Generation of Admissible Grid Topologies for Coupled-Resonator Filters

This work introduces an algorithm for the generation of admissible grid topologies for coupled-resonator microwave filters, capable of introducing a high number of transmission zeros in the filter response (for a given number of resonators). Both regular and frequency-dependent couplings are allowed in the generated topologies. This algorithm is used to create regular grid topologies with various shapes, e.g. rectangular, triangular, diamond⋯. The exhaustive synthesis of the generated topologies is carried out through a numerical procedure recently introduced. Several synthesis examples are reported in the paper to validate the proposed algorithm.