SWITCHABLE INDUCTOR

• US 20020044027A1
• Filed: 07/15/1999
• Published: 04/18/2002
• Est. Priority Date: 07/17/1998
• Status: Active Grant

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: ZHOU, SHU-ANG, WIKBORG, ERLAND
• Granted Patent: US 6,556,849 B2
• Time in Patent Office: Days
• US Class Current: 333/99S
• CPC Class Codes: H01P 3/081 Microstriplines

Abstract

An inductor for microwave frequencies has a substantially planar structure and is constructed of a transmission line designed as a linear microstrip element made of a central line comprising normal electrically conducting material, such as a suitable metal. The microstrip element has a width which is varied by making areas at sides of the central line superconducting. In changing the effective width of the microstrip the inductance thereof is changed accordingly. The areas at the sides of the microstrip element are located directly at the central, normal metal conductor. These areas have in the non-superconducting state some electrical conductivity which can be rather low but owing to the fact that they contact the normal central metal conductor only at a very narrow edge instead of contacting it at a large surface they do not significantly affect the transmission characteristics of the transmission path when the superconducting areas are in their normal state.

Claims

1. An inductor for microwaves, the indictor comprising:

a central microstrip line made of an electrically conducting material exhibiting no superconducting properties above a considered temperature; and

regions made of a material exhibiting superconducting properties above the considered temperature, the regions being located at sides of the central microstrip line and in the same plane as the central microstrip line.

2. The inductor of claim 1, wherein the central microstrip line has a shape of a strip of a uniform width.

3. The inductor of claim 1, wherein the regions have shapes of strips of uniform widths.

4. The inductor of claim 3, wherein all the regions have a same width.

5. The inductor of claim 1, further comprising control means for making an electrical current flow through the inductor, thereby bringing, when the inductor is above the considered temperature and the regions are in a superconducting state, the regions to change to a non-superconducting state.