多频体制下虚拟阵列映射聚焦方法

New Mapping Focus Method for Virtual Array under Multiple Carrier-Frequency

针对常规虚拟孔径系统设计复杂、运算量大等问题,提出一种多载频体制下虚拟孔径阵列合成方法———映射聚焦法.该方法利用了频率分集的思想,通过对不同载频接收回波的导向矢量进行推导,将频率分集与空间分集相互结合,得到了空域目标的非等间隔采样,为方便常规超分辨方法的广泛推广,通过宽带映射聚焦方法,将非等间隔空域采样转换为空间均匀采样回波,得到了等距半波长下的虚拟接收阵列.有别于传统的阵列插值以及基于高阶累计量的虚拟孔径方法,映射聚焦方法通过简单的插值运算,就可以得到较好的虚拟阵列回波.对不同参数下单目标俯仰角参量估计的仿真结果表明,与传统虚拟孔径方法相比较,映射聚焦法比常规的高阶累积量方法在测角精度上提高了近15 dB.

Since the design of the conventional virtual aperture is too complicated, and the calculation is too expensive, a virtual aperture array synthesis method （mapping focus method, MFM） based on multiple carrier-frequency is proposed. The method makes use of the idea of frequency diversity, which deduces the direction vectors of different carrier-frequencies to combine frequency diversity and the space diversity for achieving the spatial nonuniform sampling echo. In order to make it more convenient for the generalization of the conventional super resolution algorithms, the MFM method is utilized to change the target echo from the non-uniform sampling to uniform sampling. The virtual array of half wavelength are obtained finally. The proposed method differs from the conventional array interpolation and the virtual aperture study based on higher order accumulations, it only utilizes the simple interpolation to achieve better virtual array echo. Simulations on the elevation estimation of different parameters show that under the same circumstance, the MFM can improve 15 dB in the angle estimation precision, compared with the conventional virtual aperture methods based on higher order accumulations.