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[alva1018]

Hi,
Right now I'm doing the research about GNSS reflection, but has confused about the polarization.
The synthetic aperture radar (SAR) has different polarization mode, such as HH, VV, HV and VH, means different polarization type of transmitter and receiver. But theoretically, a V-pol antenna can not receive the H-pol EM wave, and the EM wave will not change the polarization vertically when it reflected from the ground (it do changes 180 degrees if the incident angle is larger than Brewster' angle, but still be H-pol).
So here comes the question, why a V-pol antenna can receive a H-pol EM wave?
I'm guessing I missed something important, anyone kind enough to tell me?
Any help appreciated!