Patent ID: 8049660

Claim:
A radar apparatus comprising: at least one array transmitting antenna comprising an array of antenna elements having a fixed pitch, for transmitting a beam of electromagnetic waves, and a plurality of receiving antennas spaced apart with a fixed pitch, for receiving resultant reflected waves from a target and producing respective received signals corresponding to said received waves, phase control circuitry configured to supply transmission signals to said antenna elements of said array transmitting antenna, and to apply phase control to said transmission signals for sequentially shifting said beam to cover successively different beamwidth ranges of direction within an extent which at least includes a predetermined target detection range, direction detection circuitry configured to detect a direction of a target within said target detection range, said detection based upon a phase difference between said received signals of said receiving antennas and upon a beamwidth range of said transmitted beam at a time of said detection; wherein, designating β1 as an extent of a range of directions within which said phase difference does not exceed 360°, where β1 is determined by said pitch of said receiving antennas, and designating (k×β1) as an extent of said target detection range, where k is greater than 1, and designating α1 as a difference between respective orientation directions of a main lobe of said transmitted beam and a grating lobe of said transmitted beam, where α1 is determined by said pitch of said antenna elements of said array transmitting antenna; said pitch of said antenna elements of said array transmitting antenna and said pitch of said receiving antennas are respectively predetermined such that the following relationship exists: α1 =k×β 1.