A simulation of multipath effects on the cross-polarization discrimination in microwave line-of-sight links

A ray-tracing algorithm was utilized to examine the relationship between cross-polarization discrimination (XPD) and co-polar attenuation (CPA) in microwave links between satellites and ground stations. The code accounted for the curvature of the earth, the transmitter and receiver altitudes, the frequency, path length, gains, the co-polar and cross-polar amplitude and phase patterns of the antennas involved, and the refractive index, dielectric constant and conductivity of the earth. The XPD-CPA relationship is studied with line-of-sight atmospheric refractive index data obtained for a microwave link. CPA is found to increase with the path length and decrease with the height of the antenna. The effect was independent of frequency or polarization. Finally, results are discussed from use of the model to investigate multipath propagation effects in frequency reuse microwave links.