Resonant Element and High Frequency Filter, and Wireless Communication Apparatus Equipped with the Resonant Element or the High Frequency Filter

摘要

What is disclosed is a resonant element that causes a signal input from an input terminal to resonate at a predetermined resonance frequency and outputs it to an output terminal. The element has 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 the other end of the transmission line series is a grounded end, the transmission lines are categorized into a first transmission line, which is a transmission line having a fixed length, and a second transmission line, which is a transmission line to which the switch one end of which is a grounded end is connected in series at a point between it and an adjacent transmission line, the transmission line in one end side of the transmission line series in a first section extending from a intersection point of the transmission line series and the hotline to one end of the transmission line series and the transmission line in the other end side of the transmission line series in a second section extending from the intersection point to the other end of the transmission line series are the second transmission lines, the first transmission lines are provided in the first section and the second section, and the resonance frequency is switched by turning on/off the switch to change the sum of the lengths of the transmission lines through which the signal passes.