If what you have to work with is a treeless, postage stamp sized lot and overly vigilant community association, a ground mounted vertical is likely your best option. Based on my experimentation here, a ground mounted vertical probably won't work quite as well as a dipole at 6/10 of a wavelength above ground or a full wave loop, especially for stateside contacts, but as long as you install at least 60 ground radials, it will work well enough for DX to keep your Amateur Radio enjoyment up for a long, long time! Also, on the low bands, it's difficult to get dipole antennas up to optimum height. That's why a vertical can be a good choice for those bands, at least as a transmitting antenna.
One argument favoring verticals is that they are excellent DX antennas because of their low take off angle, but the myth behind that thinking is well explained here. To summarize, a ground mounted vertical with only 16 radials will have an excellent looking pattern and its strength is DX, but when you examine the numbers, you realize it only has 2.21 dBi of gain. A dipole at the proper height will provide 8.71 dBi of gain with a reasonably low take off angle.
A vertical has a good, low angle radiation pattern in all directions, but with 16 radials has only 2.21 dBi of gain. Graphic courtesy Tom Rauch, W8JI.
From my observations, the reality is that while a ground mounted vertical with 60 ground radial's strength is DX and occasionally superior to a dipole, it doesn't quite match a dipole for DX in most cases. For stateside contacts it compares less favorably and can be down by up to several S units. Still, if your limited space or neighborhood restrictions limit your options to a vertical, with 60 ground radials, it works well enough to make it well worth building one!
I Couldn't Help Wondering...
I am really happy with my current antenna farm, but I'm always interested in trying something new. I also wanted to see for myself just how good or bad verticals really are. I decided to compare a ground mounted Hy-Gain AV-12 AVQ, Triband HF vertical for 10M, 15M & 20M to my loop and dipole antennas.
Experiment 1 - Vertical Attached to Ground Rod with No Radials
I started by simply planting the antenna on a ground rod:
A vertical attached to a ground rod without radials can fool you into thinking it is working,
but as soon as you compare it to another antenna, you will realize it is a poor performer.
The results were as expected for a ground mounted vertical without ground radials - uninspiring. But, here's a really important point. If you don't have a reference standard antenna like a dipole (or any other antenna) to compare it to, it is easy to think the antenna works well. Even without ground radials, you hear 59 signals on the vertical, you call them and they answer you, so all must be good?
Then you switch over to a dipole, the 59 signals jump to 59+20, all other signals are 2-5 S units higher than they were on the vertical, you hear many more stations on the band that you didn't even realize were there and the lack of the vertical's performance becomes obvious. Without a comparison antenna, there would have been no way to determine just how poorly the antenna was working. If all you have is a vertical antenna and nothing to compare it to, it is easy to believe the antenna is performing better than it really is.
For contesting, I suspect the vertical would be extremely difficult to maintain an hourly QSO run rate higher than the teens, if that, with the antenna in this configuration, without 60 ground radials.
Experiment 2 - Vertical with 60 Ground Radials
The next step was to try the antenna with an adequate number of ground radials. Based on my research, 120 ground radials are considered optimum and the professional standard, but 60 ground radials will achieve 80% of that efficiency, so I used 60 ground radials, each 16.5 feet long, which is roughly 1/4 wavelength on 20 meters. I ordered 1,000 feet of 18 AWG wire from the Wireman (part # 501):
I was impressed with this wire and I wouldn't hesitate to order more for other projects. It was inexpensive (1,000 foot roll was only $52 in 2014) and with each of the 60 radials cut to 16.5 feet long, the 1,000 foot quantity was about perfect.
Installing the radials was much quicker and easier than I imagined. I didn't bury the radials, but I otherwise cut them (with Brad's help), laid them all out by myself and soldered them up in just about 2-3 hours.
To make soldering the ground wires together easy, I cut a 30" loop of wire and put marks every 1/2 inch with permanent marker, so I would have relatively even spacing of the radials.
30" wire loop to which the 60 ground radials will be attached. Marks every half inch to help with spacing.
The loop also has four wires that connect to the ground rod:
60 ground radial wires soldered to the loop, plus 4 wires running form the loop to a clamp on the ground rod.
I just put a bend in the end of each ground wire and then crimped them against the loop. Then I pulled them out straight, put a roughly 2" bend in the far end and stuck it in the ground, just to keep it in place. After all the ground radials were pulled in place, soldering them to the 30" loop was easy and only took a few minutes.
After the radials were all connected, the difference between a vertical with no ground radials and a vertical with 60 ground radials was obvious! The vertical's performance increased dramatically! It also had a much better SWR curve on 10M (15 & 20 were already okay). In many cases, the loop or dipole were now only 1-2 S units better than the vertical. In some cases, the vertical was equal or even slightly better!
From here in Maryland, my first contact with the vertical was W1AW/4 in Florida. He was slightly better on the loop, but I went ahead and called him on the vertical with 100 watts. He had several stations calling him, but he answered me on my first call.
I then heard ZS2XD (South Africa) running a frequency. With 100 watts it took four calls to get through the moderate pile up on the vertical. He gave me a 55. Once I established contact, I asked him if I could do an A/B comparison between my vertical and my loop. He said it was about the same, but the vertical might be slightly better. That's what I heard here on receive as well. I think South Africa might be in a null of the loop, but still, not bad.
On a stateside net I was able to do an A / B comparison and the vertical didn't fare as favorably, being 2-3 s units down, but all the stations were west, in the sweet spot of my dipole. DX stations seem to compare most favorably.
The takeaway from this is that, if you can put up a dipole at 6/10 of a wavelength above ground or a loop, that will probably work best (besides a beam of course). A vertical might not be the ideal antenna for anyone with enough room for a dipole, but with 60 ground radials, a vertical covers enough points on the globe with enough signal strength to keep Amateur Radio fun and interesting for a long time! If a vertical is your best option, go for it, but don't skimp on the ground radials! 60 ground radials are a must! It only takes a few hours to install the radials, it's cheap and you'll enjoy the results for decades!
Here are a few other even less expensive, more stealthy vertical ideas to ponder:
A ground mounted vertical for 20, 15 and 10 meters can be very stealthy and low profile. It could even be disguised as a short flag pole!
For the radiator, you could either use rigid aluminum, or if there is a handy branch, you could just pull up copper wire with a line, using PVC to keep each of the three radiator wires spaced a few inches apart. It would only be about 16.5 feet high on 20M, 11 feet on 15M and 8.2 feet on 10M. It would definitely be tough to see. Here is a concept drawing for what I have in mind:
20M, 15M and 10M vertical concept drawing.
Here is another stealthy, 40 meter vertical antenna design that Shawn, N3TEE sent along that you can implement with a single tree. Shawn writes:
If you really want to get a good performance try a 20m vertical dipole fed with 450 ohm ladder line and tune with a manual tuner for working 20m-10m or an elevated 40m ground plane with 3 radials fed with 450 ohm ladder line and tune with manual tuner. I have used this antenna with very good results and used 80m and 160m at reduced power.
Image courtesy Shawn, N3TEE.
I started doing some casual Goggling on radials for ground mounted verticals. It is interesting stuff. To boil it down...
- If you expect your vertical to be anything more than a glorified dummy load, you've got to install LOTS of ground wires. Just connecting it to a ground rod or laying out a dozen radials isn't going to cut it. Sure, burying 60 radials is hard work, but it is a one time task, good exercise (that is a heck of a lot easier than digging a tower base) and you'll likely be satisfied with the resulting performance for years to come. Otherwise, you are going to be frustrated and disappointed.
- Professional broadcast stations use 120 ground radials at 1/4 wave length.
- The absolute minimum number of radials for any kind of reasonable performance is 30 radials, but plan on 60.
- The exact length of radials is not important.
- 60 ground radials will yield 80% of the the professional standard, so the returns diminish after 60.
- Ground radials do not have to be 1/4 wave length. In fact, 1/10 wavelength is fine if you are only going to put out a few dozen, but the more you put out, the closer to 1/4 wavelength they should be. For 20 meters, 1/4 wavelength is about 16.5 feet, which isn't long, so plan on 16.5 feet. That requires just slightly less than 1,000 feet of wire (16.5 X 60 = 990 feet). You can easily do that for only about $52 using part 501 at the Wireman (2014 pricing).
- If you do decide to use less than 1/4 wavelength ground radials, it is much better to use a LOT of short radials than just a dozen 1/4 wavelength radials.
- Radials don't actually have to be buried. You can use a hammer and staples to hold them against the ground, about every 18 inches or so. Within a year, the grass will have grown around them so that they will essentially be buried anyway and the staples will keep them down so you can mow in the mean time.
Two important safety tips and a disclaimer: First, contact with overhead power lines can kill you! Always be mindful of the location of your power lines, your ladders, handling antennas, other metallic objects, etc. Second, you should always evaluate the placement of your antennas and address any RF exposure risks as detailed here. Any actions that you take based upon the information presented here shall be solely at your own risk. Neither N3FJP Software, our employees or any of our contributors shall be held liable for any actions taken based upon the information presented on this website.
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