A Broadband Filtering Duplex Patch Antenna With High Isolation

This letter presents a broadband duplex patch antenna with high isolation and filtering performance. The proposed duplex antenna consists of one radiating patch and two sets of resonator-based filtering channels as a feeding network. The broadband performance is realized by employing multimode resonators to excite the patch antenna. To improve the isolation between two channels, two sets of resonators are employed. The lower band channel resonator can generate a transmission zero in the upper band, and the upper band channel resonator can also produce a transmission zero in the lower band. Thus, high isolation between the two channels can be obtained. For demonstration, the duplex antenna is fabricated and measured. The measured impedance bandwidths of the lower and upper band channels are 10.6% (1.95-2.17 GHz) and 6.9% (2.5-2.68 GHz), respectively. High isolation of better than 45 dB is realized between the two channels.