Synthesis of N-Foster-Section Filter With Maximum 2N Prescribed Transmission Zeros by Heuristic-Aided Graph Search

A graph-search-based optimization method to synthesize Foster-section-cascaded filters is introduced. A heuristic cost function that determines the direction of the graph search, is presented, and the optimization algorithm does not require the gradient calculation of the cost function. Auxiliary features of the optimization that can improve the heuristic efficiency and the quality of the result are explained. Several successful synthesis examples and designs of the synthesized filters are given.