Optimal Synthesis for Multi-Band Microwave Filters

In this paper a new method for the synthesis of asymmetric multi-band filters is presented. The major improvement of the latter is that it not only computes optimal reflection zeros but also optimal transmission zeros of the filtering function of the usual low-pass prototype. The computational part consists of a differential correction-like algorithm proven to be convergent, and which guarantees the optimality of the response. Practical information is given for the implementation of such an algorithm. The process is validated by the design of a dual-band filter from asymmetric specifications, which yields a 9th degree filter.