Patent ID: 8463200

Claim:
A wireless communication apparatus comprising: a first antenna for receiving a predetermined signal that is transmitted by an external transmitter at a reference frequency; a reception circuit including a frequency conversion circuit and a signal strength detection circuit, the frequency conversion circuit including an oscillator that outputs a frequency signal at a predetermined frequency and being configured to frequency-convert signals input to the reception circuit based on the frequency signal output from the oscillator, the signal strength detection circuit being configured to detect strength of the frequency-converted signals output from the frequency conversion circuit and output an RSSI (Received Signal Strength Indication) voltage that represents the detected strength; an impedance matching circuit that performs impedance matching between the first antenna and the reception circuit, the impedance matching circuit having a variable impedance; a second antenna for receiving the frequency signal output from the oscillator of the frequency conversion circuit of the reception circuit; a first switch that is arranged to selectively electrically connect one of the two antennas and the reception circuit to the impedance matching circuit while disconnecting the other antenna from the impedance matching circuit; a second switch that is arranged to selectively electrically connect and disconnect the first antenna to and from the reception circuit; a signal processor that, when the first switch electrically connects the reception circuit to the impedance matching circuit and the second switch electrically disconnects the first antenna from the reception circuit so that the predetermined signal received by the first antenna is input to the frequency conversion circuit of the reception circuit via the impedance matching circuit and the first switch, processes the frequency-converted signal output from the frequency conversion circuit; and a controller that, when the first switch electrically connects the second antenna to the impedance matching circuit and the second switch electrically connects the first antenna to the reception circuit so that the frequency signal received by the second antenna is applied to the impedance matching circuit, controls the impedance of the impedance matching circuit so as to bring the RSSI voltage output from the signal strength detection circuit of the reception circuit into agreement with a reference RSSI voltage.