Patent ID: 8564384

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 M reactance circuits, where M is an even number of 4 or larger, 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 at the inherent resonance frequency corresponding to a circumference length of the single loop conductor line; reactance values of said M reactance circuits are equal to each other; M/2−1 reactance circuits of said M reactance circuits, which are referred to as first reactance circuits, are connected to said single loop conductor line at connection points between a position K 1 arbitrarily set on said single loop conductor line and a position K 2 apart from the position K 1 along a clockwise part by half an electrical length of one circumference of said single loop conductor line except at said position K 1 and at said position K 2 so as to divide said clockwise part at an equal electrical length interval based on said inherent resonance frequency; M/2−1 reactance circuits of said M reactance circuits except said first reactance circuits are connected to said single loop conductor line at connection points between said position K 1 and said position K 2 along a counter-clockwise part except at said position K 1 and at said position K 2 so as to divide said counter-clockwise part at the equal electrical length interval based on said inherent resonance frequency; two remaining reactance circuits of said M reactance circuits are connected to said single loop conductor line at said position K 2 ; said variable resonator resonates at a varied resonance frequency that is fixed in response to the reactance values, 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.