Design of a SIW Wide-Band bandpass filter loaded by DGS

In this paper, a miniaturized broadband bandpass filter operating in microwave band is designed based on substrate integrated waveguide (SIW). The filter periodically etches symmetrical concave grooves on the metal surface of SIW, forming a defected ground structure (DGS) which produces the high-frequency conduction and the band gap effect, respectively. In addition, this design strengthens the out-band rejection and reduces the circuit area. The filtering effect in passband is realized by the combination of the high-pass characteristic of substrate integrated waveguide and low-pass characteristic of defected ground structure. The results of simulation show that the center frequency of the filter is 26GHz, and the passband range is from 22.5GHz to 29.5GHz, in which the return loss is less than −10dB and the insertion loss is higher than −2dB.