Broadband Modeling Using Numerical Coupling Matrix Reconfiguration Methodologies for Microwave Filters

Abstract

This letter presents a direct bandpass (DB) synthesis approach for wideband reactive filters based on numerical matrix reconfiguration techniques. Unlike previous works that find analytical solutions derived from similarity transformations or circuital analysis, the proposed methodology directly computes the final reactive coupling matrix (CM) leveraging nondeterministic algorithms to match given transfer functions to prescribed target topologies. This approach eliminates the need for intermediate analytical steps, enabling the direct extraction of target topology lumped elements in the normalized domain by reformulating the classical CM nodal representation. The method is validated through the synthesis and fabrication of a wideband bandpass filter (BPF) up to 40% of fractional bandwidth (FBW). The extracted values are scaled and fine-tuned for practical implementation.