Hi Roger,
Going from left to right, or right to left, with both sides being circular is in that 30db loss realm. I recall it being more like 20db, but once you get in that range, a few db either way kind of doesn't matter. In practice it's not quite that bad, since in practice nothing is perfectly circular, but, yeah, not a recipe for success.
Crossing circular (either handed) with linear is 3db, I believe. Or was it 6? Anyway, not impossibly bad. Hopefully you also have a preamp at the antenna, which will offset a lot of this. If not, I'd invest in one, regardless of the polarization topic.
I have a pair of switchable beam antennas for satellite work. My observation is that most of the newer satellites these days appear to be linear, and I've noticed that while there appears to be some difference between right vs left on the ground, crossed with their linear signals, most of the time it's not fatal. Either can work for at least part of the pass.
Bottom line is that you've got a workable antenna. Try it and see what you get.
Greg KO6TH
Roger Cooper wrote:
About 10 years ago got interested in sat radio and bought a Left Circular Quadrifilar Helix Antenna which got good review in QST. Didnt use it and now retired and trying to get on sat. Evidently most ham sats are right circular and depending on what I read. there is a 30db OR 3db loss going from one circular polarization to another. Which is it?
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