Patent attributes
An array antenna includes a first end portion that has a first plurality of antennas arranged with a spacing d therebetween and a second end portion that has a second plurality of antennas arranged with the spacing d therebetween. In the array antenna, a spacing between respective antennas in both the first and second end portions and are closest to a central portion is set to 2d, which is a value obtained from multiplying 2, which is the number of the antennas constituting each of both end portions, by the spacing d for both end portions. The antennas in the antenna array are continuously selected as a transmitting antenna by switching, and continuously emit transmission signals. The antennas in the antenna array are also successively selected as a receiving antenna by switching. In this way, by switching between transmission and reception of the antennas of the antenna array, nine reception channels CH1 through CH9 that are arranged with a uniform phase difference therebetween are obtained.
