Novel synthesis of wideband filter using open-short-circuited stepped impedance resonators

A wideband filter consisting of a cascade connection of open-short-circuited stepped impedance resonators (OSSIRs) is proposed with a corresponding synthesis theory. The pseudo-Chebyshev-function-based formulae are derived to design the wideband filter with an arbitrary fractional bandwidth. By introducing the center frequency of the passband as a designable parameter, the distance between the center frequencies of the passband and spurious can be also controlled in our novel synthesis technique. To validate the proposed technique, a wideband filter with a bandwidth of 3-5GHz is designed, simulated, fabricated and measured. The measured responses of the filter agree well with the simulation and theoretical ones, which validates the effectiveness of the newly-proposed filter structure and the corresponding design scheme.