合成孔径雷达系统通道带宽优化设计方法研究

针对合成孔径雷达(SAR)图像质量指标与系统通道带宽的关系,对通道带宽进行优化设计。以Butterworth带通滤波器为例模拟SAR系统通道特性,利用驻定相位原理推导了滤波器引入的相位误差的表达式。引入通道带宽系数的概念,对相位误差进行勒让德正交展开,得到相位误差均方差与带宽系数和时间带宽积之间的定量关系式,进而确定带宽系数与图像质量指标之间的定量关系。在此基础上,提出SAR系统通道带宽优化设计方法,给出了带宽系数的下限,为SAR系统工程带宽设计提供了理论基础。

The Optimization of Channel Bandwidth Design for Synthetic Aperture Radar System

The optimization of channel bandwidth design for the synthetic aperture radar(SAR) system is studied in this paper by analyzing the relationship between the SAR channel bandwidth and the image quality.The channel is simulated by Butterworth filter.The approximate expression of the phase error is derived according to the stationary phase principle,which is caused by the nonlinear-phase-frequency property of the filters in both the transmission and the receiving channel of the SAR system.It is indicated that each Legendre polynomial term of the phase error is related to Time-Bandwidth Product and the bandwidth coefficient,which is defined as the ratio of filter-bandwidth to signal-bandwidth.Based on the relationship between the bandwidth coefficient and the image quality,the optimization method for the SAR system channel bandwidth design is presented,in terms of which an illustrational minimum boundary of the bandwidth coefficient is given.