Dual-mode substrate integrated waveguide (SIW) bandpass filters with an improved upper stopband performance

Dual-mode substrate integrated waveguide (SIW) filters with improved upper stopband attenuation is presented. The filter is comprised of TE₁₀₂ and TE₂₀₁ modes waveguide resonator. The proposed filters are implemented using substrate integrated waveguide (SIW) technology featuring compact size, low cost, and high power-capacity. A simple solution for improving the upper stopband performance while maintaining compact size realization is provided. The stopband improvement is achieved by using defected ground structure (DGS) which is etched on the ground plane of the SIW cavity. Compared to previous-reported SIW filters with improved stopband achieved by lowpass cleanup filters, the proposed approach provides a relatively compact realization while reducing the complexity of the overall structure. Simulation examples of single- and double-cavity dual-mode SIW filters are realized using EM simulations for demonstrating the underlying principle.