Quintuple-Mode W-Band Packaged Filter Based on a Modified Quarter-Mode Substrate-Integrated Waveguide Cavity

A novel quintuple-mode filter in one cavity is proposed by modifying a quarter-mode substrate-integrated waveguide (SIW) cavity. Modes can be independently controlled by dimension parameters of the resonator. The quintuple-mode resonator is packaged to prevent electromagnetic leakage, and pillars are added to remove spurious cavity resonances introduced by the packaging. A W-band filter is designed and fabricated by using benzocyclobutene (BCB) polymer as dielectrics. The microelectromechanical systems (MEMS) fabrication process is demonstrated in detail. This filter offers the advantages of easy integration with other active devices. It is suitable for 3-D integration of millimeter-wave and sub-terahertz transceiver systems. Four transmission zeros (TZs) are obtained to improve the stopband, and insertion loss is 1.97 dB at 89 GHz with a fractional bandwidth (FBW) of 22.5%. Simulated results agree with measured results.