A Compact Waveguide Slot Filtering Antenna Based on Mushroom-Type Surface

A mushroom-type surface-based waveguide slot filtering antenna is proposed herein. First, using a mushroom-type surface replacing the conventional metal plane in the bottom of a rectangular waveguide, a novel filtering waveguide is achieved. This filtering waveguide functions as a bandstop filter when the surface performs as a perfect magnetic conductor. Then, a filtering waveguide slot antenna is obtained by cutting radiating slots on the top of the filtering waveguide. Compared with a traditional waveguide slot antenna, the proposed antenna has nearly the same radiation characteristic while realizes an additional filter selectivity with almost no extra volume occupancy. A prototype is demonstrated in Ku -band with operating in 12.25-12.75 GHz and rejecting over 14.0-14.5 GHz, which can be a candidate for receiving antenna of satellite communication. The measured results agree well with the designed ones, showing a suppression level stronger than 40 dB in the rejecting band.