PURPOSE: To restrain the reception of the unnecessary reflected waves from a sea surface by controlling the phase of an antenna array elements in accordance with the transmission and reception thereby to form a preset beam pattern.
CONSTITUTION: The phase shift of a phase shifter 2 corresponding to the antenna elements arranged vertically in an array is controlled through a beam control circuit 5 and a drive circuit 4. Then, the pattern transmitted from an antenna 1, which constitutes a single antenna of all the antenna elements, has a sufficiently small gain in the vicinity of the elevation of 0 degrees. Upon reception, the phase shifter 2 is so controlled that the beam pattern of each unit antenna formed by the plural antenna elements of each half wavelength of the radar waves for each time after the reception become equal. Then, the reception having the rear surface reflection restrained is performed by the transmitted pattern having little sea surface reflection is performed to measure the target angle in high accuracy.
OOMAE TAKAO
TANAKA YASUTOSHI
