NOT work I'm sure.

Stu AF6IT
 
RE: Mythical Antennas  
by WB2WIK on February 5, 2010 Mail this to a friend!
>RE: Mythical Antennas Reply
by K1DA on February 5, 2010 Mail this to a friend!
There are some very sound engineering reasons to use 43 feet as a vertical, I am sure 8JI might explain it to you.<

::Sure, since Tom has not chimed in, I looked up his comments about 43' vertical antennas for HF and they are this (cut and pasted):

"43 foot verticals have a place where convenience and flexibility outweighs raw performance. With a good ground system and very good short feedline, they work on any frequency above ~5 MHz with reasonable performance. They are virtually useless on 160 meters and somewhat lack luster on 80.

The key for performance with any vertical antenna near on on earth is the ground system. Without a good ground radial system, performance will not be good.

With a good radial system a good vertical will be about 5 to 8 db down from a dipole at most distances, but that is still plenty of signal. If it was my choice for a multiband vertical, I'd buy a 6BTV Hustler or a similar good trapped vertical. A reasonable trap vertical will out do the gimmick antennas.

Tom W8JI"
 
RE: Mythical Antennas  
by WB2WIK on February 5, 2010 Mail this to a friend!
>Mythical Antennas Reply
by KB3IYM on February 5, 2010 Mail this to a friend!
Thank you for this well written article. I am interested in loop antennas, which were conspicuous by their absence. It is my conjecture that they would work every bit as well as a "real" resonant dipole.
Any thoughts on this?<

::I can't answer for Alan, but since he was trying to de-bunk "Myths," I guess he omitted loop antennas because there aren't many myths about them.

They work well, and model predictably.

A loop is resonant on any frequency where it's non-reactive (just like any other antenna), and a loop has the advantage of going through resonance on all harmonics, both odd and even (unlike a dipole, where this occurs only on odd harmonics), so it's easy to match on several bands -- often, even without a tuner!
 
RE: Mythical Antennas  
by K0FF on February 5, 2010 Mail this to a friend!
N1LQ said: "I have used a homemade G5RV, a 133 ft. Carolina Windom and a Par End-Fedz half-wave antenna over the past 32 years of Dx'ing.
According to Alan my 342 DXCC confirmed countries, all done with 100 watts, no tower, no beam and no linear must all be 'mythical QSO's'.
Funny... I got all the cards. Hmmm... "

Amen. Go the ARRL Website, download the DXCC list.
Seach any "GURU's" call letters. If he is at or above 340, listen to what he KNOWS. If not, or not even listed at all, listen to what he THINKS.

Those that CAN, DO IT.
Those that CAN'T, MODEL IT.\


Geo>K0FF
 
Mythical Antennas  
by K9ZF on February 5, 2010 Mail this to a friend!
Like a few others have pointed out, being able to work DX is not a good way to judge an antenna.

I've noticed a few hard core VHF Ops in the thread so I'll use my Rover for an example:-) From my here in southern IN, EM78, on any given contest weekend, I can work K9NS up in EN52 pretty reliably. I can also work K8GP over in FM08 more often than not. That is a pretty darn good range on VHF. However, I often struggle working "little pistol" stations in the next grid over...

My point is, just because I can work some good DX doesn't mean my station is outstanding. It means that K9NS and K8GP are good enough to hear even my little station!

How much of the "work" is the DX station doing on his side of the QSO......???

73
Dan
--
Amateur Radio Emergency Service, Clark County Indiana. EM78el
K9ZF /R no budget Rover ***QRP-l #1269 Check out the Rover Resource Page at:
<http://www.qsl.net/n9rla> List Administrator for: InHam+grid-loc+ham-books
Ask me how to join the Indiana Ham Mailing list!
 
RE: Mythical Antennas  
by W8JII on February 5, 2010 Mail this to a friend!
N8QBY:"Where is Vito when you don't need him? Anyone heard from Vito? Is he still on the top side of the grass? "

Vito is alive and well but for personal reasons will no longer be contributing to E-Ham
 
RE: Mythical Antennas  
by WB2WIK on February 5, 2010 Mail this to a friend!
>Mythical Antennas Reply
by K9ZF on February 5, 2010 Mail this to a friend!
Like a few others have pointed out, being able to work DX is not a good way to judge an antenna.

I've noticed a few hard core VHF Ops in the thread so I'll use my Rover for an example:-) From my here in southern IN, EM78, on any given contest weekend, I can work K9NS up in EN52 pretty reliably. I can also work K8GP over in FM08 more often than not. That is a pretty darn good range on VHF. However, I often struggle working "little pistol" stations in the next grid over...

My point is, just because I can work some good DX doesn't mean my station is outstanding. It means that K9NS and K8GP are good enough to hear even my little station!

How much of the "work" is the DX station doing on his side of the QSO......???

73
Dan<

::Very good observation, and 100% correct. A lot of being able to work "DX" on any band, whatever it is, is operator skill, good timing and simply being there when the DX is. If someone only has one hour per week to operate and that's all the free time he has, getting to DXCC Honor Roll can take more than a lifetime.

If someone can operate 10 hours a week and is a good operator using skill and experience, knowledge of propagation and when the DX will be where, he can achieve Honor Roll status in a lot less than a lifetime, using simple antennas that don't even need to work particularly well.

The only way to judge how an antenna works is to compare it to other antennas at the same location, at the same time.

I remember in the June 1987 VHF contest, operating from FM27 at the VA coast, I worked all 50 States in 30 hours on 50 MHz. I "think" that was the first time a 6m WAS was made in the course of a single contest. I received hundreds of QSL cards from places like HI and AK and everywhere begging to confirm the grid, the State, anything.

Every one of those guys probably thought he had a great 6m antenna to work so far.

Hint: It wasn't their antennas doing the work, it was mine!

WB2WIK/6
 
Debunk THIS!  
by K0FF on February 5, 2010 Mail this to a friend!
K9ZF said: "I've noticed a few hard core VHF Ops in the thread so I'll use my Rover for an example"

For the hard core VHF/UHF ops on this thread, change my comments to read;

Go to ARRL Webpage.
Go to VHF/UHF/Microwave/EME Standings
Enter the call letters of your favorite antenna "GURUs"
etc.etc.


Geo>K0FF
 
RE: Mythical Antennas  
by KW6LA on February 5, 2010 Mail this to a friend!
Alan,

Nice Fire starter my friend .

Quote: According to Alan my 342 DXCC confirmed countries, all done with 100 watts, no tower, no beam and no linear


Well I have done most of that with QRP and a Dipole antenna. What does that prove….. Skip was darn good to you on
those days, but you won’t CONSISTANLY get good reports with a Bum antenna system. I cant understand why Ham’s
will still argue junk science when it comes to antennas. You can resonate just about anything with a tuning devise. Case
and point : my 160 meter mobile antenna has a 1.2 to 1 match and reactance about 7 on a 12ft. whip and cap hat. Well
guess what the efficiency is ? Maybe 2 % on a good day. All Alan is trying to say is be aware of mystique out there with
antennas. Oh yeah, Some of the ( work the world on my G5RV/ 17 mtrs. ) may not know the guy with the Yagi @ 80 ft.
made it happen. I love to work those guys on my Mosley beam, then switch to my 40 meter dipole / tuner. Hey where
did you go ? ? ? ? Humm ? ? ? well I still like my G5RV @ 20 ft. BTW my IC 7800 came today Ug !

Thanks Alan, From the other Half !

KW6LA
 
RE: Mythical Antennas  
by W4VR on February 5, 2010 Mail this to a friend!
I've been using horizontal dipoles, not inverted vees, for years. They are the best antenna you can put up and they only cost a few bucks worth of wire and coax. If you want gain from a dipole, simply add a parasitic element or two. Many of the antennas the author describes are just a way to make money off the poor unsuspecting and technically-uneducated ham!
 
RE: Debunk THIS!  
by WB4QNG on February 5, 2010 Mail this to a friend!
Personally I wish all the hams in the world would forget all these silly antennas and just get some 400 foot towers with 11 element mono beams for 10-80. Then maybe I could actually work someone with my 5 watt 817 with the 3 foot whip.
Terry
WB4QNG
 
RE: Mythical Antennas  
by WA8FOZ on February 5, 2010 Mail this to a friend!
Wonderful article, Alan. Too bad some folks don't know what dBi means. Too bad as well that we are such an irrational species.

No one I know says that we must not use "compromise" antennas - heck, everything we do in the physical world is some sort of compromise. But isn't a bit of clarity refreshing? Isn't it nice to know as clearly as possible what exactly it is that we are doing?

Oops, sorry, I forgot: it's actually better to do like the broadcast personalities recommend and let others think for us.;>

73,
Bill
 
RE: Mythical Antennas  
by WB2WIK on February 5, 2010 Mail this to a friend!
>RE: Mythical Antennas Reply
by W4VR on February 5, 2010 Mail this to a friend!
I've been using horizontal dipoles, not inverted vees, for years. They are the best antenna you can put up and they only cost a few bucks worth of wire and coax. If you want gain from a dipole, simply add a parasitic element or two.<

Or just install the dipole over reasonably good conductive earth.

As has been pointed out here a few times now, it's easy to verify that a half wave dipole over earth, properly installed, yields >8 dBi (about 6 dBd) gain. Yes, a dipole has "gain over a dipole," because dBd figures are expressed for free space, which unless we're astronauts, we don't have.

Verticals don't have this gain, only horizontal antennas do.

It's easy for a modest beam to achieve 12 dBd gain, because the first 6 dBd is free.

Installing a field of radials or wire mesh in the ground beneath your horizontal antenna, extending for several wavelengths in all directions, increases the gain of a simple dipole and doesn't involve any climbing. :-p
 
RE: Mythical Antennas  
by KW6LA on February 5, 2010 Mail this to a friend!
Steve,

A great point for new Hams, and the ones that didn't study.

DBi is a measurement that compares the gain of an antenna with respect to an isotropic radiator (a theoretical antenna that disperses incoming energy evenly over the surface of an imaginary sphere.)

dBd compares the gain of an antenna to the gain of a reference dipole antenna (defined as 2.15 dBi gain).

To convert dBi to dBd:
Gain in dBd = gain in dBi - 2.15 dB
Gain in dBi = gain in dBd + 2.15 dB

Love antenna work, wires too.

KW6LA
 
Mythical Antennas  
by N4MB on February 5, 2010 Mail this to a friend!
Alan, I appreciate your writings, particularly your compendium of mobile amateur radio information.

I accept the facts offered in this article, but your style is, well, hostile. Perhaps this article shows what potential hams see as a barrier to entry into ham radio - an elitist attitude that attempts to diminish the value of others based on aptitude and the level of knowledge of a certain topic. This writing comes across as arrogant elitism, separating yourself from "the masses," and condescending to those who lack the "capacity" to understand specific elements of electromagnetic theory.

It has been my observation that the vast majority of amateurs are the users of appliances - transceivers, antenna systems and periphery germane to the desired mode of operation. Even "home brew" projects usually consist of the construction of a pre-designed appliance. We shouldn't diminish the value of this - everyone adds value, whether it be from designing a new transceiver or buying one to keep manufacturers interested in making stuff for ham radio. The more of us there are, the better off the hobby will be.

We would do better as a community to establish standards of measurement to so that hams can actually measure the effectiveness of these devices and report on them in a standardized manner, rather than broadside criticism of "mythical" designs.

The lack of standardized testing of antennae has been a mystery to me for years. Manufacturer's claims rarely reveal how the specifications were calculated or measured. QST doesn't do field antenna measurements or critique designs mathematically. We're left with eham.net's review column and Word Of Mouth to make decisions about the assembly of a station unless we DO want to make a serious investment to understand antenna theory. Many hams just want to put something together and communicate.

It is obvious that hams have unexplained prejudices that have no correlation to fact when it comes to antenna design, brand name, performance and expectations. "I've worked XX countries (or states or whatever) with that (rig, antenna, QTH, call sign.) "20 dB over S9" is NOT a measurement unless it is compared to something else.

Human beings have a habit of attributing results to events that have no bearing whatsoever. "It was God's will", "We're a Ford family", "The Saints deserve to win the Super Bowl" are statements I've heard today that illustrate this. None of them make sense factually, yet the people who said these things believe them as fact.

Subjective statements about results with stupid antenna design is simply another one of those human fallacies, and, try as we might with facts, we will never change this. When facts elude people for whatever reason, (usually not "capacity" to understand, but rather education and NEED to understand) they fit their observations to the facts that fit their frame of reference. When someone spends $500 on the newest 43 foot vertical, they're going to believe that they chose wisely and their own perception of results will be skewed toward that conclusion.

The entire concept of marketing is based around understanding these notions and promoting products based on that understanding. MFJ understands this - they have two or three different lines of antennas that accomplish the same things. Within those lines, there are very similar designs - including a couple of 43' verticals.

Is this about functionality or efficiency? No, simply marketing, making money on the good names of MFJ, Hy-Gain and Cushcraft with the broad market segments they cover.

Antenna marketing in the pages of the magazines and on the Internet is often based on anecdotal evidence and specific use cases. If an antenna such as one of the off-center designs meets the needed postion of the ham's feedline vs. support, perhaps that ham will purchase that antenna.

As often as not, the use case and anecdotes will drive the selection of an antenna. ("My pappy had one of these in the air 20 years. It survived two hurricanes." "George had one of these and he worked 5B DXCC in 3 months.")is less compelling to me than, "I only have space for a 15 foot turning radius."

Is it fraudulent to make claims about antennas that aren't true? Probably not legally because the barrier to proof is high - who is going to educate a judge or jury on antenna theory? Morally - only if the seller/marketer understands and intends to defraud.

The manufacturers and sellers of some of the types antennas you mentioned are good people selling something that people like. It may not be the best for the customer, but they make a living doing it, and they're meeting a consumer demand, like Coke, Pepsi and Budweiser. Welcome to American marketing and capitalism?

eHam provides a forum for the exchange of data. I think we need to get better at specifically identifying issues and comparing products. The "Ballot Boxes" are stuffed and many products get 4+ ratings that don't deserve it.

So, to conclude my rambling diatribe, I suggest that we, as a community, do the following:

- Post reviews, but keep them as objective as possible. Find ways to compare products to similar products.

- Establish a list of specifications we want to know about popular antennas and ways to measure them vs. manufacturer claims. Measure, calculate, post!

- Identify BS and myths as such, giving a good reason for saying so. Allow this to be done on the review page of the product, huh, eHam?

- Avoid Stupid Antenna Evaluations - "I compared this to a dipole at 40 feet and had an S9 versus an S3" makes a lot more sense than "I worked 4 VK's in 10 minutes..."

- Be nice. Make positive suggestions, let's keep as many of these manufacturers in business as possible, but let's get them to be honest about their products. The more vendors, the more competition, better value for all of us.
 
RE: Mythical Antennas  
by W7ETA on February 6, 2010 Mail this to a friend!
"Some users are so enamored with their choice, they ignore the inherent problems associated with them."

Sounds pretty straight forward to me.

"....your style is, well, hostile. Perhaps this article shows what potential hams see as a barrier to entry into ham radio - an elitist attitude that attempts to diminish the value of others based on aptitude and the level of knowledge of a certain topic. This writing comes across as arrogant elitism, separating yourself from "the masses," and condescending......"

"Subjective statements........is simply another one of those human fallacies, and, try as we might with facts, we will never change this......."

Have you considered that individuals filter the world with built in filters, little voices in their head. The voice in your head proclaiming "hostile", "elitist", "diminishing others", "barrier to entry" may be subjective, purely a localized phenomena?

Could it be "None of them make sense factually, yet the people who said these things believe them as fact."?

Bob
 
RE: Mythical Antennas  
by N2EY on February 6, 2010 Mail this to a friend!
"Someplace along the line, the notion got started that the G5RV was an all-band antenna."

The G5RV IS an "all-HF-band" antenna, IF you consider what the bands were back when G5RV developed it, and read the actual articles on how it works.

Back in the 1950s, when it originated, the 30, 17 and 12 meter bands were not allocated to amateurs. That leaves 80, 40, 20, 15 and 10 meters.

In addition, back then most of the world (outside Region 2) only had 3.5 to 3.8 on 80 and 7.0 to 7.1 on 40.

So the requirements for an "all-HF-band" antenna were quite different than today.

On top of that, the rigs then in use could usually match an SWR of 3 or 4 to 1 with no real problem.

The result was that the G5RV design would work about as well as a resonant half-wave dipole on "all HF bands".

Note that in the original designs the 31 foot matching section is made from real open-wire line, not plastic Twin Lead with holes punched in it. The lack of a balun comes from the fact that the original feeder was 72 ohm Twin Lead (yes, there was such a thing).

The G5RV, like many other small multiband antennas, is a compromise developed for those who don't have the resources for lots of better antennas. As long as those compromises are kept in mind, and the antenna is built as intended, it's a great antenna for its size and complexity.

73 de Jim, N2EY
 
Mythical Antennas  
by N8CMQ on February 6, 2010 Mail this to a friend!
It always boils down to KISS...
Keep It Simple Stupid!
And the flamers will attack over every little spelling mistake or error of memory...
I base all my antenna design on proven theory, and I work the world on a few watts.
 
RE: Mythical Antennas  
by W4VR on February 6, 2010 Mail this to a friend!
WIK wrote: "As has been pointed out here a few times now, it's easy to verify that a half wave dipole over earth, properly installed, yields >8 dBi (about 6 dBd) gain. Yes, a dipole has "gain over a dipole," because dBd figures are expressed for free space, which unless we're astronauts, we don't have."

When I add parasitic elements to a dipole, I model the dipole by itself at the installation height, then compare the gain results with the dipole and parasitics at the same height...this gives you the gain of the antenna in dB.
 
RE: Mythical Antennas  
by K1DA on February 6, 2010 Mail this to a friend!
You miss the POINT, WB2WIK, as others on here have mentioned, 43 feet avoids some nasty issues with multiband matching which appear with "resonant length antennas"
For example, a 60 foot 80 meter vertical turns into a more difficult to match half wave on 40, and a full wave on 20. Angle of radiation issues aside, if you understand why a Highgain 18 HT "Hytower" is designed as it is this will make sense. A Hytower needs insulated stubs and an insulating collar for the whip section. I've had one since '77 and it is a great antenna but the "multibanding arrangement" requires mantainence. The 43 foot design avoids all of that and still provides good performance with a very clean physical design. Must be why JI's outfit sells them, eh?
 
RE: Mythical Antennas  
by W4VR on February 6, 2010 Mail this to a friend!
K1DA points out: "43 feet avoids some nasty issues with multiband matching which appear with "resonant length antennas.""

He's right. Model a 43-foot vertical (with a ground screen) on several bands and find out for youself what happens to the feed point impedance....and then model a vertical that's resonant on one band and see how difficult, but not impossible, to match on other bands.
 
RE: Mythical Antennas  
by K0FF on February 6, 2010 Mail this to a friend!
K1DA said: Angle of radiation issues aside, if you understand why a Highgain 18 HT "Hytower" is designed as it is this will make sense. A Hytower needs insulated stubs and an insulating collar for the whip section. I've had one since '77 and it is a great antenna"

In my opinion the 18HT is one of the "smartest" antennas ever designed. It even used the end fed 3/4 wave concept on 20 meters, a configuration earlier bashed as useless ( it's not). If a ham understands how an 18HT works, he has done his homework.

Except they are expensive. An enterprising ham with some wire and a tree can do nearly as well (or better actually). My version is a 66 foot tall wire with a coaxial trap at the top and another about 66 feet horizontal from there. . Just like that it works 80 and 160 ( needs radials) Add some more wires for 40 and 20 to the same feedpoint. Keep the wires apart as they will spark if too close.

The 18HT should be a ham cult classic.

Geo>K0FF
 
RE: Mythical Antennas  
by KL7AJ on February 6, 2010 Mail this to a friend!
Actually a 43 foor vertical on top of a 43 foot mast might be a killer antenna. The problem with the 43 foot vertical in its normal application is that maximum current point is always right near the ground. This is great for A.M. broadcasting, but not much else.


eric
 
RE: Mythical Antennas  
by N3OX on February 6, 2010 Mail this to a friend!
"The 43 foot design avoids all of that and still provides good performance with a very clean physical design. Must be why JI's outfit sells them, eh?
"

DX Engineering is not "JI's outfit."

As far as I know, W8JI does paid design for them, and is clearly an important part of that business, but does that mean W8JI necessarily implicitly puts his personal stamp of endorsement on every product they sell?

There is no way these antennas present a nice, moderate impedance on 80m and 160m. The capacitive reactance is substantial. On 40m and up, you can make this case... with a short good feedline and stout UNUN and good tuner, it is a moderate impedance antenna and usually is OK. On 80m with a loading coil (and on other bands with matching networks), it's a sweet antenna (I had a wire version for a while and it was great, if a little narrow. Tubing will fix that). On 80m without a loading coil, you're probably getting significant power loss in the feedline. On 160m if you don't have a lot of feedline loss and run high power you'll probably arc something or destroy your tuner.

DX Engineering is a great company, but remember that DX Engineering is a business and as such it would be stupid of them to not sell popular antennas. But based on the fact that they sell UNUN fed 43 footers as 160m and up antennas, I have to conclude that not everything DX Engineering sells is based on best practices electrical engineering.

K0OD owns a DX Engineering (not that brand matters) 43 footer and he has reported in these forums that he got something like 10-11dB better performance on 160m with a simple home-made loading coil.

If you think it's a good 160m/80m antenna just because W8JI's callsign is prominent on DX Engineering's site and W8JI is a pinnacle of low band knowledge, well, that's your choice.

But it's really not very good on 80 and 160, and care must be taken with the feedline to make it perform "fine" on the higher bands. Check it out yourself. Try adding a monster loading coil and see what happens on 160.

But if you've got a good ground system, take it easy with the power output when you try the loading coil so you don't arc over your base insulator. 13kV is nothing to sneeze at. And I especially don't recommend trying a 160m test with your antenna tuner right out at the base with full power, unless you're mad at it.

Now, if you don't believe me because I'm not W8JI and you think that W8JI *must* think these things are a good idea because DX Engineering sells them, well... I think that's a weird way to assess antenna performance.

73
Dan
 
RE: Mythical Antennas  
by N3OX on February 6, 2010 Mail this to a friend!
"In my opinion the 18HT is one of the "smartest" antennas ever designed"

Yep, using a giant inductive coax stub to load it on 80m is incredibly clever. It mid-loads the antenna, while making it easy to tune from the bottom... you can add inductor kits in series with the inductive stub to lower the frequency or put it on 160... but the inductor electrically appears to be up at the whip/tower junction so that you get the advantage of mid-loading with more current below the break point and higher radiation resistance.

What a cool idea!

It's a little mechanically tricky, sure, but the advantage there is clear.

And on the other bands, having a bunch of self resonances with decoupling stubs makes it easy for the antenna system to handle high power efficiently.

I understand the appeal of having a simple single stick with no tuning or setup, but something like the Hy-Tower has a lot of advantages over the 43 foot vertical, electrically speaking.

"It even used the end fed 3/4 wave concept on 20 meters, a configuration earlier bashed as useless ( it's not)"

I think the transmission line stub formed by the "80m wire" inside the tower helps the performance on 20m.

A quick and dirty model of a uniform 2 inch vertical loaded at the midpoint by the same stub that loads the antenna to resonance on 80m shows that the stubbed vertical has perhaps 3dB better 20m gain below 14 degrees elevation than it would as a simple 53 foot stick.

So it's not just a loading stub on 80m, it's may also be a phasing stub on 20.

I agree with you that the 3/4 wave vertical isn't useless... it is not nearly as bad when viewed in terms of actual gain at low angles instead of concentrating on the high angle lobes. But I can find a stubbed configuration in my "toy model" antenna that both resonates on 3.6 MHz and has maximum gain on 20m in the lowest angle main lobe, instead of a high skyward lobe like the antenna without the stub.

I think it's possible that the Hy-Tower may be so clever that the marketing department is missing a big opportunity ;-)

73
Dan
 
RE: Mythical Antennas  
by N3OX on February 6, 2010 Mail this to a friend!
Here's the toy model comparison plot.

http://n3ox.net/files/53_foot_stubload.jpg

Anyone with a Hy Tower and a weather balloon or helicopter want to measure their 20m elevation pattern and see if this is how the Hy Tower works on 20m?

73
Dan
 
RE: Mythical Antennas  
by N2EY on February 6, 2010 Mail this to a friend!
KL7AJ writes: "The problem with the 43 foot vertical in its normal application is that maximum current point is always right near the ground."

???

On 80 and 160, that's true.

On 40 meters, the maximum current point is 10 feet above the ground.

On 20 meters, the maximum current point is 27 feet above the ground.

The other bands are left as an exercise for the reader.

73 de Jim, N2EY
 
RE: Mythical Antennas  
by N6AJR on February 6, 2010 Mail this to a friend!
The "perfect" dipole is the Steppir, as it is actually resonant on ever band it can function on. as a beam they do well also and even as a vert they do alright. the key is the antenna is the right length for any freq you tune it to.


As a point of interest here is a little something to play with on the subject of resonance. You will need a mfj 259 and a field strenf=ght meter, and a couple of antennas.

You will need to use a mfj 259 antenna analyzer ( or equivlent), and a couple of antennas in the same range but different frequencies, like a 2 meter antenna and an air band antenna.

First put on the 2 meter antenna and tune the analyzer from the low end to the hi end of the 114 to 170 position on the 259b.

If you watch the field strength meter it will be at or near the zero mark through most of the sweep. When you get int the 144 to 148 range you will see the FSM show an increase then a decrease in power as you go through the 2 m antenna's resonance range.

From 114 to about 144 mhz the Field AStrength Meter will be at the low end. It will jump up through the 144-148 mzh zone and then drop low from 148 or so till the 174 mark.

Now put on the air band antenna. Do the same sweep with the 259b. You will see the field strength meter now run up from about 118 to about 122 mhz and be on the bottom on all other frequencies. This is when the air band antenna is resonant.

When the antenna is in its resonant portion it "couples more power to the aether" . The whole time the mfj 259b is putting out the same couple of miliwatts across the band.

As you enter the resonant " sweet spot" of the antenna it transmits you best signal. You have the best eficiency in transfering power to the air waves.

This is one reason why a Steppir antenna is so good, because it can be tuned for that " sweet spot" on every part of every band in its range.

So resonance and swr are not every thing, but they do make a difference.

Just my opinion, you're milage may vary... :)
 
RE: Mythical Antennas  
by WB2WIK on February 6, 2010 Mail this to a friend!
>RE: Mythical Antennas Reply
by W4VR on February 6, 2010 Mail this to a friend!
K1DA points out: "43 feet avoids some nasty issues with multiband matching which appear with "resonant length antennas.""

He's right. Model a 43-foot vertical (with a ground screen) on several bands and find out for youself what happens to the feed point impedance....and then model a vertical that's resonant on one band and see how difficult, but not impossible, to match on other bands.<

::Except most smart people would never do that. As Tom W8JI pointed out, a good trap vertical (which is actually resonant on each band) not only performs well but is well matched also. Tom actually stated he'd rather have a Hustler 6BTV (trap vertical) than a 43' vertical because overall it's likely to work better.

They both require an extensive radial system, and that's where most of the "work" comes in when installing any kind of vertical! :-)
 
RE: Mythical Antennas  
by K0FF on February 6, 2010 Mail this to a friend!
N6JAR>
Does the steppir alway tune for a natural 1/4 wave or will it do 3/4 wave ( or more odd quarter waves) on some bands? Geo>K0FF
 
RE: Mythical Antennas  
by WB2WIK on February 6, 2010 Mail this to a friend!
Geo, you have complete control over that with the SteppIR, up to its physical limits since the dipole is only about 33' long.

Obviously, it can only be 1/2 WL on 20 meters.

But it can easily be 3/2 WL on 6m.

Its "pre-sets" (element lengths that are memorized) are set by the user.
 
RE: Mythical Antennas  
by K0FF on February 6, 2010 Mail this to a friend!
Thanks Steve. I am WAY out of date, about10 years as a matter of fact, have been on an entirely other project for quite a while. Never even heard of a 43 foot vertical until checking back into eHam recently.

The steppir is very interesting and the diople would be fun to play with. Remnds me of the old "cliffdweller" motorized antenna from long ago.

How do they handle element spacing in the beam version? Resonant elements or no, the spacing would be optimum for only one band ( it seems to me at this time, not knowing). Geo>K0FF
 
RE: Mythical Antennas  
by N3OX on February 6, 2010 Mail this to a friend!
"How do they handle element spacing in the beam version? Resonant elements or no, the spacing would be optimum for only one band ( it seems to me at this time, not knowing)."

They use compromise spacing for decent performance on each band.

The ability to do away with bandwidth constraints on SWR and pattern by having several different configurations within one band gives them some flexibility to use good close-spaced designs that would fail to cover a whole band with good properties if they used fixed element lengths.

So I think the booms are shorter than you'd expect out of a usual antenna that covers 20m.

The two element beam seems to have a 57 INCH boom length, under 0.07 wavelength!!

I can get about 4dB gain over a dipole and 20dB F/B at 14.200MHz with a driver director configuration in EZNEC, but at 14.000 the F/B drops off to 12dB and the gain drops 1dB.

But if you can adjust your elements, who cares?

I expect all of the SteppIR beam configurations would be pretty sad at the band edges as fixed-element yagis.

73
Dan
 
RE: Mythical Antennas  
by K0FF on February 6, 2010 Mail this to a friend!
Dan said They use compromise spacing for decent performance on each band.
Thanks Dan, gotta get one of those things, if for nothing else than to measure and compare it.
Since I am no longer competitive, I can do what is fun for me, which is play with antennas.

when someone asks "what are you running" I say 100 Watts and then give the antenna rundown, coax feed, grounding system, etc. Never a rig model number.

Geo>K0FF
 
RE: Mythical Antennas  
by N2EY on February 6, 2010 Mail this to a friend!
N6AJR writes: "When the antenna is in its resonant portion it "couples more power to the aether" ."

No, that's not true.

N6AJR: "As you enter the resonant " sweet spot" of the antenna it transmits you best signal. You have the best eficiency in transfering power to the air waves."

Not really.

The reason "resonant" antennas are so popular is that they can be made to present a pretty good match to coax without a matching network at the feed point.

Consider the 5/8 wave vertical vs. a 1/4 wave vertical. Over the same good ground screen, the 5/8 wave has a small amount of gain in the most favored direction, compared to the 1/4 wave. Yet the 5/8 wave isn't resonant; it requires a matching network at the feedpoint.

N6AJR: "This is one reason why a Steppir antenna is so good, because it can be tuned for that " sweet spot" on every part of every band in its range."

The SteppIr is electrically simple and mechanically complex. That's its tradeoff. All antennas involve tradeoffs, and multiband antennas involve multiple tradeoffs.

For example, compare a 16 foot SteppIr vertical to a ~20 foot one-piece vertical with a good remote ATU at the feedpoint, and you'll see that on the bands from 20 through 10 there is no significant difference.

Consider also how much even the small SteppIr vertical costs, including the control box and cable.

N6AJR: "So resonance and swr are not every thing, but they do make a difference."

Sorry, it's just not that simple.

73 de Jim, N2EY
 
RE: Mythical Antennas  
by WB2WIK on February 6, 2010 Mail this to a friend!
>RE: Mythical Antennas Reply
by K0FF on February 6, 2010 Mail this to a friend!
Dan said They use compromise spacing for decent performance on each band.
Thanks Dan, gotta get one of those things, if for nothing else than to measure and compare it.
Since I am no longer competitive, I can do what is fun for me, which is play with antennas.

when someone asks "what are you running" I say 100 Watts...<

When someone asks me "what are you running?" I say "the quarter mile in about 75 seconds. It used to be faster when I was younger, but those days are behind me."
 
RE: Mythical Antennas  
by WB2WIK on February 6, 2010 Mail this to a friend!
Jim N2EY pretty much has it nailed.

The SteppIRs work very well for their size and are highly versatile since they can be remote tuned for *any* frequency between their lowest and highest rated. Also, the 3-4 element beams can be "reversed" in a few seconds, not the 30 seconds it takes to turn a rotator 180 degrees, by just swapping the element lengths.

Very slick idea, but not without some potential problems due to mechanical complexity and the fact that there's a DC control cable running along with the coax and just as susceptible to ESD, EMP, etc -- which can wipe out the control box electronics occasionally.

Still, innovative and they do work well.
 
RE: Mythical Antennas  
by N3OX on February 6, 2010 Mail this to a friend!
I actually think the SteppIR verticals are *almost* silly. Not quite, but almost.

I don't feel that way about the *beams.* While you do have to accept mechanical complexity and different failure modes (and price), the beams can do a lot of stunts that no other beams can do.

The verticals don't really work any different for the complexity. The only real advantage I can see is that when using the base-load add on kits on the band where the antenna is around 1/8th wavelength, you can cover the whole band instead of a sliver.

But I can do that with a motor driven roller inductor (or, somewhat less efficient but just as effective retuning-wise, a really big variable capacitor in series with the inductor).

The latter is what I do with my base loaded 60 foot vertical on 160m. It's practically a necessity... I get a lot of shift in my resonant point with weather changes.

I suppose you could make some interesting ground mounted vertical beams using several SteppIR verticals and custom firmware... ;-)

73
Dan



 
Mythical Antennas  
by W0ELH on February 6, 2010 Mail this to a friend!
Hi Alan, Great article. My only pet peeve is the use of the words "antenna tuner" instead of matchbox. The "tuner" does not do one thing to tune an antenna. The antenna matching device or "matchbox" simply matches the output impedence of the transmitter to the impedence of the antenna. Other than that, well done!
73, Garry
 
Mythical Antennas  
by N6TZ on February 6, 2010 Mail this to a friend!
Like so many articles, some truth and some great pseudo-science. Off center, end fed, windoms, verticals, and others all have their places.

Does anyone remember the "clothes line" folded dipole. It road on pulleys so the feed point could be moved from end to center to accomodate a good match for the open line on many bands.

Baluns have their places also, just don't abuse them.

Verticals of all types have their places, but usually noisier on receive than horizontal antennas.

Want to have fun, put up a pair of half wave spaced 20 meter verticals 17 feet tall and switch them between end fire and broadside. Don't do it in the city as the noise will be a problem, but out in the rural with space, you will enjoy switching between them and seeing instant receive ambience chnges. If you want to match each at the bottom, make them 34 feet tall for a bigger bang for the buck. Yes, put some radials at the base of them in both configurations.

You can see my 160 to 30 meter vertical at:
http://earthsignals.com/N6TZ (case sensitive) It is a little more than the usual ham wants to chew off.

I would use 54 feet for a multiband vertical height instead of 43 feet as is so common right now. 54 feet will also avoid most resonant points and give more height for 80 meters.

I will challenge the idea that a multiband quad is inferior the traditional multiband yagi. You have to use a quad to appreciate them, and I have had three of them in the past. I prefer the diamond configuration. Right now I use a Hex Beam because of lack of yard space.

Hal, N6TZ n6tz@arrl.net
 
RE: Mythical Antennas  
by W9PMZ on February 7, 2010 Mail this to a friend!
"::Except most smart people would never do that. As Tom W8JI pointed out, a good trap vertical (which is actually resonant on each band) not only performs well but is well matched also. Tom actually stated he'd rather have a Hustler 6BTV (trap vertical) than a 43' vertical because overall it's likely to work better. "

On the whole I agree with this statement. But on 80M the antenna is only useable, even with an antenna tuner, over a very narrow window. (unless of course you want to go out and constatly adjust the stinger atop the resonator)

At least with the 43' vertical you can forget the loading coil the 6BTV has and tune the 43' vertical for operation across the band.

73,

Carl - W9PMZ
 
RE: Mythical Antennas  
by N2EY on February 7, 2010 Mail this to a friend!
WB2WIK writes: "Jim N2EY pretty much has it nailed."

TNX Steve..

WB2WIK: "The SteppIRs work very well for their size and are highly versatile since they can be remote tuned for *any* frequency between their lowest and highest rated."

I'm not sure what you mean by "for their size". The verticals are just quarter-wave worked against ground or radials; they're no better or worse performers than one made of, say, aluminum downspouting.

The big difference is the multibanding.

WB2WIK: "Very slick idea, but not without some potential problems due to mechanical complexity and the fact that there's a DC control cable running along with the coax and just as susceptible to ESD, EMP, etc -- which can wipe out the control box electronics occasionally."

I looked up the prices on the website and saw $649 for the *small* vertical - without radials, surge suppressor or unun (which they call a "balun" but is really a line isolator).

It's not clear to me whether that price includes the controller and control cable. Even if it does, $649 is a lot to pay for a quarter-wave vertical that covers 20 through 10 on HF.

The thing about real-world amateur radio HF antenna installations is that they're no more than 10% electrical engineering and no less than 90% mechanical engineering. There are lots of great designs that are mechanically impractical - for most hams, anyway.

For example, if I could have only one HF antenna, it would be a dipole up high and in the clear, fed with real open-wire line and a good balanced Transmatch. Of course the main problem with such an antenna is having the space and high supports for it - which is all mechanical engineering, not electrical.

73 de Jim, N2EY
 
RE: Mythical Antennas  
by W4MY on February 7, 2010 Mail this to a friend!
I enjoyed reading this article. I want to hear more about this 8 dbi dipole. I went to alot of effort to put up a 40M 2L monoband yagi (@75') to get 5.5 dbd (8.5 dbi) gain. Maybe I was wasting my time?

...Marty / W4MY
 
RE: Mythical Antennas  
by N3OX on February 7, 2010 Mail this to a friend!
No, Marty, you weren't wasting your time. Read back in the thread.

Ground reflection gain is real gain.

A 40m dipole about 75 feet off the ground has about 8dBi gain at 26 degrees elevation.

A beam at that height has approximately the same gain vs. that dipole as the free space comparison. It's not guaranteed to be exactly the same dBd gain increase, but it will be close.

I'm playing with a close spaced driver-director antenna, not optimized, at 75 feet and in free space in EZNEC. The gain difference over average earth is about 4dB, while in free space it's more like 4.8.

But the beam has a gain of 12dBi @ 26 degrees elevation.

If yours is really 5.5dBd and that holds up at the elevation it is installed at, then your beam will be a 13.5dBi gain antenna.

A dipole ONLY has 2.13 dBi gain in *free space,* and its reflection in the earth forms sort of a phased array with the dipole that increases the gain.

73
Dan
 
RE: Mythical Antennas  
by N2EY on February 7, 2010 Mail this to a friend!
W4MY writes: "I want to hear more about this 8 dbi dipole."

As N3OX points out, that's the theoretical maximum gain of a half-wave dipole, in the most favored direction, at certain heights above ground (in the case cited, 75 feet).

The thing to remember is that it's a theoretical, perfect lossless dipole over theoretical, perfect ground. And it's compared to an isotropic source, so the ground reflection gain is about 6 dB, with the rest coming from dBd - vs - dBi.

73 de Jim, N2EY
 
RE: Mythical Antennas  
by K9MHZ on February 7, 2010 Mail this to a friend!
>>>>by W4MY on February 7, 2010 I enjoyed reading this article. I want to hear more about this 8 dbi dipole.<<<<


LOL! I think you nailed it!


A lot of junk science in antennas comes from the fact that lots of real and sometimes complicated science goes into them, but they're relatively easy to make and market compared to a piece of electronics for example. Any yayhoo can dream up a Flamethrower 1000 with 12 dB (forget dBd and dBi...doesn't matter) gain, that will have you working 40 countries the same afternoon that you put it up.
-Antron 99
-Anything Isotron
-Many etc's.
Claims are made with impunity, and production of these "products" is relatively easy....and so it goes.


Still, there is that pesky problem of bandwidth and multiple bands. If it's not bigger, higher, and open wire, then compromises are going to be made. The challenge is to not stray too far from what we know, and to leave the snake oil on the dealers' shelves.

MHO,

Brad, K9MHZ
 
RE: Mythical Antennas  
by N2EY on February 7, 2010 Mail this to a friend!
W0ELH writes: "My only pet peeve is the use of the words "antenna tuner" instead of matchbox."

I AGREE!

But I prefer the term "Transmatch" because it describes what the thing actually does: it matches the transmission line to the transmitter.

73 de Jim, N2EY
 
RE: Mythical Antennas  
by N3OX on February 7, 2010 Mail this to a friend!
W9PMZ says:

"At least with the 43' vertical you can forget the loading coil the 6BTV has and tune the 43' vertical for operation across the band. "

But you probably stand to lose 4dB or 5dB in the feed system, not including UNUN loss, and assuming perfect 4:1 impedance transformation. (You'll lose less if you have shorter coax, I assumed about 60 feet of RG-213)

That probably actually compares poorly with a loaded vertical that's shorter, provided the ground system is good. It's probably not so different if both antennas have a poor ground system (poor grounds, among other things, cause less coax loss, trading it off for loss in the dirt). There's another problem, too, which is heavily installation dependent. If you use a bad length of coax, you may be in for significant tuner loss. The 60 feet I used is a GOOD length, because it transforms the low impedance on the coax side of the UNUN up to a more reasonable impedance for a tuner to handle. If you needed 100 feet, in addition to the 5dB coax loss, you'd stand a good chance of having a dB or two of tuner loss.

Of course all of this depends on everything but the kitchen sink, which is probably my least favorite thing... there are lots of design issues to make this thing efficent while being able to handle high power. Low power guys have it all wrapped up. Stick an inexpensive autotuner at the base. But then you can't run more than 100-200W, not without spending THOUSANDS on an autotuner that still won't handle legal limit.

You can build switched matching networks like I do, but that doesn't seem to hold a whole lot of appeal, even if the 80m network is just 20 turns of #12 or #10 house wire on a piece of PVC drain pipe used as a tapped coil betwen antenna and ground.

http://n3ox.net/projects/lowbandvert/networks_lg.jpg

A couple different coil taps solve the bandwidth problem. But adding a bunch of stuff at the base is not what most people want out of their expensive commercial antennas.

So you can just ignore it and let 'er rip. You'll make plenty of contacts with high power to a 43 foot vertical on 80m. After all, in terms of most 80m contacts, 3dB or 5dB loss probably isn't that damaging. I've worked 144 countries on 80m, some with 100W to that base matched 40 foot wire vertical, and the rest with a full size quarter wave 60 foot vertical over a middling ground system.

Some of those have been "real good DX" like JA, V6, 3B7, VQ9... And if you run 1500W to a 5dB loss system, you still end up 7dB ahead of me.

73
Dan




 
RE: Mythical Antennas  
by K1BXI on February 7, 2010 Mail this to a friend!
W0ELH said ....."The "tuner" does not do one thing to tune an antenna. The antenna matching device or "matchbox" simply matches the output impedance of the transmitter to the impedance of the antenna."

Does it not also match the output of the antenna to the load, in this case the receiver?...... It may not mechanically tune the antenna, but it sure does electrically......it's called a conjugate match.

John
 
RE: Mythical Antennas  
by N3OX on February 7, 2010 Mail this to a friend!
"The thing to remember is that it's a theoretical, perfect lossless dipole over theoretical, perfect ground."

A real #10 copper wire dipole 75 feet above "Average" ground has a gain of about 7.8 dBi @ 26 degrees elevation.

Ground reflection losses are pretty negligible for high horizontally polarized antennas. Putting the antenna over saltwater gives about 1dB more gain. Putting it over poorer ground (0.001 S/m instead of 0.005 and dielectric constant 5 instead of 13) gives around 1dB less, not quite.

Literally perfect ground is not really different from saltwater in an appreciable sense. The most profound effect I've noticed of changing earth type on horizontal dipoles is on side null depth at very low angles.

Otherwise, a high dipole is an antenna that's awfully close to its "idealized" counterpart. The wire resistance is negligible compared to the radiation resistance, and the earth reflections depend rather weakly on the earth characteristics.

73
Dan
 
RE: Mythical Antennas  
by N3OX on February 7, 2010 Mail this to a friend!
"W0ELH said ....."The "tuner" does not do one thing to tune an antenna. The antenna matching device or "matchbox" simply matches the output impedance of the transmitter to the impedance of the antenna." "

I like to think of an antenna tuner as an adjustable storage tank for energy that helps the transmitter shove electrons around in whatever is at the output of the tuner.
 
RE: Mythical Antennas  
by N2EY on February 7, 2010 Mail this to a friend!
K1BXI writes: "It may not mechanically tune the antenna, but it sure does electrically......it's called a conjugate match."

No, a Transmatch/matchbox/antenna tuner *in the shack* does not tune the antenna electrically.

What it does is to match the impedance at the shack-end of the *transmission line* to something the rig likes - usually 50 ohms resistive.

Of course when that happens, the entire *system* - matcher, transmission line, and antenna - is at resonance.

A true "antenna tuner" would be installed at the antenna end of the transmission line, not the shack end. And some are!

But for many if not most hams, "ATU" or "antenna tuner" means a device at the rig, in the shack, not at the antenna feedpoint.

73 de Jim, N2EY
 
RE: Mythical Antennas  
by KI4SDY on February 7, 2010 Mail this to a friend!
A good article, but Alan should have made the point that all antennas are dipoles or some variation of a dipole.

The question is; if wire half wave dipoles are such great performing antennas compared to all others, then why doesn't Alan have one mounted on his vehicle? The answer is; application! No one antenna is the best for every radio application. That is why we have so many types and configurations of antennas that perform well for specific applications.
 
Mythical Antennas  
by KX3DX on February 7, 2010 Mail this to a friend!
I would like to better understand your comments on end-fed antennas. If possible, can you provide specific electrical engineering reference and mathematical example?

Thanks,
Dave
kx3dx
 
RE: Mythical Antennas  
by K1BXI on February 7, 2010 Mail this to a friend!
Jim.......Does not the tuning network at the source end change what the load end is looking into?

When receiving, the antenna is the source and the receiver is the load, only the network is at the other end of the feed line. But what the out put terminals of the antenna see are now also matched to the network, and for want of a better explanation, the conditions are "electrically" changed at the antenna terminals with the tuner in line, even at the transmitter end.

Seems to me this is what a conjugate match does. It doesn't work in just one direction. The whole system is matched for maximum transfer of power....both ways.

Some like to say a tuner fools the transmitter, in that case they could say it also fools the receiving antenna.

John
 
RE: Mythical Antennas  
by K0FF on February 7, 2010 Mail this to a friend!
W4MY writes: "I want to hear more about this 8 dbi dipole."

As N3OX points out, that's the theoretical maximum gain of a half-wave dipole, in the most favored direction, at certain heights above ground (in the case cited, 75 feet).

The thing to remember is that it's a theoretical, perfect lossless dipole over theoretical, perfect ground. And it's compared to an isotropic source, so the ground reflection gain is about 6 dB, with the rest coming from dBd - vs - dBi.

73 de Jim, N2EY "

Jim or anyone, please send me a picture of the plot that shows this, thanks.

Geo>K0FF GEOelectronics@netscape.com
 
Ant. Tuner-Transmatch-Matchbox?  
by K0FF on February 7, 2010 Mail this to a friend!
The actual technical name is Line Flattener.
Although it is rarely used in ham publications.

Geo>K0FF
 
RE: Ant. Tuner-Transmatch-Matchbox?  
by K1BXI on February 7, 2010 Mail this to a friend!
Was Walt Maxwell wrong when he wrote "My Antenna Tuner really does tune My Antenna"? (QST,August 1976)

John
 
RE: Ant. Tuner-Transmatch-Matchbox?  
by N3OX on February 7, 2010 Mail this to a friend!
"Was Walt Maxwell wrong when he wrote "My Antenna Tuner really does tune My Antenna"? "

No, but the title is not the article :-)

Whether or not an antenna tuner "tunes an antenna" is a matter of semantics, a matter of what you MEAN by "tunes an antenna" and how you like to divide up "antenna" and "antenna system," and has caused all manner of argument over the years.

If you analyze a given tuner, feedline, and antenna system mathematically that will give you one answer. Of course, that's what Walt Maxwell did for various situations, and many others have done correctly for specific cases. Each specific case has one answer.

If you ask a hundred hams "what does an antenna tuner do?", even for one specific case, you may get a dozen answers.

I think I know what I'll be doing :-)

73
Dan
 
Mythical Antennas  
by KL7AJ on February 7, 2010 Mail this to a friend!
I think we need to focus on the original intent of this article...which is excellent.

The point is, NONE of the antennas mentioned are BAD antennas. I've used them all. It's just that none of them are worthy of the genuflection they have received within ham radio circles. I think the G5RV is most guilty in this regard. It's an okay antenna. But it's a piece of wire.

I think that's the bottom line.

Eric
 
RE: Mythical Antennas  
by N3OX on February 7, 2010 Mail this to a friend!
George,

Here you go...

http://n3ox.net/files/40dip_height.jpg

Will send email with attachment too.
 
RE: Mythical Antennas  
by K1BXI on February 7, 2010 Mail this to a friend!
Good explanation Dan, thanks.

Alan......nice article, always enjoy your writings.

Eric, you mean my home brew G5RV is just a piece of wire!! I thought it had some mythical magic that I haven't found yet.... You busted my balloon....

John
 
RE: Mythical Antennas  
by VO1FZ on February 7, 2010 Mail this to a friend!
Lots of talk about 43' monopoles, 6btv's, 18ht's, SteppIR verticals, and so on.

I've used verticals before and found them useful and it's time to add another vertical. I waffle between a fan vertical ground mounted, a 6btv, or a Butternut (either hf2v or hf6v).

I was hoping for some critical comment on the Butternut verticals and I'm surprised nobody has tackled them here. I like their theory of operation and I'm thinking they might have a good home here for 80 and 40 meters. Their "dirty little secrets" articles ring mostly true to me, although I'm not quite comfortable with the trap losses quoted for other verticals.

So- Butternuts. Hocum or Hurray?
 
dipole has gain over a dipole?  
by K0FF on February 7, 2010 Mail this to a friend!
Antenna gain is the result of warping or changing the field of the antenna. If the field is changed in such a way that it is now higher in some favored direction, then the antenna is showing gain in that direction (only). In some other direction the antenna has a corresponding loss. No extra net power actually exists.
In this sense, "direction" means three dimensions- left/right up/down.
Some propagation modes require angles of takeoff different from others.
This army antenna manual mentions that for skywave communications in a range of zero to 250 miles, the antenna radiation pattern preferred is straight up!
http://www.globalsecurity.org/military/library/policy/army/fm/24-19/Ch3.htm
We have a name for that, NVIS- Near Vertical Incident Skywave. Not so cool for DX work though.

"A dipole has gain over a dipole"?? Yes it does, in the sense that a dipole mounted at a height above earth in terms of degrees of wavelength, will have a different pattern than a dipole mounted at some other height. Simple. When the height is referred to in wavelength, that is 1/2 wave, 5/8 wave instead of feet, it will apply to any frequency. Therefore it is easy to realize that a certain optimum height in feet for a 40 meter dipole will not be the same height to a 10 meter antenna.

GAIN OVER ISOTROPIC? Isotropic is the figment of someone's imagination. Since it does not and can not exist, why muddy the water with cutesy statements that exist only in computer program!? No wonder QST banned antenna gain claims years ago!

BUT WHAT ANGLE OF TAKEOFF IS THE DESIRED ONE?. Well it depends on what you want to do. Working HF roundtable nets in a range of less than 1000 miles or so? Then a higher angle would be preferred.

BUT want to consistently work DX on the other side of the world? Go for the lower angles. And it matters if it is E skip or F skip also. Bigtime ( much more on this soon, my article "Is my antenna too high" due out soon here on eHam).

Now to answer "How much of the work is the DX station doing?". The answer is *NONE*. DX has nothing to do with distance. DX has to do with giant pileups and being the strongest signal at the DX location. Different antennas will accomplish this, depending on the frequency being used, time of day, distance etc. For a sort period of time the "new country" St Barts was the biggest DX in the world. I worked that one with one call on the antenna that I selected for that task, a raised halfwave bottom fed vertical. Also worked on 6M with my lowest mounted beam, chosen for that purpose as it was the proper one for that path.

MY FAVORITE ANTENNA? It is the one I am presently testing or working with.
That might be a 6 ounce backpacker all the way to a tower mounted behemoth.

Can a 43 foot tall antenna work on 80 and 160? Yes but not by tuning it from the bottom. A top loaded 43 foot tube should work rather well on 80, much less well on 160.

In my day, a ham turned on the radio to see what was on the radio. He also built an antenna to see what would it do. He also logged on paper with a pencil. He waited for a paper QSL card to arrive in he mail. Much has changed, some for the better.

Geo>K0FF
 
RE: Mythical Antennas  
by K0FF on February 7, 2010 Mail this to a friend!
VO1FZ asked:
So- Butternuts. Hocum or Hurray?

The HF2V is a well designed antenna, and if it is raised, provided with raised radials and the top loading wires is a very good
performer on both 80 and 40.
Methods of doing all that here:
http://www.bencher.com/pdfs/00156IZV.pdf
This is the 80/40 antenna I selected for my trailer tower. An LJE Radial plate provides for the raised radials.


As far as the HF6, I personally think it is superbly designed. Don Newcomb is a bit of an idol of mine, and I would design
a multiband vertical just like his, if I were as smart as he is!
Details here:

http://www.bencher.com/ham/index.php?main_page=page_4

be sure to click on the "dirty little secrets" link and follow though the articles there.

Notice that he uses the multiple of odd quarter wave theory to make the entire length of the antenna hot on the higher frequencies.

Geo>K0FF
 
RE: dipole has gain over a dipole?  
by WB2WIK on February 7, 2010 Mail this to a friend!
>dipole has gain over a dipole? Reply
by K0FF on February 7, 2010 Mail this to a friend!

"A dipole has gain over a dipole"?? Yes it does, in the sense that a dipole mounted at a height above earth in terms of degrees of wavelength, will have a different pattern than a dipole mounted at some other height. Simple. When the height is referred to in wavelength, that is 1/2 wave, 5/8 wave instead of feet, it will apply to any frequency. Therefore it is easy to realize that a certain optimum height in feet for a 40 meter dipole will not be the same height to a 10 meter antenna.<

::But actually, it could be. Now that we have software that quite accurately predicts results if all the variables are reasonably well known, we can see that a 1/2-WL dipole at 1WL has about 6 dBd gain (at about 25 degrees above horizon) compared to the same dipole in free space. But it also has that gain at 2WL and at 3WL, just at slightly different angles, all of which are useful for making contacts.

When I see beam antenna manufacturers stating dBd gain "when installed 70 feet above earth," I think that's an entirely reasonable way to rate the gain of an antenna. Under such conditions, a 20m dipole starts out with 6 dBd gain, so adding parasitic elements just increases it from there.

The "when installed at..." disclaimer is about the same as rating an automobile's gas mileage "when driven at 60 mph on a level surface." It's different at 10 mph and at 90 mph, or if climbing a mountain.

Might as well set reasonable, understandable test parameters.

73

Steve WB2WIK/6
 
RE: dipole has gain over a dipole?  
by N3OX on February 7, 2010 Mail this to a friend!
K0FF says: "GAIN OVER ISOTROPIC? Isotropic is the figment of someone's imagination. Since it does not and can not exist, why muddy the water with cutesy statements that exist only in computer program!? No wonder QST banned antenna gain claims years ago! "

I responded to this in private, and I will respond to it in public.

dBi gain is "absolute zero gain" for antennas. The only way to get less than 0dBi gain is to add losses to the antenna. 0dBi is a very well defined conceptual concept. "Take your power and spray it out in a sphere in every direction"

It is not a cutesy number from a computer program, it is a long used physical reference point. And while it is not something that can result from a buildable antenna, it is a very useful concept. It is simply the antenna pattern that results from least possible focusing of your power.

K0FF says: "Antenna gain is the result of warping or changing the field of the antenna. If the field is changed in such a way that it is now higher in some favored direction, then the antenna is showing gain in that direction (only). "

Exactly. And that's what makes dB with "respect to isotropic" such a useful concept. It's the least warped and changed pattern possible. It has no peaks and no nulls. It radiates all the power, but not in any preferred direction. I think a lot of people object to it because you can't "build an isotropic source" without having a bunch of phase incoherent sources but who cares? I can *imagine* sending RF power in every direction equally. That's what it's for. It's just a common reference zero point to compare two other antennas.

K0FF says: " No wonder QST banned antenna gain claims years ago! "

Actually, they accept modeled results and they want the numbers in dBi.

Quoted directly from http://www.arrl.org/ads/ :

"All advertising performance claims derived from antenna modeling must indicate that they are calculated. As a minimum, we expect to see the peak free-space gain (in dBi referenced to isotropic) at a manufacturer-specified frequency. "

73
Dan
 
RE: dipole has gain over a dipole?  
by K0FF on February 7, 2010 Mail this to a friend!
Dan said:
"K0FF says: " No wonder QST banned antenna gain claims years ago! "

Actually, they accept modeled results and they want the numbers in dBi. "

Thanks Dan I stand corrected. I am out of date, all I remmber is the hllaballoo when they originally dropped the reference many years ago.

As far as istropic, I repect your desire to live in a 4 pi steradian world if you wish.

Meanwhile I wear my 2 Pi steradian rose colored glasses.

Geo>K0FF
 
Mythical Antennas  
by WU2X on February 7, 2010 Mail this to a friend!
"K0BG breaks down misinformation using antenna theory"

I beg to differ, there are too many statements made in this article that are just personal statements with no backing references, personal experiments or otherwise. You should have picked one of your nit picks and focused on it with real data.
 
RE: Mythical Antennas  
by N3OX on February 7, 2010 Mail this to a friend!
""Thanks Dan I stand corrected. I am out of date, all I remmber is the hllaballoo when they originally dropped the reference many years ago.
"

I think they brought it back partially because a ham can take the dimensions of the antenna, make a guess at what's inside any traps or other doodads, download 4NEC2 or MMANA, or buy EZNEC, and essentially verify the manufacturer's gain claims for themselves, even for fairly complicated antenna designs.

And so can the ARRL technical staff.

Not too long ago, this was the exclusive purview of university and government computing facilities. Not too long before that, there was NO way to practically do method-of-moments antenna gain calculations. You would have had to buy and test everything.

Of course, you can dismiss wild claims with simple knowledge of antennas, but to catch manufacturers padding a yagi gain 2dB would have been tougher. I think it can be done now by just about anyone if they put in some work.

The NEC-2 code is extremely well tested. I have much less ability to measure to enough precision to directly verify and validate, but others have done so. Things like verticals that interact heavily with that "dirt" stuff are hopeless in terms of predicting absolute gain or gain relative to a reasonably high horizontal antenna, but I think you can nail the properties of beams relative to each other to absurd precision if you actually know how they're built.

For trap yagis, we have to guess what's in the traps... that adds uncertainty....

But I bet hams could validate the comparison between measurement and modeling on a monobander to within a fraction of a dB gain over a reference dipole if you had a big enough area for testing and took a lot of data with good averaging.

I'm personally satisfied with OTHERS' tests of the modeling code, coupled with the occasional spot check, but I can't measure anything to enough precision to tell you conclusively whether or not my flag antenna has 20dB or 22dB F/B or if my 12 element 432 yagi has 5.5 or 6.5dB gain over my 4 element 432 yagi... but I can say that my measurements haven't been significantly inconsistent with model predictions either.

I wish we had some more high profile well conducted tests of measurement vs. modeling by hams, just because there's a lot of mistrust of the models. But what the modeling programs actually do is very fundamental... it's just a numerical solution for the fields around the antenna, and if you do that carefully it's basically an exact result.

If you leave stuff out that the near field interacts with heavily, or don't really know how that stuff is composed in terms of its dielectric and conductive properties, you can't get good results out of the model. But for HF beams on towers at least, they're up there in the clear and since ground properties only weakly change the ground reflection gain, models are going to be pretty good.

73
Dan
 
RE: Mythical Antennas  
by W9PMZ on February 7, 2010 Mail this to a friend!
"A couple different coil taps solve the bandwidth problem. But adding a bunch of stuff at the base is not what most people want out of their expensive commercial antennas. "

The comment was made about a 6BTV. The loading coil for 80M is at the top of the antenna.

I'm not sure how adding circuits at the base will help.

73,

Carl - W9PMZ
 
RE: Mythical Antennas  
by AB7E on February 7, 2010 Mail this to a friend!
I have to agree with WU2X. There is very little theoretical justification for getting hung up on the semantics of what is or isn't a "dipole", and much of this article is simply a rancorous declaration of the author's bias or personal interpretation of terms. A half-wavelength piece of wire radiates equally well no matter where you feed it as long as you account for the different impedance levels and the asymmetry of the system ... both of which are possible to do. There is nothing "mythological" about it.

I really don't understand why so many hams get hung up on how to refer to a particular antenna, or whether something is such-and-such antenna or not. There would be a lot better understanding of antennas if people just considered what the current distributions on the various conductors look like and how the resultant fields interact instead of what to call the thing. I guess it's easier to remember a name than to actually visualize how it works.
 
RE: Mythical Antennas  
by BHARDIMON on February 7, 2010 Mail this to a friend!
At least in KOBG's view, If it's not a resonate dipole, it's nothing but a dummy load. I will say, he writes his dogma very well and why so many goons come along and say "Alan, Great article as usual"
 
RE: Mythical Antennas  
by WB2WIK on February 7, 2010 Mail this to a friend!
No callsign, no credibility.
 
RE: Mythical Antennas  
by K1DA on February 7, 2010 Mail this to a friend!
If there is a performance problem with the 43 foot vertical because the "current point" is close to the ground, consider the "universal" ("BTV") trap vetical design (against which the 43 is compared) where the higher frequencies are radiated from progressively lower segments of the stick. It's no better than a single band 1/4 wave ground plane sitting flat on the ground. Is a 43 foot vetical particularly good above 20? No. Is a quarter wave sitting on the ground much better? Perhaps, but either way a ground plane OR dipole at 25 feet is a better choice.

Looking at and understanding the 18 HT will tell you much , looking at VHF colinear antennas (even the much maligned ringo ranger) is also interesting. RF doesn't somehow change at VHF, the goals of feedpoint match, efficiency , and angle of radiation are the same, the "tricks" would work at HF but for the mechanical contstraints.
 
RE: Mythical Antennas  
by K1DA on February 7, 2010 Mail this to a friend!
BTW was there not an AM broadcast station near 1400 kc out in the midwest which used a "Franklin" colinear for a long time. Perhaps someone remembers the details, I don't recall enough to start a Google yet.
 
RE: Mythical Antennas  
by N5TGL on February 8, 2010 Mail this to a friend!
"I will say, he writes his dogma very well and why so many goons come along and say "Alan, Great article as usual""

"No callsign, no credibility."

A callsign does not always indicate credibility, as I'm sure you are aware. I agree with BHARDIMON on his point, callsign or not.
 
RE: Mythical Antennas  
by KG6MZS on February 8, 2010 Mail this to a friend!
John, K1BXI wrote:

>>>>Good explanation Dan, thanks.

Alan......nice article, always enjoy your writings.

Eric, you mean my home brew G5RV is just a piece of wire!! I thought it had some mythical magic that I haven't found yet.... You busted my balloon....<<<<

John;

When I first got on the air with a G5RV it was like magic to me. Was is Arthur C. Clarke that said "Any sufficiently advanced technology is indistinguishable from magic?" As I learned about antennae the G5RV was mostly demystified for me. Not totally, but I'm a guy that still derives some enjoyment from Santa Claus...

It's too bad that some people get so ego-invested in *being right* that they become obsessively compelled buzz-kills. Yes, I know that when I say I worked 7k QSOs barefoot in 150 DXCC entities in the depths of sunspot cycles 23/24 with a home-brew G5RV with a used $450 FT-100D that this is anecdotal. I'm sure a mountain-top beam array with a kilowatt would blow that away. However no grumpy, crabby, sour old curmudgeon is going to take that sense of awe and wonder and accomplishment away from me.

I've since moved on and learned more as my aptitudes and budget have allowed but I doubt that any more gray matter or any more money could have given me any more satisfaction in the hobby. Learning from articles like this *do* give me more enjoyment of the hobby, so thank you Alan for taking the time and making the effort to constructively contribute to the hobby - even if the contribution isn't perfect.

As I said before: all the fun is in the pursuit of perfection, which is a good thing because none of us (and that includes the know-it-all killjoys) ever get there.

73 de Eric, KG6MZS
 
My antenna tuner really does......  
by K0FF on February 8, 2010 Mail this to a friend!
K1BXI said: "Was Walt Maxwell wrong when he wrote "My Antenna Tuner really does tune My Antenna"? (QST,August 1976)

John "

For those that don't have Walt Maxwell's article or books handy (shame on you!), G3TXQ explains it eloquently here:


http://www.karinya.net/g3txq/tuner_match/

Have fun

Geo>K0FF
 
RE: Mythical Antennas  
by AB7E on February 8, 2010 Mail this to a friend!
W0ELH: "The "tuner" does not do one thing to tune an antenna."

N2EY: "A true "antenna tuner" would be installed at the antenna end of the transmission line, not the shack end."


That's all garbage, and another case where hams let semantics obscure an understanding of what really happens. Forget whether it is called an "antenna tuner" or a transmatch or whatever ... if you put a network of passive elements ANYWHERE along a transmission line it will transform the impedance of the antenna.

If you put Network A at the feedpoint of the antenna it will transform the impedance of it to something else. If that transformation cancels out the reactance, it is said to "tune" the antenna. Depending upon the components chosen, some of that transformation will generate loss.

If you put a length of transmission line between the antenna feedpoint and Network B, the parameters of Network B will be transformed by that transmission line per standard transmission line theory and be presented to the antenna just as if a network was at the feedpoint. Lumped element Network B and the transmission line simply form a different network that transforms the feedpoint impedance of the antenna to something else. If that transformation cancels out the reactance of the antenna, it "tunes" it EXACTLY the same as did Network A. Depending upon the components and transmission line chosen, some of that transformation will generate loss.

Whether the combination of lumped Network B and the transmission line have more or less loss than Network A alone is purely a matter of the choice of components (both lumped and transmission line), and it is entirely possible that a wise choice of components for Network-B-plus-transmission-line would have less total system loss than Network A.

I'm not smart enough with networks to know for sure, but I suspect that it might even be possible to find a combination of Network B and a transmission line that gave a broader SWR curve than Network A alone (without significant additional loss) since you can choose which direction the reactance of a transmission line changes with frequency (depending upon its length relative to a wavelength). If I am wrong about that, hopefully someone will correct me.

Here's another way of looking at things. Let's say I connect a feedline between my antenna and rig, and the system is not matched. Now I install a lumped network in a weatherproof box out near my antenna and connect it across the feedpoint of the antenna via some length of transmission line. I then tune the lumped network so that the antenna end of that transmission line presents an impedance at the antenna terminals that gives me a good match back at the shack. Is that combination of lumped elements and transmission line an "antenna tuner"? Sure it is. Is it at the antenna? Yup. If I selected the lumped network properly (the one in the weatherproof box) and found a 50 ohm tap somewhere in it, could I haul my rig out there and drive the antenna from there? Yes ... (neglecting of course the fact that now I'd have an unterminated length of feedline still running to my shack). If the length of transmission line between the network in the weather proof box and the antenna feedpoint was long enough, I could pick up the box and the rig and bring both back to the shack.

So what on earth is the difference, other than a name?

Dave AB7E
 
RE: Mythical Antennas  
by KL7AJ on February 8, 2010 Mail this to a friend!
Yep....and anyone who's even SEEN a Smith chart knows this to be fact. A Conjugate match is a conjugate match. This has been accepted knowledge since Ernst Lecher demonstrated standing waves before WW1.

If I had any say in the matter, I'd replace the current amateur exams with one 5 question test based on Byron Goodman's article, "My Feedline Tunes My Antenna."

But then there'd be nothing to argue about interminably on ham forums.

Eric
 
RE: dipole has gain over a dipole?  
by KL7AJ on February 8, 2010 Mail this to a friend!
After crawling around broadcast towers with a General Radio 916 impedance bridge for a quarter century, I have a great deal of confidence in both NEC-2 modeling and Mininec 3, at least for relatively simple structures. Modeling must never be a substitute for common sense, but NEC-2 has a long long track record with some of the most demanding customers, namely the U.S. Navy and NASA.

It is a shame that ARRL felt it necessary to stop publishing gain figures. There ARE reliable ways of dertermining this...even with ground reflections...all you have to do is STATE the conditions, so they can be reproduced. This is done for commercial and military antennas all the time....no reason ham antennas can't be subject to the same scrutiny. NO need to throw the baby out with the bathwater.

One thing that would really increase the reliability of gain measurements is to specify that the antenna be
tested with NO transmission line. It's real easy to build a small transmitter to install at the feedpoint. This way you'd eliminate bogus gain figures from antennas like the Isotron.

Eric
 
RE: Mythical Antennas  
by IZ4KBS on February 8, 2010 Mail this to a friend!
AB7E wrote:

"That's all garbage, and another case where hams let semantics obscure an understanding of what really happens. Forget whether it is called an "antenna tuner" or a transmatch or whatever ... if you put a network of passive elements ANYWHERE along a transmission line it will transform the impedance of the antenna."

No doubt. But if your feedline is a long run of coax and you put the tuner at the rig end then you are likely to not even need the tuner at all: your rig will see a 50 ohm load flat across all bands. Regarding radiation efficiency of such a system, well, have a guess.
 
RE: Mythical Antennas  
by AB7E on February 8, 2010 Mail this to a friend!
IZ4KBS: "But if your feedline is a long run of coax and you put the tuner at the rig end then you are likely to not even need the tuner at all: your rig will see a 50 ohm load flat across all bands. Regarding radiation efficiency of such a system, well, have a guess."

That's a horrible way to make an "all band antenna". All you really have is a distributed dummy load between you and the antenna. Besides, it takes a pretty long section of coax to do what you say, at least at HF. Check it out with a program like TLW (which comes free with the ARRL Antenna Book) and you will see what I mean. No need to guess what the actual radiated power will be, either ... TLW will tell you that as well. Hint: very little.

Dave AB7E
 
Mythical Antennas  
by W0CGR on February 8, 2010 Mail this to a friend!
Good Job Alan you big ole spoil sport.

ur pal
W0CGR
 
RE: Mythical Antennas  
by IZ4KBS on February 9, 2010 Mail this to a friend!
AB7E wrote:

"That's a horrible way to make an "all band antenna". All you really have is a distributed dummy load between you and the antenna. Besides, it takes a pretty long section of coax to do what you say, at least at HF. Check it out with a program like TLW (which comes free with the ARRL Antenna Book) and you will see what I mean. No need to guess what the actual radiated power will be, either ... TLW will tell you that as well. Hint: very little."

Dave,

my post was ironic. It was meant to counter the argument according to which having a tuner at the near end of the transmission line is the same as having it at the far end. It is the same if you are only interested in matching the rig, but, with coax, it is not the same if you also want to radiate some power. When I said you may even do without a tuner I was referring to the fact that if your coax is long enough losses would be so high that it would match your transceiver the same way a dummy load would do. And with the same efficiency too. Matching the rig and radiating some power do not necessarily come together, but we are saying the same thing here. So, the only sensible way to match at the near end is to use some kind of low-loss feeder -- like ladder-line -- between the tuner and the antenna. If you rather must use a non trivial length of coax then you should definitely put your tuner at the far end of that coax.
 
RE: Mythical Antennas  
by N5TGL on February 9, 2010 Mail this to a friend!
"So, the only sensible way to match at the near end is to use some kind of low-loss feeder -- like ladder-line -- between the tuner and the antenna. If you rather must use a non trivial length of coax then you should definitely put your tuner at the far end of that coax."

The losses due to standing waves are far, far less than you might think, even with evil ol' coax. :)

From Water Maxwell's Reflections II, Chapter 1:

"in a 100-foot length of nonfoam RG-8, an SWR of 5:1 adds only 0.46 dB loss to the matched (that is, flat)line loss of 0.32 dB at 4.0 MHz. So out almost to the ends of the band, less than 1/12 of an S unit is lost because of the SWR, an imperceptible amount at the receiving end."

If you haven't yet, read the whole chapter here: http://w2du.com/Chapter01.pdf there's a lot of good info there.
 
RE: Mythical Antennas  
by AB7E on February 9, 2010 Mail this to a friend!
IZ4KBS: "Dave, my post was ironic".

My sincere apologies to you. I should have realized that you were being facetious when I read your post, but given the stuff that gets written here it is sometimes difficult to tell. ;)

73,
Dave AB7E
 
Mythical Antennas  
by K5YEF on February 9, 2010 Mail this to a friend!
A sobering read...
 
RE: Mythical Antennas  
by KL7AJ on February 9, 2010 Mail this to a friend!
End feeding a dipole is not nearly so problematic as center feeding HALF a dipole. :)
And end fed Hertz has an impedance of a maybe 1000 ohms (over average ground conditions) which gives an SWR of around 20, which is "tolerable" on decent coax.

However a 40 meter dipole, operated on 80 meters has a huge reactive component, and an SWR of nearly 600:1. For all practical purposes, this is infinite SWR. The line losses under this condition are about 95% per 100 feet....even on 80 meters with semi-decent coax! So, in this case it REALLY needs to be resonated. With a good loading coil, a 40 meter antenno on 80 meters is a comfortable 4:1 or thereabouts.

Bottom line: Reactance is FAR more detrimental to SWR than "resistive" mismatching. Mr. Smith's magical map shows this quite clearly too.

:)

eric
 
RE: Mythical Antennas  
by N3OX on February 9, 2010 Mail this to a friend!
"The losses due to standing waves are far, far less than you might think, even with evil ol' coax. :)
"

No they're not. And also they are. And usually they're quite near what I think they are :-)

The quote you provided was likely about use of a dipole at one end of the 75/80m band when the dipole is tuned for the other end. That is a very reasonable application of an antenna tuner on a coax fed antenna in the shack. Using a tuner when the SWR is 5:1 or perhaps even 10:1 is often no big deal.

But another seemingly typical attempted use of a tuner in the shack with coax is to use a 40m dipole on 80m.

In that case, with an antenna impedance of 16-j860 ohms and 100 feet of RG-8 non-foam coax, the SWR is 568:1, not 5:1, and the coax loss is not a mere 0.46db extra, it's more than 15dB. Attempting to use a 40m dipole on 20m with the same coax results in a SWR of 100:1 and nearly 10dB of line loss. This is *also* something people try to do.

None of this stuff is a question of good or evil, nor is it an issue that can be answered even approximately with a blanket statement. You have to look at the loss in the line. You have to look at how the line transforms the antenna impedance, and how the tuner loss acts with that impedance.

Sometimes the loss is negligible, sometimes it's obscene, but it's not necessarily a mystery. NEC-2 programs will give you a good guess at the antenna impedance, and I use VK1OD's line loss calculator:

http://vk1od.net/calc/tl/tllc

which will tell you the line loss and calculate the shack end impedance for you

and W9CF's tuner simulator, using that shack end impedance:

http://fermi.la.asu.edu/w9cf/tuner/tuner.html

With this set of tools, you don't have to do much guessing. If you aren't up on antenna modeling to get a good stab at the impedance, simple antenna types like dipoles and verticals will sometimes have impedance charts listed online or in antenna books.


73
Dan
 
Use a 40 M diopole on 20M?  
by K0FF on February 9, 2010 Mail this to a friend!
Dan said;Attempting to use a 40m dipole on 20m with the same coax results in a SWR of 100:1 and nearly 10dB of line loss. This is *also* something people try to do."

Yes I do that all the time. Bend the 40 M dipole into a loop, close the ends, feed it with coax and a 4:1 Balun, or tune the length of the coax, or use a 75 Ohm coax transformer. Better, mount it more or less vertically and make the feedpoint 17% up one of the sides.

This is a rule of thumb for full wave loops. I wonder if readers are more interested in rules of thumb, practical applications, clever mechanical "tricks", and practical experience, OR arguments about modeling? Let the readers decide, lets do a vote in the
SURVEY Section of eHam.

By the way, isn't 10 dB really called a B?

Geo>K0FF
 
RE: Use a 40 M diopole on 20M?  
by WB2WIK on February 9, 2010 Mail this to a friend!
>Use a 40 M diopole on 20M? Reply
by K0FF on February 9, 2010 Mail this to a friend!


By the way, isn't 10 dB really called a B?<

::Must be the same reason my 1000mg vitamin C pills aren't called a G.
 
RE: Use a 40 M diopole on 20M?  
by AB7E on February 9, 2010 Mail this to a friend!
K0FF: "I wonder if readers are more interested in rules of thumb, practical applications, clever mechanical "tricks", and practical experience, OR arguments about modeling?"

The problem with rules of thumb, practical applications, clever tricks, and practical experience is that there is almost never any objective frame of reference, and a huge percentage of it is bogus. If you summarized every statement or claim about antennas ever to have been posted here on eHam, you'd have nothing but a monstrous mess and you'd never be able to sort out the garbage from the truth without some sort of theoretical analysis ... and modeling is nothing more than automated theoretical analysis. I'll take modeling any day for an honest assessment of most antennas (some are very difficult to model), and the only arguments I've seen ABOUT modeling are from people who don't know how to use it and aren't willing to learn.

73,
Dave AB7E
 
RE: Use a 40 M diopole on 20M?  
by N2EY on February 9, 2010 Mail this to a friend!
K0FF writes: "Bend the 40 M dipole into a loop, close the ends....This is a rule of thumb for full wave loops."

But then it's no longer a dipole, and no longer easily usable on 40 meters.

K0FF: "I wonder if readers are more interested in rules of thumb, practical applications, clever mechanical "tricks", and practical experience, OR arguments about modeling?"

I think most readers are more interested in those things IF the following are observed:

1) Rules of thumb are identified as such, and the limitations of them spelled out.

2) Practical applications and mechanical tricks are really practical and safe.

3) Practical experience is explained in a way that the inexperienced can understand.

This isn't meant as a criticism of anybody in particular, least of all K0FF. But too often, on online forums, I'll see stuff that doesn't follow those rules.

For example, more than once I've seen stuff where the author clearly didn't understand the difference between the neutral (white) wire and the ground (bare or green) wire in house electrical wiring, and treated them as if they were the same thing. They're not, of course, and an inexperienced reader could get into trouble thinking they are.

As for arguments about modeling, Heidi Klum is #1 on my wish list. Anybody want to argue about that?

73 de Jim, N2EY
 
RE: Use a 40 M diopole on 20M?  
by WB2WIK on February 9, 2010 Mail this to a friend!
>RE: Use a 40 M diopole on 20M? Reply
by N2EY on February 9, 2010 Mail this to a friend!
As for arguments about modeling, Heidi Klum is #1 on my wish list. Anybody want to argue about that?<

::No. But hands off, I saw her first.
 
Mythical Antennas  
by N6MUK on February 10, 2010 Mail this to a friend!
Oh man... Shush up about the Hustler 6BTV!! Don't let my secret out.
 
Mythical Antennas  
by AC5WO on February 10, 2010 Mail this to a friend!
It's easy and inexpensive for hams to measure VSWR at the transmitter end of coaxial cable, so hams spend way to much time and effort on this one aspect of antenna performance. In the end, getting RF currents to flow in conductors at the corect distance from ground and other conductors is more important than the details of mechanical support and feedline coupling.

If an antenna is small compared to a wavelength, it can't be very directional. Differences in performance will be due to reducing RF power wasted as heat and getting a usable spacing above ground.

I would argue that a center fed half wave dipole has the advantage of being easy to reproduce and two band fan dipoles are almost as easy with a significant coaxial cable cost savings. Might consider the G5RV or and offset fed dipole where only one horizontal wire radiator is allowed, but would expect tuning for low VSWR on several bands to be more time consuming.

A cubicle quad is a yagi. It just uses square loops instead of linear elements, but the principle of using passive elements to add directivity is the same. Might as well argue about the merits of different boom materials or the color of the conductors.
 
RE: Mythical Antennas - Quads  
by VE3VID on February 12, 2010 Mail this to a friend!
I usd a G5RV 20 years ago when I first got on the air. Was it great? Probably not. Was it great fun....right on!!! I worked Falkland Islands my first HF qso with that crappy G5RV.

As for quads, I built a 2 element 40m delta in 2007 when the band conditions started slipping. Its a bear to turn and needs maintenance constantly - its performance speaks for itself. Besides its a huge bloody monster & I love it....hihi :)

David

ve3vid@arrl.org
 
RE: Mythical Antennas  
by NX8P on February 14, 2010 Mail this to a friend!
I agree with KB4WEC. I've experimented with many types of antennas (G5RV, no radial verticals, verticals with radials, balun/no balun designs, etc.). It is "back to the basics" for me which is a 135 foot balanced dipole (doublet) fed with high quality transmission type 300 or 450 ohm twin lead fed thru a good tuner. It has the lowest loss of any antenna out there. While adding a tuner and working non-resonant frequencies does add loss and inefficiencies it is still better than the "flavor of the year" antennas these companies are selling just to make a buck. One of the best aspects of this type of dipole is that a person can get the parts to build it for next to nothing and still out perform the "exotic" antennas out there. Like many of the dipole, doublet, etc. antenna articles state. . . don't be afraid to experiment with different types of installations. You will surprised what a good ole fashion doublet can do.
 
RE: Mythical Antennas  
by K5YF on February 14, 2010 Mail this to a friend!
Since there are already 12 million, 451 thousand, 822 posts to this article I might as well add to the noise.

1) If mobile antenna "shootouts" are not a true measure of antenna performance, neither is an antenna on a mobile tower versus an antenna on a stationary tower.

2) Ground reflectivity, permeability, and conductivity varies unpredictably from one location to another no matter the distance... even over the ocean. (Go ask the Navy or NOAA if you don't want to believe that) It is currently impossible to precisely know the exact amplitude or angle of an RF wave at any given moment. Only approximations can be deducted with a LOT of measurement. Fortunately, approximations have worked pretty well for us so far, and seem pretty much predictable to a point.

3) A "whole bunch" of folks are talking to a "whole bunch" of other folks on Amateur Radio without emitting a "whole bunch" of RF in an efficient manner. But talking we are.

4) There is less known about how RF and antenna "systems" actually work than a "whole bunch" of engineers are willing to admit. A big number of scientists trying to sell their latest research also are remiss to admit same, never mind the antenna manufacturers. But a scientist worth listening to might say, "We just don't know all the variables yet." Scientists know more about how light travels around than they do about how mono-plane electromagnetic radiation (RF) travels around. (I'm perfectly happy discussing the difference between "know", "think we know", and "in theory it works thus" with anyone who cares.)

P.S. This article generated a lot of traffic for eHam :-)

-Brandon
-K5YF
 
RE: Mythical Antennas  
by W3ATM on February 14, 2010 Mail this to a friend!
I have to agree. The more I learn about antenna performance and design the more I go back to the basics. I had an internet bought G5RV with a coax feed when I started out and now I have an inverted dipole I made from scratch. I ran ladder line straight to the tuner from the wire dipole and it works great. Plus I am proud that I built it from scratch! Also built my own 2 element, 20 meter, Yagi and had a lot of fun with that and also a vertical 160 meter where I wrapped the wire around PVC and that also worked. Lotsa fun. Great website!
73s
Bill
 
Mythical Antennas  
by AB3KI on February 15, 2010 Mail this to a friend!
Hi Alan

This is not an article about antennas - it is an article about HAM ATTITUDES about antennas. Big difference.
 
RE: Mythical Antennas  
by KG4YMC on February 20, 2010 Mail this to a friend!
Hi, don't know if its the band conditions or if I am just lucky, but have just made contact with I4gad in italy. He said I was 5 -3, with my inferior g5rv and ten watts 30 feet with my radio wavz 104 "junk" antenna. I am useing an panasonic 7 21 50 radio, 100 feet of rx8 coax, no balam but am useing an mfj mobile tuner and it tuns up perfect on 40 and l5 and will tune up on 6 also. don't let my antenna hear from the experts . I have also gotten hawaii, alaska,poland, spain rotundra., ecct with it . anyway, it it works don't fix it., or let the experts 'dis it " kgymc anway, conditons are improveing on 15, have heard japan ( ok haven't worked ) but is band conditons getting better ? at last , happy days 73 and good dx again.. terry " antenna on the ground, antenna on the ground , feel like a fool with antenna on the ground ' sung to tune of j' pants on the ground , couldn't resist" hi
 
RE: Mythical Antennas  
by G0KYA on February 25, 2010 Mail this to a friend!
Oh dear,

My 20m end fed half wave is fantastic and there is no sign of RF on the coax - shame it shouldn't work.

My 80m OCFD also works very well - shame again.

But I do agree that the G5RV doesn't match well on anything other than 20m. It is best fed as a doublet.

Steve G0KYA
 
RE: Mythical Antennas  
by W5LZ on February 25, 2010 Mail this to a friend!
I'll bet Alan is just absolutely heart broken over all the unfavorable comments!
I also think that a close look will show that he didn't say that none of the 'controversial' antennas mentioned wouldn't 'work'. He did say that there are a lot of misconceptions about them, and just about any other antenna you can think of. Hmm, that would seem to follow considering what the title of this thread is, wouldn't it?
That '8 dBi' gain with a dipole antenna is really going to be fun! Can you imagine all the speculation about this 'miraculous' antenna? Wonder how many new thingys will come out with '8 dBi' gain and be 'roved' by reference to 'K0BG's idea? Go back, take a very close look at exactly what was said, and then use your imagination just a little bit. I'll bet you can figure out ways of doing it. (If I can see possibilities, I certainly don't see why anyone else can't. :))
Whatever...
---

All puns, intentional or other wise, are definitely intended!
 
RE: Mythical Antennas  
by W5DXP on February 26, 2010 Mail this to a friend!
Well, I don't want to "break Alan's heart" but the professional definition of a dipole does include an end-fed half-wavelength antenna. From "The IEEE Dictionary": "dipole antenna - Any one of a class of antennas having a radiation pattern approximating that of an elementary electric dipole."

You see, the professional definition doesn't have anything to do with the physical "fishin' poles" used to build the antenna. The professional definition depends upon the *electric poles*, i.e. voltage maximum points, existing at the ends of a dipole - electrical, not physical poles. (Calling a 1/4WL piece of #24 stranded wire a "pole" doesn't make sense to me.) :-)

On the subject of a 43 foot vertical, there is a good reason for that length based on radiation patterns (not feedpoint impedance). The minimum length for a dipole, recommended by Walter Maxwell, is 3/8WL. That would imply the minimum length for a monopole is 3/16WL which on 4 MHz is 46 feet for a thin-wire. For aluminum tubing, it would be shorter than 46 feet, e.g. 43 feet. The maximum acceptable length for a monopole is around 5/8WL which on 14.3 MHz is 43 feet.

Thus 43 feet for a monopole is a good compromise for an 80m-20m monopole and is not too bad on 17m. If 40m-10m operation is preferred, a 22 foot monopole is a good choice (I've used one of those with an SG-230 autotuner at the base.)

Alan, all in all, a very informative article.
--
73, Cecil, w5dxp.com

 
Mythical Antennas  
by K5IID on February 26, 2010 Mail this to a friend!
While I generally agree with most of what was said there is one point on which I wish to differ.
The article that Quads were not less noisy than other antennas... this may be true to some extent. However, when it comes to rain or snow static I have experienced quads versus "regular" antennas fist hand.
To me the quad is definately quieter.
Tom K5IID
 
RE: Mythical Antennas  
by ZENKI on February 26, 2010 Mail this to a friend!
"If 40m-10m operation is preferred, a 22 foot monopole is a good choice (I've used one of those with an SG-230 autotuner at the base.)"

Its a shame they dont make legal limit tuners like the SGC230. Something that will handle 2500 watts to make up for network losses.

In this months QST the SGC230 rated well in the review of verticals and antenna tuners. There is an interesting claim in the QST review, the claim is that auto tuners work better when bolted to a metal plate, some models anyhow.
 
Mythical Antennas  
by K4TER on March 2, 2010 Mail this to a friend!
De-bunking the de-bunker...

A dipole has no gain advantage over he screwdriver I have mounted on the roof of my airstream trailer... Come on--I invite you to test it.
 
RE: Mythical Antennas  
by KD8GHK on March 22, 2010 Mail this to a friend!
All I've got to say is I'm coming up on 3 years as a ham. I still don't completely understand RF theory, and probably never will. You can claim what you like from any antenna in any situation - environmental and installation variables can make the best antenna in the world an absolute piece of junk for the next guy. Last year I was helping a friend figure out some issues with an Icom 738 and we proceeded to put approx. 10 watts into his cantenna on SSB - can't remember frequency. Needing a signal for SSB I ID'd and proceeded to talk at random - not having HF priveleges I didn't worry because the signal wasn't going anywhere. right? Wrong! I switched to his call and on a cantenna in his basement from Michigan we worked an Ohio station, a Texas station and a Utah station. At this exact moment in time I can officially say it's the best HF antenna I've ever used!
 
Email Subscription
You are not subscribed to discussions on this article.

Subscribe!
My Subscriptions
Subscriptions Help

Related News & Articles
What's On Your Handheld?


Other Antennas Articles
Nearly Cheap Homebrew QRP Vertical