Thanks Steve -- I stand corrected.
I've never played with that part of EZNEC before!
73 -- Larry -- W1DYJ
----- Original Message -----
From: "Steve Hunt" <steve@karinya.net>
To: "Tower Talk List" <towertalk@contesting.com>
Sent: Saturday, July 03, 2010 3:58 AM
Subject: Re: [TowerTalk] Why horizontally polarized antennas?
> 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:
> http://www.karinya.net/g3txq/temp/hexbeam_vandh.png
>
> 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:
> http://www.karinya.net/g3txq/temp/hexbeam_vpolarisation.png
>
> 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
> positions.
>
> 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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