A narrow band and high selectivity half‐mode substrate integrated waveguide bandpass filter with interdigital slots

Abstract

AbstractA novel in‐line half‐mode substrate integrated waveguide (HMSIW) bandpass filter with interdigital slots has been proposed in this letter. Here, the interdigital slot shows attenuation resonance characteristics and generates a finite frequency transmission zero (TZ). The proposed filter generates two TZs without additional coupling or extra space and exhibits wide stopband characteristics. To validate this method, the in‐line two‐pole quasi‐elliptic bandpass filter is synthesized and fabricated on RT/Duroid 5880 substrate using printed circuit board technology. The experimental results show that center frequency, 3‐dB fractional bandwidth, insertion loss, and return loss are 3.6 GHz, 6.0%, 1.9 and 18 dB, respectively, and are very much similar to the simulated S‐parameters.