Substrate Integrated Waveguide based dual-band bandpass filter using split ring resonator and defected ground structure for SFCW Radar applications

In this paper, we present a novel dual-band highly selective bandpass filter using Substrate Integrated Waveguide (SIW) technology. Designed bandpass filter is a combination of SIW structure with high-pass characteristic, single rectangular split ring resonators (SRRs) as parallel LC resonator & dumbbell- shaped defected ground structure (DGS) with band rejection characteristic. Here, designed filter has pass band with high rejection values of -15.24 dB and - 18.43 dB and the insertion loss of 0.250 dB and 0.361 dB at 6 GHz and 8.55 GHz respectively. Designed SIW based dual-band bandpass filter has 3-dB fractional bandwidth (FBW) of 2.85% and 2.22% at 6GHz and 8.55 GHz respectively. The physical dimension of proposed structure is of 42 mm x 21 mm (1.77 lambda(g) x 0.88 lambda(g)). All the simulations and optimizations of the proposed structure are carried out in the Ansoft HFSS (high frequency structure simulator) software based on the finite element method. In order to verify the functionality of the proposed filter, structure is fabricated and tested.