Variable frequency superconducting microstrip line resonator

Abstract

The invention relates to a variable frequency superconducting microstrip line resonator, which comprises an upper-layer superconducting resonator structure, a lower-layer superconducting thin film and a dielectric substrate positioned between the upper-layer superconducting resonator structure and the lower-layer superconducting thin film. The variable frequency superconducting microstrip line resonator is characterized in that: the upper-layer superconducting resonator structure comprises a continuous main strip line, one or more external microstrip lines and one or more switches; one or two ends of the main strip line form an interdigital coupled structure with the one or more external microstrip lines; the interdigital coupled structure is formed by intersecting the port comb crotch structure of the main strip line and the port comb crotch structure(s) of the one or more external microstrip lines, and the port comb crotch structures of the main strip line and the one or more external microstrip lines do not contact each other; the external microstrip lines are grounded through the switches; and the grounding state, off state or state combinations of the one or more external microstrip lines are controlled by the one or more switches to change the resonance frequency of the resonator. The variable frequency superconducting microstrip line resonator has the advantages of high quality factor, wide variable frequency range, a great number of variable frequency points and frequency control accuracy, is easily made, and can be used for designing and manufacturing high-performance variable frequency band-pass, band elimination, high-pass, low-pass and multi-band superconducting filters.

Description

technical field [0001] The invention belongs to the field of microwave technology, and relates to a frequency-variable superconducting microstrip line resonator. Background technique [0002] Since the surface resistance of superconducting materials in the microwave frequency range is two to three orders of magnitude lower than that of conventional metal materials, superconducting filters composed of superconducting microstrip line resonators have excellent filtering characteristics. The basic composition of the conductive microstrip line resonator includes an upper layer superconducting resonator structure 11, a lower layer superconducting film 12, and a dielectric substrate 13 between the upper and lower layers of superconductors, such as figure 1 shown. Wherein, both the upper resonator structure 11 and the lower conductor thin film are superconductors; the substrate can be made of magnesium oxide substrate, lanthanum aluminate substrate, sapphire and other materials. I...

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Problems solved by technology

At present, there are two main implementation methods of variable frequency superconducting filters that have been published: one is to suspend a dielectric sheet above the superconducting microstrip line resonator, and change the suspension height of the dielectric sheet by mechanical movement, thereby changing the superconducting filter. The difficulty in realizing the resonant frequency of the resonator is that it is difficult to realize a micro-mechanical control device that requires extremely high precision and works at low temperature. The disadvantage is that the frequency conversion response is slow; another way is to connect a varactor in series with the superconducting resonator , the impedance value of the varactor is changed by the power supply device to affect the resonant frequency of the resonator. The difficulty of its realization is that it is difficult to integrate discrete components on the surface of the superconducting substrate, and the design error is large. The disadvantage is that the introduction of the varactor will greatly reduce the The quality factor of the superconducting resonator, which leads to the increase of the filter insertion loss and the decrease of the passband performance

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