A Novel High Selectivity Sheet-Metal Diplexer with Frequency Dependent Couplings

A novel high selectivity sheet-metal diplexer with multiple transmission zeros using frequency dependent couplings (FDC) is proposed. Compared with the traditional cross coupling, the frequency dependent couplings can generate additional flexible and controllable transmission zeros. We introduced the FDC structure between two sheet-metal resonators, and we used odd-even mode method to analyze its resonance characteristics. To demonstrate the effectiveness of the presented method, we synthesized and simulated a sheet-metal diplexer centered at 2660MHz and 2785MHz, the simulated results are well matched with the synthesis response, which verified the effectiveness to design high selectivity sheet-metal diplexer.