Antenna apparatus

An antenna apparatus comprising:

• an antenna element that processes a signal in a first frequency band and a signal in a second frequency band with a frequency band that is different from the first frequency band;
• a switch including a common terminal that is electrically connected to the antenna element side;
• a first signal path provided between a first input/output terminal of the switch and a first communication circuit;
• and
• a second signal path provided between a second input/output terminal of the switch and a second communication circuit;
• wherein
• the first signal path includes a radio-frequency (RF) circuit and a phase shifter;
• the RF circuit has an impedance that is open or shorted in the second frequency band as seen from the antenna element side;
• the phase shifter includes:
• a first port electrically connected to the switch side;
• a second port electrically connected to the RF circuit side;
• a first coil electrically connected between the first port and ground;
• a second coil that magnetic-field couples to the first coil with a coupling coefficient of less than 1, and that is electrically connected between the second port and the ground;
• and
• a capacitor provided between the first port and the second port;
• and
• the phase shifter provides a phase shift, and an impedance in the second frequency band of the first signal path as seen from the common terminal is open in a state of the switch in which the common terminal and the first input/output terminal are electrically connected and the common terminal and the second input/output terminal are electrically connected.