Cross-Polarization Reduction of Shorted Patch Antenna by Using Coupled TM0,1/2 Mode

A shorted patch antenna (SPA) has a major issue of high cross-polarized radiation in the H plane, which has greatly limited its applications. This article presents a simple technique to overcome this fundamental disadvantage of the SPA by creating and exploring the coupled TM
_0,1/2
mode. The resultant antenna is termed the cross-polarization suppressed SPA (XPS-SPA). A theoretical model is developed to provide physical insight into the reduction of cross-polarized radiation and to determine the optimal width for the coupled elements. Several types of SPAs were designed and fabricated to validate the analysis. Measured results show that the novel antenna not only achieved a reduction of 25 dB in the peak level of cross-polarized radiation but also an enhancement of 1.2 dB in the gain and miniaturization of 22% in the electrical size as compared with those of the conventional SPA.