Correlated LFM Waveform Set Design for MIMO Radar Transmit Beampattern

Multiple-input multiple-output radar has many advantages over the phased-array radar system due to the waveform diversity, one of which is the greater flexibility to design the transmit beampattern. Hence, waveform set design for transmit beampattern has become an attractive topic, and many methods have been proposed in recent years. However, previous methods cannot synthesize the waveforms with constant-envelope and easy-generation properties. In this letter, we propose to design a set of correlated linear frequency modulation (LFM) waveforms to solve this problem. First, the covariance matrix of the LFM waveform set is analyzed, and the formulation of the transmit beampattern is obtained accordingly. Since the transmit beampattern is mainly affected by the frequency steps and initial phases of the LFM waveforms, the correlated LFM waveform set design problems are formulated by optimizing these parameters for different beampatterns. The resulting problems are solved by adopting the constrained nonlinear optimization, and the LFM waveforms are obtained consequently. The designed waveforms have the properties of constant-envelope and easy generation, and can match the desired transmit beampattern properly. Simulation results demonstrate the superiority of our proposed method.