Compact bandpass filter based on single isosceles right triangular substrate integrated waveguide cavity and modified complementary compact microstrip resonant cell

Abstract

An isosceles right triangular Substrate integrated waveguide cavity is presented. By etching the modified complementary compact microstrip resonant cell on the metal upper surface of isosceles right triangular SIW cavity, different bandpass filters are realized by using different feed ports. The triangular SIW bandpass filter with two right-angle sides as feed ports is designed and implemented. The center frequency is 17.8 GHz, the fractional bandwidth is 36.52%, the in-band insertion loss is less than 0.3 dB, and the in-band return loss is better than -20 dB. The existence of two transmission zeros in stopband significantly improves selectivity of the filter.