Compact Substrate Integrated Waveguide BPF for Wideband Communication Applications

A new compact substrate integrated waveguide (SIW) bandpass filter (BPF) is presented in this paper as a candidate for use in wide bandwidth X-band applications. The proposed filter is constructed by embedding two semi-circular slots have been in the SIW structure from the input and the output sides. The simulation and performance evaluation of the proposed filter have been carried out using Microwave Studio Suite of Computer Simulation Technology CST. A parametric study reveals that the insertion of these slots has successfully led to the compact size and the wide bandwidth. The cavity dimensions are 13.6 × 10.6 mm while the overall filter dimensions are 28.5 × 16mm using a substrate with relative permittivity of 2.2 and thickness of 0.245 mm. The resulting filter exhibits a return loss less than −15 dB and insertion loss approaching to 0 dB over the passband. The proposed filter offers a −3 dB fractional bandwidth of about 68.4% centered at 11.7 GHz. The compact size offered by this filter makes it a suitable for use in designing microwave and millimeter-wave circuits.