PURPOSE: To attain a reception front end in a form of a module by mixing a reference signal to a feeding system of each antenna element in loose coupling and correcting a frequency and phase shift between intermediate frequency conversion outputs by each independent local oscillator from a reception signal of each array element based on the reference signal.

CONSTITUTION: Outputs of antenna elements 1-3 and a pilot signal mixed via couplers 4-6 from an oscillator 7 are converted into a 1st intermediate frequency signal by frequency converters 8-10, a local oscillating frequency of each frequency converter is not completely identical and the 1st intermediate frequency signal differs by the difference. Voltage variable local oscillators 14, 15 control a 2nd intermediate frequency being the output of mixers 11, 12 of the same frequency and phase as the output frequency of the mixer 18 to make the difference zero. A pilot signal extracted from the control voltage by band pass filters 17-19 is subject to phase comparison by phase detectors 20, 21 and smoothed by low pass filters 22, 23. The operation is established by the pilot signal and when the frequency of the output signal of the antenna element does not differ much from the frequency of the pilot signal, the operation is established at the same time.