[amsat-bb] Right Hand Left Hand CP

[Ronald Long <rlong3@xxxxxxxxxxxxxxx>]

This problem has a long, long history. I personally first dealt with it 
while an intern at RCA Laboratories in 1954.

Refer to "The Radio Amateur's Satellite Handbook" by Martin Davidoff, 1998 
edition, page 9-6, Circular Polarization Sense. (Similar material is in all 
editions but will be on a different page, use the index.)

Martin states that physicists (usually thinking about optics I suppose) and 
electrical engineers (IEEE Standard) define RH and LH polarization sense in 
opposite ways.

Not to bore you with too many references but Kraus, Antennas, First 
Edition, 1950, page 471 talks about this confusing situation as well. The 
basis of the problem is whether you are looking in the direction of 
propagation or in the opposite direction. Clockwise circular polarization 
wave approaching is the same as counter clockwise circular polarization 
wave receding.

I have a 'clarification addendum' sent out by KLM (we are talking 15 years 
ago) which says: " Since AMSAT has choosen (sp) to use the IEEE version of 
right-hand left-hand definition, the instructions for generating right-hand 
circularity in your 420-450-1BC KLM manual will in fact produce left-hand 
circular."

Since Mike Stahl, I believe, designed the KLM antennas (he was the M) and 
subsequently designed the M2 antennas (Mike and his son), you would think 
that by now they would realize that they are selling to electrical 
engineers and would get the manual corrected.
I cannot verify that the M2 manual is incorrect but it appears to be so 
from the recent postings. So beware. To uplink to AO-40 you want RHCP-IEEE 
definition and if you have an antenna with a polarization switch you will 
most likely want it to generate RHCP with the relay de-energized.

ron long w8gus@amsat.org


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