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[TowerTalk] Modeling over ground was: Re: H frame for 10 or 15m

To: towertalk@contesting.com
Subject: [TowerTalk] Modeling over ground was: Re: H frame for 10 or 15m
From: Pete Smith <n4zr@contesting.com>
Reply-to: n4zr@contesting.com
Date: Tue, 16 Aug 2011 10:35:43 -0400
List-post: <towertalk@contesting.com">mailto:towertalk@contesting.com>
I agree that the azimuth pattern will be the same, but the elevation 
pattern will be quite different, and to my mind is a lot more 
important.  We're not doing EME here.  For example, if I model against 
ground, and put the antennas at heights of 50 and 100 feet, my 14 MHz 
vertical pattern is very broad and clean, with no second lobe below 35 
degrees or so.  If I select only the lower antenna in the 50/100 stack, 
the clean main lobe moves up from 12 to 20 degrees, which can be a very 
useful capability late in an opening.

73, Pete N4ZR

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On 8/16/2011 9:33 AM, Jay Kesterson K0GU wrote:
>     The azimuth pattern will be much the same over ground. If you
> vertically stack antennas very close together you can see interaction
> between the antennas that can degrade the azimuth pattern. Although it
> might improve the elevation pattern (the useless lobes that can cause
> noise pickup from under the antenna). However if you don't have fairly
> flat ground IMO modeling over ground may or may not give you accurate
> results unless you have a program that compensates for the local terrain.
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