[amsat-bb] Circular and elliptical polarization question.
dphelps1 at ameritech.net
Tue Mar 11 18:10:48 PDT 2014
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.
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