Design of Waveguide Slot Filtering Antenna With Wide Suppression Bandwidth

This letter presents a waveguide slot filtering antenna that uses two filtering technologies to achieve a wide suppression bandwidth (SBW). The filtering response is achieved by a frequency-selective surface (FSS) and a coaxial waveguide filtering converter (CWFC). The FSS loaded on the internal bottom of the waveguide slot antenna serves as the first-stage out-band filtering. The CWFC, which realizes the filtering response and impedance matching, acts as the second-stage out-band filtering, providing a wide SBW is obtained with high suppression levels. To verify the design concept, a wide SBW waveguide slot filtering antenna is designed, fabricated, and measured. The measured results show that the proposed antenna obtains the -10 dB impedance bandwidth of about 13.6% (9.42-10.79 GHz) and the stable gain of about 11.5 dBi with the cross-polarization levels less than -30 dB in the main beam, and the SBW of about 24.6% (11.68-14.95 GHz) with suppression levels above 41.5 dB.