Vertically Stacked Trisection SIW Filter With Controllable Transmission Zeros

This letter proposes a novel trisection filter by stacking three substrate-integrated waveguide (SIW) cavities vertically. The trisection topology can be divided into two cascaded second-order topologies in the vertical direction, which can make the filter structure more compact. Moreover, two transmission zeros can be controlled independently by changing the signs of coupling coefficients between the adjacent stacked SIW cavities. Finally, a third-order filter sample is fabricated using printed circuit board (PCB) technology, and the measured S-parameters have good agreement with the simulated ones.