A Simple Wideband Dual-Beam Filtering Patch Antenna Exploiting a Pair of Degenerate Modes

In this letter, a simple wideband dual-beam filtering patch antenna under the operation of a pair of degenerate modes is proposed. Initially, the working mechanism of radiation pattern reshaping is theoretically elucidated through far-field analysis. It substantiates that the incorporation of slots and shorting pins can alter the patch peripheral electric field distributions, thus reshaping the radiation pattern of TM02mode from theyoz-plane to thexoz-plane. By varying the length of slots, the maximum radiation direction of reshaped TM02mode can be aligned with that of TM20mode, thereby providing a foundation for wideband dual-beam radiation. Furthermore, the antenna structure introduces two radiation nulls so as to improve out-of-band selectivity, whose positions can be effectively tuned by the incorporation of slots length and diameters of shorting pins. Finally, a prototype of the proposed dual-beam filtering patch antenna with a low-profile structure was designed. The measured results are consistent with the simulations, strongly verifying the effectiveness of the proposed method.