An efficient design approach for planar microwave multiplexers

An efficient design approach for planar diplexerlmultiplexers is described. Mutual coupling effects due to the power divider and the fiters, as well as (radiation) losses and dispersion are included in an extended coupling matrix representation of the overall diplexer structure. The coupling matrix represents a surrogate model for the EM structure for which the model parameters are determined using a commercial EM simulator. Optimization of the surrogate´s element values avoids the direct use of an EM simulator and thus accelerates the optimization of the planar dlplexers by orders of magnitude. Examples of dlplexers with parallel coupled fiters and hairpin resonator filters illustrate the efiiciency of the approach.