What is the effect of antenna cross-polarization over a line-of-sight VHF or UHF path?
Modulation sidebands might become inverted
Received signal strength is reduced✓Bonne réponse
Signals have an echo effect
Nothing significant will happen
Explication
Cross-polarization means the transmitting and receiving antennas are oriented at right angles, so the receiving element intercepts only a small part of the arriving field. Over a direct line-of-sight path there is no ionosphere to scramble the polarization, so the mismatch shows up as a large drop in received signal strength, often 20 dB or more.