FDA Radar Ambiguity Function Characteristics Analysis and Optimization

Frequency diverse array (FDA) radar provides new application capabilities and potentials due to its range-dependent transmit array beampattern. As radar ambiguity function (AF) is an effective tool to analyze the range (time delay) and Doppler resolution characteristics of various radar systems, this paper derives and analyzes the FDA radar AF characteristics in a general way. These characteristics provide some insights into optimal FDA parameters design and are helpful for comparing delay-Doppler performance of the FDA radar with conventional phased-array radar. Furthermore, this paper optimally designs the frequency increments for better FDA radar AF with the simulated annealing algorithm. The optimization object is to minimize undesired range-angle-dependent sidelobes, so that we can focus the transmit beampattern to desired range-angle sections and simultaneously null undesired interferences. All the derived expressions and methods are verified by numerical results. The results also validate that the FDA indeed offers advantages over traditional phased array in delay-Doppler radar applications.