Generalized synthesis and design of symmetrical multiple passband filters

In this paper, we present a new synthesis method for a generalized symmetric multiple band bandpass filter. By using frequency transformations on the low pass prototype, the poles and zeros of the single/dual band filtering function are obtained. These poles and zeros are combined and re-arranged to get the multiband filtering function. The coupling matrix is obtained from this multiband filtering function. A variety of filters are synthesized in order to validate the proposed theory. A triple band and quadruple band filters have been designed, fabricated and measured. The measured results have good agreement with the simulated results.