RADAR APPARATUS AND METHOD FOR TRANSMISSION AND RECEPTION BY RADAR APPARATUS
In a radar apparatus, either a plurality of transmission antennas or a plurality of reception antennas include a first antenna group disposed in a first direction and a second antenna group disposed in a second direction different from the first direction, and an other of the plurality of transmission antennas and the plurality of reception antennas include a third antenna group disposed in a third direction different from each of the first direction and the second direction.
1 . A radar apparatus, comprising:
transmission circuitry, which, in operation, transmits a transmission signal using a plurality of transmission antennas; and
reception circuitry, which, in operation, receives a reflected wave signal using a plurality of reception antennas, the reflected wave signal being the transmission signal reflected by an object, wherein
either the plurality of transmission antennas or the plurality of reception antennas include a first antenna group disposed in a first direction and a second antenna group disposed in a second direction different from the first direction, and
an other of the plurality of transmission antennas and the plurality of reception antennas include a third antenna group disposed in a third direction different from each of the first direction and the second direction.
2 . The radar apparatus according to claim 1 , wherein:
the radar apparatus is installed in a vehicle, and
the first direction and the second direction are different directions with respect to a vertical direction and a horizontal direction, the vertical direction being a height direction of the vehicle, the horizontal direction being a forward traveling direction of the vehicle and a direction orthogonal to the forward traveling direction of the vehicle.
3 . The radar apparatus according to claim 1 , wherein
the first direction and the second direction are different directions with respect to a vertical direction and a horizontal direction, the vertical direction being a gravity direction, the horizontal direction being a direction orthogonal to the gravity direction.
4 . The radar apparatus according to claim 2 , wherein
the third direction is a direction coinciding with the horizontal direction.
5 . The radar apparatus according to claim 1 , wherein
a minimum spacing between the first antenna group and the second antenna group is greater than an aperture length of the third antenna group.
6 . The radar apparatus according to claim 1 , wherein
the first antenna group and the second antenna group include one or more shared antennas.
7 . The radar apparatus according to claim 1 , wherein
an antenna arrangement included in the first antenna group and an antenna arrangement included in the second antenna group have line symmetry with respect to a line orthogonal to the third direction.
8 . The radar apparatus according to claim 2 , wherein:
a spacing between adjacent antennas of the third antenna group in the horizontal direction is dT×D H ,
a spacing between adjacent antennas included in the first antenna group in the horizontal direction is dRH 1 ×D H ,
a spacing between adjacent antennas included in the first antenna group in the vertical direction is dRV×D V ,
a spacing between adjacent antennas included in the second antenna group in the horizontal direction is dRH 2 ×D H ,
a spacing between adjacent antennas included in the second antenna group in the vertical direction is dRV×D V ,
the D H and the D V are values in a range of 0.45 to 0.8 times the wavelength of the transmission signal, and
the dT is a value equal to or greater than 2, each of the dRH 1 and the dRH 2 is a value equal to or greater than 1.
9 . The radar apparatus according to claim 1 , wherein
a spacing between adjacent antennas is an equal spacing in each of the third antenna group, the first antenna group, and the second antenna group.
10 . The radar apparatus according to claim 1 , wherein
a spacing between adjacent antennas includes one or more unequal spacings in at least one of the third antenna group, the first antenna group, and the second antenna group.
11 . The radar apparatus according to claim 1 , wherein
the third antenna group includes a plurality of sets of at least some antennas arranged in the third direction.
12 . The radar apparatus according to claim 1 , wherein
the either the plurality of transmission antennas or the plurality of reception antennas include a plurality of the first antenna groups and a plurality of the second antenna groups.
13 . The radar apparatus according to claim 1 , wherein
the plurality of transmission antennas include two types of antenna elements differing at least in size.
14 . The radar apparatus according to claim 1 , wherein
the other of the plurality of transmission antennas and the plurality of reception antennas include a fourth antenna group disposed in a fourth direction different from the third direction.
15 . The radar apparatus according to claim 2 , wherein:
the other of the plurality of transmission antennas and the plurality of reception antennas include a fourth antenna group disposed in a fourth direction different from the third direction, and
the third direction and the fourth direction are different directions with respect to the horizontal direction and the vertical direction.
16 . The radar apparatus according to claim 14 , wherein
the first direction, the second direction, the third direction, and the fourth direction are different from one another.
17 . The radar apparatus according to claim 14 , wherein
the third antenna group and the fourth antenna group include one or more shared antennas.
18 . The radar apparatus according to claim 15 , wherein:
a spacing between adjacent antennas of the third antenna group in the horizontal direction is dTH 1 ×D H ,
a spacing between adjacent antennas included in the third antenna group in the vertical direction is dTV 1 ×D V ,
a spacing between adjacent antennas of the fourth antenna group in the horizontal direction is dTH 2 ×D H ,
a spacing between adjacent antennas included in the fourth antenna group in the vertical direction is dTV 2 ×D V ,
a spacing between adjacent antennas included in the first antenna group in the horizontal direction is dRH 1 ×D H ,
a spacing between adjacent antennas included in the first antenna group in the vertical direction is dRV 1 ×D V ,
a spacing between adjacent antennas included in the second antenna group in the horizontal direction is dRH 2 ×D H ,
a spacing between adjacent antennas included in the second antenna group in the vertical direction is dRV 2 ×D V ,
the D H and the D V are values in a range of 0.45 to 0.8 times the wavelength of the transmission signal, and
each of the dTH 1 , the dTV 1 , the dTH 2 , the dTV 2 , the dRH 1 , the dRV 1 , the dRH 2 , and the dRV 2 is a value equal to or greater than 1.
19 . The radar apparatus according to claim 1 , wherein:
the other of the plurality of transmission antennas and the plurality of reception antennas further include a fourth antenna group disposed in a fourth direction different from the third direction,
the third direction is a same direction as the first direction, and
the fourth direction is a same direction as the second direction.
20 . The radar apparatus according to claim 1 , wherein
a spacing between adjacent antennas in the third antenna group is equal to or greater than one wavelength of the transmission signal.
21 . A method for transmitting and receiving a radar signal, comprising:
transmitting a transmission signal using a plurality of transmission antennas; and
receiving a reflected wave signal using a plurality of reception antennas, the reflected wave signal being the transmission signal reflected by an object, wherein
either the plurality of transmission antennas or the plurality of reception antennas include a first antenna group disposed in a first direction and a second antenna group disposed in a second direction different from the first direction, and
an other of the plurality of transmission antennas and the plurality of reception antennas include a third antenna group disposed in a third direction different from each of the first direction and the second direction.