60 GHz Fabry-Pérot Cavity Filtering Antenna Driven by an SIW-Fed Filtering Source

This work introduces a new design of a Fabry-Perot cavity (FPC) antenna with great filtering response based on a novel filtering feeding scheme. Unlike the traditional method of adopting frequency selective surfaces to achieve filtering characteristic, the proposed strategy focuses on the feeding source. We can obtain an excellent filtering response by utilizing a performance-improved filtering antenna to act as the source of the FPC antenna. To validate the concept, we first propose a new substrate-integrated-waveguide-fed (SIW-fed) filtering antenna element working in a 60-GHz band. By using the slotted radiating patches, two radiation nulls are first generated, respectively, on each side of the operating band. We then design a stepped-impedance waveguide feeding structure and a pair of U-shaped hairpin lines to introduce another two radiation nulls to improve the suppression level in the stopband. The proposed filtering antenna prototype shows a - 10-dB impedance bandwidth of 57.5-66.6 GHz as well as a maximum gain of 7.9 dBi. Based on such feeding sources, an FPC antenna is developed and validated. It achieves a 3-dB gain bandwidth from 58 to 65.6 GHz, a peak gain of 15.8 dBi, and a suppression level of over 24 dB. The proposed antennas are good candidates in 60-GHz sensing or communications systems.