Research On SAR Raw Echo Simulation Method Based On Electromagnetic Scattering

As an active microwave sensor,synthetic aperture radar(SAR)can effectively detect and image ground targets,and is widely used in hydrology,geology,military reconnaissance and other fields.In order to detect interested targets,a variety of SAR systems have been developed to meet the requirements of information acquisition,which greatly increases the cost of SAR image acquisition.For some non cooperative targets,it is very difficult to obtain their SAR images.With the development of computer simulation technology and electromagnetic computing technology,SAR raw echo simulation technology based on electromagnetic simulation is gradually developed,and is rapidly applied to the echo simulation practice of various systems of synthetic aperture radar.Under this background,this paper mainly studies the SAR raw echo simulation method based on electromagnetic scattering,which mainly includes the following three parts:Firstly,the basic principle of SAR is studied.This paper introduces the acquisition process of SAR signal,including the geometric relationship of SAR,the form of transmitted signal,the form of received signal and the Doppler characteristics of the signal.Then,the processing methods of SAR signal are introduced,including the basic principles of quadrature demodulation,pulse compression and imaging algorithm.The echo simulation method based on point target and azimuth by azimuth electromagnetic simulation are introduced,and their disadvantages are discussed.Secondly,aiming at the problem that it is difficult to introduce Doppler history into the existing SAR echo simulation methods,the extrapolation boundary setting and nearfield and far-field transformation methods in the existing methods are improved,and a waveform forming method suitable for stripmap SAR is proposed.Using the near-field electromagnetic simulation data in single azimuth,the Doppler history is accurately compensated,and the received electric field of antenna in all azimuth is obtained.After orthogonal demodulation and imaging algorithm processing,the SAR image are obtained.Finally,the difference between spotlight SAR and stripmap SAR is analyzed to solve the problem that the error of waveform forming method increases in the simulation process of spotlight SAR echo.Then the multi angle RCS curve of the target is simulated,and the complete synthetic aperture of spotlight SAR is divided according to the multi angle RCS of the target.Then the two-dimensional received electric field of each sub aperture is obtained by waveform forming on each sub aperture,and the received electric field of the target on the whole aperture is obtained by azimuth stitching.