Compact T-septum substrate integrated waveguide (TSSIW) filter with wide stopband

Proposed is a compact fourth-order band-pass filter based on T-septum substrate integrated waveguide (TSSIW) resonators. By introducing a T-septum in the conventional SIW cavity, the TSSIW resonator has lower resonant frequency and wider monomode bandwidth. In order to verify our theory, a TSSIW filter sample is fabricated in low-temperature co-fired ceramic technology, and good agreements are obtained between simulated and measured S-parameters. In comparison with planar SIW cavity filters, the proposed filter has compact size, better frequency selectivity, and wider stopband.