Radar apparatus

1. A radar apparatus comprising:

transmission circuitry, which, in operation, transmits a transmission signal by using a plurality of transmission antennas; and

reception circuitry, which, in operation, receives a reflected wave signal that is the transmission signal reflected from an object by using a plurality of reception antennas, wherein

either one of the plurality of transmission antennas or the plurality of reception antennas includes a plurality of first antennas arranged at different positions in a first direction, a plurality of second antennas arranged at different positions in a second direction perpendicular to the first direction, the plurality of first antennas arranged at the same position in the second direction and the plurality of second antennas arranged at the same position in the first direction, and a third antenna different from any of the plurality of first antennas and the plurality of second antennas,

one of the plurality of first antennas constitutes one of the plurality of second antennas,

the third antenna is arranged at a first spacing in the first direction from the position of the plurality of second antennas, and is arranged at a second spacing in the second direction from the position of the plurality of first antennas,

a first aperture length of the plurality of first antennas in the first direction is greater than the first spacing, or a second aperture length of the plurality of second antennas in the second direction is greater than the second spacing,

the first spacing is an integer multiple of at least one spacing of the plurality of first antennas, and the second spacing is an integer multiple of at least one spacing of the plurality of second antennas,

the other one of the plurality of transmission antennas or the plurality of reception antennas includes a plurality of fourth antennas arranged in the first direction, and a plurality of fifth antennas arranged in the second direction, the plurality of fourth antennas arranged at the same position in the second direction and the plurality of fifth antennas arranged at the same position in the first direction, and

one of the plurality of fourth antennas constitutes one of the plurality of fifth antennas.

2. The radar apparatus according to claim 1 , wherein

an aperture length of a virtual reception antenna made up of the plurality of transmission antennas and the plurality of reception antennas is wider in the first direction than in the second direction.

3. The radar apparatus according to claim 1 , wherein

the third antenna is arranged in the first direction on a side where a larger number of the plurality of first antennas are arranged with respect to the position at which the plurality of second antennas is arranged.

4. The radar apparatus according to claim 1 , wherein

the third antenna is arranged in the first direction on a side where a smaller number of the plurality of first antennas are arranged with respect to the position at which the plurality of second antennas is arranged.

5. The radar apparatus according to claim 1 , wherein

the number of antennas in the first direction is greater than the number of antennas in the second direction in the plurality of transmission antennas and in the plurality of reception antennas.

6. The radar apparatus according to claim 5 , wherein

in at least one of the first direction and the second direction, a difference between a spacing of the plurality of transmission antennas and a spacing of the plurality of reception antennas is an integer multiple-value of the first spacing or the second spacing.

7. The radar apparatus according to claim 5 , wherein

in at least one of the first direction and the second direction, an antenna spacing of either one of the plurality of transmission antennas or the plurality of reception antennas is longer than an antenna aperture length of the other one of the plurality of transmission antennas or the plurality of reception antennas.

8. The radar apparatus according to claim 5 , wherein

the first direction is a horizontal direction.

9. The radar apparatus according to claim 1 , wherein

a spacing of the plurality of fourth antennas in the first direction is wider than the first aperture length of the plurality of first antennas.

10. The radar apparatus according to claim 1 , wherein

antenna spacings in the first direction of at least either one or both of the plurality of transmission antennas and/or the plurality of reception antennas are unequal spacings.

11. The radar apparatus according to claim 1 , wherein

the plurality of transmission antennas and the plurality of reception antennas are arranged in an L shape, a T shape, or a cross shape.

12. The radar apparatus according to claim 1 , wherein

a value of the first spacing or the second spacing is any value within a range of 0.45 times to 0.8 times as long as a wavelength.

13. The radar apparatus according to claim 1 , wherein

the first aperture length of the plurality of first antennas in the first direction is greater than the first spacing, and the second aperture length of the plurality of second antennas in the second direction is greater than the second spacing.

14. The radar apparatus of claim 1 , wherein

a plurality of the third antennas are provided, and

all of the plurality of third antennas are arranged at the first spacing from the plurality of second antennas in the first direction, or are arranged at the second spacing from the plurality of first antennas in the second direction.

15. The radar apparatus according to claim 14 , wherein

all of the plurality of third antennas are arranged at the first spacing from the plurality of second antennas in the first direction, and are arranged at the second spacing from the plurality of first antennas in the second direction.

16. The radar apparatus according to claim 1 , wherein

the first spacing is equal to at least one spacing of the plurality of first antennas.

17. The radar apparatus according to claim 16 , wherein

the second spacing is equal to at least one spacing of the plurality of second antennas.