FDA radar with chirp diversity for achieving ultra-low range sidelobe level and enhancing range resolution

Abstract

The composite beam scanning characteristics of coherent frequency diverse array (FDA) radar induces a decline in range resolution, which is restored by increasing the beam dwell time through the Barker codes. However, this approach can lead to a rise in the range sidelobe level (RSL) and a loss of spatial interference suppression capability. For FDA radar, common methods of reducing the RSL can lead to a loss in signal-to-noise ratio (SNR), while methods of enhancing range resolution can result in a decrease in interference suppression capability and Doppler tolerance. In this paper, we investigate a novel transmission diversity technique, namely element-to-element chirp diversity, to reduce RSL and enhance range resolution. The proposed approach is predicated on shaping the power spectrum of the aggregated transmit signal, making it approximate the local Gaussian power spectrum and the power spectrum of the baseband waveform, respectively. The method’s underlying mathematical principles are thoroughly analyzed, and the favorable properties of the optimized waveform have been evaluated using the ambiguity function. Extensive numerical and instance results demonstrate a significant reduction in the RSL and an enhancement in range resolution. Specifically, our approach circumvents any loss in processing SNR and substantial degradation in spatial interference suppression capability.