[TowerTalk] What do do on 80 when height restricted?

[Jim Brown]

On Mon,10/24/2016 5:10 AM, john nistico wrote:
> My son KC2PWX is looking for a solution to a 80 meter antenna, problem is he has about 30-35 vertical feet he can go. He is using a ground mounted 5btv but is is awful on 80. Any idea?

How many radials and how long are they?  The 5BTV is a loaded quarter 
wave vertical, so it requires radials -- without radials, it's a 
worm-warmer.  On the ground, it needs a LOT of radials.

Can he raise it off the ground at all?  Doing so does two things. It 
reduces ground losses, and it allows the use of resonant radials, at 
least two per band, and four is better.

What is his ground quality?  Verticals are highly dependent on ground 
quality -- they work 3-6 dB better over good soil than poor soil, and, 
as we all know, much better than that over salt water.

Horizontally polarized antennas don't care about ground quality, they 
only care about height, and higher is better, at least within the 
capability of we mere mortals on 80M.

I've studied these factors a LOT, have written it up in an applications 
note for National Contest Journal and the NCCC newsletter, and have done 
several presentations at Pacificon and to several ham clubs. The 
presentations and the applications note are on my website.

There's also a talk about getting on 160M from a small lot, which is 90% 
about antennas, and the only viable antennas on 160M are some form of 
verticals. To apply these fundamental concepts to 80M, simply divide all 
the dimensions by 2.

http://k9yc.com/AntennaPlanning.pdf
http://k9yc.com/VertOrHorizontal-Slides.pdf
http://k9yc.com/VerticalHeight.pdf
http://k9yc.com/43FtVertical.pdf
http://k9yc.com/160MPacificon.pdf

BTW -- excellent work by N0AX and K7LXC more than 15 years ago setting 
up and measuring the performance of a dozen or so multiband HF verticals 
showed that antennas that are some form of certer-fed vertical dipoles 
are better performers than those that are some form of loaded vertical 
working against radials, and that antennas that use some form of 
inductive loading are POORER performers than those that use other forms 
of loading. The Cushcraft R-series (they tested the R8), the Force 12 
verticals, the Hy-Gain AV-series, and the Gap Titan are center-fed 
dipoles. The Hy-Gain AV-680 covers 80M, and from the description looks 
like a decent design, but I can't find a spec sheet for it that lists 
its height. The manual recommends mounting it at least 8 ft above ground.

73, Jim K9YC