A Low Profile Shorted-Patch Antenna With Enhanced Bandwidth and Reduced H-Plane Cross-Polarization

A low profile shorted-patch antenna (SPA) with enhanced bandwidth and reduced the H-plane cross-polarization (cross-pol) is proposed in this communication. Initially, the radiated field of a conventional SPA is theoretically investigated. It is demonstrated that its high cross-pol of the H-plane radiation patterns can be reduced by introducing a pair of shorting walls underneath the nonradiating edges of the SPA. Then, the width of the radiating patch is progressively enlarged so as to decrease the resonant frequency of TM
_1/2,2
mode. After that, an array of six shorting pins is loaded underneath the patch radiator toward pushing up the resonant frequency of TM
_1/2,0
mode. In addition, the linear Slots 1 and 2 are cut on the rectangular patch to reduce the resonant frequency of TM
_3/2,0
mode and achieve a good impedance matching, respectively. With these arrangements, all of these three radiative modes are reallocated in proximity to each other, leading to the formulation of the improved SPA with low profile, wide-bandwidth, and low cross-pol performances. Finally, the proposed antenna is fabricated and measured. The measured results show that its impedance bandwidth is extended up to about 26.2% under triple-mode resonance. In addition, its thickness is maintained as small as about 0.059 free-space wavelength. In particular, the H-plane cross-pol of the SPA is successfully decreased to below -12.3 dB over the operating band.