Standing wave ratio measuring circuit and communication apparatus

A standing wave ratio measuring circuit comprising:

• an amplifier circuit which amplifies a transmission signal;
• a first circulator which outputs the transmission signal amplified by the amplifier circuit in a direction of a transmission/reception antenna, and that outputs a reception signal received by the transmission/reception antenna to a reception system;
• a traveling wave acquiring unit which acquires the transmission signal before being input to the amplifier circuit as a traveling wave when a request to measure a standing wave ratio is detected;
• a traveling wave bypassing unit which allows the traveling wave acquired by the traveling wave acquiring unit to travel to the reception system while bypassing the amplifier circuit;
• a second circulator provided in the reception system which outputs the traveling wave bypassing the amplifier circuit through the traveling wave bypassing unit in a direction of the first circulator;
• a control unit which controls the amplifier circuit such that the traveling wave output from the second circulator travels in the direction of the transmission/reception antenna via the first circulator;
• a reflected wave acquiring unit which acquires a reflected wave, which is the traveling wave reflected in the vicinity of the transmission/reception antenna, at a location after the second circulator in the reception system;
• and
• a measuring circuit which measures the standing wave ratio using the traveling wave acquired by the traveling wave acquiring unit and the reflected wave acquired by the reflected wave acquiring unit.