Focusing linear arrays operating in a sequential mode

The authors describe multiple target detection using a linear array, operated in the sequential mode. In this approach, the firing of the elements is sequential: one element is transmitting with all the elements receiving. A novel processing technique is presented which allows multiple target detection without tapering or phase shifting hardware, and which includes focusing at any range. Three examples are presented for a real array in the sequential mode: (1) detection of far field scatterers with focusing at infinity, (2) detection of finite range scatterers with focusing at infinity, and (3) detection of finite-range scatterers with proper focusing. The sequential operation and processing allows the simultaneous detection of all the targets within the elementary 3-dB beam. The synthesized array pattern is shown to be much better than that of the standard parallel operation, which requires a set of phase shifters of each direction sine. It is concluded that the implementation of sequential processing is straightforward and storage is minimized by accumulating the data in terms of phase index