Circular polarized waves invert (i.e. RHCP switches to LHCP) upon reflection. For example, precision GPS antennas need good cross-pol rejection to keep the LHC

Circular polarized waves invert (i.e. RHCP switches to LHCP) upon reflection. For example, precision GPS antennas need good cross-pol rejection to keep the LHCP from multipath (reflections from buildings and ground) from interfering with direct RHCP from the satellite. In general, linear polarized waves retain their polarization, but I believe there are special cases (such as Brewster angle on dielectrics) where you can get some depolarization. From what I read a while back, on an IEEE article on this orbital polarization, the number of orthogonal modes you can achieve is limited by antenna construction, and it definitely can't handle multi-path; strictly point-to-point microwave link. I'll bet rain will really mess it up, more so than your typical rain fade. Still very cool though, and I still don't have my head wrapped around it, despite 20 years of RF/Microwave engineering.