Patent ID: 7248216

Claim:
A calibration apparatus for an array antenna having a plurality of antenna elements, comprising: calibration signal producing means for producing a calibration signal for each of said antenna elements; transmission means for outputting, to said antenna element, said calibration signal produced by said calibration signal producing means together with a transmission main signal at a predetermined transmission radio frequency; reception means for receiving a reception main signal with a predetermined reception radio frequency from said antenna element; calibration signal detection/frequency conversion means for detecting said calibration signal from the output of said transmission means to convert the detected calibration signal into a predetermined reception radio frequency and for outputting the converted calibration signal together with said reception main signal to said reception means; relative phase difference detecting means for detecting said calibration signal from an output of said reception means for each of said antenna elements to obtain a relative phase difference between said calibration signals; and phase correcting means for correcting a phase difference with respect to one of or both said transmission main signal and said reception main signal on the basis of said relative phase difference obtained by said relative phase difference detecting means.