Miniaturized Two-Dimensional Multi-Channel SIW Bandpass Filter Bank with High Selectivity

<p>A multi-channel bandpass filter bank based on Substrate Integrated Waveguide (SIW) is presented in this letter. Based on the SIW orthogonal resonant modes, a miniaturized two-dimensional multi-channel bandpass filter bank is realized through SIW square cavities. Depending on the placement of the feed ports, the Substrate Integrated Square Cavity (SISC) technique is utilized to attain the propagation of the two orthogonally oriented transverse electric modes (TE102 and TE201) which resonate on the same frequency and bandwidth. The coupling matrix synthesis and coupling windows are the control parameters for the bandwidth. Proper placement and adjustments of the feed ports and the coupling windows generate better transmission and bandpass responses in each channel. However, to further ensure higher isolation while a wider fractional bandwidth is attained, a pair of slotlines are imprinted along a specific diagonal of each cavity. An archetype of a 3 x 3 array of bandpass filtering channels with a center frequency at 8.65 GHz has been designed, simulated, and measured to validate the proposed method. The proposed work yielded good filtering characteristics, high isolation, a comparatively wider fractional bandwidth, and a smaller device size.  </p>