Far-field cancellation of cross-polarisation based on mirroring subarrays of densely arranged PDM apertures

Achieving highly directional planar array antennas with sufficient cross-polarisation discriminations (XPDs) is crucial for satellite communications based on the polarisation-division multiplexing (PDM). In this work, the authors propose a robust three-step approach that can be used to significantly enhance the XPD of such array antennas in the normal and nearby directions based on mirroring subarrays, especially when the radiation elements are densely arranged. Theoretical, simulation and experimental results show that by dividing an in-phase feed array into two or four identical subarrays and properly mirroring them with a differentially feeding, the XPD can be remarkably enhanced by means of far-field cancellation, regardless of the scale and the XPD of the original array. It provides a practical and robust solution to obtain compact PDM antennas satisfying strict XPD requirements.