W8WWV - Dipoles versus Verticals

Greg Ordy


Introduction

I guess it must be human nature to try to sort and rank similar items. Discover the best place to take a vacation, the fastest sports car, the golf ball that will travel the furthest, the safest part of town, the best football team. Much of life seems to consist of debating the correct ranking with the people around us. I'm all for learning and debating, but often times these exchanges end up heated and painful. The usual reason is that one or both sides decides that their opinion on some single topic is a referendum on their whole character and value as a human being. So, when I disagree with your choice for fastest sports car, you hear that I am saying that you are a dumb, ignorant fool. Of course some people do indeed put forth their case in such a personal attack style, and that is not much fun to witness either.

Sometimes, two parties will have a disagreement without even really understanding what their assumptions and goals are. For example there could be a disagreement over the best sports car. After much debate, we learn that one side is really taking about the fastest sports car, and the other is talking about the sports car with the best handling in tight curves.  Until this difference becomes apparent, the discussion is, at best, a waste of time.

Another common source of argument and disagreement is not being clear about the difference between best, and best value. In the world of amateur radio, this is often seen in disagreements about different radios. Every so often a new top of the line radio comes out from one of the popular brands. Some people point out the new features and performance, and if it is truly a top of the line radio it probably is excellent (for that point in history). But then other people will chime in that they will never trade in their old and faithful Boat Anchor 100, noting that it can make about all of the contacts that the fancy new radio can. When you look closely at the different points of view, it is often clear that one side is discussing features and performance without concern for the cost of the radio. The other side is unable to separate the cost part of the equation. They always need to be considering value, which could be expressed as cost per function, as opposed to pure function. If you don't make it clear what you consider important, than these discussions can turn into arguments, and mainly due to misunderstanding. My own experience, and not just in radio, is that you usually pay a premium price to obtain the latest and best, but that the best value is always obtained in something which is a few years old, and probably used. A 10 year old transceiver which might cost $500 on the used market will make probably 99% of the contacts that a new $3000 transceiver can. I'm happy to say that the used radio is a better value. On the other hand, the new radio probably does have a lot of extra bells and whistles, as well as provide higher performance. I'm happy to say that it is the better radio. Sometimes the people who seek better value ridicule the person willing to spend top dollar for the new gizmo. I've always found this thinking a bit puzzling since it is necessary for somebody to buy the new and expensive item in order for it to become used and a better value. As they say, it takes all kinds.

 

One of the classic arguments in amateur radio is whether a dipole or vertical is the best antenna. I get the sense that conventional wisdom believes that the dipole is better. This is usually summed up with the criticism that a vertical is an antenna that radiates equally poorly in all directions. Part of the reason that the debate rages is that different operators report wildly different results when using the two different antennas. This particular debate is often carried out without benefit of the details of the circumstances and expectations of the operators. As such, it is usually never an apples to apples comparison, but rather an apples to oranges fruit salad.

I would like to try to use this page to look at some of the differences between dipoles and verticals. Part of that journey will be through the prism of my own experiences.

My Own Experiences

I was first licensed back in 1969. I was a 15 year old who had to convince his mother to drive 60 miles into Chicago so that I could take a radio exam. That was back in the days when (for other than the novice license) you had to visit an FCC Field Office to take the amateur radio exams, administered by FCC employees. The FCC Chicago Field Office was in the Federal Building, and that was also the time of the Chicago Seven trial. That heated trial caused the installation of metal detectors at the building, which were very new at the time. Just driving into Chicago from the rural farming area was an experience, then, we had to go through a metal detector, which seemed like some sort of science fiction device. Who would have guess that 30 years later they would become standard at so many places, such as schools.

The testing room was a rather cold office with a set of school-like desks. In the middle of one room was a Morse Code generation machine. My fate rested with that machine. Back then, you were given the receiving test first, which could be given to a number of people at once. If you flunked out, you had to leave, no sense in taking the transmission test, or the written test, after all, you failed. I handed in my written page, and all that came back was the news that I passed. That put me in line for the transmitting test. Now, one by one, each passed receiving applicant got to take center stage and transmit. While the test was specified to be several minutes long, it seemed to be a common convention  that once the examiner decided you passed, he told you to stop. After all, there was a line waiting.

Finally, you got to the written exam. In many ways this was easy part. In fact, on one day I took the 13 WPM Morse Code test, as well as the General and Advanced tests, as well as a commercial license test. I never used the commercial license, but when you are 15, everything seems to be about getting licenses, especially that drivers license.

Licenses gave way to radios, and I was able to convince my parents that helping me buy a Heathkit HW-100 would lead to a good learning experience.

All of this was going very smoothly, but then I needed an antenna. We lived in an apartment at the time, We were on the top floor, and very fortunately, on the end of the building. We were on the third floor, which really was the 2 1/2 floor, since the first floor was partially underground. After a few poor ideas (well, poor antennas), my solution was to take a bare solid wire and hang it out of my window, dropping about 60 feet  of wire down to the ground. I went outside in the middle of the night, and using a long wooden pole, I was able (after a lot of work) to bring the wire around the side of the building, under our bathroom and kitchen windows, and around the other corner, ending on our balcony. The building had a brick exterior, and I was able to run the wire in the mortar joint between the bricks. That helped support the wire, and made it nearly invisible. Back in my bedroom, the shack, I had a simple L network tuner consisting of a variable capacitor and inductor mounted on the lid of a wooden box, which was a woodshop project at school.

This end-fed wire actually worked, and worked better than all of the other dumb ideas I played with. In retrospect, I realize that 1969 was near a peak in the sunspot cycle, and that will make about any antenna look good (on the shortwave bands). I spent a lot of time ragchewing with several other hams in the area on 40 meters. Another helpful circumstance was that one of the hams (Al, K9CCL) ran a Collins S-Line with the 30S-1 amplifier, and had a delta loop antenna for 40 meters pulled to the top of his 90 foot tall tower. In many cases I would work stations because they would call Al, and I would end up getting a (poor!) signal report out of it. For example, this is how I worked Antarctica on 40 meter SSB. This situation helped that antenna work a lot better than it really was.

My point is that circumstances started me down the road of using an end-fed long wire with a tuner on all of the lower bands. If nothing else, the antenna was great value, costing next to nothing, and allowing me to make contacts on all of the bands available on the radio.

After high school came college, and some moving around to several rented places where antennas had to be temporary. The end-fed long wire was replaced with a dipole fed with twin lead back into a Johnson Viking Matchbox tuner. The dipole was as long as it could be to fit between the two highest trees which I could use. This antenna was also a very good value, providing coverage on all shortwave bands for very little investment.

What happened next was a lot of my adult life, including moving to a house on a 5 acre lot. I was rather inactive in the hobby then, but I always had that station (a Kenwood TS-440 replaced the HW-100) with the all-band dipole, and in the back of my mind I knew that more space would open up all sorts of antenna choices, if I wanted to put them up.

Finally, some invisible force drew me back into the hobby. As I started to operate a little more, I found that my home intercom system was very sensitive to RF, and my transmitter would generate interference, especially on 40 meters, what had been my favorite band, in the old days. Being an intercom, noise and interference was efficiently distributed to all 9 wall speakers located all over the house. My own conclusion was that the problem was that I had open wire line so close to the house. I wanted to replace it with coax, but still have that all-band antenna. Even then I was smart enough to know that it's usually acceptable to run rather high SWRs on open wire line, but a bad idea (due to excessive loss) on coaxial cable. So, I needed a multiband antenna that matched well to 50 Ohms on all bands. The antenna that caught my attention was the Butternut HF-6 vertical.

Yes, I had heard that a vertical was an antenna that radiated equally poorly in all directions, but this one offered all-band operation with a good match to coax. But what about the need for radials? Radials always seemed to introduce magic to verticals. Are they essential or optional? Can they be elevated, or laid on the ground, or do they have to be buried? Boy, that seemed like a lot of work. How many radials? How long?

While I had few answers to begin with, the good news was that I had a large open area about 150 feet from the house which also happened to be located over my septic tank leech field. It was just open field, and I figured that it was far enough from the house that RFI would be greatly reduced, and hopefully eliminated. The feedline would have to run over the grass, but this was an experiment, after all, and if the antenna worked out, I could consider burying the feedline.

I drove down to the local Amateur Electronic Supply (AES) store and came back with a small box all full of aluminum tubes and inductors. I drove a few feet of metal pipe into the ground to act as a mount, and in an afternoon I had the Butternut vertical antenna proudly pointing at the sky. From living  in a more rural area I had already started shopping at stores that catered to farmers, and I knew that I could buy an entire 1/4 mile of wire for electric fences for something like $7 (USD). So, I got a spool of electric fence wire, and for good measure I drove an 8 foot copper ground rod into the ground next to the mounting pipe. I simply wound the fence wire around the top of the ground rod, and as I added radials I kept making a big nest of wire around the ground rod. After 24 radials, I got out the propane torch, heated up the mass of metal, and applied a few feet of solder. My radials were some strange mix of 20, 40, and 60 feet long wires. It probably looked more like an antenna crop circle than anything else. I was unclear about the length versus resonance issues, and these lengths seemed to be nice for bands such as 80, 40, and 20 meters.

Upon going back into the house, my whole amateur radio experience changed. First, the RFI was gone. No noise, no interference, no hot microphone on the lips, all gone. The important difference was that I was now hearing and working stations that I never knew existed. I should also mention here that again, this was at a good point in the 11 year sunspot cycle. Still, this antenna was clearly much better than the dipole, especially on DX, which now seemed almost easy to work. I remember a turning point when I happened to wake up on a weekend morning, right near sunrise. It was the weekend of some contest, although I didn't know which one, and really didn't care. I set the radio to the 80 meter phone DX window, and there was a station in New Zealand calling CQ contest. I gave him a quick call, and without smoke or mirrors, I worked a ZL on 80 meters. The other side of the world on 80 meters with 100 watts and a vertical. This seemed impossible with the dipole.

Perhaps more than anything else, I now had two antennas to play with. It was possible to switch back and forth and note that in some cases the vertical was better, and in some cases the dipole was better. Speaking very generally, the vertical was better for DX, and the dipole was better for local stations. But the truth is that I could still work local stations with the vertical, even if they were stronger with the dipole. That twin lead hanging out of the window, with its associated RFI, soon became a real ugly sight, and it was a happy day when the dipole came down. It was a good trade-off (for me) to steal some signal strength from the armchair copy locals and give them to the DX, which often times brought the DX out of the noise.

Not that I was amazed, but it was soon clear that antennas were the primary factor in having a station that could work the largest number of other stations. Over the years a tower and beam went up, and I currently have 7 verticals, several miles of radials, and a whole mess of strange receiving antennas for the lower bands. The drawing board is still full of ideas. I certainly have better antennas, but I bet that the best antenna value was the Butternut. I added the 17 and 12 meter kit, and that one antenna gave me 7 band operation for around $300 (USD). Yes, that was more than the dipole with open wire transmission line, but for what interested me, it also performed much better. In the spirit of full disclosure I also added linear amplifiers, going through the 800 watt and then 1500 watt level. That certainly helps, but a lot of my antenna work happened before I added the first amp, and on reception the amp doesn't matter. I can tell that I can hear more, and as we all know, if you can't hear them, you can't work them. Now, my 5 acres seems way too small for a real antenna farm. As they say, the grass is always greener on the other side of the fence.

All along this journey I had to confront many of the rumors, old wives tales, and conventional wisdom about antennas. It wasn't so much that all of this lore was wrong, but rather the devil was in the details, and often times there were unstated assumptions which created confusion until you took them into account. Another factor that entered the picture was that I started to model and simulate antennas. This added an analytical dimension to the experimentation.

The remainder of this page will consist of some of the lessons I learned along the way. Looking back, the journey was, is, and I bet will be, the fun.

Simulation Results

Within reason, the dipole/vertical question can be answered with antenna modeling or simulation. Let's start there.

Butternut HF-6 versus the MFJ1278

ground loss, radials, height, take off angle

Can My Antenna Be Too High?

Another piece of conventional wisdom is that you should get as much wire as high as you can in the air in order to have the best antenna. Within reason, there is a lot of truth to that simple idea. There are cases, however,  when an antenna can indeed be too high.

One example is the height of a directional antenna such as a Yagi or quad located on top of a tower. It might very well be true that higher is not better.

I used the NBS 5-element Yagi model supplied with the EZNEC modeling software.

take off angle, free space pattern, effect of ground, distribution of arrival angles. LAWSON LEESON

 

 

Can I ever have too many Antennas?

No.

From time to time, and contact to contact, the best antenna will change. Even what might appear to be a much weaker antenna will have its moments. I would suspect that a 5-element 20 meter monoband Yagi mounted at 70 feet would be generally much better than a 20 meter inverted vee mounted at 15 feet (the apex) off of the ground. Still, there will be contacts when that low inverted vee will provide a stronger signal. If a given operator happens to favor operating in large roundtable contacts with many participants (such as the typical net), they may prefer an omnidirectional vertical to a directional antenna, even if the directional antenna has substantially more gain in its favored direction.

Perhaps the only antenna which is ever excessive is the one that falls down on your neighbor's property.

I started off in amateur radio with one antenna for all bands. Now, I seem to want many antennas for each individual band. I would certainly choose many antennas over many radios. 

This page is currently under construction. Check back soon.

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Last update: Saturday, August 30, 2003 12:01:48 PM
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