Cross-coupled substrate integrated waveguide filter with sharp sideband performance

In this paper, an X-band cross-coupled substrate integrated waveguide (SIW) filter with sharp sideband performance is proposed. The negative coupling is implemented by 201 TE -mode response in the fourth oversized cavity, which is combined with positive coupling to generate transmission zeros(TZs) for improving the sideband performance.The filter with a passband of 11.5GHz~12.5GHz is fabricated on a single-layer substrate with the standard PCB process. Measured results show that, the in-band insertion loss is 1.2dB, and the stopband attenuation is better than 50dB, it has sharper transition performance at both the upper sideband and lower sideband, compared to the traditional direct coupling SIW filters.