Dual Band Modified Complementary Split Ring Resonator Loaded Substrate Integrated Waveguide Based Bandpass Filter

This study presents a dual-band bandpass filter design that implements microstrip to substrate integrated waveguide (SIW) transition to decrease radiation losses. The proposed filter is designed with using four complementary split ring resonators (CSRR) to minimize its size and to gain double negative property. A bowtie shaped slot is etched inside CSRR to have a second resonance at the spectrum. After the simulation results are performed the designed filter is fabricated on a Rogers RT5880 dielectric substrate and the experimental results are compared with the simulation results. The proposed filter has center frequencies at 6.57 and 12.55 GHz with fractional bandwidth (FBW) of 22.05% and 26.29%, respectively. Moreover, the presented filter offers the best bandwidth-to-size result with the size of 0.327 lambda(g) x0.352 lambda(g) (where lambda(g) is the wavelength at the first passband's center frequency).