Design of a High-Power Superconducting Filter With Novel DGS Structures

A novel defected ground structure (DGS) resonator with improved power handling capability is proposed in this paper. The current density distribution of the DGS resonator is simulated and compared with that of the complete ground structure (CGS) resonator. Simulation shows that the maximum current density of the DGS resonator is lower than that of the CGS resonator. Two four-pole bandpass high-temperature superconducting filters centered at 2.9 GHz with a fractional bandwidth of nearly 1.5% are designed and fabricated using the DGS and CGS resonators, respectively. The measured maximum handling power is 37.3 dBm for the DGS filter at 77 K, which is higher than that of 34.1 dBm for the CGS filter.