| 摘要 |
By the present invention, satisfactory directionality is realized even when the magnetic coupling coefficient is low in a directional coupler. A directional coupler (1) is provided with a main line (2), a secondary line (3), and impedance converters (4, 5). The main line (2) is connected between a signal input port (RFin) and a signal output port (RFout). The secondary line (3) is coupled to the main line (2) by a coupling capacitance and mutual inductance. The impedance converters (4, 5) are connected between a coupling port (CPL) or isolation port (ISO) and the secondary line (3), the impedance referenced from the secondary line (3) and the impedance referenced from the port side are different, and impedances referenced from the secondary line (3) match each other. |
