Substrate integrated waveguide band-pass filter with coupled complementary split ring resonators

This paper presents a design of bandpass filter applied to ultra-wide band RFID system (IEEE standard 802.15.4f), by combining SIW´s high-pass property with the loaded CSRR played as low pass filter. The working mechanism of CSRR, single-cell CSRR on SIW structure and SIW-coupled CSRR pair is introduced. The principle of CSRR equivalent circuit of SIW transmission line and SIW-coupled CSRR pair is analyzed and achieves good agreement with configuration of the structure. The resonant frequency of CSRR is set at transmission zeros at stopband. The measured 3 dB passband bandwidth is 5.5-8.25 GHz with insertion loss less than 2dB. The stopband extends from 8.5 GHz to 11.5 GHz with better than 30 dB rejection.