Patent ID: 7944330
Filing Date: 2011-05-17
Classification: H01P

Abstract:
1. A resonant element that causes a signal input from an input terminal to resonate at a predetermined resonance frequency and outputs the signal to an output terminal, comprising: a transmission line series that includes a plurality of transmission lines connected in series with each other and intersects with a hotline that connects the input terminal and the output terminal; and a plurality of switches, wherein at least one of one end and an other end of said transmission line series is a grounded end, the transmission lines are categorized into first transmission lines, each of which is a transmission line having a fixed length, second transmission lines, each of which is connected in series to one of the first transmission lines, and a third transmission line, which is connected in series to one of the first transmission lines and one of the second transmission lines, the plurality of switches include a switch having a grounded end and another end that is connected to a point between the first transmission lines and the second transmission lines, and a switch that is connected in parallel to the third transmission line, one of the second transmission lines is provided in the one end side of said transmission line series in a first section extending from an intersection point of said transmission line series and the hotline to the one end of the transmission line series and another of the second transmission lines is provided in the other end side of said transmission line series in a second section extending from the intersection point to other end of the transmission line series, the third transmission line is provided in at least one of the first section and the second section, the first transmission line is provided in the first section and the second section, and the resonance frequency is switched by turning on/off said switches to change the sum of the lengths of all of the transmission lines through which the signal passes.