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Re: [TowerTalk] Field Strength comparison

To: towertalk@contesting.com
Subject: Re: [TowerTalk] Field Strength comparison
From: "Lux, Jim" <jim@luxfamily.com>
Date: Sat, 4 Sep 2021 20:19:01 -0700
List-post: <mailto:towertalk@contesting.com>
On 9/4/21 8:05 PM, Wes wrote:
For an illustration try this: http://www.cuminglehman.com/wp-content/uploads/Introduction_to_Antenna_Test_Ranges_Measurements_Instrumentation.pdf

and look at the figure on  page 4.  This shows the usual antenna range situation where the test antenna is receiving a signal from a point, or small aperture source.  This is how I would run this comparison.  I think, but do not know for sure, that I would use the larger dimension of the vertical(s) as the "D" in the equation.  The idea is to have a plane, or near plane, wave over the whole aperture of the test antenna in both directions.  Note that some antennas, Yagis for instance, can have an effective aperture larger that the physical aperture.

Wes  N7WS


But that's the 2D^2/lambda  - and that comes out strangely small.   And it's not effective aperture (that's more about voltage/power at the feed) - this is about the physical optics.

D =30m (across the 4 square diagonally) is almost certainly bigger than the height of the 80m elements (20m?)


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