Synthesis of Low-Pass Elliptic Filters for MIC as a Class of Non-Commensurate Distributed Circuits

A new synthesis technique of low-pass elliptic filters particularly suited for realization in printed circuit version is presented. The synthesis is based on the use of non-commensurate transmission line sections and stubs. Microstrip filters of seventh order with cutoff frequency in the X-band have been fabricated and measured in the frequency range 2-18 GHz. The performance is shown to be quite satisfactory particularly in the pass-band.