Showing papers by "Keiji Enpuku published in 1992"
TL;DR: In this paper, an analytical expression for the kinetic inductance of the coplanar stripline is given using the conformal mapping technique, and it is shown with the London equation and the two fluid-model that the microwave loss is directly proportional to the kinetic induction.
Abstract: In order to determine transmission line parameters of superconducting coplanar striplines with thickness smaller than the magnetic penetration depth of the striplines, in which the influences of enlarged kinetic inductance and strongly nonuniform current distribution make it useless to apply the conventional design formula developed for normal conductors, we have conducted theoretical and experimental studies on the geometrical effects of the kinetic inductance and the microwave loss of the thin coplanar striplines. The analytical expression for the kinetic inductance of the coplanar stripline is given using the conformal mapping technique, and it is shown with the London equation and the two fluid-model that the microwave loss is directly proportional to the kinetic inductance. The comparison has been made between theory and experiment concerning the kinetic inductance and the microwave quality factor of NbN coplanar striplines with various thicknesses and widths. It is shown that the observed characteristics are well modeled by the analytical expression.
49 citations
TL;DR: In this article, a complete circuit model of a dc superconducting quantum interference device coupled to a multiturn input coil has been developed, and the rf properties of the coupled SQUID can be calculated using only the given parameters of the SQUID.
Abstract: A complete circuit model of a dc superconducting quantum interference device (SQUID) coupled to a multiturn input coil has been developed. With this model, it is shown that the rf properties of the coupled SQUID can be calculated using only the given parameters of the SQUID. There are no adjustable parameters. The resonant structures in the SQUID characteristics caused by the presence of the input coil have been quantitatively studied. Methods to suppress the resonant structures have also been investigated. It is shown that the present circuit model explains well the experimentally observed rf properties of coupled SQUIDs. The present circuit model is therefore useful for the design of highly sensitive SQUIDs.
25 citations
01 Jan 1992
TL;DR: In this article, the characteristics of a dc SQUID coupled to a multiturn input coil have been investigated by using an expanded model of the circuit, and the resonant structures in the rf properties of the coupling circuit have been observed.
Abstract: In order to study the characteristics of a dc SQUID coupled to a multiturn input coil, rf properties of the coupling circuit between the SQUID and the input coil have been investigated by using an expanded model of the circuit. We observe resonant structures in the rf properties of the coupling circuit, which means that the SQUID coil in the presence the input coil can not be expressed by a simple inductance, in contrast to the isolated SQUID. The resonant structures can be suppressed with damping resistances. A model for the coupling circuit is also obtained.
1 citations