Design and performance of miniaturized HTS coplanar waveguide bandpass filters with highly packed meanderlines

We propose the new and highly accurate design theory of the high T_c superconducting (HTS) miniaturized coplanar waveguide (CPW) bandpass filters (BPFs) with highly packed meanderlines. BPFs are designed using the external quality factor (Q_e) and coupling constant (k) (Q-k method). These parameters are estimated from the transmission coefficient obtained by the 2.5-dimensional electromagnetic field simulator. Moreover, the Q-k method is compared with the J-b method (designed using admittance inverter and susceptance slope parameter) presented previously; in this way we confirmed that the Q-k method has higher accuracy than the J-b method. We realized the design of a the highly packed meanderline CPW BPF (5 pole, center frequency = 2 GHz, fractional band width = 15 MHz, ripple = 0.1 dB) in a 3.5 mm × 8 mm substrate.