A Dual Wideband Filter Design Using Frequency Mapping and Stepped-Impedance Resonators

A dual-wideband filter design implemented by stepped-impedance resonators, which involves the frequency mapping approach, is presented in this paper. The dual-band filter can be divided into two parts: the wideband virtual passband filter and the narrowband virtual stopband filter. Both filters are designed by conventional synthesis methods, under the assumption that the common connecting lines serve as J- and K-inverters simultaneously. The basic building resonators formed by paralleling open- and shorting-stubs are implemented by unbalanced stepped-impedance resonators, exhibiting the desired resonating frequencies and susceptance slope parameters at these two bands. Two filters are tested to validate this design.