A radar transmitter transmits a radar signal through a transmitting array antenna at a predetermined transmission period, and a radar receiver receives a reflected wave signal which is the radar signal reflected by a target through a receiving array antenna. A transmitting array antenna and a receiving array antenna each include multiple subarray elements, the subarray elements in the transmitting array antenna and the receiving array antenna are linearly arranged in a first direction, each subarray element includes multiple antenna elements, the subarray element has a dimension larger than a predetermined antenna element spacing in the first direction, and an absolute value of a difference between a subarray element spacing of the transmitting array antenna and a subarray element spacing of the receiving array antenna is equal to the predetermined antenna element spacing.
1. A radar device comprising:
radar transmission circuitry which, in operation, transmits a radar signal through a transmitting array antenna at a predetermined transmission period; and
radar reception circuitry which, in operation, receives a reflected wave signal which is the radar signal reflected by an object through a receiving array antenna, wherein
the transmitting array antenna and the receiving array antenna each include a plurality of subarray elements,
the subarray elements are linearly arranged in a first direction in each of the transmitting array antenna and the receiving array antenna,
each subarray element includes a plurality of antenna elements,
a dimension of each subarray element in the first direction is larger than a predetermined antenna element spacing, and
an absolute value of a difference between a subarray element spacing of the transmitting array antenna and a subarray element spacing of the receiving array antenna is equal to the predetermined antenna element spacing.
2. The radar device according to claim 1 , wherein the predetermined antenna element spacing is not smaller than 0.5 wavelength and not larger than 0.75 wavelength.
3. The radar device according to claim 1 , wherein:
the subarray elements in one of the transmitting array antenna and the receiving array antenna are further arranged in a second direction orthogonal to the first direction,
the dimension of each subarray element in the first direction is larger than the predetermined antenna element spacing,
the absolute value of the difference between the subarray element spacing of the transmitting array antenna in the first direction and the subarray element spacing of the receiving array antenna in the first direction is equal to the predetermined antenna element spacing,
the dimension of the subarray element in the second direction is not larger than the predetermined antenna element spacing, and
the subarray elements are arranged in the second direction at the predetermined antenna element spacing.
4. The radar device according to claim 3 , wherein the subarray elements arranged in the second direction are shifted from each other in the first direction by the predetermined antenna element spacing.
5. The radar device according to claim 1 , wherein:
the subarray elements in one of the transmitting array antenna and the receiving array antenna are further arranged in a second direction orthogonal to the first direction,
the dimension of each subarray element in the first direction is larger than the predetermined antenna element spacing,
the absolute value of the difference between the subarray element spacing of the transmitting array antenna in the first direction and the subarray element spacing of the receiving array antenna in the first direction is equal to the predetermined antenna element spacing,
the dimension of the subarray element in the second direction is not larger than the predetermined antenna element spacing,
the subarray elements are arranged in the second direction at a spacing ((√3)/2) times larger than the predetermined antenna element spacing, and
the subarray elements adjacent to each other in the second direction are shifted from each other in the first direction by a spacing (½) times larger than the predetermined antenna element spacing.