[time-nuts] Antenna question about RHCP/LHCP I'm sure a time-nut can answer

[Dr. David Kirkby]

This is not exactly a time related question, but I'm sure the subject must be of 
interest to time-nuts using GPS.

If one transmits from an antenna such as a helical one, RHCP, can the same 
antenna be used for reception, or does the helix need to be wound the other way?

If you google this topic, there seems to be a lot of confusion about whether the 
TX antenna and RX antenna need to both have RHCP or whether one needs to be LHCP 
and the other RHCP.

Given GPS uses circular polarization, I'm hoping someone here will know.

It would appear there are different definitions of "circular polarization", with 
one considering it from the point of view of the source, and the other 
considering it from the point of view of the receiver. The IEEE apparently uses 
the former, and others (especially optics) use the opposite.

http://en.wikipedia.org/wiki/Circular_polarization

My aim was to make a gain measurement of two circular polarized antennas. I have 
two identical antennas, but are unsure if the signals should be received 
strongly, or whether theoretically no signal would be received. (Of course in 
practice, one never achieves perfect polarization, so there will always be a 
signal detected, even if cross-polarized.