Achieving spatial multi-point focusing by frequency diversity array

This paper proposes a class of frequency diverse array (FDA) for achieving time-varying spatial focusing for multiple targets. On the basis of single-target focusing of FDA, sequential focus at the four points is achieved by controlling the time period. The effects of frequency offset on the range of focusing area are derived. Since FDA is narrowband in nature, the relative operating bandwidth is limited to be 10%. Under the limitation of the bandwidth, the sequential multi-target focusing in the far-field is achieved. To validate the proposed method, numerical examples of eight-element FDA are reported and discussed.