Circular Patch Resonator Loaded Compact SIW Filter with Harmonic Suppression

In this paper, based on a hybrid structure using the patch resonator and substrate integrated waveguide (SIW) cavity, a compact bandpass filter (BPF) with a wide stopband is proposed. The patch resonator is connected with two SIW cavities by coplanar waveguide lines at both ends. It can not only extend the order of the proposed filter but also suppress the TE201and TE202 modes of the SIW cavity. In addition, the offset orthogonal ports can prevent the propagation of the $\mathbf{TE}_{102}$ mode of the SIW cavities. Thus, a wide stopband is achieved by suppressing the first three spurious modes. For validation, a prototype was fabricated and measured.