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[Articles Home]  [Add Article]  

DX as an Antenna Measurement Tool

Alan Applegate (K0BG) on November 4, 2011
View comments about this article!

DX As An Antenna Measurement Tool

All antennas, no matter how they're configured, follow irrefutable laws, long since set down by the likes of Maxwell, and Kirchhoff. You can't refute them, and you can't repeal them. They are in any context, cast in stone! That fact, however, doesn't stop entrepreneurial antenna designers from trying to redefine the laws. They even resort to advertizing claims that even P. T. Barnum would be proud of! One of those claims is often this: "Work more DX with our antenna than any other!" Speaking of which...

For some amateurs, chasing DX is a passion rivaling that of any great war. Imagine being first on the all-time DXCC Honor Roll list? Wow! Actually, quite a number of amateurs have worked more than 325 countries. Once you achieve this level, it is rather difficult to pick up one more. But, even if you're on the bottom of the list, it can be just as exciting adding one more to the list. There are a lot of other amateur radio awards too ("Worked All States," and "Worked All Continents" for example), but they just don't have the mystique that the DXCC has. Perhaps it is the assumed difficulty of working DX stations. If that's your thought, here's something to ponder.

If one selects the correct band and mode of operation, erects even a minimal antenna, and drives said antenna with just a few milliwatts, it is possible to communicate with another amateur anyplace on the face of this earth, DX or otherwise. All that is required is a lot of patience, thrown in with a goodly dose of radio wave propagation, and Walla! Simple as that! Obviously, the more elaborate the station (bigger and higher antennas, more power, better receiver etc.), the easier it is to capture the really rare ones like Bouvet Island, 3YA, and increment your DXCC Honor Roll standing. However, the ability or ease of working a DX station, rare or not, it not a measure of any antenna parameter, period! Yet, you'd think it was by the number of amateurs who cite their DX exploits as a means of justifying their antenna installation, no matter what it is, or isn't! Like SWR, if it is a measurement, it is the level of novety for those who cite it.

To sum it up, I believe Tom Rauch, W8JI, said it best: "We should wipe the false idea from our minds that feedpoint impedance indicates efficiency, or that a log full of contacts means our antenna has high efficiency. It is very tough to judge a ten-fold change in antenna efficiency based on a log book."

Alan Applegate, K0BG
Roswell, NM

Member Comments:
This article has expired. No more comments may be added.
 
DX as an Antenna Measurement Tool  
by K3TN on November 4, 2011 Mail this to a friend!
It is definitely tough top judge the efficiency of an antenna from a log book but it is really, really easy to discern the difference between two antennas by trying to work DX with the two different antennas.

I have a 135' off center fed dipole I use for most HF bands and a 51'T vertical I use for 160. I can call TX3T all night long on the Windom on 160 and not get through. I switch to the 51'T and I get through - I can easily prove by working TX3T on 160 that the T is a more efficient antenna on 160.

If I call 8P9NX on 15m with the T antenna he doesn't hear me. If I switch to the Windom, he comes back and says Hi. I can easily prove that the Windom is a more efficient antenna on 15m than the T.

After using the T on 160 I often forget to switch back to the Windom, and I have pretty much empirically proven that the T is a worse antenna on 10-40M under all conditions. But it is true that there could actually be times in a particular band opening where some lobe on the T may point at just the right angle in the just the right direction to out-perform the Windom on the higher bands, but that is like saying even a broken clock is right twice per day!

Even easier of course would be switching in a nice multi-element yagi...

So, yes - saying "my noodle works great because it gets 1:1 SWR and I worked Elbonia" does not make sense. But actually working stations far away is a great way to compare antennas to select the most efficient on that band at that time.

73, John K3TN
 
RE: DX as an Antenna Measurement Tool  
by M6GOM on November 4, 2011 Mail this to a friend!
I fully agree. My antennas have all suddenly developed the ability to work the world on 10m in the last few months even though nothing has changed at my QTH.

Also there is the "contest antenna" law which states that in a contest even the crappiest antenna will suddenly appear to work a whole lot better.
 
RE: DX as an Antenna Measurement Tool  
by KY6R on November 4, 2011 Mail this to a friend!
I recently used HFTA to get a better idea what my yagi "looks like" and it was an eye opener - disproved all of the ideas I had based on modeling my yagi over flat ground - which is what the antenna manufacturers do. I also looked at the different heights that it should be at - and made believe I had a stack of three at different heights. That and EZNec+, VOAACAP and VOAAREA are my favorite software tools.

I'm up to 328, with more than 300 using home brewed wire antennas and 200 watts or less. (My goal when I started was to use only home brewed antennas). Yes - its really slow after 325.

I agree with your idea - you put up the best you can - given your situation, continually work on your DX-ing skills, and good things happen and big fun happens.

The best part is the learning break throughs. This is when being an "amateur" is most fun!
 
RE: DX as an Antenna Measurement Tool  
by VE7IG on November 4, 2011 Mail this to a friend!
If you have an antenna range and plenty of test equipment and your main interest is testing antennas then you can come to all sorts of great conclusions
about the efficiency of antenna A over antenna B.
However, antennas are not put up just for testing.
The proof is in what you can do with them. If you only have room for average antennas and you can work
good DX with them, then who cares what the pundits tell you. I'd feel sorry for the guy who took his
antenna down because an expert told him it was inefficient and didn't work. I've been told that
quarter-wave slopers are unpredictable and can't be
well modeled using NEC. My 160m sloper (and those of several friends here in VE7) works extremely well on 160 and yielded log page after log page of DX during the last sunspot minimum and that is what counts! Sure it would be nice to have a 4-square on 160 or even a full-size vertical but for most of us that is totally out of the question.
 
RE: DX as an Antenna Measurement Tool  
by KB9SXC on November 4, 2011 Mail this to a friend!
WOW...
1/4 wave vertical ham stick in the middle of Chicago backyard + 75 feet of coax + 10m Radio Shack 20W transceiver - hello Japan... I agree with you - when bands are open just about anything works as an antenna...
 
RE: DX as an Antenna Measurement Tool  
by NI0C on November 4, 2011 Mail this to a friend!
I agree with VE7IG's comments above.

If your goal is to write scientific studies of antennas, then of course, a logbook full of DX QSO's serves only as anecdotal evidence. But if your goal is a logbook full of DX contacts, then you put up the best antennas you can afford and proceed to operate.

73,
Chuck NI0C
 
RE: DX as an Antenna Measurement Tool  
by W2RI on November 4, 2011 Mail this to a friend!
Alan, I don't really agree with you
a) Yes, given the right propagation, almost any antenna will allow you to make contacts
b) If an antenna is properly matched so that it radiates effectively then how the antenna "performs" depends on how efficiently the RF is directed to the target location - is it focused, and what is the take-off angle?
Clearly some antennas are better suited than others for communicating with a particular location.
c) In a pile-up, while it obviously depends on the DX operator, in many cases the biggest signal wins. Ergo, a directional antenna such as a quad or yagi is far more likely to bust the pile-up than a dipole.
 
RE: DX as an Antenna Measurement Tool  
by N3OX on November 4, 2011 Mail this to a friend!
NI0C writes:

============
"If your goal is to write scientific studies of antennas, then of course, a logbook full of DX QSO's serves only as anecdotal evidence. But if your goal is a logbook full of DX contacts, then you put up the best antennas you can afford and proceed to operate. "
=============

Chuck, the word "best" there is a really loaded word if you're someone who's actually trying to achieve the best bang for the buck. How do you know what the "best" is without some kind of objective measurement? Here's a simple example. I built a 10 foot tall 40m vertical.

http://n3ox.net/projects/n3oxflex/

I characterized it quite thoroughly with field strength comparisons against a quarter wave vertical and found that it was a bit worse than 1dB down from a quarter wave. I proceeded to work this list of stations with it with 500W:

DK3FW 59
V55V/P 59
N7TLL 57
DF2BO 56
F5TTI 57
EA3BOX 58
ZS6TQ 349
DL7SPR 34
IW3IBK 59
OZ8BV 58
LU9ESD 57
ZS3D 58
HA8RM 59
ON8DM 59+5
FP/M0TOC 59
WB9JOX 59
FR/DJ7RJ 559

All those QSOs were in regular weeknight operation and most were at least a bit casual so the "59" reports are as "honest" as 59 reports get... with the exception of V55V who was running kind of a pileup. Now, let's imagine you love 40m but are restricted in what you can erect height-wise but you can put in some radials. You're trying to choose a 40m antenna, and you're looking to increase your 40m country count from 200 on upward. You know that a 40m quarter wave vertical would be a good choice but you think the neighbors might object to a 33 foot pole in your backyard.

Which piece of information about my 10 foot tall antenna is more useful for planning purposes? My list of QSOs, many of which I could POTENTIALLY have made on much worse antennas with much less power, or my objective field strength measurements and my description of the experiments I did to get them? Do they give you the same amount of confidence in your ability to work XZ and 3W on 40m long path if you chose to build my short antenna?

What I *actually do* in the real world with an antenna is what's important to *me.* I enjoy using an antenna I made to work DX contacts... all the better if it's something a bit unusual. I was sad to take down my short vertical but I wanted to get back on Topband (I in no way have enough room to have both of them up at once... )

But when I tell OTHER people to build it, I can give them a list of contacts a mile long and they might not actually know how my antenna works... maybe they saw a similar list of contacts from a mobile station. Maybe they know that propagation from W3 is a lot better than propagation from W0 ... there are so many other factors. Patient ops can work a couple hundred countries on 40m with 20W ERP. That doesn't bode well if all I tell you about my small antenna is that I worked a short list of easy DX with 500W. Other ten foot tall 40m antennas over my radials could be 3, 6, or 10dB worse than this one and still maybe make the same list of contacts.

But if I compare my antenna carefully and quantitatively to a quarter wave ground mounted vertical with adequate radials and report that number they can more immediately translate to a familiar experience. "A bit more than 1dB worse than a 1/4 wave vertical over a 50 foot square radial field of 27 radials installed on Riverdale, Maryland dirt" is a more succinct summary of everything I could ever tell them about the contacts you can make with it. It's a lot of information in a small package.

Now I don't expect people to test things to the extent that I tested them. And there's no reason for people to waste time trying to "optimize" a single thing if they're enjoying their time on the air.

But when you decide you need a BETTER antenna, there are better and worse measurements of BETTER ;D
 
DX as an Antenna Measurement Tool  
by KT4EP on November 4, 2011 Mail this to a friend!
I'm having a lot of fun and making numerous contacts each day from 20 meters to 10 meters using a home brew loop hanging vertically off the tower over to a mast while transmitting 5 watts PSK31.. Ukraine to South America and all over Europe and the USA. I can see China, Japan, and Australia on the waterfall with the loop but they can't hear my 5 watts.
73
Keith
KT4EP
Bartlett, Tn
 
RE: DX as an Antenna Measurement Tool  
by N3OX on November 4, 2011 Mail this to a friend!
I should add one more comment...

Antenna performance to the few dB level almost never matters for DXing within some reasonable limits. The signal margin is almost always such that you can make up for some antenna deficiency with skill, timing and persistence.

But in those rare cases where detailed antenna performance DOES matter in DXing, you probably find out when you **lose your one shot at something important**
 
RE: DX as an Antenna Measurement Tool  
by K8AG on November 4, 2011 Mail this to a friend!
I think it all depends on why we participate in amatuer radio. If simply making the farthest contact is "your thing" then I would say the most engineered metal at the optimum height on both ends, each running full legal power, will make a contact with little more than the skill to turn on the equipment.

For me it is not that we make a QSO happen, but how we make it happen. Some of us like to work DX on both the hunter and prey ends. Each takes certain operator skills. I have been delving into QRPp of late. That takes many of the same skills, but also some different skills.

Yet some of us are into emmcomm and digital modes any of the many things to do as radio amateurs. All take some of the same and some different capabilities.

It's "whatever floats yer boat."

73, JP, K8AG
 
DX as an Antenna Measurement Tool  
by AE6RV on November 4, 2011 Mail this to a friend!
"Walla!" ????
 
RE: DX as an Antenna Measurement Tool  
by K0BG on November 4, 2011 Mail this to a friend!
Let's don't forget an important point that John alluded to, perhaps unknowingly.

If you have two antennas, A & B, and A garnered you more DX than B, you might assume that A was more efficient. In reality, it just means at the time the incoming angle and direction favored antenna A. At some other incoming angle and direction, B might be better than A. This said, the fact one made more DX contacts hasn't a darn thing to do with efficiency, of effectiveness.

Alan, KØBG
www.k0bg.com

 
RE: DX as an Antenna Measurement Tool  
by W2RI on November 4, 2011 Mail this to a friend!
They only speak English and Klingon in Roswell, not French!
 
DX as an Antenna Measurement Tool  
by NU4B on November 4, 2011 Mail this to a friend!
Haven't we been here before. This topic is strangely familiar.
 
DX as an Antenna Measurement Tool  
by W3PRL on November 4, 2011 Mail this to a friend!
Interesting comments and thought I'd add my 3 cents. I've got me one of those cheap wires hanging between the trees....it looks like a drooping V with the ladder line hitting the ground when the trees blow real hard. My coax is that cheap gray stuff running about 150' into the window of my shack. I use a bathroom towel between the window frame and window seal to keep the bugs out. Once inside, that cheap coax runs to a MFJ-998 Intellituner, then off to either my FT-950 or my TS-830s. On occasion I flip the switch on my 911H...no pun intended I did change the model of my amp, so that I can bust the door down once in a while. My logbook, quite impressive !! I've lived in two separate locations over the past 10 years and have learned alot about propagation and antenna's. Most of them guys out there working the big antenna's in DX Land are rather amazed at my signals from the droopy G5RV - 39 Bucks gets me all around the world......and that's what I love about this hobby !! If I don't work em today, maybe tomorrow !!!

de W3PRL

 
RE: DX as an Antenna Measurement Tool  
by N4KC on November 4, 2011 Mail this to a friend!
Whew! Alan, the headline scared me. I thought you might have been out in that desert sun too long! I get your point and agree. Antenna manufacturers need to find other points of differentiation besides "It works more DX than the competition." Lazy--and ineffective--marketing!

Aside for all eHam authors and posters: If you want to use the word "Voila!" then you should use it correctly. Not "Viola!" which is a perfectly fine stringed instrument. Or "Walla!" which is half a city in Washington State. :-)

Don N4KC
www.n4kc.com
www.donkeith.com
(Don's new book, UNDERSEA WARRIOR, is now
available at bookstores everywhere)


 
DX as an Antenna Measurement Tool  
by NK2U on November 4, 2011 Mail this to a friend!
All bets are off if you're trying to use an Isotron as an antenna. Voodoo, snake oil, witchcaft are some of the ways to describe that "antenna."

de NK2U
 
RE: DX as an Antenna Measurement Tool  
by KY6R on November 4, 2011 Mail this to a friend!
I only buy antennas that sound cool - like "The Rock Crusher" . . .
 
RE: DX as an Antenna Measurement Tool  
by N3OX on November 4, 2011 Mail this to a friend!
K0BG writes:

=================
"you have two antennas, A & B, and A garnered you more DX than B, you might assume that A was more efficient. In reality, it just means at the time the incoming angle and direction favored antenna A. At some other incoming angle and direction, B might be better than A. This said, the fact one made more DX contacts hasn't a darn thing to do with efficiency, of effectiveness. "
=================

If A always gets you more DX than B then A is more effective. That "always" is a tricky thing but let's not pretend that a basic on-air A/B test is a bad idea.

An on-air A/B test will not easily expose 2dB differences but it will fairly easily expose 6dB or 10dB differences like noticeable efficiency problems or bad nulls.

An on-air A/B test is one of the most basic scientific tools anyone has to assess their antennas. It has pitfalls and the limitations of the on-air A/B test can be problematic. I've seen nonsensical A/B tests like comparing two 80m inverted vees that are hung a foot apart in the same plane from the same tower. That's useless because it's not two antennas. QSB makes it so that the dB error in a A/B test are large. You can't really check the gain of a two element yagi against a dipole in the same direction with an on-air A/B test unless you make tons of measurements. Possibly the most dangerous feature of an A/B test is people who don't recognize that there's something wrong with the test when an antenna greatly EXCEEDS expectations.

But you certainly can check for bad problems and you certainly can discover that some antennas are miles better than others. This is a crucial step in the rational assessment of antennas. It is unacceptable to discourage people from putting up two antennas and directly checking them against each other because we're worried about subtle errors.

The sources of error and how you need to set up the antennas (enough distance, etc) are important topics of discussion but throwing our hands up and suggesting that A/B tests are meaningless is not good.

You have to have a really special pathological situation for antenna A to win over and over again when antenna B is really better. If antenna B is SUPPOSED to be better it's important to think long and hard about why antenna A is winning. If you don't know which is better or it could be either, and you're being honest with yourself about whether or not you actually can notice a difference as you do many tests, it is almost certain that the outcome of the A/B test is valid.

 
RE: DX as an Antenna Measurement Tool  
by KE7FD on November 4, 2011 Mail this to a friend!
I suppose if we were talking about light bulbs, it might be easy to see distinctions between differing methods of generating light. Some types are more efficient than others: Florescent vs. incandescent vs. LED. Some bulbs produce more heat than light; others more light than heat. To bring the analogy back to radio, the antenna that generates more RF signal than heat would be preferred, I suppose. Sound antenna design and efficiency really does matter. If only we could "see" the RF coming off our antennas like we can see light with our eyes, antenna adjustment and tweaking would be easy. (Now where did I put that analyzer?)

As a novice operator many years ago I once worked a few stations using a light bulb as a dummy load, but I don't recommend that method with today's solid state rigs. The neighbors might really have reason to complain with elaborate strings of lights atop a tower. Let's see, would that be incandescent , neon or LED...?

Glen
KE7FD
 
RE: DX as an Antenna Measurement Tool  
by N5MOA on November 4, 2011 Mail this to a friend!

K0BG said:

"if you have two antennas, A & B, and A garnered you more DX than B, you might assume that A was more efficient. In reality, it just means at the time the incoming angle and direction favored antenna A. At some other incoming angle and direction, B might be better than A. This said, the fact one made more DX contacts hasn't a darn thing to do with efficiency, of effectiveness."
-------------------------------------------------------
A/B test are just as valid a test as any other, particularly if you are A/B testing verticals.

Antenna (A) 1/4w vertical with a bunch of ground radials is going to beat the pants off antenna (B) 1/4w vertical with one radial.

The fact you could make more dx contacts with antenna (A) is directly attributable to it being more efficient and effective for working dx.

Yes, propagation is the major factor, and there are isolated times you can talk around the world with just about anything for an antenna.

However, 99.9% of the time, it helps to have the most efficient antenna you can. A/B testing is one way to determine if you have that or not.



73, Tom
N5MOA




 
DX as an Antenna Measurement Tool  
by K0RGR on November 4, 2011 Mail this to a friend!
If my Sweepstakes score gets a lot better than the year before, I conclude that the changes to my station might have helped. However, propagation will probably get a big part of the credit this year. I expect to spend a lot of time on 10 - last year, it was 15 and not too much of that. That alone should be good for a couple hundred Q's.

Field Day this year was a killer - I doubt we will beat that score anytime soon, with 10 open most of the night. We had a couple hundred Q's on 6, too.

Last year all I had was a vertical. This year, I have a rather droopy dipole to supplement it. The dipole hears better on 10 meters, the vertical hears better on 20 and below. I expect to use them both a lot.


 
RE: DX as an Antenna Measurement Tool  
by K0BG on November 4, 2011 Mail this to a friend!
Maybe I didn't make my comment clear enough. All of the arguments are true, but just to a point.

Efficiency doesn't have a darn thing to do with the capability of an antenna (or working DX). Beverages are a very good example. They're rather lossy efficiency wise, but on top band they're just the ticket.

The aforementioned A/B comparison observations notwithstanding, they still don't prove gain, efficiency, or any other tangibility with certainty.

Alan, KØBG
www.k0bg.com
 
RE: DX as an Antenna Measurement Tool  
by K6AER on November 4, 2011 Mail this to a friend!
Put all your money into the antenna. If any money is left over just buy a radio. Any radio will do.
 
RE: DX as an Antenna Measurement Tool  
by N6RK on November 4, 2011 Mail this to a friend!
A few comments on A/B testing.

To test a transmit antenna, it is not necessary
to work rare DX pileups, or even work anything
at all. Simply listen to DX stations (which
don't need to be in rare DXCC countries) and
compare S meter readings between antenna A
and B. Notice I said S meter readings. Not
signal to noise ratio. A/Bing S/N is a
test is to see how well the antenna receives.
If you don't have a calibrated S meter, insert
an attenuator in series with the better antenna
and adjust it until the A/B comparison is a tie.
The attenuator reading is then the dB advantage.
Of course you need to do an appropriate suite
of A/B tests, because conditions can vary.
The reason why this works is the reciprocity
principle.

To illustrate this, my 160 meter vertical will
receive JA3YBK at something like 20 dB over S9
but the noise level is S9. A full size dipole
at the admittedly low height of 60 feet will
produce S9 from JA3YBK with a noise level of
something like S2. Without working JA3YBK with
both antennas, I know I will be 20 dB stronger
on the vertical. OTOH, I can hear JA3YBK much
better on the dipole, although copy is adequate
on the vertical.

In the recent DX contest, as usual, I found that
I was able to break some pileups very easily
while other stations in the same country were
deaf to me. I find that to be a very unreliable
indicator of anything.
 
RE: DX as an Antenna Measurement Tool  
by W1JKA on November 4, 2011 Mail this to a friend!
Nice practical article Alan.My DX measuring tools are my ears coupled with 3 basic proven antenna designs (which ever one works best at the time),I like to call it proper-ear-irrigation.
 
RE: DX as an Antenna Measurement Tool  
by AE5X on November 4, 2011 Mail this to a friend!
"The aforementioned A/B comparison observations notwithstanding, they still don't prove gain, efficiency, or any other tangibility with certainty."

Of course they do. An A/B test "outperforms" modeled comparisons or any real form of measurement over time at a particular installation when tangibility (DX in the log) is what matters. In fact, there's no better way to compare two antennas.

John AE5X
http://www.ae5x.com/blog
 
RE: DX as an Antenna Measurement Tool  
by AA4PB on November 4, 2011 Mail this to a friend!
The typical HF antenna gain is somewhat less than 10dB. Propogation gain on the other hand can be 20-30dB or more.
 
RE: DX as an Antenna Measurement Tool  
by N4JTE on November 4, 2011 Mail this to a friend!
I agree with 99% of what the author is presenting especially since the bands are finally coming out of the doldrums and Allan is correct that it's all about prop/ sunspots on the now open upper bands. Anything will work on 10 meters when the prop gods are in your favor and your mobile is heard in East Africa, means nothing as far as antenna performance other then some power is getting out.
A true test of any antenna is it's consistancy thru all kinds of prop and sun cycles, as I spend most of my efforts on 40 I have concluded that a well designed wire beam will excel and level the playing field when chasing DX or anyone else I wish to qso with during the last few low cycles.
My one% disagreement would be that a well engineered gain antenna will perform well in weak prop on the 40 and 80 meter bands and as such there is less luck of the draw involved when one learns to optimise their antenna experiments and be one those stations that everybody can hear regardless of the sunspot number, a good majority of the time.
In other words, build the best gain antenna you can put in the air and don't wait for the sunspots to show up.
I usually have three 40 meter wires up and switchable/ reversable, sorta like ABCDEF daily/ monthly/yearly tests which allows me to have mucho antenna testing comparisons to compare during the up and down cycles and seasons,, works for me. Dx contacts are but a small part of these evalutaions.
Tnx Allan,
Bob


Bob
 
DX as an Antenna Measurement Tool  
by K8DO on November 4, 2011 Mail this to a friend!
I know what is more important and it is the gorilla on the keyer, not the super antenna farm...
I have a friend who can walk into a contest, sit down in front of a radio, and in seconds have a run rate going that is double what the best operator in the crew was doing right before he walked in...
He operates his home station on a city lot with a single 80 foot tower and routinely cranks out 3.5 meg scores in CQWW with modest antennas...
 
DX as an Antenna Measurement Tool  
by AB9TA on November 4, 2011 Mail this to a friend!
All I really need in life is a piece of wire in the trees and some friendly propagation.

And then: Voila! I can now contact Walla! Walla! Washington..

73!
Bill AB9TA
 
More than One Slippery Subject Here  
by AI2IA on November 4, 2011 Mail this to a friend!
Alan presents a subject that invites confusion if not read very carefully.

It is not completely true that antenna performance is cast in stone by the laws of antenna operation. These "laws" go only so far.

The reality is that the installation, orientation, location, and even the imperfections of a given antenna do more to either increase its effectiveness or decrease its effectiveness.

Look at it this way: An antenna "model" is not the actual antenna standing near your shack. The map is not the territory. What you intended to build is not the same as what you built. If you think so, take it down and put it up again and unless you do that with uncommon exactitude, what you get the second time around will behave in a way not quite the way it was the first time.

This is why some of us, if not all of us, are fascinated and a little obsessed with antennas.

- Ray Mullin, ai2ia
 
DX as an Antenna Measurement Tool  
by WB0HZL on November 4, 2011 Mail this to a friend!
I really enjoyed the article and all the comments - like the "contest antenna" one. Comparing antennas is fun and gives on some sort of idea how they work for you.

Now for a lighter comment and one that has proven very true for me. The effectiveness of an antenna is based upon where it is placed and what DX you are trying to work (DX is relative to the band one is working). My antennas always seemed to work better in Germany than in the US when chasing DX on 15 meters.

Love this discussion.

73,
Trent
 
RE: More than One Slippery Subject Here  
by N3OX on November 4, 2011 Mail this to a friend!
AI2IA writes:

==================
"Look at it this way: An antenna "model" is not the actual antenna standing near your shack. The map is not the territory. What you intended to build is not the same as what you built. If you think so, take it down and put it up again and unless you do that with uncommon exactitude, what you get the second time around will behave in a way not quite the way it was the first time.
"
===================

I personally think a lot of good antenna design is to try to move toward things that work the same way every time you put them up even if you're a little sloppy.

Antennas that are too sensitive to their surroundings can't be trusted.

:)
 
RE: DX as an Antenna Measurement Tool  
by WA6MJE on November 4, 2011 Mail this to a friend!
When I work JT65-HF, receivers all over the world measure my signal report and sent it into www.hamspots.net. It is a built in feature of the software. I can A/B two antennas in this mode and see the signal report results and differences in almost real time. It is like having dozens of field strength meters placed across six continents tuned to my signal. If I get consistently better reports with antenna A compared to antenna B over a five or ten minutes of trials on the same day under the same conditions with essentially the only variable being either antenna A or B, am I not using DX as an antenna measurement tool? The proof of the pudding is in the tasting. Using signal reports sent to a reverse beacon I can see better reports from more stations with A, and lower signal reports from less stations with B, and indeed some DX stations to not decode me at all with B, to me this is pretty convincing evidence that A is better than B. This conclusion is based on objective not subjective data. It is an experiment that can be replicated under differing conditions with consistent findings across replications. While agree that simply having log book entries with DX is not evidence of antenna performance. On the other hand, with instantaneous world wide reverse beacon signal reports used to collect and report data on A/B antenna performance trials in a controlled experiment to me is using DX as an antenna measurement tool. I would not see any benefit in ignoring this data as I continue to improve upon my antenna designs.
 
RE: DX as an Antenna Measurement Tool  
by WB4TJH on November 5, 2011 Mail this to a friend!
While skill certainly is an important factor, one must firstd be heard.
 
DX as an Antenna Measurement Tool  
by N3QE on November 5, 2011 Mail this to a friend!
It is also possible to work stations around the world with 100W and a pretty lousy antenna. (When I was a kid I had a HW-100 and some twinlead stapled on the side of thouse as an antenna. I fondly remember working Japan many afternoons after school on the 15M CW band.)

W8JI's Gotham review sent me rolling on the floor laughing my ass off. http://www.eham.net/reviews/detail/4094
 
RE: DX as an Antenna Measurement Tool  
by N4UM on November 5, 2011 Mail this to a friend!
How about using statistical measures to evaluate antennas?

Most of us would agree that there are many variables affecting the appparent superiority of one antenna over another at any one point in time. Frequency, wave angle, direction, time of day etc.

Although these things are beyond our direct control we can use randomization procedures to gain some measure of "statistical" rather than manipulative control.

The simplest example would be to flip a coin to chose antenna A or antenna B before each QSO. A record is them kept of the received signal report. It really doesn't matter much what the basis is for a particular report since, in the long run, variations in signal reporting methods will balance out - as will many of the other variables affecting antenna perfomance such as frequency, direction, wave angle etc.

If there is no difference in the two antennas the ratio of the variance between the two antennas signal reports should be no different than the variance within each of the two separate sets of signal reports.

One may then apply statistical "tests of significance" to compare the two antennas in question.

This is a very simple design (a simple randomized design). It consists of randomly choosing to use antenna A or antenna B and recording the results over many trials with different stations. Obviously there will be lots of sources of variation besides differences in the two antennas affecting the results.

A somewhat more sophisticated design would be to run multiple A vs. B comparisons with the same station over many trials with different stations. In this type of design (a repeated measures design) sources of variation, such as those talked about earlier, are automatically controlled for and removed as sources of "error variance." When such extraneous sources of variance are removed it becomes easier to detect any systematic differences that may actually exist in the performance of the two antennas. A repeated measures design is more sensitive than a simple randomized design in detecting performance differences in the two antennas.

Statistical techniques such as analysis of variance and analysis of covariance have been quite helpful in the more "inexact sciences" when dealing with these sorts of problems.

Received signal reports can indeed be used as a way of evaluating antenna performance if one is willing to spend the time and effort to go about it in the right way! Whether or not it is worth it...is another question!
 
DX as an Antenna Measurement Tool  
by KC5PIE on November 5, 2011 Mail this to a friend!
I agree 100%
All that I use on 2-m is a home brew 1/4 wave ground plane and so far have worked 25 states on a mere 45 watts (fm). Persistence goes a long way. {grin}
73
 
RE: DX as an Antenna Measurement Tool  
by NI0C on November 6, 2011 Mail this to a friend!
N3OX wrote:

"Which piece of information about my 10 foot tall antenna is more useful for planning purposes? My list of QSOs, many of which I could POTENTIALLY have made on much worse antennas with much less power, or my objective field strength measurements and my description of the experiments I did to get them? Do they give you the same amount of confidence in your ability to work XZ and 3W on 40m long path if you chose to build my short antenna?

What I *actually do* in the real world with an antenna is what's important to *me.*
.....
But when I tell OTHER people to build it, I can give them a list of contacts a mile long and they might not actually know how my antenna works... maybe they saw a similar list of contacts from a mobile station."


Dan, your comments and questions are, as usual, spot on. I would argue though-- and your comment concerning the "ability to work XZ and 3W on 40m long path" would seem to support-- that the composition of the list of DX contacts matters, and that achieving WAZ, for example, might be a good measure of DX performance, at least on the low bands.

If you have an 80m or 160m antenna design that will fit my backyard constraints that might be superior to antennas I have used, a tangible way of getting my attention would be to tell me you had completed WAZ on 80 or 160 meters using the new design.

73,
Chuck NI0C

 
DX as an Antenna Measurement Tool  
by VE3CUI on November 6, 2011 Mail this to a friend!
"...To sum it up, I believe Tom Rauch, W8JI, said it best: "We should wipe the false idea from our minds that feedpoint impedance indicates efficiency, or that a log full of contacts means our antenna has high efficiency. It is very tough to judge a ten-fold change in antenna efficiency based on a log book."

Believe me, I'm speaking from my experience as a newbie Ham in 1971 when I say that the complete ABSENCE of ANY stations shown as having been worked in the log indicates LOW efficiency in the antenna department!

Strange, but as my antennas improved, the log book started to fill-up, too. What Tom have to say about THAT phenomenon...?! : >)

~73~
 
Theory is not reality.  
by AI2IA on November 6, 2011 Mail this to a friend!
I live on a lot that is 55 feet by 200 feet. The house is at one end. I have 17 HF antennas here. Some are wire antennas. Some are yagi antennas. One is a multi-band vertical antenna. In addition for VHF/UHF I have three disk cones, some mult-element yagi vertical and horzontal, and some vertical antennas. I have inverted vee antennas, offset fed dipoles, folded dipoles, and long wire antennas.

I use these one at a time. I inspect them regularly. Some have varying degrees of corrosion on them at various spots. Also there are eight trees of a good size that have antenna wire running through them.

Now, do my antennas interact with each other? I suspect that they sure do! Would anyone like to attempt to get a radiation pattern for each band out of this gaggle of antennas? Probably not.

Do my antennas work? They certainly do! I have no problems with them and the rigs have no problem either.
Do I get DX? Yes, of course. In my opinion, the folks who go deep down into the minute details of the models and the theory are missing out on the fun of just operating. It's the mathematicians and the antenna theory people who go mad, not the operators.
 
RE: DX as an Antenna Measurement Tool  
by N3OX on November 6, 2011 Mail this to a friend!
NI0C writes:

=========
"If you have an 80m or 160m antenna design that will fit my backyard constraints that might be superior to antennas I have used, a tangible way of getting my attention would be to tell me you had completed WAZ on 80 or 160 meters using the new design. "
==========

I certainly agree with that... The COMPLETION of low band WAZ is one of those things that is difficult enough that a poor RX or TX antenna actually materially decreases your probability of finishing. The error bars on that antenna's performance are tightened by the fact that I probably didn't work Zone 22 with 200W ERP from my full legal limit amp.

The composition of the list of contacts does matter provided you've heard enough details to get the full picture.

At the same time, if you insist on only ever using "battle tested" antennas, you might miss your chance to try something. This is especially true because it's not actually necessary for someone to be as good at or as committed to your desired goal to design a superior antenna for your situation... Maybe their circumstances just don't allow them to achieve the goal you're interested in. Maybe they like antennas a lot more than they like DXing.
 
RE: DX as an Antenna Measurement Tool  
by NI0C on November 7, 2011 Mail this to a friend!
quotes from N3OX:

"At the same time, if you insist on only ever using "battle tested" antennas, you might miss your chance to try something."

On the other hand, as VE7IG pointed out above, one can also be discouraged from trying something if one listens to some of the advice given by theorists who don't take into account real world constraints that people encounter.

Here's an example. Several years ago, I was facing the limitations imposed by my HF-2V on 160m. After experimenting with top-loading schemes, I was looking for something better. I read a review of the Cushcraft MA160V that VE9DX wrote here on eHam. Then I read some comments on the Top Band Reflector by people who hadn't actually tried the antenna, but had opinions about it anyway. I was put off by some of their remarks, but ended up trying the antenna based on VE9DX's experience. I'm glad I did. Due to the constraints of my property, it's the best I can do on 160m. I won't achieve WAZ with it, but I do have 29 zones worked...


"...it's not actually necessary for someone to be as good at or as committed to your desired goal to design a superior antenna for your situation... Maybe their circumstances just don't allow them to achieve the goal you're interested in. Maybe they like antennas a lot more than they like DXing."


This is true, Dan, and I do not mean to disparage the work of theorists. I found the article above rather off-putting, though, as it seems overly dismissive of practical experience. I think we need a balance between theory and practice. I think an antenna review is missing something if it isn't peppered with some real world anecdotes from the station log.

73,
Chuck NI0C

 
RE: DX as an Antenna Measurement Tool  
by AD7II on November 8, 2011 Mail this to a friend!
Amen, K6AER. ("Put all your money into the antenna. If any money is left over just buy a radio. Any radio will do.") Well said. And when buying a home, put all your money into the lot. If any is left over, add a house. The lot will appreciate, the house will depreciate. And the less house you have, the more room you have for antennas.
 
RE: DX as an Antenna Measurement Tool  
by KO3D on November 8, 2011 Mail this to a friend!
"c) In a pile-up, while it obviously depends on the DX operator, in many cases the biggest signal wins."

I've reached the conclusion that it is the DX operator who makes the biggest difference when running lower power. It's simply a matter of his preferring to answer the large stations. I've had DX answer my 100W vertical with 1500W calling next to me because it seemed he wanted to give a weaker signal a chance. This is reinforced by the fact that during a contest when my call's needed they suddenly hear me better. Also note that 50 US stations can call in a pileup and the DX can hear the rare country through it.
 
RE: DX as an Antenna Measurement Tool  
by N3OX on November 8, 2011 Mail this to a friend!
NI0C writes:

=============
"Here's an example. Several years ago, I was facing the limitations imposed by my HF-2V on 160m. After experimenting with top-loading schemes, I was looking for something better. I read a review of the Cushcraft MA160V that VE9DX wrote here on eHam. Then I read some comments on the Top Band Reflector by people who hadn't actually tried the antenna, but had opinions about it anyway. I was put off by some of their remarks, but ended up trying the antenna based on VE9DX's experience. I'm glad I did."
==============

I have a lot to say on this topic because I absolutely agree we need to balance theory and practice but I also think we need to be careful about what practice really tells us and also what PREDICTIONS are actually NEEDED by people. There's a big difference between electromagnetic theory and what we might call "amateur radio success theory" but I think that a lot of people see them as the same thing and that causes a great deal of trouble.

I have rewritten a long version of this comment enough times that I think I have to write an article :)
 
RE: DX as an Antenna Measurement Tool  
by NI0C on November 8, 2011 Mail this to a friend!
Dan,
Your article sounds like a worthwhile endeavor. I'll look forward to seeing it.
73,
Chuck NI0C
 
RE: DX as an Antenna Measurement Tool  
by N0AZZ on November 9, 2011 Mail this to a friend!
Tom has designed some of the best antennas around his Short vertical array sold by DX Engeering is the best receiving antenna I have ever owned. I have yagi's for all bands up to 40m and wires for 80/160 also use a vertical for 10-80m bands with 64 radials plus a single 160m vertical.

Up till the time I installed the array I had no idea of all the stations that were coming back to my calls that I couldn't hear before. I am unlimited as far antennas go live in the country on a farm.


There is quite a difference between antennas when you can switch between 7 different ones easly I use a Bird coax switch. Then switch between 4 transcevers and a SDR setup that go from QRP to QRO.
 
RE: DX as an Antenna Measurement Tool  
by W7ETA on November 13, 2011 Mail this to a friend!
Great prose OM--easy to read and understand.

The theory that the amount of DX one works proves how good an antenna is indeed flawed.

Many years ago I learned this simple truth: correlation is NOT causation.

73
Bob
 
RE: DX as an Antenna Measurement Tool  
by KD8NGE on November 15, 2011 Mail this to a friend!
Gentlemen,
Thank you for this interesting line of discussion.
I learned long ago the veracity of the adage, "A little knowledge is a dangerous thing" when it finally became clear to me that I know just enough to get in trouble.
My lot is small; my QTH is in a HOA; my antenna thus far is long magnet wire NVIS with a tuner, which works fine for its usual radius; my magnet wire vertical component used to hang over the top fork of a mostly dead tree in the back yard, until a severe wind storm took down the wire.
When you share your ideas and your experience, you are benefiting more than just the participants in the thread.
73, Will, KD8NGE
 
DX as an Antenna Measurement Tool  
by W4FOX on November 15, 2011 Mail this to a friend!
I agree with this article completley.

"If one selects the correct band and mode of operation, erects even a minimal antenna, and drives said antenna with just a few milliwatts, it is possible to communicate with another amateur anyplace on the face of this earth, DX or otherwise."

I am a prime example of this statement. I have a home made 10 meter DP cut for 28.400 MHZ that hangs under a porch that is about 14 feet above the ground in my apartment complexe. I use a max of 90 watts out (dependinging on contact) on the radio and have been able to talk all over the world. I have been having the time of my life.

W4FOX
Jeff
 
DX as an Antenna Measurement Tool  
by KA4JNB on November 17, 2011 Mail this to a friend!
I thought AD7II was going to mention this aspect of DXing, but didn't quite make it.

And that is what Real Estate agents drum into their customers-LOCATION, LOCATION, LOCATION!!

I learned a valuable lesson too late in life. As an avid DX chaser, I made the mistake of not examining a topo map before buying my home site. Because of strict CC&R's imposed in my subdivision, I chose a lot reaching 425' back into the forest, where antennas can easily be hidden. (And my primary antenna was a full wave 2 el, 5 band Lightning quad hung from a maple tree limb, with the bottom elevation of 8 feet).

With this setup I was reaching the world, except those few countries I very much needed in Asia. At that point in my new life I learned that the highest point in my county is 300 yards Northwest of my QTH, and I am in the lowest elevation in my subvision!

If I had waited a year to build and move, my house could have been the one on top of this barrier.

However, with the fantastic improvement in propagation lately, even the barrier is being overcome. I got VK9CM, and am hearing both Veitnam and Cambodia evenings, and will get them yet

I obtained 5BDXCC and 5Band WAS at my old location in the same county, with the quad at 40 feet,and a full wave 80 mtr German quad strung directly over a 3 acre pond. (With an antenna tuner, that quad could work 80 to 2 meters, till the beavers cut down the trees it hung from!!)

Happy dxing, and try to not resent ARRL taking countries away faster than they add them. 73, Ira
 
RE: DX as an Antenna Measurement Tool  
by W4HV on November 18, 2011 Mail this to a friend!
I love hearing how the scientifically minded feel it needful to expound on angles of radiation, take-off angles, gound effects, and various others they must have satisfied before they will believe anything! Science also says the bumblebee can't fly!
Our reality is that when we can hear and talk to people on the air it is a good antenna!. That is over simplifying I know. Its really hard to convince someone who has worked 310 countries on 100w and a basic dipole that it could have been easier on a different antenna.
Personal experience is hard to combat because it is personal and subjective in its nature. Honestly, a resonable comparision can be made by operating the same equipment from the same station with the same operators. Band conditions do indeed play a part in it, as does operator skill! It can, however, be extrapolated that one antenna is better than another when lets say field day scores vary on a 2a station from 1100 qso's on one year to just over 300 antoher year with the only change that is controlable being a change of antenna! This actually happened to Kingsport Amatuer Radio Club!..The logs do prove something..Either there was major solar flare, the operators didn't op or the antenna used in the lower score SUCKED! It could be expected that the social situation could have changed and no one tried hard, or they all got loaded and didn't care(not likely with that group). There was a major flare..Space weather says not so!..Or the antenna used the second time just stunk!..So yes a log can prove some things if it is used with wisdom to discern the other qualities..Partiularly when other clubs operating were within 10% of their previous years score(which is the norm for such operations.)..So yes logs can prove some things if used in the right circumstances! They can be a good lab experience if adjusted for the control group of stations operating at the same tiome from within close ranges of less than 50 miles.
I know this happened on the field days 3 yrs ago and 2 years ago!.. The difference was the antenna used.. This year the antenna used in the high score year was used at the Johnson City, TN groups field day and yield a significant increase in score.. So yes it can tell something is different. The numbers are just less clear than range measurements.
 
DX as an Antenna Measurement Tool  
by VE3CUI on November 19, 2011 Mail this to a friend!
"...I love hearing how the scientifically minded feel it needful to expound on angles of radiation, take-off angles, gound effects, and various others they must have satisfied before they will believe anything! Science also says the bumblebee can't fly...!"

RIGHT ON, W4HV!---you're a man close to my own heart!

~73~ de Eddy VE3CUI - VE3XZ
 
RE: DX as an Antenna Measurement Tool  
by W7ETA on November 22, 2011 Mail this to a friend!
"Science also says the bumblebee can't fly!"

Science does not say anything.

Researchers document their research, interpret the results, and then assert conclusions in a peer review journal.

Other researchers will criticize the paper.

The researcher's paper might withstand the test of time.

I suspect the statement that researchers cannot explain how or why a bumblebee flies is an old wives tail, mythology akin to a penny thrown off the Empire State building can kill people at street level.

73
Bob
 
DX as an Antenna Measurement Tool  
by W6OGC on November 28, 2011 Mail this to a friend!
I eavesdropped on an interesting QSO in progress recently. The ham was explaining the importance of various factors in working DX, etc. The most important factor, he claimed, is propagation, then location, then antenna, then operator prowess, then equipment.

If the bands are not open, go watch TV, I believe he said. For location, being up high, on a hill vs. in a valley, near the coasts vs. inland etc. The point is a good operator can do very well with modest gear, a decent antenna is better but location and propagation count most. Interesting! The lesson here is put more money and effort into your antenna than the gear, and master operating skills.
 
DX as an Antenna Measurement Tool  
by KF6A on December 7, 2011 Mail this to a friend!
I believe you're quoting Tom out of context to support your flawed premise, which also assumes that anything Tom says is axiomatic.

You can flap your gums all you want and quote anyone you wish in an attempt to support your underachievement but a log full of stations is more proof of performance than a forum filled with bullshit and a whole lot of talk.

Money talks and bullshit walks. That axiom holds true in every walk of life. In contesting I've beaten many people who have a lot more money invested than I have, running a lot more power than I do and who live in a much better RF location. What does that prove? I don't know, you tell me since you are taking the position as the "expert".

The bottom line, regardless of limitations or amount of money is how you do compared to your peers? How do you compete compared to others with stations similar to yours? How do you compete with stations supposedly inferior or superior to you yours?

Exactly what does that mean? Does that mean some can do better with less? Most certainly yes! Does that mean antenna A is better than antenna B? Not necessarily. Skill can most certainly trump absolute antenna performance and money spent but the returns diminish very quickly and at some point no amount of skill can surmount the amount of money spent. Does that mean the person who spent the most amount of money has the most knowledge as to what works best? I say no, and I show what I know by competing in contests with what I have, with what I've installed compared to others.

To talk about DX as an antenna measurement tool requires a context. Where one lives (propagation makes all the difference and I can tell you moving from CA to MI made a GINORMOUS difference in what and the amount of DX I can work), how much about antennas one knows (if one knows squat about antennas and installs his station with built-in issues then the results are not necessarily normal nor comparable to other setups). The situation you've set up has nothing to do with antenna knowledge or performance and depends on someone else with a huge contest station to support your premise. You claim DX performance is NOT proof of performance, but I state it is, in context. What have YOU done to support your statements? Stated differently, what performance proof do YOU have to support your statements?
 
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