【摘要】 在研究电离层对电磁波信号传输影响的基础上,重点分析了电离层延迟对星载SAR(合成孔径雷达)宽带信号的色散影响.电磁波经过电离层传输后,对不同频率的信号造成的时间延迟不同,所以宽带SAR信号经过电离层后会引起波形的畸变.详细推导了经过电离层传输后的雷达回波表达式,并且在该回波表达式的基础之上,提出了基于该色散信号的改进匹配滤波器.改进后的匹配滤波器可以成功地将受电离层色散效应影响的信号补偿为正常SAR回波信号.仿真证明了该补偿方法的正确性,从仿真结果中可以看出信号的色散效应在补偿之后得到了明显的消除.更多还原

【Abstract】 This paper studies the phenomenon of the electromagnetic signals transmitting in the ionosphere and analyzes the ionosphere delay dispersion of wideband signals of space-borne SAR(Synthetic Aperture Radar)particularly.After transmitting in the ionosphere,the signal’s time delays which are caused by the ionosphere are different on different frequencies.So the wide band chirp signal of SAR will be distorted.In this paper,a detailed derivation of the signal model of radar echo after transmission through the ionosphere is discussed,and on the basis of the above model,an improved matched filter is introduced.Using the proposed matched filter,the dispersion signals can be compensated successfully to overcome the time delay caused by ionosphere.Simulation results prove the validity of the proposed compensation method.更多还原