Compact Diplexer Based on Stub-loaded Dual-mode Resonator

A compact diplexer based on stub loaded dual-mode resonator is presented in this paper. The optimized T-junction microstrip line combines two independent dual-mode resonator filters. This dual-mode configuration is easily controllable resonant modes and transmission zero position, improving the filter and diplexer frequency response. The fabricated diplexer with the lower and upper resonant frequencies at 1.95 GHz and 2.14 GHz is designed to verify the proposed configuration. The proposed diplexer has isolation better than 21 dB, and insertions are better than 1.1 dB in both channels.