Improvement of power handling capability and out-of-band rejection for HTS stripline filter with shuttle-shape resonators

A high-temperature superconducting stripline (SL) transmit filter with shuttle-shape resonators is described that improves power handling and out-of-band rejection. A cascaded quadruplet (CQ) design is used to produce a pair of attenuation poles for obtaining sharp cutoff characteristics. The shuttle-shape resonators improve power handling and out-of-band rejection. Placement of additional patch conductors in the upper layer of the resonator edges further improves power handling. An electromagnetic simulator based on the moment method was used to design a four-pole SL CQ filter with shuttle-shape resonators (5.0-GHz center frequency and 100-MHz bandwidth). Simulation using the electromagnetic simulator showed that the out-of-band rejection was improved and frequency response of the filter was nearly symmetric. The maximum current density of the shuttle-shape filter was approximately 19% lower than that of a four-pole SL CQ filter with straight-line resonators. That of the shuttle-shape filter with the additional patch conductors was approximately 24% lower.