Miniaturized Shielded Dual-band SIW Filter Based on Novel Slotlines with High Selectivity and Controllable Transmission Zeros

This study proposes a miniaturized dual-band substrate integrated waveguide (SIW) filter by loading novel slot line resonators. These slotlines divide the whole SIW cavity into two identical resonators. The fundamental mode is used to form the first passband and the higher mode forms the second passband. The center frequencies of both passbands are below the cut-off frequency of the original SIW cavity. Miniaturization is thus achieved. Two transmission zeros are introduced by source-to-load coupling, therefore achieving the harmonic suppressing and good out-of-band rejection. A prototype is fabricated and measured, and the measured result agrees well with the simulated data. This filter exhibits good performance including compact size, low loss and good out-of-band suppression.