RESONATOR, FILTER, COMPOSITE FILTER DEVICE, TRANSCEIVER, AND COMMUNICATION APPARATUS

摘要

PROBLEM TO BE SOLVED: To provide a resonator of a low loss having a constant resonance frequency independently of a critical temperature. SOLUTION: A resonance electrode 2 on which a superconducting film 21 and a metallic film 22 are layered in this order is formed on one principal side of a dielectric board 1. A ground electrode 3 comprising a superconducting film 21 and a metallic film 22 layered is formed on the entire other principal side of the dielectric board 1. Thus, the resonance electrode 2, the dielectric board 1 and the ground electrode 3 configure the microstrip resonator. Since the superconducting film acts like an electrode at a temperature lower than the critical temperature and the metallic film acts like the electrode at a temperature equal to and higher than the critical temperature, the length of the superconducting film 21 is selected longer than the length of the metallic film 22 to make the resonance frequency at the low and high temperature operations almost coincident with each other so that the resonator has a constant resonance frequency characteristic over a wide temperature range. COPYRIGHT: (C)2004,JPO