A Ka-Band Iris-Loaded Waveguide Slot Antenna With Enhanced Out-of-Band Suppression

This paper presents a Ka-band waveguide slot array antenna with a simple structural upgrade that is capable of enhancing out-of-band suppression for mitigation of potential strong interference signals. The enhanced suppression is enabled by employing rectangular irises that are uniformly distributed along the propagation direction of the waveguide. A prototype of the waveguide slot array antenna is designed and experimentally demonstrated. Measured result of the engineered antenna shows good in-band radiation performance, i.e., a reflection coefficient of less than -10 dB from 31.6 to 34.28 GHz (a relative bandwidth of 8.1%) and corresponding realized gains of 13–14.5 dBi. Compared to the conventional waveguide slot antenna without loading any iris, the implemented antenna achieves a reduction of 11.3–18.5 dB in the out-of-band realized gains at 38.25–40 GHz.