Reconfigurable Wideband Bandpass Filters based on Dual Cross-Shaped Resonator

In this paper, a class of reconfigurable wideband bandpass filters based on dual cross-shaped resonator (DCSR) is studied. The proposed DCSR consists of shunt opened stubs loaded at the end of their parental shunt stub. This configuration can effectively produce additional poles and zeros to the wideband bandpass filter, and therefore providing an overall good in-band response with simultaneous shape cut-off. By introducing some tunable devices (i.e. pin diodes, varactors), the bandwidth of proposed filter can be easily adjusted to accommodate specific applications. In addition, a controllable notch is generated in the passband to reduce the strong interfering signal happened in wideband operation. A DCSR bandpass filter operating at 6 GHz is designed, fabricated and measured. The fractional bandwidth (FBW) centers around 102.2% with ±19% tuning range. Meanwhile, the notch can lie between 3.0 GHz to 7.9 GHz.