[amsat-bb] Re: Circular and elliptical polarization question.

Lizeth Norman normanlizeth at gmail.com
Tue Mar 11 21:28:57 PDT 2014

I use a pair of Elk V-Uhf antennas fed in phase for VHF. The UHF side is
covered presently by an Arrow II 7x2 (fed by a spdt coaxial relay).
Very portable and relatively compact. Not much wiring, so to speak.
Working on a simple, robust rotator from K3NG.
Your project is a bit more complex. I suspect that you'll need a homebrew
antenna range to evaluate the performance before, during and after testing.
The real problem is gathering data and more importantly, determining if
your changes made any positive impact on the design.
See HDL.exe on Google for more info on how to build one. (Horn, Dish, Lens)
Norm n3ykf

On Tue, Mar 11, 2014 at 9:10 PM, Douglas Phelps <dphelps1 at ameritech.net>wrote:

> I read in 'The Satellite Handbook' that I can mount to linear yagis side
> by side (and at right angles) and I will get elliptical polarization.  My
> two questions are:
> 1. Is their a formula or rule of thumb that will tell me how elliptical
> (or non circular) the waveform will be as a factor of the separation
> between the two antennas? (I would expect that the greater the separation
> the more elliptical the waveform(farther from circular)).
> 2.  I would think that the closer the better.  I know when you mount two
> yagis next to each other, in the same plane, there is a minimum separation
> distance to prevent the antennas from affecting each other but with cross
> polarization intending circular polarization, the closer the better.  Does
> this make sense?
> The reason I am asking is that I want to mount  arrow antennas with the
> same element sets at right angles and offset a quarter wavelength, with the
> correct phasing harness and the WRAPS AZ/EL to create a portable auto
> tracking satellite setup that can be disassembled and easily moved. Yes, I
> know the VHF offset will be wrong for UHF but I intend to re-drill the UHF
> antenna holes so that both the VHF and UHF will be offset a quarter
> wavelength.
> The matching system used by arrow does not allow the crossing of the same
> wavelength antenna on the same boom.
> I would appreciate and advice from those that are more competent with
> antenna theory than myself.
> Doug K9DLP
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