Miniaturized dual-band substrate integrated waveguide filters using complementary split-ring resonators

A novel design concept for compact dual-band substrate integrated waveguide (SIW) filters using the complementary split-ring resonators (CSRRs) is presented. By loading two different types of CSRRs on the waveguide surface, two passbands propagating below the waveguide cutoff frequency are generated separately. The proposed structure allows relatively independent control over the center frequencies and the coupling coefficients. The working principle is illustrated and the filter design methodology is examined. Two two-pole filters with dual-band operation are demonstrated, showing advantages in terms of the compact size, good selectivity and stopband rejection, easy fabrication and integration with other circuits.