10 Meter Vertical Antenna Questions

[KM4GGD]

I have several vertical antenna questions but I'm going to start with height first. Not a question of how high is best but simply, "how high is this antenna?" (see diagram)

I live on the side of a mountain about 3,600' above sea level. There is very little flat ground around where the antenna can be installed so I have it hanging from a tree (on the side of the mountain) with the bottom of the antenna about 25' above the (sloped) ground. From that point it's another 20' to a wide section of flat ground below.

There are no radials on the antenna at this time. I bought the radial kit and installed it but there was no difference in transmit or receive quality so I took them off for now. I plan to experiment with different locations and higher trees and at that time I'll try them again.

In anticipation I'll answer some expected questions.

(*) I chose the Solarcon A-99 because it's an inexpensive antenna to experiment with. If I get positive results I'll probably upgrade to a better performing antenna but if I don't, I won't loose any sleep over what I spent on this one.
(*) I've been using a 10 meter dipole but my local ham club is starting up an HF net and almost everyone is getting better results with a vertical. We're all between 30-50 miles apart. I've tried both the dipole and vertical and I'm in agreement, for some reason the vertical is out performing the dipole hands down.
(*) We are all in mountainous areas and most of us are over 2,500' above sea level.

The big problem at this time is I don't know what I don't know. And to start with, I don't know how high above ground this antenna actually is. My goal is to place it at approximately 1.5 wavelength above ground, or about 53' for 10 meters. But with so much sloped ground below the antenna I don't know what to expect the radiation pattern to look like.

So how high is this antenna now? Is it 25' high or is it 45' high?

Thanks in advance!

 

[chrissim]

Your vertical is elevated and won't suffer the consequences of potentially poor ground conductivity. However, you should have radials, or counterpoises as I call them when using an elevated vertical. From the ARRL:

"Without a decent radial system,the vertical is a poor cousin to the dipole."

Radials essentially create the "other half" of the antenna - your vertical. More from the ARRL:

"A vertical is a dipole with half of its length buried in the ground or “mirrored” in its counterpoise system."

With no radials, I can't imagine the impedance of your vertical.

This link may help you:
The Mystery of radials

I don't have extensive experience with verticals, elevated or otherwise. But I'm yet to read anything pertaining to a vertical that omits radials/counterpoises from their design ground mounted or elevated.

 

[vagrant]

If most everyone else is running vertical, you should do the same and avoid phasing issues with your local group. Phasing won't do you any favors on TX or RX.

That ground plane kit is interesting. Your results reflect those of others I know that have tried it and others I have read about with it. Still, for local stuff, I would think the ground plane would help a little.

I have used an I-MAX 2000 (no radial kit) at 16' and 33' AGL and did not notice a significant difference with received signals on 10 meters during a weekly local net. The same with my TX signal. Still, the higher the better as far as I'm concerned as I use it for more than a local weekly net.

I'm wondering what's going on with that tree and if it is causing you some trouble. Is it some old snag with nothing growing on it?

Obviously the signal is blasting away from the hillside with that setup. If you're not using a 1:1 choke at the feed point, some of the coax is the other half of that antenna. (Not that you need a 1:1 on there unless you're getting RFI in the shack)

As to the height of your antenna, it is 25' above the slope below and 45' above the flat area, or what your drawing represents as flat. That tree and hillside are probably adjusting the dynamics of that antenna more than the height.

Here's the thing, and you're already on the right path, experiment with what you have because my location is different from yours.

 

[prcguy]

The Antron A99 is a half wave end fed, similar to a J-pole but with transformer type matching. It doesn't need a ground plane to operate although it has poor decoupling from the coax and will have some feed line radiation. Ground radials can address that or a common mode choke balun on the coax would also work.
prcguy

Your vertical is elevated and won't suffer the consequences of potentially poor ground conductivity. However, you should have rade cials, or counterpoises as I call them when using an elevated vertical. From the ARRL:

"Without a decent radial system,the vertical is a poor cousin to the dipole."

Radials essentially create the "other half" of the antenna - your vertical. More from the ARRL:

"A vertical is a dipole with half of its length buried in the ground or “mirrored” in its counterpoise system."

With no radials, I can't imagine the impedance of your vertical.

This link may help you:
The Mystery of radials

I don't have extensive experience with verticals, elevated or otherwise. But I'm yet to read anything pertaining to a vertical that omits radials/counterpoises from their design ground mounted or elevated.

 

[chrissim]

You may want to read the below link. W8JI is widely recognized as one of the authorities in amateur radio. Pay particular attention to what he has to say about vertical end fed antennas at the bottom (in bold).

End-fed Vertical and J-pole

I would assume this applies to the antenna under discussion.

 

[vagrant]

"The gain over a dipole is now a few db at some really low angles, so it can be better than a dipole. At slightly higher angles for shorter skip, the dipole takes over and can be several dB better than the vertical.

This change is entirely the result of altering height and feedline/mast length!!! No antenna changes were made!" - From W8JI's page

Indeed, this is what the op is experimenting with. Everyone's experience is unique due to their respective locations and setup, coax, radio, ground, etc. The op's intention is to use it for a local net.

 

[chrissim]

I'm not disagreeing with a single point made thus far by anyone nor am I trying to be contentious. The OP seems to want to know more about what he's using and why it's behaving the way it is. I believe the last link I posted achieves much of that.

I did not realize the Antron (Solarcon) 99 was an end fed antenna. When that point was made, I immediately recalled numerous discussions on another forum in which some were bemoaning the fact that such antennas will often exhibit common mode issues. This is why I posted Tom's link (W8JI).

Saying that, if I were to erect such an antenna, I would at the least supply a 1:1 current choke at the feedpoint to help in preventing currents on the feedline.

 

[KM4GGD]

This link may help you:
The Mystery of radials

Thank you Chissim and thanks for the link. Good stuff, confusing at times but good stuff non-the-less.

If most everyone else is running vertical, you should do the same and avoid phasing issues with your local group. Phasing won't do you any favors on TX or RX.

Agreed, and during the net we switched from vertical to dipole a couple of times and the vertical was king that night.

That ground plane kit is interesting. Your results reflect those of others I know that have tried it and others I have read about with it. Still, for local stuff, I would think the ground plane would help a little.

I have used an I-MAX 2000 (no radial kit) at 16' and 33' AGL and did not notice a significant difference with received signals on 10 meters during a weekly local net. The same with my TX signal. Still, the higher the better as far as I'm concerned as I use it for more than a local weekly net.

Radials did nothing for transmit or receive. I tested with Charlie (about 35 miles away) both with the radials on and then with them off. No difference. I ended up leaving them on, couldn't hurt right? I later raised the antenna another 40' . The extra height did make a difference for Charlie, who's signal improved slightly as did mine to him. But unfortunately it but did nothing to improve the signals of those stations that were already difficult to hear nor did it help them hear me. It's clear that the surrounding mountains will not submit to intimidation via radials or extra height.

The following day I brought the antenna back down to earth and it was hanging with the radials just 3" above the ground. I had gone inside for lunch and DX started going wild. I spent an hour with different hams (mostly in TX and FL) who were gracious enough to work with me as I raised and lowered the antenna from inches above the ground to 60' in the air. For the most part, NOBODY reported any difference whatsoever. Certainly gave credence to the adage that you can talk on a wet noodle when conditions are right.

Anyway, after all that testing it appears that (for me and my location) close range 10 meter vertical communication works just about the same regardless of height and that radials (on this antenna anyway) was money poorly spent. I'll admit it makes no sense but I guess that's why they call it Antenna Theory...