PURPOSE: To suppress the occurrence of the degradation of the search capacity (coverage and precision) due to the variation of frequency, by providing a frequency control circuit and a signal/information processing circuit.

CONSTITUTION: The frequency control circuit changes the frequency on a basis of a frequency changing program and gives frequency channel information to a reference signal generating circuit and a signal/information processing circuit 14. The signal/information processing circuit 14 receives this information, and an optimum value of hit verification in a horizontal plane, a value correcting the azimuth of an antenna beam, and a value correcting the difference between intervals, at which the antenna beam is directed to a specific target, and the rotational cycle of the antenna are operated in a detection reference control cicuit 146. These results are sent as control signals to a sweep correlation circuit 143 and a phase calculating circuit 144.