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Re: [TowerTalk] Why horizontally polarized antennas?

To: Tower Talk List <>
Subject: Re: [TowerTalk] Why horizontally polarized antennas?
From: Steve Hunt <>
Date: Sat, 03 Jul 2010 08:58:17 +0100
List-post: <">>
No - it IS the polarization of the far field signal resolved as separate 
horizontal and vertical components.

Take a look at the two components for a hexbeam as predicted by EZNEC:

Note the shape of the vertically polarized (red) component.

Now take a look at the actual MEASURED azimuth response of a hexbeam, 
using a vertically-polarized sense antenna:

The "skew" in the vertically polarized component is caused by 
common-mode current in the vertical coaxial band interconnects; I was 
making the measurements to understand the effect of alternative choke 

It demonstrates how careful you need to be when trying to plot radiation 
patterns. Depending on the polarization of the sense antenna, you can 
achieve quite different results. You would have to combine the results 
from a vertical and a horizontal sense antenna to produce the "normal" 
EZNEC "Total Field" plot. You also need to take care to avoid 
common-mode current on the sense antenna feedline if you want to be sure 
what you are actually measuring.

Steve G3TXQ

Larry Banks wrote:
> If memory serves me well -- that is simply a vertical or horizontal cut 
> through the plot 3D plot.  It is not the polarization of the field.
> 73 -- Larry -- W1DYJ


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