Substrate Integrated Waveguide Dual-Band and Wide-Stopband Bandpass Filters

In this letter, a new coupling structure implemented on a single-layer substrate and its application to design substrate integrated waveguide (SIW) dual-band and wide-stopband bandpass filters are presented. The TE
₁₀₁
and the TE
₁₀₂
modes of SIW cavity are used to design the proposed filters. By adjusting the dimensions of the coupling structure, the coupling coefficients of TE
₁₀₁
and TE
₁₀₂
modes can be controlled that can be used to design wide-stopband and dual-band bandpass filters. In the dual-band filter design, a slotline perturbation is used to lower the resonant frequency of TE
₁₀₂
mode while it has little effect on TE
₁₀₁
mode. To validate the proposed design approach, two SIW bandpass filters (wide-stopband and dual-band) are designed, fabricated, and measured.