Feasibility of dual-polarized antenna arrays for GNSS receivers at low elevations

A dual-band dual-polarized compact antenna array is designed for intended use in robust global navigation satellite receivers. The four-element antenna array is connected to an eigenmode-based decoupling and matching network to compensate for the radiation efficiency degraded by mutual coupling. The resulting eigenmodes of the array are then fed to an RF-IF front-end for down-converting, filtering, and power amplification. Finally, the signals are carried to a digital receiver for decoding and tracking. Field measurements proved the usability of certain left-hand circular polarized modes for receiving the navigation signals, particularly at low elevations. This possibility enhances the receiver robustness against polarization distortion caused by multipath, and thus improves the tracking accuracy. Measurements help also to decide which left-hand modes should be selected for a practical dual-polarized receiver if the number of channels available for array signal processing is limited.