Polarization Combining and Equalization for Aeronautical Mobile Telemetry

This paper examines the relationship between polarization diversity combining and equalization in the context of aeronautical mobile telemetry (AMT). The receive antennas currently used in AMT combine the linear polarizations using a 90° hybrid coupler to synthesize circularly polarized signals. Maximum likelihood (ML) polarization combining is developed for this application. Computer simulation results show that equalizing an ML combined channel achieves a lower bit error rate than equalizing circularly combined signals. The performance improvement is achieved at the cost of estimating the channel.