Design of Controllable Dual-Band Bandpass Filter Based on Dual-Mode Metal Plate Coupled Resonator

This article presents a controllable dual-band filter design based on a dual-mode metal plate coupled resonator (DM-MPCR). Both inductive window and cylinder post couplings were adopted to obtain independent inner coupling control. Extra cylinder post was also loaded in the first and last resonators to achieve external coupling control flexibility. Also, beneficial from the mixed-coupling features of DM-MPCR, a novel dual-parallel coupling topology path was formed, which generates multiple transmission zeros (TZs). The designed dual-band filter was fabricated using 3-D metal printing for rapid demonstration. The measured results agreed well with the simulated ones.