Compact substrate integrated waveguide (SIW) transversal filter with triple-mode microstrip resonator

A novel fourth-order substrate integrated waveguide (SIW) transversal filter with triple-mode microstrip resonator is presented. The triple-mode resonator is etched on the top metal layer of SIW cavity, so compact size can be achieved. The coupling scheme of filter exhibits transversal characteristic, and the design principle of the filter is simple. The filter has compact size and wide stopband in comparison with conventional SIW filters. An open stub was added on the port to get better frequency selectivity. Two SIW filter samples are designed and fabricated, with good agreement achieved between the measured and the simulated S-parameters.