Compact dual-band bandpass filter based on composite right/left-handed substrate integrated waveguide loaded by complementary split-ring resonators defected ground structure

Abstract

A new dual-resonance substrate integrated waveguide (SIW) resonator structure which combines composite right/left-handed SIW with complementary split-ring resonators defected ground structure is presented and analyzed in this paper. The proposed resonator structure possesses these performances, such as a much lower steep cutoff frequency as compared with the ordinary SIW of the same footprint, a high passband transmission zero, and two controllable resonant frequencies. Based on the proposed resonator structure, a compact two-order dual-band bandpass filter is designed, which operates at 5 and 7.5 GHz. The bandwidths are 3 and 4.2% and the corresponding insertion losses are 2.42 and 2.62 dB, respectively. The steep cutoff frequency in low passband left edge and transmissions zero in high passband right edge are also achieved at 4.8 and 8.1 GHz, a good out-of-band rejection is obtained. The size of the filter is only 0.28λg*0.27λg. The measured and simulated results are in good agreement, which validates the characteristic of the proposed resonator structure.