Compact SIW bandpass filter for wideband millimeter-wave applications

a compact substrate intergrated waveguide (SIW) bandpass filter (BPF) is proposed for millimeter-wave (mmW) application. Four vias are located inside the SIW cavity in the form of rotationally symmetrical structure to provide transmission zeros at upper-stopband. As design examples, one substrate integrated waveguide bandpass filter prototype using Low Temperature Co-fired Ceramic (LTCC) on single layer substrate is designed and experimentally examined. The measured results show that the filter achieves a passband insertion loss of 0.8 dB at 50 GHz, return loss below -13dB and 3-dB fractional bandwidth of 30%.