A compact bandpass substrate integrated waveguide (SIW) filter with compact microstrip resonant cell (CMRC) resonators

Abstract

The technology of substrate integrated waveguide (SIW) and compact microstrip resonant cell are combined and a novel compact and high performance bandpass filter (BPF) is proposed in this paper. The SIW cavity, as the basic frame structure of this bandpass filter, provide high-pass characteristics, and it has the advantages of relatively high quality factor and low insertion loss. The compact microstrip resonant cell (CMRC) etched on the top metal plane of the SIW cavity behaves as a low-pass filter, and it can also effectively reduce the size of the filter. Moreover, a flexible bandwidth and center frequency can be achieved by properly adjusting the cutoff frequencies of the SIW and CMRC. In order to verify the proposed design method and structure, a bandpass filter having a center frequency of 4.5 GHz and a 3 dB bandwidth of 1.26 GHz is design, fabricated, and experimentally evaluated. The measured results are in good agreement with those obtained by theory and simulation.