Design and preparation of single-chip HTS coplanar waveguide bandpass filters

An extremely low-loss, sharp cut-off, single-chip high-temperature superconducting (HTS) coplanar waveguide (CPW) bandpass filter (BPF) was designed and prepared; such filters are useful for future telecommunications systems. A nine-pole CPW BPF having a centre frequency (f₀) of 10 GHz and fractional bandwidth of 1.5% (whose chip size is less than 10 mm square) was designed, and confirmed by a computer simulation (HP-Momentum). In order to realize fully two-dimensional HTS filters, we make use of meanderline geometry and interdigital capacitance coupling. In order to make the BPF compact, we clarify the cross-coupling between meanderlines and modelling of the corner bend of the transmission lines. Experiments with a prototype miniaturized CPW BPF (three-pole) on 10 mm square YBCO film are also presented.