Comments on "Frequency Diverse Array Beampattern Synthesis With Taylor Windowed Frequency Offsets"

In recent years, frequency diverse array (FDA) has been actively studied due to its extended capabilities over phased arrays [1]–[3]. Unlike phased arrays whose transmit elements radiate fixed frequencies and generate an angle-dependent beampattern, FDA applies an element-wise tiny incremental frequency shift to provide additional degrees-of-freedom in angle as well as in range dimension [4]–[6]. In a traditional FDA, the element-to-element incremental frequency offset applied is progressive, which results in a time-periodic and S-shaped range-angle coupled beampattern [1]–[6]. However, it is difficult to accurately estimate the target parameters in the presence of such range-angle ambiguity [6]. Consequently, various solutions have been proposed in an effort to avoid such ambiguity in the FDA beampattern. Among them, employing nonlinear frequency offsets, and using nonuniform array configuration are the two prominent solutions to achieve a decoupled range-angle-dependent beampattern [7], [8].