Patent attributes
Transmission antennas are aligned at a reference distance along a preset direction of alignment. The aperture width of a first reception antenna in the direction of alignment is set to a first width which is less than the reference distance. Second reception antennas each have an aperture width in the direction of alignment set to a second width which is the first width or less and are aligned at a distance which is less than the reference distance along the direction of alignment. The distance between the position of the center of the first reception antenna and the phase center of a second reception antennal located closest to the first reception antenna among the second reception antennas is set to a length that is greater than or equal to the value obtained by multiplying the reference distance by the value obtained by subtracting 1 from the number of transmission antennas.
