Revisiting the Generation of Cross-Polarization in Rectangular Patch Antennas: A Near-Field Approach

In this work, the cross-polarized radiation from a rectangular patch antenna was studied as a consequence of the asymmetries (or disturbances) in the near field of the antenna. It was shown that the asymmetry of the probe location results in asymmetry in the near fields in the vicinity of the antenna, causing high cross-polarized radiation in the H plane of the antenna. These near-field disturbances show a varying trend with the variation of the frequency or dimensional parameters of the antenna, which ultimately affects the far-field cross-polarized radiation. Having developed the near-field model of the cross-polarized radiation, this approach is then applied to two important known configurations with low cross-polarized radiation, namely, differential feeding (for a single patch antenna) and rotational feeding (for an array antenna). The new approach presented here provides an insightful, visualization-based understanding of the cross-polarized radiation from a rectangular patch antenna.