[TowerTalk] Field Strength comparison

[Lux, Jim]

On 9/4/21 3:36 PM, Stan Stockton wrote:
> How far away (minimum) should a receive antenna be located if you wanted to accurately measure the difference between a couple of vertical arrays - let’s say, for example a 4 Square and a single vertical.
>
> Thanks… Stan, K5GO
>
The traditional guide line for antenna ranges is 2 D^2/lambda, where D 
is the diameter of the antenna.  That has to do with the phase 
difference from a plane wave being small enough that the gain isn't 
significantly wrong (I can't remember if it's 0.1 dB or what, and I'm 
too lazy to calculate it now).

For a 80 m foursquare, it's roughly 30 meters across (1.414 * 20m) so 2 
* 900/80 = 180 meters away