Discrete Fourier Transform Based Closed-Form Algorithm to Design Desired Beampattern for Frequency Diverse Array Radar

Abstract

In contrast to phased-array radar, where the transmission of signals along the array elements is carried out at same carrier frequency, frequency diverse array (FDA) radar transmits signals of linearly increasing frequency across the array. As a consequence, the beampattern of an FDA radar becomes range, angle, and time dependent, which is different from phased-array radar that provides only angle dependent beampattern. In this work, to focus the transmitted power from an FDA radar in the desired region-of-interest a novel algorithm is proposed. The proposed algorithm exploits the discrete-Fourier-transform to find the weights of individual antenna elements of the array. The proposed algorithm is tested both on continuous wave (CW) CW-FDA and pulsed-FDA radars. The beampattern of the proposed CW-FDA radar changes linearly with respect to the range in contrast to “S” shaped beampattern of the conventional CW-FDA radar, which is more difficult to deal with. An accurate transient time is calculated for beam formation in far field for FDA radar. Simulation results validate our assumptions.