As an emerging array processing technique, frequency diverse array (FDA) differs from conventional phased-array in that it employs a frequency increment across the array elements. The use of frequency increment provides FDA with an array factor with joint range-angle dependency, which finds wide applications in joint range-angle target localization and range-dependent interference/clutter suppression. In the open literature, an ideal point-like target in far field is generally assumed for FDA signal modelling. However, the reflectivity characterization for more realistic targets, which are not ideally point-like and even extended in range and azimuth angle, has not been reported for FDA radar. In this paper, we establish an echo signal model of FDA radar for a general target, and then analyze the statistics of the echo signal amplitude. More specifically, we reveal the amplitude de-correlation property between different FDA elements due to the use of frequency increment, which provides useful insight into frequency increment design. The target reflectivity characteristic analysis is validated by numerical results.

frequency diverse array; radar cross section; reflection coefficient; frequency de-correlation; extended target