On Fri,3/31/2017 5:37 PM, john@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
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|