Interactive Filter Synthesis for Microwave Software Tools

One of drawbacks in most filter design tools is a straightforward computation procedure that leads to single solution: filter specification is met with an approximation function whose edge frequencies and maximum passband and minimum stopband attenuations are equal to the specified ones. In this paper we propose an interactive design in which we can choose different edge frequencies and attenuations, with respect to the specified ones, but still meet the specification. The proposed design can implement the Chebyshev approximation with modification due to the different port resistances. Our interactive design allows the change the filter parameters in order to meet the specification with the most appropriate margins. The design algorithm is implemented in MATLAB and WIPL-D Microwave. Synthesized filter schematic can be exported as WIPL-D Microwave project for further analysis.