Investigations into improved isolation in Co- to cross-polar radiation fields of a single-fed circularly polarized patch antenna

The radiation performance of a circularly polarized (CP) single probe-fed truncated corner square microstrip patch has been enhanced by employing (i) a metal (PEC) ring contouring the patch on the patch side of the CP antenna, and (ii) a multi-section ring defect in the ground plane (GP) of the CP antenna. The concept has been validated by designing a CP patch with a conventional GP, a CP patch with a PEC ring contouring the patch and a ring type defect in the GP of the conventional CP patch. Proposed configurations appear to be ideal for many circularly polarized wireless and satellite communication applications. Simulated results confirm axial ratio (AR) of about (i) 1.1 dB for a CP antenna with a PEC ring contouring the patch and (ii) 0.1 dB for a CP antenna with ring type defect in the ground plane; compared to an AR of 2.7 dB for a conventional CP antenna, indicating an improvement in cross polarized (XP) isolation. AR bandwidth has also been improved by 70% in case of PEC ring contoured CP patch and almost 100% in case of ring type defected ground structure (DGS) integrated CP patch when compared with conventional CP antenna. These improvements have been achieved without affecting any other parameters such as impedance bandwidth and peak gain of the antenna.