Chebyshev Synthesis for Multi-Band Microwave Filters

In this paper, a new method for the synthesis of (possibly) asymmetric dual-band or multi-band filters is presented. The latter generalizes the classical Chebyshev synthesis in that it computes the optimal solution of a max-min optimization problem specified in terms of the filtering function of the usual low-pass prototype. The computational part of the method consists of a Remez type exchange algorithm. As an example the design of a dual-band filter from asymmetric specifications for the SPOT5 spacecraft is considered, and yields a 7th degree filter that replaces advantageously the usual solution made out of 2 separate filters "diplexed" by means of waveguide junctions at their input/output ports