SIW‐based interdigital bandpass filter with harmonic suppression

A novel configuration of interdigital bandpass filter based on the substrate integrated waveguide (SIW) technology is proposed. In addition to the interdigital resonators in SIW that determine the main response/characteristics of the filter, narrowing the width of the SIW at the center of the filter and additional vias at its input and output parts act as two additional control mechanisms to achieve the desired filter response. Moreover, dumbbells are etched to the ground side of the microstrip feeding sections at both ends of the filter to improve its harmonic suppression. A prototype filter is designed and fabricated for verification. The measured results are in good agreement with the simulations, and the filter exhibits very good harmonic suppression. © 2015 Wiley Periodicals, Inc.