Frequency diverse array radar with non-uniform array spacing based on sigmoid function

As a widely recognized electronic beam steering concept, frequency diverse array (FDA) radar is an effective and feasible solution to provide beam scanning ability in both angle as well as range dimension as a function of time. However, the conventional FDA radar employing progressive incremental frequency offsets across the array elements generates an S-shaped and range-angle coupled beampattern. As such, the FDA beampattern can be decoupled into range-angle dimensions by employing non-linear frequency offsets or using non-uniform arrays. Frequency offsets design has been extensively researched in recent years, whereas non-uniform arrays were given little attention so far. In this paper, we propose a novel FDA radar with a unified configuration of non-uniform linear array, and non-linear frequency offsets to achieve a high-resolution dot-shaped range-angle dependent beampattern. More specifically, the non-uniform inter-element spacing is calculated using the sigmoid function, and non-linear frequency offsets are generated by logistic map, and triangular window function. Simulation results clearly demonstrate the performance advantages of the proposed FDA radar in terms of beam width and side lobe levels.