Polarization Diversity Gain and Base Station Antenna Characteristics

Dual polarized antennas are traditionally characterized in terms of port-to-port isolation and coand cross-polar radiation patterns. In this paper we instead identify the critical parameter when the antenna is used as a sensor in a polarization diversity reception system. This turns out to be the fareld coupling between the two channels. We calculate the antenna output power correlation and diversity gain, using maximun ratio combining, under Rayleigh fading conditions. Two di erent antennas are compared: a dual polarized aperture coupled patch and a slanted dipole con guration, both over an in nite groundplane. We show that the aperture coupled patch provides lower output correlation and higher diversity gain than the slanted dipoles in all investigated cases.