Wideband MIMO radar exhibits great potential in achieving the goals of high resolution imaging, but it also suffers from the electromagnetic signal congestion and interference problems, especially for radar that works in Very High Frequency (VHF) and Ultra High Frequency (UHF) band. To solve this problem, a cyclic iterative method for designing orthogonal sparse frequency waveforms is proposed. Firstly, the desired spectrum is used as an auxiliary variable, and a new objective function is constructed based on both the mean square error of the spectrum of transmitting waveform with the desired one and the integration side-lobe levels. The optimization model is established under the constraint that the waveform is constant envelope meanwhile the spectrum magnitude lies between the pre-established upper and lower bounds. Then, under the framework of cyclic iterative algorithm, fast Fourier transform and spectral decomposition techniques are used to improve computational efficiency. Simulation results show that the proposed method has good performance in designing orthogonal sparse frequency waveforms with low auto-correlation and cross-correlation side lobes.%甚高频(VHF)和超高频(UHF)宽带MIMO雷达在实现目标高分辨与成像方面表现出巨大潜力,但也面临着工作频段拥塞和电磁信号干扰问题.针对这一问题,该文提出一种基于循环迭代的宽带MIMO雷达正交稀疏频谱波形设计方法.首先,将期望频谱矩阵作为待优化的辅助变量,综合考虑最小化发射波形频谱与期望频谱之间的均方误差以及积分旁瓣电平为目标函数,以发射波形恒模和期望频谱幅度满足上、下界约束为条件建立优化模型;然后,在循环迭代的算法框架下,为提高运算效率,利用快速傅里叶变换和谱分解技术实现模型的求解.仿真结果表明,优化波形较现有方法具有更好的稀疏频谱特性,同时还具有低自相关旁瓣和互相关性.
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