Accurate design of high-performance diplexers for mobile communication base stations applications

This work describes a modified approach for extracting the equivalent circuit parameters, as there are the resonant frequency of each resonator, the coupling bandwidths and the external Qs from multi-port Y-matrix and group delay of the input reflection coefficients. The extractions of equivalent circuit parameters and the fine tuning for three-dimensional simulating models are achieved by utilizing the EM simulating software HFSS. Then, a novel method for designing microwave diplexers is proposed. Compared to the methods existed, all interacting effects are allowed taking into account. One circuit parameter can be related to one dominate geometrical variation in the three-dimensional model. The detailed design steps illustrating the design of a diplexer for mobile communication base stations applications are presented. The designed device with a novel tunable electrical coupling structure is then fabricated. The comparison between measurements and simulations has validated the new design method with high efficiency.