Patent ID: 8324988

Claim:
A variable resonator, comprising: a single loop conductor line provided on one surface of a dielectric substrate; a ground conductor provided on either said one surface or an other surface opposite to said one surface of said dielectric substrate; at least two switches; and at least three reactance circuits, wherein each of said at least two switches has one end electrically connected to said single loop conductor line and an other end electrically connected to said ground conductor, and each of said at least two switches is configured to select interchangeably electrical connection or electrical non-connection between said ground conductor and said single loop conductor line; connection positions on said single loop conductor line where said at least two switches are connected are different from each other; said single loop conductor line has an inherent resonance frequency having one wavelength or an integral multiple thereof corresponding to a circumference length of the single loop conductor line; reactance values of said at least three reactance circuits are equal to each other; said at least three reactance circuits are electrically connected as branching circuits to connection points on said single loop conductor line at an equal electrical length interval based on said resonance frequency; said variable resonator resonates at a varied resonance frequency that is fixed in response to the reactance values of said at least three reactance circuits, the varied resonance frequency being different from said inherent resonance frequency; only one of said at least two switches is selected to be rendered in a conducting state; and only a bandwidth at the varied resonance frequency changes in response to the selection of said only one of said at least two switches with the varied resonance frequency being constant.