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[Articles Home]  [Add Article]  

20 dB for $48.60

from Steve Katz, WB2WIK on January 18, 2009
View comments about this article!

"Editor's Note: Due to the popularity of some of eHam's older articles, many of which you may not have read, the eHam.net team has decided to rerun some of the best articles that we have received since eHam's inception. These articles will be reprinted to add to the quality of eHam's content and in a show of appreciation to the authors of these articles."





20dB for $48.60

Steve Katz, WB2WIK/6

0x08 graphic

Overview

Antennas, antennas, antennas!

They are our transducers to the ether, and are what make our wireless equipment work. Yet, for various reasons, many hams seem unconcerned about them.

Deed restrictions (CC&Rs) are probably a leading cause of hams having poor antennas, although plain old apathy seems at least as big a problem. Budget should never be the problem, since so many excellent antennas are available as used items either very cheaply or free, and of course some great designs can be homebrewed for almost nothing. And we find that often times, the ham with no antenna had enough of a budget to buy a $1000 radio. Hmph.

This subject is too vast to address in a brief article, so I'll focus on a single, popular design: HF Vertical Antennas. Even more specifically, inexpensive HF vertical antennas which are typically base-fed, trapped or loaded designs requiring a counterpoise or image plane in order to function properly. Among all the commercial designs on the market, the Hustler 4BTV-5BTV-6BTV are likely the best bang for the buck products currently out there, although Butternut HF6V-HF9V, Hy-Gain 12AVQ-14AVQ-18VS and DX88, and others can be good deals, too.

The products listed, and other popular commercial models, have one thing in common: They are not ground-independent, and have no factory supplied counterpoise. They are trapped or loaded, base-fed antennas that not only work better with radials, they work only with radials.

Any antenna can make contacts. Good ones make stronger, longer-distance contacts more reliably. With a 100W transmitter and a good antenna, many of the signal reports you receive should be `Wow, great signal - very, very strong, S9+ here.' If you don't commonly get such reports, you're definitely missing out on a lot of stuff that could be worked, but you're not going to hear it, and it's not going to hear you, either. A simple, inexpensive vertical antenna can produce such reports, repeatedly. The difference between a vertical that does get the `you're blowing me out of my chair' reports and one that doesn't is simple deployment.

50 Million Frenchmen Can't Be Wrong

That's a really old phrase, and I'm not even sure where it started - but it fits the situation. If you use modern antenna modeling software, you'll see that any current-fed vertical fed at its base, which usually means it's , or t image plane, usually made from wire radials, in order to reduce its vertical angle of radiation and reduce ground losses. When one installs such a vertical, say a 5BTV for example, on the ground without any radial system, it will generally demonstrate a good impedance match (to 50 Ohm coax), and nice, smooth, low curve plotting VSWR against frequency. That's a sure sign that it stinks.

In reality, this antenna should have a feedpoint impedance of about 30 Ohms (VSWR = 1.7 or so), and have sharp, narrow resonance curves if you plot VSWR against frequency. If the vertical has VSWR < 2.0 across the whole 40 meter band, you've got a problem, because the antenna's incapable of that. What's making the VSWR nice and low is ground loss, which appears in series with the antenna current and directly reduces antenna efficiency (both transmitting and receiving). My 6BTV is resonant at 7150 kHz, and VSWR climbs to about 3:1 at 7000 and 7300 kHz, which is about right. That's because my installation has very little ground loss - and that's because I have radials that work.

How much difference does this really make? That's a really interesting question, and although computer modeling shows the effects of radials with regard to feedpoint impedance and radiation angle, it doesn't demonstrate the real-world difference in what can be heard and worked. Simply using the antenna with easily added or removed radials (using alligator clips to attach them) is more demonstrative.

Having a battery-powered, portable HF receiver is very cool, if you're experimenting with antennas. This is because you can bring the “rig” pretty close to the antenna, and instantly assess whether a change you've made is for the better, or not. I sometimes use my little Ten-Tec SCOUT for this, but any shortwave receiver with an S-meter and an external antenna jack works. I also have an MFJ-259B Antenna Analyzer, as do, evidently, thousands of others - almost everybody I chat with seems to have one. It's a good investment.

Reality Check

Here's what I did, and have done many times. It's very interesting, and it yields great results:

-First, I installed a 6BTV vertical on my lawn, in the back yard, on a 4 feet long, 1-1/2 inch diameter pipe driven into the ground. That leaves about 3' of mast remaining above the ground, and is exactly what the Hustler assembly instructions recommend for a “no radial” installation. (In my opinion, Hustler makes good vertical antennas and gives lousy advice. Under no conditions should these antennas be used without radials, if you want to work DX.)

-I connect a short piece (about six feet) of coax to the feedpoint, and using the MFJ-259B, plot impedance data (R+jX or R-jX) vs. frequency across all bands, 80-40-30-20-15-10 meters (which is all this particular antenna covers).

-Then, I roll out four 32' long insulated wire radials, tying off the ends with plastic insulators and string to support them in position so they are laid out like sloping spokes of a wheel, spaced about 90 degrees apart from each other. I line the radials up so they can all be connected to the base of the antenna (aluminum mounting bracket), and install an alligator clip at the “antenna” end of each radial, so they can be quickly connected, or disconnected. I clip the radials to the antenna mounting bracket. (The radials slope gently away from the base of the antenna, towards the ground, but never actually touch the ground. This is an important note.)

-Next, I tune through the 40 meter band once again, using the MFJ-259B, and once again plotting impedance vs. frequency. Note the curve is much sharper, now, although the resonant frequency (where X = 0) usually doesn't change much. Also, the R is now lower.

-Then, I disconnect the MFJ-259B and replace it with the HF receiver, tuned to 7335 kHz. That's a “beacon” signal, so to speak, generated by station CHU in Ottawa, Ontario, almost exactly 3000 miles from my home. It's weak during the day, and strong at night, but can almost always be heard unless there's been a huge solar flare or other incident that just wipes out the ionosphere. I tune in CHU, and note the S-meter reading.

-Next, I disconnect the radials by unclipping them from the antenna base. If I can still hear CHU, I log its signal strength. Note, often times, disconnecting the radials causes me to lose the CHU signal altogether, making this test rather dramatic. On a typical evening, around gray line when CHU starts `pounding in' at S9+, disconnecting the radials can cause the signal strength to drop almost into the noise - a 9 S-unit change. Umm, how many dB is that? A lot. I re-connect the radials by clipping them back on to the antenna base bracket.

-Reconnecting the MFJ-259B, I tune it to 7150 kHz and observe the indication, then walk around in a circle, making each radial 2' longer, by clipping another 2' length of wire (Radio Shack clip lead) onto the end of each one. I go back to the MFJ-259B and observe the indication. Quite a difference! Resonant frequency of the antenna has dropped from 7150 kHz to 6940 kHz, completely out of the band! Well, that's about right. This verifies that the radials are tuning the antenna, and capable of changing its resonance, and the proportion change is about correct for the radial length change. Golly, does this mean that the radials are, quite literally, half the antenna? You bet it does.

-I unclip the extra 2' long leads, which were an experiment only to verify that the radials were affecting resonance. Now, I roll out four insulated radials cut to 16-1/2' long each, and perform the same set of tests on 20 meters, again using the MFJ-259B, but this time using the WWV signal at 15.000 MHz as the test beacon. This is impressive, but since I only live about 850 miles from WWV, this reception test is not a good indicator of `low angle' antenna performance: Even a very high-angle antenna will hear WWV quite well here. So, if possible, I do this test between 4:00 and 6:00pm local time during a weekday, when the ARRL CW practice and bulletins are broadcast on 14.047 MHz. The W1AW signal is strong and steady, and there for nearly two hours, so this gives me plenty of time to experiment. And, W1AW is nearly 2700 miles from me, so it's a better `low angle' signal.

-Note the differences, once again, using the MFJ-259B and the beacon signal received, this time using 20 meters. Holy cow. W1AW is S9+30 with the radials, and only S6 without them. How could that be? Of course it can be. The radials bring down the antenna's vertical angle of radiation (and also reception) to a useful angle for W1AW's signal. That means, the angle should now be low enough for working DX, too.

Try it. It's quite a test, and if you haven't actually performed a test just like this, you're doing your vertical quite a disservice.

Real Life

I couldn't leave my 6BTV mounted to a pipe on the lawn, in the back yard. The radials would eventually get tripped over and mowed down. Kids, dogs and other organisms would cause the demise of the whole system in pretty short order, here. Plus, even though I don't mind the way antennas look, this installation was pretty ugly, even to me. I scanned the horizon and found a better place: The roof of the house.

My personal solution was to install an 8' tall Glen Martin Engineering 4-legged roof tower at the peak of the roof of our single-story home; although, frankly, a cheap 3' Radio Shack tripod probably would have sufficed. I used the stronger GME roof tower to provide for the future, when I might want to put something larger and heavier up there. Then, I made multi-band radials using combinations of heavy-duty 300 Ohm twin lead and other conductors, until I had two radials for 80m; four radials for 40m; two radials for 30m; four radials for 20m; and four radials for 10m. I don't have separate 15m radials because the quarter-wavelength radials for 40m seem to work well as three-quarter-wavelength radials on 15m. (I did try, with and without separate 15m radials, and even as nitpicky as I am, could hardly tell any difference.)

0x08 graphic

Photo B: Close-up view of the 6BTV base connections, viewed looking up from the roof. I used the `radial attachment point' mounting holes in the horizontal part of the 6BTV aluminum base bracket assembly, as well as additional holes in the vertical part of the same bracket. Here you can see what appears to be nine (9) terminals making radial wire connections; in reality, those nine terminals are carrying 16 total conductors.

So, my current system has 16 radials, four per band for 40-20-10m, and two per band for 80-30m. This isn't ideal, but works pretty well and doesn't look too crazy up there on the roof. (I did, at one time, have 24 radials on the same vertical. I took eight down, selectively, and now have the `minimum' configuration that actually works.) My current radial system uses 405 feet of insulated wire. At about $.12/foot, that's a $48.60 investment to make a $200 vertical antenna actually work properly. A very wise investment, indeed.

Of course, I encourage others to scrounge, and it should be possible to come up with radial wire that costs absolutely nothing!

Alternative

For those having sufficient real estate to effectively ground-mount such a vertical, I've found the proper way to do this is to sink the base of the vertical nearly to earth, e.g., have the feedpoint within a few inches of the ground, and use lots and lots of wire radials either laying on, or buried beneath (doesn't matter) the soil. In this situation, the radials need not be resonant, but merely need to be plentiful.

Experimenting several years ago with a very large piece of property in upstate New York, and feeding a vertical against a ground-mounted radial field, I found the first few radials did virtually nothing. The next few helped. The next few helped more. And so it went, until we reached about 64 radials. After that, adding more radials didn't have much effect. In our case, we used VSWR measurement as an indication of whether the radials were actually doing their job: After about 64 radials, adding more hardly changed the antenna feedpoint impedance, indicating that we probably had enough.

Using that particular vertical, we could work global DX on 160 meters, which was the idea. Without the radial field, we couldn't hear any global DX, so it wouldn't matter if they heard us, or not.

I've found, both experimentally and also by researching others' data, that a lot of wire radials 20' long each is sufficient for amateur-band work with a ground-mounted vertical. 64 such radials would be 1280 feet of wire. I can buy a 50 lb. spool of #14 ga copper wire for about $100, and such a spool contains 3160' of wire. Thus, 1280' is about $40.50 worth. Not bad.

Summary

I have a tower and beams, too. But the vertical is a great go-to antenna, for when the beam's aimed the wrong way, or for use in a `round table' QSO. And I currently have no beams for 30-40-80 meters, so this vertical, and one or two simple wire doublets, is all I have. The vertical almost always outperforms any sort of doublet: G5RV, Windom, dipole - whatever - when working DX. Last night (August 7, 2002), I worked A71MA in Qatar `first call' on 20 meter phone, using the vertical and a barefoot TS850S. That's not `works great,' that's getting through on the first call, in a small pileup of perhaps 3-4 dozen stations I could hear calling Mohammad. With a vertical. And 100 Watts. And, oh yes: He did give me a `59+, very strong signal' report. I know he meant it, since he gave others `56,' `57' and `58' reports, right after me.

Photo C: Here is a close-up side view of the 6BTV base and some of the radial wires and attachments. I use Scotch 88 electrical tape to securely attach all the insulated radial wires to the 2 inch diameter support pipe below the antenna's base, so the mechanical strain of the wires is supported by the tape, rather than the lug terminals. The lugs and attachments last much longer this way.0x08 graphic
(In the background, a bit of my tower can be seen - it's about 50 feet away.)

Radials. They make verticals really work.

WB2WIK/6

Member Comments:
This article has expired. No more comments may be added.
 
20 dB for $48.60  
by K0BG on January 18, 2009 Mail this to a friend!
This article is still relevant, and will remain so.

From my perspective, the same can be said for mobile antennas. It is easy to gain 20 dB by properly installing a mobile antenna, but for some reason, few are willing to do so. In fact, most mobile operators not only resort to abbreviated mounting schemes, they resort to abbreviated antennas too!

If you're satisfied with the resulting poor performance, great! But don't justify it with inane references.

Alan, KØBG
www.k0bg.com
 
20 dB for $48.60  
by AE6QF on January 18, 2009 Mail this to a friend!
CHU is no longer on 7335. They're now on 7850, {USB}.

73, Quiet-Finger, AE6QF
 
20 dB for $48.60  
by KC8CXZ on January 18, 2009 Mail this to a friend!
Thank you! Great article on verticals! It would be interesting to compare a GAP vertical's (let's say the 'Titan' or 'Eagle') performance to one described in this article. Of course, the GAP's have very few and short 'counterpoises' as compared to a typical, vertical installation with many radials, and are still known to work excellent DX. I've also heard many Hams claim the GAP is really NOT a 'true vertical' but a center loaded multiband dipole of sorts (what EXACTLY IS IT???)! Many Hams choose a GAP because of it's 'small footprint'. What is the tradeoff compared to a properly executed/installed vertical like the one in this article?

73, James
 
RE: 20 dB for $48.60  
by KI9A on January 18, 2009 Mail this to a friend!
Excellent article! Kudos not to the ham who wrote it, but, to EHAM, for re-visiting it.

73- Chuck KI9A
 
20 dB for $48.60  
by K5END on January 18, 2009 Mail this to a friend!
Steve,

I'd stumbled across this article in the archives and read it some time ago. I'd more or less forgotten that I'd read it but the content you provided remained embedded. Here is a mildly interesting account of how you helped me.

Last year someone gave me an HF6V he'd never used or even assembled. All parts were still there (amazingly) and I downloaded the instructions. Even though 6 bands might be pushing the envelope a bit, it might be useful for 40 and 80 at least.

In experimenting with the set up over the new year holiday weekend, I was subconsciously using the techniques you recommended, almost to the letter, alligator clips and all.

However, I did not use the batteries in the analyzer. A 100' extension cord and a wall wart (OK, a "yard wart?") worked OK for me. hihi

Admittedly, I made some compromises in the radials before making some CW QSOs, as this is still a work in progress, and in the beginning used just 2 radials. But HERE is the proof in the pudding.

During "phase 1" of testing (using only two radials) on New Years Day, ALL, meaning, ALL, the QSOs were near a bee line off of one of the radials. From Houston QTH I worked Wisconsin, Michigan and Ohio. Of course that is what we would expect. Nothing like good old experimental verification of theory, right? (even though the data set is very small, yes.)

One other finding you may deem of interest. There is a "recipe" in the manufacturer's instructions for making 4-band radials, using flat twin lead cut to overall length and nipped here and there at defined points for the different bands. As far as I can tell, a multi-band radial is a waste of good twin lead, as one might expect. But, like I said, nothing like good old experimental verification--even if the result is negative.

73






 
RE: 20 dB for $48.60  
by K5END on January 18, 2009 Mail this to a friend!
Steve,

I overlooked the part of your article on multi-band radials.

So you did get good results? Great.

I'm probably using the wrong recipe...

How were yours made?
 
20 dB for $48.60  
by N8RGQ on January 18, 2009 Mail this to a friend!
I run the Hustler 5BTV's here , The main reason to go with them is they are now made out of "STAINLESS" ! No rusting stainless has a 50+ year lifespan ! I have mine all "GROUND MOUNTED" , the thing to remember when ground mounting these antennas is to use a ground that is 3 foot long or a * there of 6 foot or 9 foot to keep them in wave step . Every time I get A E-mail or a call about the Antenna having bad SWR it is do to a ground rod being the wrong length or mounted to high off the ground ! Mount them 2 in. above the ground . That is the "SWEET SPOT" for this antenna . The next thing to do is get a old FRIDGE shelf or oven shelf and slide it over your ground rod . They make a great counterpoise and most are made out of stainless steal . This is what I did for my referance 5BTV , it worked so well I had to put togather a FOUR SQUARE of 5BTV's spaced at 33 ft apart ! Raidals do work if you get enough of them installed but it is alot better to use chicken wire and works alot better ! I have 33 ft by 33 ft square of it and 4 ft by 6 ft sheets of stainless steal in the four square . If you want to get the "WHAT THE HECK ARE YOU RUNING !" statement on the other end this is how it is done .
73,
Terry
N8RGQ
 
RE: 20 dB for $48.60  
by KC8VWM on January 18, 2009 Mail this to a friend!
Sheesh... I don't know about how the 50 million Frenchmen did it exactly but, just how long is it going to take me to bury 64 of these darn things?

I mean, all the neighbors are starting to stare and stuff...

Surely, someone here must have some constructive ideas & suggestions to share and make this process go much easier?

73 de Charles - KC8VWM
 
RE: 20 dB for $48.60  
by K0BG on January 18, 2009 Mail this to a friend!
I once thought like you Charles, but I learned better. I went to all of the trouble to lay radials using a cheap skill saw and an abrasive blade. A lot of work to say the least.

The second time I just laid the wires atop the grass in the early spring, and about three weeks later, you could just barely see them.

Alan, KØBG
www.k0bg.com
 
RE: 20 dB for $48.60  
by KC8VWM on January 18, 2009 Mail this to a friend!
Yup, I actually tried using a skill saw on the grass to cut grooves in the ground. Hmmm... How did you know?

I bet you were watching me right along with all those neighbors huh?

73 and thanks for the tip. :)

Charles KC8VWM

 
RE: 20 dB for $48.60  
by KC5HMC on January 18, 2009 Mail this to a friend!
I cut my lawn very short then put the radials down. The grass will grow over them fairly quickly depending on rain or water. The best method that I found was to lay them out and get a patern. Then start the staples at the end and work your way to the antenna so the radials stay fairly straight. I use the 5BTV and like it. The tilt base and radial plate are nice extras for this antenna.

Herb KC5HMC
 
RE: 20 dB for $48.60  
by WA5UHK on January 18, 2009 Mail this to a friend!
Use the edging attachment for your weedeater or borrow one. Cuts a clean 2 inch deep slice in the yard. Aluminum 7" gutter nails on the ends will hold them in place and staples used on landscaping cloth complete the job when place every 15 feet.
 
RE: 20 dB for $48.60  
by KC7NOA on January 18, 2009 Mail this to a friend!
What kind effect would this have on a supposedly top loaded vertical like the MFJ-1798??

Im planning on taking mine down this spring/summer and putting up a OCF dipole ...
 
RE: 20 dB for $48.60  
by WB2WIK on January 18, 2009 Mail this to a friend!
>20 dB for $48.60 Reply
by AE6QF on January 18, 2009 Mail this to a friend!
CHU is no longer on 7335. They're now on 7850, {USB}.

73, Quiet-Finger, AE6QF<

::Yep, that's true. This article was written over six years ago and not updated since then.

WB2WIK/6
 
RE: 20 dB for $48.60  
by N6AJR on January 18, 2009 Mail this to a friend!
Sure Steve, But what about a fan dipole..:)

for real though, radials do make a difference. we used to buy the 5 wire radio shack rotor wire in 100 foot hanks. if you short wire 1 and 2 ar rthe far end you can make an "out and back" radial for 160M ( feed the center of 1 and short 1&2 at the far end and then clip the #2 wire at 33 feet for 133 feet for 160) and the rest of wire #2 for 80 meters (make a little gap in the #2 wire then run 66 feet back to the center end for 80 m. then #3 gets cut at 33 feet for 40 m and #4 gets cut at 17 feet for 20 m and #5 wire gets cut at 9 feet for 10 meters.

2 hanks of wires gives you5 bands plus 15 m for free and a double set of radials for your vert for about 10 or 15 bucks. use an exacto nife to cutt out the short section on the # 2 wire and just cut the rest free and strip them out. you can make more radials for the shorter bands from the left overs.

I was to poor back when to use real wire, so cheap rotor wire did the trick.
 
RE: 20 dB for $48.60  
by K4ZN on January 18, 2009 Mail this to a friend!
I just want to be sure I understand....

By experimentation it has been determined that quantity 64 radials of 14ga. copper, each 20 foot long, for a multi-band ground mounted radial reduces ground losses and improves low angle performance to the point that more and longer ground or surface radials are beyond the reasonable point of diminishing returns for most amateur radio station applications?

This seem eminently more feasible than some of the recommendations I've run across (e.g. 128 radials of 1/4 wavelength ea. or about 14,000+ feet of wire for 160m).

Thanks for any further comments based on objective testing or experimentation or real experience.
 
RE: 20 dB for $48.60  
by WI7B on January 18, 2009 Mail this to a friend!

"Fifty Million Frenchmen Can't Be Wrong" (1927)

The lyrics of this humorous song compared the relatively freer attitudes in 1920s Paris with the censorship and alcohol prohibition in the United States.

I consider that an unfair comparison. We were far more stupid in the 1920s than the French - somewhat like the the thought-process behind "Freedom Fries". The idea was made into a Broadway musical "Fifty Million Frenchmen" written by none other than Cole Porter that openned on Broadway just after the Stock Market crash.

Later, the phrase "Sixty Million Frenchmen Can't Be Wrong" was the theme of a French car commercial for the US market.

73,

---* Ken
 
RE: 20 dB for $48.60  
by KC0JGJ on January 18, 2009 Mail this to a friend!
Check out the difference a ground system makes plus a practical way to install it.


This was with a flex radio.

73

KC0JGJ

 
RE: 20 dB for $48.60  
by KC0JGJ on January 18, 2009 Mail this to a friend!
Forgot to add the link.

http://uk.youtube.com/watch?v=J9a1mAAtSbE&feature=channel_page
 
RE: 20 dB for $48.60  
by N6EY on January 18, 2009 Mail this to a friend!
Steve --

That's a great point. The story illustrates it well.

I wonder how many reading this understand the significance of a 20dB incrase in signal strength.

20dB denotes a gain of 10^2 or 100 times! That 1uV signal becomes 100uV - enough to shake the ole voice coil loose.

I think with a decrease in overal disposable income, experimenting with homebrew wire antennas is a much more attractive and feasible pursuit. Even if you have to get around rules, regs, HOA's, CC&R's and make do with PB&J, a lot can be learned with good ole fashioned emperimentation.

So until we cease to exist in 2012, let's enjoy the upswing in the sunspot cycle and hang some wire.

73,
Jason N6EY
 
RE: 20 dB for $48.60  
by WN9DDV on January 18, 2009 Mail this to a friend!
CHU IS ON AM!!!
 
RE: 20 dB for $48.60  
by AE6QF on January 18, 2009 Mail this to a friend!
WN9DDV

USB with carrier is AM.

Don't try to copy 7Mc CHU on LSB---there is no LSB
See Canadian gov webpage for details.

73, Quiet-Finger, AE6QF





 
COOL ARTICLE  
by PLANKEYE on January 18, 2009 Mail this to a friend!
That's one of the coolest articles I have seen here!!

Very well written and easy to understand, ALOT of good information. Thank You!!

PLANKEYE

 
RE: 20 dB for $48.60  
by N3OX on January 18, 2009 Mail this to a friend!
"What kind effect would this have on a supposedly top loaded vertical like the MFJ-1798??

Im planning on taking mine down this spring/summer and putting up a OCF dipole ...
"

If you leave the MFJ-1798 up, you'll have a good direct comparison of which is better!

Take it down after it doesn't do you any good on any contacts anymore!

That might be instantly, that might be never. You might not know unless you try.

73,
Dan
 
RE: 20 dB for $48.60  
by VE7NGR on January 18, 2009 Mail this to a friend!
KCLNOA: "What kind effect would this have on a supposedly top loaded vertical like the MFJ-1798??"

The MFJ-1798 is built upside down. The feed point is at the top of the antenna. The rods sticking out at the top with the wire perimeter is the counterpoise. The stuff hanging off the side at the bottom are the cap hats that are top loading the antenna. Adding radials would have to be done at the top - probably not very feasible.
 
RE: 20 dB for $48.60  
by WX1F on January 19, 2009 Mail this to a friend!
Trust me...adding radials to an MFJ-1798 does NOT make it work better. I've run mine for over 3 years. However, I don't recommend buying one. The bandwidth for the lower bands (75/80,40,30) sucks. During assembly, it refused resonant tuning on both the cw and ssb portions of those bands at the same time and requires an external tuner for full coverage. For over $300, I expected more. A home brew G5RV works the same or better and costs way less. It just takes up more back yard space than I have available.
 
RE: 20 dB for $48.60  
by WB2NVY on January 19, 2009 Mail this to a friend!
Correction on dB calculation:

voltage dB = 20log(v1/v2)
20dB = 20 log(v1/v2)
log(v1/v2)=1=log(10)

20dB change in voltage is a 10x change, not 100x.
 
20 dB for $48.60  
by W8KQE on January 19, 2009 Mail this to a friend!
Are all commercial or homebrew verticals 'equally noisy', or is this related to how well they hear? Would a 'GAP' be less noisy than a vertical with radials, because of it's design difference?
 
RE: 20 dB for $48.60  
by WI7B on January 19, 2009 Mail this to a friend!

WB2NVY,

You are correct. 20dB of field signal stength is a 10-fold increase. Its not power, but voltage. But, consider what the authors state, not just the title of the article:

"On a typical evening, around gray line when CHU starts `pounding in' at S9+, disconnecting the radials can cause the signal strength to drop almost into the noise - a 9 S-unit change. Umm, how many dB is that?"

Interesting, a change of S9 units! An investigation of the S-unit/dB correlation was undertaken by VE7TMA. His results are here...

=> http://www.repeater.org/links/links2/sunit.htm

From his work, if we "assume" the ARRL Handbook standard calibraiton of S9 = 50 microvolts, then..

0.2 S1
0.4 S2
0.8 S3
1.6 S4
3.2 S5
6.3 S6
12.5 S7
25.0 S8
50.0 S9


So, for a variation of S1 to S9 we have 50/.2 = 250-fold change in field strength. Wow! Thems some awesome radials.

73,

---* Ken
 
RE: 20 dB for $48.60  
by KY5U on January 19, 2009 Mail this to a friend!
Great info! I live in a restricted neighborhood and wanted to talk on 75M. I use an 18' vertical and it works well (about 3db less than a full sized 1/4 wave).

Take 18 feet of aluminum tubing or pipe and mount it on an insulator on a 2' by 2' aluminum plate. The bottom of the vertical is about 2" off the ground. Attach one end of a coil (MFJ sells them for their $99.00 vertical or one out of an old Marine Am rig will work) to an insulator and the other end to the pipe about 18" to 24" from the bottom. I do it with a hose clamp.

Make up a 2' pigtail and hook the shield to ground and the center conductor to a clip that will clip to one of the the coil turns. Use a barrel connector and attach the pigtail to your coax to the radio. Now string 20 radials 25' long from the corners of the aluminum plate and lay on the ground. (As someone said, the grass will cover them up in no time. I used lawn staples to hold them down until this happens so i can mow the lawn over them.)

Move the clip up or down from near the bottom of the coil to match to the bottom of the 75M band.Inside your shack, you can use a tuner to match across the 75/80M band. You can use an analyzer or a batter powered rig. Remember to be at lease 50' away from the antenna to check because your body will detune the antenna if you are too close.

This antenna is not visable from the street and will take full legal power if you use glass or porcelin insluators. The EZnac software shows slightly less than 3db difference between this antenna and a full sized 1/4 wave vertical.

Normal signal report at night is 10-20 over S-9 with 500 watts. It's not the best antenna, but a good one for restricted neighborhoods. Depending on how you build it, it can be disguised as a flag pole.

P.S. I added 10 more radials and the performance over 20 radials was not noticable so I pulled them up.
 
RE: 20 dB for $48.60  
by WB2WIK on January 19, 2009 Mail this to a friend!
>RE: 20 dB for $48.60 Reply
by KY5U on January 19, 2009 Mail this to a friend!
Now string 20 radials 25' long from the corners of the aluminum plate and lay on the ground. <snip>

P.S. I added 10 more radials and the performance over 20 radials was not noticable so I pulled them up.<

::That doesn't surprise me. In fooling with vertical antennas for four decades now, I've almost always found that any observable incremental increase occurs every time you *double* the number of radials: So you'd have to go from 20 to 40 to probably notice any difference at all; after that, the next improvement would be at 80.

WB2WIK/6

 
RE: 20 dB for $48.60  
by KC8VWM on January 19, 2009 Mail this to a friend!
I don't feel "radials" only benefit "verticals"

For example in my own experiments using a horizontal OCF antenna, I found that placing a wire on the ground directly below the antenna resulted in substatial improvements to my antenna.

Later and after investigating the OCF design and radiation pattern more closely, it was determined that the feedline radiates in a vertical manner.

We know that placing ground radials around the base of vertical antennas serves to reduce ground losses.

Therefore if the feedline of an OCF antenna radiates a signal in a vertical pattern we can conclude it too may benefit from radials:

-------------v-----


-------------X-----

Where v represents the OCF feedpoint at approx. 33' above ground level. Where X represents 64 - 32.5' ground radials at ground level. The horizontal wire on the ground is approx 2-5 % longer than the OCF antenna above.

What is interesting about this modified OCF is in the fact that it exhibits very interesting local and DX angles of radiation in a single antenna design.

I have made comparisons on 20m using a 1/4 wave ground mounted monoband vertical antenna and find the OCF outperforms it most of the time on both DX and coast to coast local propogation.

Interestingly, NVIS is even more interesting because the vertical is almost deaf in comparison to the OCF. sometimes to the extent of not hearing anything at all on the vertical to 10+ db over S-9 on the OCF.

It would be interesting to compare this design to a typical OCF design in antenna modelling software.

73 de Charles - KC8VWM
 
RE: 20 dB for $48.60  
by KC8VWM on January 19, 2009 Mail this to a friend!
I forgot to mention in the above description of the modified OCF design, that the primary reason the radials are 33'5" is not because it is resonant on 40 meters but rather because the radials are as long as the vertical radiator (OCF feedline) is tall.

It has been suggested in some antenna engineering technical journals I have been reading that radial lengths are not really that critial. However it was suggested that radial legnths should equal the physical height of the radiator to be effective. (The other half / mirror image of the antenna theory.)

Any additional thoughts on actual physical vs. resonant frequency lengths when installing ground radials?

73 de Charles - KC8VWM
 
RE: 20 dB for $48.60  
by KF7CG on January 19, 2009 Mail this to a friend!
For those talking about the MFJ-1798 vertical. It behaves just like theory says a shortened vertical would for 30, 40 and 80. The cleaner the installation of stray coupling the narrower the resonances on the loaded bands.

From A vs B comparison to a full-length fan dipole, it tends to perform better on long distance paths. I like the design idea, but find that the antenna implementation has its weak points, such as the wind survivability of the loading coil bracket and the counterpoise wires. Annaying yes, but not enough to keep me from putting a second on the air after a wind storm destroyed the first.

With the antenna base at 24 feet the high current point is approximately at 40 feet. This seemss to help when 20, 15, or 10 are open. 6 works well too, but I have no good comparison data for that slightly deranged band.

KF7CG
 
RE: 20 dB for $48.60  
by N2EY on January 19, 2009 Mail this to a friend!
N6EY writes: "20dB denotes a gain of 10^2 or 100 times!"

Yep. More than 3 S-units.

N6EY: "That 1uV signal becomes 100uV - enough to shake the ole voice coil loose."

Ahhh - no.

20 dB is equal to 100 times the *power*, not voltage. 20 dB is equal to 10 times the voltage *if* the system impedance is the same.

(ten times the voltage in a same-impedance system means ten times the current, too. Ten times the voltage multiplied by ten times the current is 100 times the power).

N6EY: "I think with a decrease in overal disposable income, experimenting with homebrew wire antennas is a much more attractive and feasible pursuit. Even if you have to get around rules, regs, HOA's, CC&R's and make do with PB&J, a lot can be learned with good ole fashioned emperimentation."

Yup.

N6EY: "So until we cease to exist in 2012, let's enjoy the upswing in the sunspot cycle and hang some wire."

Why would we cease to exist in 2012?

73 de Jim, N2EY

 
RE: 20 dB for $48.60  
by KC8VWM on January 19, 2009 Mail this to a friend!
Why would we cease to exist in 2012?

73 de Jim, N2EY

---------

http://www.december212012.com/

:)
 
RE: 20 dB for $48.60  
by NB3O on January 19, 2009 Mail this to a friend!
The December 21, 2012 theory sounds like a "change we can believe in".......
 
RE: 20 dB for $48.60  
by N5EAT on January 19, 2009 Mail this to a friend!
Steve: I owned a Butternut HF6V. I raised it's feedpoint to 27 feet and added Butternut's radial kit.
I had to spread some of the radials out at various angles so as not to bunch them up as they overextended their reach to the ground.

That was the best antenna I've ever had up. It was a truly useful antenna and even though it heard in all directions - i found that to be very useful.

I have a hustler 5btv ground mounted at the present moment. It's a good performer on 40 meters, not very good on 20, and I've made my share of contacts on 80 as well. Don't ask about 20 and 15. When It gets a bit warmer in 6 weeks here, I'm going to get it off the ground and see how it performs with radials. I agree with you that it's a great piece of work for such a small price and as a tool to get a really fine antenna from a semi-humble beginning.

Good old article, advice that will stand the test of time.
 
RE: 20 dB for $48.60  
by W1NK on January 20, 2009 Mail this to a friend!
This should be required reading for anyone considering putting up a vertical. Especially those who think they can achieve "outstanding performance ... with only a simple mounting post which doubles as the ground rod" (from a well known, well established antenna manufacturer).

Just a thought... wouldn't it be great if the eHam Classics could be easily referenced with their own link under the Community heading?

Frank, W1NK
 
RE: 20 dB for $48.60  
by WB2WIK on January 20, 2009 Mail this to a friend!
>RE: 20 dB for $48.60 Reply
by N5EAT on January 19, 2009 Mail this to a friend!
Steve: I owned a Butternut HF6V. I raised it's feedpoint to 27 feet and added Butternut's radial kit.
I had to spread some of the radials out at various angles so as not to bunch them up as they overextended their reach to the ground.

That was the best antenna I've ever had up. It was a truly useful antenna and even though it heard in all directions - i found that to be very useful.<

::Yep, it is a good antenna. So's the 6BTV. In fact, they perform in a very similar manner. The HF9V is more versatile in that it covers the WARC bands. It's still a good choice, if installed correctly.

WB2WIK/6
 
RE: 20 dB for $48.60  
by W5WSS on January 20, 2009 Mail this to a friend!
Steve, As you know we have talked a few times on the air while I was working through the various steps and observing the improvements of my own vertical full size 20 meter GP mobile hilltop quick expedite antenna. I have combined both Mr.Cebiks and your recommendations which for all intents and purposes are firmly grounded in sound antenna fundamentals.
I too have found repeatable excellent results by incorporating radials. I noted dramatic signal increases during the radial tuning processes.
My Dx rates have increased markedly as a result of the multi-faceted advantages afforded by the addition of elevated radials.
A often misunderstood precaution is worhty of noting: when attaching radials to the center of the antenna which is the middle of the two parts... radials and vertical feed point, Symmetry around the semi circle is solely responsible for horizontal radiation cancellation if this step is not considered then the pure vertical radiation that contains the bulk of the antennas target toa, and maximum dbd gain will be offset by more than remnant radiation by the radials. Most hams do not realize how much this can reduce long dx signal strength.
Steve I noticed in your vertical install how well you adhered to symmetry.
I must take this opportunity to thank you for your on air help and this article in paticular! 73 w5wss
 
RE: 20 dB for $48.60  
by KC2RGU on January 21, 2009 Mail this to a friend!
I had read this article several years ago when I bought my 6BTV. I like to play with antennas a bit so I tried similar experiments and ended up with different results. In my location I ground mounted the vertical. I didn't have access to a MFJ-259B Antenna Analyzer at the time so reading SWR and looking at the S meter was all I had to go by. After I installed my antenna without radials and adjusting for the best SWR ratio on the desired frequency of each band I was disappointed that I couldn't hear but the strongest stations. Many of the stations were S9 to 20/S9. I then added a radial field consisting of 20 30 foot radials. I quickly discovered that I had to re-tune the antenna. I now was able to hear many more stations. What was surprising to me was that very few stations now hit S9 on the meter. I then set the antenna up so I could easily connect and disconnect the radials. What I discovered was that with the radials disconnected all the signals on the band were much stronger on the S meter but the noise level was also much higher. With the radial field connected I discovered that the noise level dropped way down and I could hear much weaker stations even though the signal strength of the stronger stations were less than without the radial field. My conclusion was that the radial field greatly improved the signal/noise ratio. Adding 40 more radials improved the installation.
 
RE: 20 dB for $48.60  
by LU1DZ on January 21, 2009 Mail this to a friend!
Good Job.
Many thanks...!!!
 
RE: 20 dB for $48.60  
by WI7B on January 22, 2009 Mail this to a friend!

Check out the new series of experimental articles on HF verticals beginning in QEX comparing NEC-base calculations to actual antenna systems.

73,

---* Ken
 
RE: 20 dB for $48.60  
by N2EY on January 22, 2009 Mail this to a friend!
Great article!

I bet if you put WB2WIK's advice to work, even a Gotham vertical could do a good job.

73 de Jim, N2EY
 
RE: 20 dB for $48.60  
by W8AAZ on January 22, 2009 Mail this to a friend!
One really successful ground mounted vertical I had was an old used 4BTV I believe, with a ton of radials buried. Ground mounted the vertical and layed in just barely buried radials made of some fairly fine wire I had aquired cheaply or free. Just made slits with the shovel and pushed the wire in. With a great number of radials buried, the thing apparently worked as it should and got results. The coax, however, was not buried but flat on the ground. Even then, my brother seemed to find delight in "accidentally" whacking it with the mower. The antenna is long gone by decades but I suspect the radials still abound.
 
RE: 20 dB for $48.60  
by N3OX on January 22, 2009 Mail this to a friend!
"I bet if you put WB2WIK's advice to work, even a Gotham vertical could do a good job. "

All that running out to change coil taps would make you take the radials back off again though
 
RE: 20 dB for $48.60  
by WA1KWA on January 23, 2009 Mail this to a friend!
DX Engineering (an advertiser here) has biodegradable staples for ground radials.

Though I must admit, the chicken wire idea is intriguing.

73,

Colin

WA1KWA
 
RE: 20 dB for $48.60  
by W5WSS on January 23, 2009 Mail this to a friend!
W8aaz said "The decades old radials still abound..That depends on the soil. Many broadcasting stations have resorted to as little as four elevated radials as a replacement solution to deteriorating/dissolving burried radial feilds and measurably weakening signal strength to their market audience. The concensus is that four properly tuned elevated radials will restore/rival and probably exceed measured feild strengths of a 60 radial burried system. For the average ham operator this is good news indeed because where most ground mounted installations are less than optimum due to ground clutter etc. a elevated 1/2 wave or 1/4 wave mono band ground plane and four elevated radials will transfer power at a very high percentage greater than 95%. Hence for a permenantly installed multi band radon ground plane and four elevated radials per band will work nicely. Use caution with respect to equi distance around the semi circle both at the base of the radon and at the point where each set of radials terminate do not ground them. I use non conductive stakes that are capable of with standing full legal limit. The base height of such a system need not be very high infact depending on one's target coverage about 20' up will allow 40-10m low toa dx work. When raised higher the lobes will split into secondary trajectories too high for far dx and more suited to less of either close in or dx once again height plays a significant role but far more difficult to exactly predict. Suffice to say a secondary lobe formed by base height and earth surface relate to roughly 60 degrees ...mostly angles that contain noise.The ideal location for land locked installs is in the grasslands of open pasteurs, and about 20-40 ft of base height up depending on which area of hf one prefers to optimize for. Salt water and marshes that would model so well that most land lubbers installs would just weep to see the advantage. 73
 
RE: 20 dB for $48.60  
by WY3X on January 25, 2009 Mail this to a friend!
I didn't read all the posts, but has anyone considered that radials also change the look angle from which stations are received, and that may possibly account for some of the variation in received field strength? Just a thought. -KR4WM
 
RE: 20 dB for $48.60  
by WA7VTD on February 4, 2009 Mail this to a friend!
RE. the angle at which the vertical "looks" at received signals...

It's always beneficial to open up "Low Band DX-ing"
by ON4UN.

How radials affect take-off and receive angles has
a lot to do with the far-field as well as the
near-field ground characteristics. Those circumstances, in turn, contribute to one's
assessment of the "best" ground return methodology
to employ for the vertical(s) at one's own QTH.

Great article.

73 de Kevin WA7VTD
 
RE: 20 dB for $48.60  
by WB4ROA on February 4, 2009 Mail this to a friend!
Lawn edger, 1/2 deep, narrow cut. Get a piece of copper tubing used in refrigerator ice maker water lines. Slide wire through a 6-8" piece of copper line. Secure end closest to antenna. Walk backwards with tubing pushed into ground. Lays the wire down very quickly and at the bottom of the slit.

By the time you lay the radial the slit is all but invisible.

Tried being lazy and using U-shaped pieces of rigid wire (lawn stakes) to hold the radials down. Many deer and a teenager with a riding lawn tractor made short work of surface radials.

Hank WB4ROA
 
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