Demodulator, an antenna device, and the receiving device

PROBLEM TO BE SOLVED: To provide a compact and inexpensive demodulator, antenna device and receiving device which can have a simple circuit configuration while maintaining the accuracy of a reception sensitivity. SOLUTION: The demodulator includes a space diversity receiving device 36 for selecting any of high frequency signals transmitted through power supply lines 4 from antenna devices 20 located in the vicinity of a plurality of antennas 5 or combining the high frequency signals, a demodulation circuit 31 for demodulating the high frequency signal selected or combined by the space diversity receiving device 36, and a control voltage generating circuit 320 for generating a DC control voltage to adjust a frequency characteristic of an impedance matching circuit 22 built in the antenna device 20 to fall in an allowable range in response to a receive frequency, superimposing such DC control voltages and outputting the superimposed voltage to a power supply line 4. COPYRIGHT: (C)2010,JPO&INPIT