Wideband filtering waveguide antenna based on the stepped impedance resonator

A wideband filtering waveguide antenna is proposed. The stepped impedance waveguide resonator is used to obtain three resonance modes, widening the bandwidth from 1.9 to 5 GHz. Besides, the antenna integrates a band-stop filter, which consists of four rectangular resonant cavities, without increasing the lateral and vertical dimensions of the entire antenna. The integrated filter effectively suppresses the antenna gain near 16 GHz, which is outside the working band. Additionally, groove resonance is used to increase the gain of antenna by 4 dB, and two pair of grooves which resonant at different frequencies are employed to increase the bandwidth of realised gain. Finally, a prototype has been developed, the measured relative impedance bandwidth (|S-11| < -10 dB) of the proposed antenna is 49.6% at the centre frequency of 11 GHz, and the 3 dB gain bandwidth is 5.1 GHz.