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

[Jim Brown]

On Tue,10/25/2016 12:35 PM, Tom_N2SR via TowerTalk wrote:
> Go back and read K9YC's articles about many short radials close to the feedpoint.  Isn't the idea to reduce/eliminate losses?

Exactly right. With on-ground radials, more copper is better, longer is 
better.  I covered this in great detail in the piece about 160M.

>     
> When I added added the HF2V, I had about 4 radials and the BW on 80 was about 150 kc.  I kept adding radials, and the bandwidth kept dropping - which is good, since that means that that ground losses are being reduced.
> The bandwidth finally dropped to about 50 kHz.  For an 1/8 wave antenna, that is pretty good.

Yes. AND loss in coax is quite small on 160 and 80M, so it's very 
practical to use a tuner in the shack once you've got it close to 
resonance in the middle of the range where you want to work. This is a 
great application for big coax (RG8 or RG213 size), not for power 
handling, but to reduce loss with mismatch.

Also, it really helps to raise the antenna and use elevated radials. 
While it's BEST for those radials to be resonant, I'd put in as many 
shorter ones as I could before giving up. NEVER let the perfect be the 
enemy of the "good enough." And best, by far, is one of those vertical 
dipoles that doesn't need radials.

Yes, top-loading is ALWAYS a good thing if it doesn't reduce the overall 
height of the vertical section. If, for example, you're using conductive 
guy wires as top loading, the vertical part of the guy wire will shorten 
the effective height of the radiator, reducing its efficiency.  Let's 
say that you've got a 40 ft tall radiator, are guying it with wires that 
form a 45 degree angle with the ground, and the conductive section of 
the guy is 14 ft long. Doing the trig, the wire drops 10 ft, so the 
effective height of the radiator is 40 ft - 10 ft  = 30 ft. This means 
that SOME top loading is a good thing, but don't overdo it, or try to 
tie off the guys as far from the antenna as possible.

73, Jim K9YC