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将多极化星载SAR系统与距离向数字波束形成技术相结合,提出了多极化星载SAR“空分+码分”工作方式.在“空分+码分”工作方式下,发射信号时,在一个脉冲重复周期内首先水平极化天线发射子脉冲,为水平极化的正线性调频斜率线性调频信号,延时一定时间后,垂直极化天线发射子脉冲,为垂直极化的负线性调频斜率线性调频信号,实现码分;接收信号时,方位向和距离向多孔径同时接收,利用距离向数字波束形成分离出前后脉冲所对应的各极化回波分量,实现空分.该系统脉冲重复频率等于单极化SAR系统脉冲重复频率,同时距离向使用数字波束形成技术有效降低了距离模糊.文中分析了主要系统参数,包括脉冲重复频率、孔径间发射脉冲延时、模糊度,并与传统单极化SAR进行了比较.仿真结果表明多极化星载SAR采用“空分+码分”工作方式是可行的,并具有较好的特性.
Combining multi-polarization spaceborne SAR system and distance-to-digital beamforming technology, a multipolarized spaceborne SAR “space division + code division” working mode is proposed. In the working mode of “space division + code division” , When the signal is transmitted, the horizontal polarized antenna transmits a sub-pulse first in a pulse repetition period, which is a horizontally polarized positive chirp slope chirp signal. After delaying for a certain time, the vertical polarized antenna transmits sub-pulses, which are vertical Polarization of the negative linear chirp slope chirp signal, to achieve code points; receive signal, the azimuth and distance to the multi-aperture simultaneous reception, the use of distance from the digital beam separation before and after the pulse corresponding to the polarization echo components, to achieve Space division.The pulse repetition frequency of the system is equal to the pulse repetition frequency of the unipolar SAR system, and the distance beamforming technology effectively reduces the distance ambiguity.This paper analyzes the main system parameters, including the pulse repetition frequency, the emission pulse delay between the apertures , And compared with the traditional unipolar SAR.The simulation results show that the multi-polarization spaceborne SAR is feasible and has better characteristics by using the “space division + code division” working mode.