A Triple-Mode Cylindrical Cavity-Backed Slot Filtering Antenna with High Selectivity

This paper proposes a high selectivity slot filtering antenna using a single circular waveguide cavity. Two slots are respectively constructed on the bottom and top sides of the cylindrical cavity to form a feeding slot and a radiating slot. By appropriately rotating the two slots and offsetting them from the axis of the cavity, the TM
010
mode and two TE
111
degeneration modes of the cavity resonator can be excited and radiated. The three modes work together and a cavity-backed slot antenna with a three-pole bandpass response is obtained. Due to the input/output coupling characteristics of the three modes, a radiation null can be introduced on both sides of the passband to improve the selectivity of the antenna. The simulated results show that the proposed filtering antenna has a fractional bandwidth of 4% at the center frequency of 10 GHz and a flat realized gain greater than 7 dBi within the passband.