A Dual-Beam Filtering Antenna Based on Dual-Mode Patch Loaded With π-Shaped Vias

In this paper, a dual-beam filtering patch antenna is proposed, wherein a symmetrical π-shaped metal vias-loaded dual-mode patch and a cross-shaped metal strip are utilized. The dual-mode patch resonator is realized through the loading of metal vias in the weak field region of mode TM21, which effectively moves mode TM01 closer to TM21. Using a cross-shaped metal strip to excite the dual-mode patch resonator not only provides a reflection zero and broadens the bandwidth, but also generates two radiation nulls through zero coupling, thus improving the frequency selectivity. Compared with reported dual-beam filtering patch antenna, the proposed design with the novel dual-mode patch resonator has a wide stopband, enhanced frequency selectivity, small size and a low profile. Measurements show that the antenna exhibits a 10-dB impedance matching bandwidth of 13% (3.23 GHz – 3.69 GHz), with two radiation nulls at 3.15 GHz and 3.88 GHz and a measured 15 dB stopband of 2.14 $f_{0}$ .