[TowerTalk] 80 Meter beam

[Jim Brown]

On Fri,3/31/2017 5:37 PM, john at kk9a.com wrote:
> I think a 4sq is about as good and it has greater
> bandwidth.

Vertically polarized antennas are strongly affected by ground quality. 
If you have good to very good ground conductivity and have a good radial 
system, that 4-sq will work great. But if you have poor ground 
conductivity, it won't, even with a zillion radials. It's VERY easy to 
see this in a simple NEC model. Build a quarter wave vertical, put a 1 
ohm load at the base (a near perfect radial system), model it with Very 
Good Ground, plot the vertical pattern (2D), save the plot. Then change 
to Very Poor, plot the vertical pattern, then add the plot of very good 
ground that you just saved. The difference is loss in the far field (FAR 
beyond where your radials end).

Horizontally polarized antennas do NOT depend on ground conductivity, 
they depend only on HEIGHT, and especially on low bands, higher is better.

73, Jim K9YC