Abstract: A directional coupler includes a multilayer body including a plurality of stacked dielectric layers, a main line including a first main line portion and a second main line portion which are connected in series to each other in this order and that is provided in the multilayer body, and a sub-line including a first sub-line portion and a second sub-line portion which are connected in series to each other in this order, the first sub-line portion being electromagnetically coupled to the first main line portion, the second sub-line portion being electromagnetically coupled to the second main line portion, and the sub-line being provided on one side in a stacking direction with respect to the main line in the multilayer body.

Abstract: A variable-frequency resonance circuit includes first and second input/output terminals and a resonance circuit portion. The resonance circuit portion includes a first inductor and first and second LC series circuits. The resonance circuit portion is connected between a ground and a transmission line that connects the first and second input/output terminals. The first LC series circuit includes a second inductor and a variable capacitor connected in series with each other. The second LC series circuit includes a third inductor and a fixed capacitor connected in series with each other. The first and second LC series circuits are connected in parallel between the first inductor and a ground. The first and second inductors are configured such that positive-coupling mutual inductance is produced therebetween.

Abstract: A directional coupler includes a main line, a sub line, and a first parasitic element. The main line includes a first main line portion. The sub line includes a first sub line portion electromagnetically coupled with the first main line portion. The first parasitic element receives a first magnetic flux which is generated by the first main line portion when a current flows through the first main line portion and generates a second magnetic flux passing through the first sub line portion due to electromagnetic induction.

Abstract: A directional coupler includes a multilayer body including a plurality of stacked dielectric layers, a main line including a first main line portion and a second main line portion which are connected in series to each other in this order and that is provided in the multilayer body, and a sub-line including a first sub-line portion and a second sub-line portion which are connected in series to each other in this order, the first sub-line portion being electromagnetically coupled to the first main line portion, the second sub-line portion being electromagnetically coupled to the second main line portion, and the sub-line being provided on one side in a stacking direction with respect to the main line in the multilayer body.

Abstract: A directional coupler includes a multilayer body including a plurality of stacked dielectric layers, a main line including a first main line portion and a second main line portion which are connected in series to each other in this order and that is provided in the multilayer body, and a sub-line including a first sub-line portion and a second sub-line portion which are connected in series to each other in this order, the first sub-line portion being electromagnetically coupled to the first main line portion, the second sub-line portion being electromagnetically coupled to the second main line portion, and the sub-line being provided on one side in a stacking direction with respect to the main line in the multilayer body.

Abstract: A directional coupler includes a main line, a sub line, and a parasitic element. The main line includes first and second main line portions formed substantially in a spiral shape, as viewed from a first direction. The second main line portion is positioned in a second direction which is perpendicular to the first direction, as viewed from the first direction. The sub line includes first and second sub line portions formed substantially in a spiral shape, as viewed from the first direction. The first and second sub line portions are electromagnetically coupled with the first and second main line portions, respectively. The second sub line portion is positioned in the second direction, as viewed from the first direction. The parasitic element is superposed on the first main line portion and the second sub line portion, as viewed from the first direction.

Abstract: A directional coupler includes a main line, a sub line, and a parasitic element. The main line includes first and second main line portions formed substantially in a spiral shape, as viewed from a first direction. The second main line portion is positioned in a second direction which is perpendicular to the first direction, as viewed from the first direction. The sub line includes first and second sub line portions formed substantially in a spiral shape, as viewed from the first direction. The first and second sub line portions are electromagnetically coupled with the first and second main line portions, respectively. The second sub line portion is positioned in the second direction, as viewed from the first direction. The parasitic element is superposed on the first main line portion and the second sub line portion, as viewed from the first direction.

Abstract: A directional coupler includes a main line, a sub line, and a first parasitic element. The main line includes a first main line portion. The sub line includes a first sub line portion electromagnetically coupled with the first main line portion. The first parasitic element receives a first magnetic flux which is generated by the first main line portion when a current flows through the first main line portion and generates a second magnetic flux passing through the first sub line portion due to electromagnetic induction.

Abstract: A variable-frequency resonance circuit includes first and second input/output terminals and a resonance circuit portion. The resonance circuit portion includes a first inductor and first and second LC series circuits. The resonance circuit portion is connected between a ground and a transmission line that connects the first and second input/output terminals. The first LC series circuit includes a second inductor and a variable capacitor connected in series with each other. The second LC series circuit includes a third inductor and a fixed capacitor connected in series with each other. The first and second LC series circuits are connected in parallel between the first inductor and a ground. The first and second inductors are configured such that positive-coupling mutual inductance is produced therebetween.

Abstract: A directional coupler includes a multilayer body including a plurality of stacked dielectric layers, a main line including a first main line portion and a second main line portion which are connected in series to each other in this order and that is provided in the multilayer body, and a sub-line including a first sub-line portion and a second sub-line portion which are connected in series to each other in this order, the first sub-line portion being electromagnetically coupled to the first main line portion, the second sub-line portion being electromagnetically coupled to the second main line portion, and the sub-line being provided on one side in a stacking direction with respect to the main line in the multilayer body.