Cross-Polarization Discrimination and Port-to-Port Isolation Enhancement of Dual-Polarized Antenna Structures Enabling Polarization MIMO

This letter presents port-to-port isolation and cross-polarization discrimination (XPD) enhancement techniques for dual-polarized (DP) antenna topologies. Both port-to-port isolation and XPD of DP-antenna degrade due to unwanted cross-coupling signals from one port to another port. Since high port-to-port isolation and XPD are imperative for realization of DP multiple-input-multiple-output (DP-MIMO), the proposed antiphase excitation scheme enabling undesired cross-coupling cancellation for DP-antenna element and array presents significant promise for the implementation. The fabricated differential DP-antenna designed for 57-71 GHz frequency bands exhibits more than 30 dB of port-to-port isolation over 8 GHz of bandwidth and also demonstrates up to 36 dB of XPD with >25 dB over the whole bandwidth. The modulated transmitter (TX) signal measurements on the proposed differential DP-antenna integrated TX exhibits on average less than 1 dB of error-vector-magnitude degradation in comparison with the single-polarized case, which proves the benefits of the proposed isolation enhancement technique for DP-MIMO.