Elliptic-disc filters of high-T/sub c/ superconducting films for power-handling capability over 100 W

Abstract

On the future digital communication system, distortion of transmitted signals should be eliminated as much as possible for high communication quality. However, the need to both minimize distortion of signal amplifiers and continue to provide good filtering protection can become difficult to achieve with conventional devices. In this paper, the RF coplanar circuit filter using elliptic-disc resonators is proposed and investigated, This proposition makes it possible to miniaturize power filter circuits and to realize high performance of power ability of high-temperature superconducting (HTS) filters. An end spread signal coupling electrodes is investigated in order to adjust the coupling degree between disc and feedline circuits and provide proper characteristic impedance of circuit. Two-mode coupling operation in the elliptic disc are then explained. Electromagnetic-field distribution change caused by this mode coupling can protect current and heat concentration, and realize power-handling capability over 100 W. Finally, the design principle of a multiple-disc filter is introduced for high performance of out-of-band rejection and passband flatness. It has been confirmed that an elliptic-disc resonator filter can bring out the excellent performance of HTS materials.

HTS dual-mode filters with power property improved by a tunable dielectric plate

“…The similar phenomenon was reported in Ref. [6], which mentioned the contribution of connectors, cables, RF radiation and some measurement setup errors rather than dissipation loss. As the LaAlO 3 plate approached to the filter pattern, the insertion loss kept constant until about 37 dB m input power.…”

“…For applying to HTS transmit tunable filters, we have been studying the feasibility of HTS disk resonators tuned by moving an upper dielectric plate which is actuated by a piezo-motor [5]. In general, microstrip dual-mode disk filters are attractive for increasing power handling capability and compactness [6,7]. We present the improved power properties such as higher power handling capability and lower intermodulation distortion using an upper dielectric plate with an upper conducting plate for dual-mode on HTS disk resonator filters [8,9].…”

Power-Handling Capability of Superconducting Filters Using Disk- and Ring-Type Bulk Resonators

“…Many researchers have increased the power-handling capability of superconducting band-pass filters (BPFs) by improving the filter structure. Such improvements have been reported for sliced microstrip Manuscript line resonators [3], [4], for microstrip-disk resonators [5]- [8], and for HTS thick film resonators [9]- [11]. Bulk superconducting GdBa 2 Cu 3 O y (GdBCO) fabricated by using a modified quench and melt growth (QMG) method [12] have a surface resistance (R s ), that is low enough to be used in microwave filters [13].…”

A Novel Microwave High-Temperature Superconducting Reaction-Type Transmitting Filter for Mobile Base Stations

“…One of the substantial reasons for this is their low power-handling capability caused by high surface-current concentrations on the superconducting devices. Research and development of HTS transmitting filters have been concentrated mostly on dual-mode filters employing patch resonators for the dispersion of surfacecurrent and hence low current densities [1], [2]. Dual-mode filters have difficulties to realize sharp cutoff and miniaturization at the same time since it requires considerably large resonator size to construct.…”