Miniaturized Substrate Integrated Waveguide Compact Band-pass Filters with CMRC Technique

In this paper, a compact and high performance planar bandpass filter (BPF), based on the substrate integrated waveguide (SIW) and the compact microstrip resonant cell (CMRC) technique, is proposed. The SIW cavity has the advantages of high quality and low insertion loss, provides a highpass characteristic. In order to reduce the filter dimensions, three CMRC structures resonators are etched on the upper metal surface of the SIW cavity which behave as a lowpass filter. And it can reduce the circuit size over 50%. To verify the proposed design method and structure, a compact bandpass filter having a center frequency of 5.8 GHz, insertion loss of -0.9 dB and a 3 dB bandwidth of 1.6 GHz is evaluated. The desired bandwidth and center frequency of the proposed filter are given by adjusting the cutoff frequencies for SIW and CMRC. The simulated results obtained by CST and HFSS simulators are in good agreement.