Wide stopband substrate integrated waveguide filter using corner cavities

A type of substrate integrated waveguide (SIW) `corner cavity` is proposed. For each corner cavity, two transmission zeros (TZs) can be introduced and the location of either TZ can easily be controlled by adjusting suitable geometrical parameters. Using the corner cavities, a novel SIW filter with wide stopband characteristic is implemented. The central frequency of the filter is 20 GHz, and the first spurious appears at about 40 GHz, which is two times the central frequency. In addition, the measured stopband attenuation of the filter is better than 50 dB from 21.24 to 37.71 GHz.