| Along with the development of target recognition technology faster and faster,the need of high-resolution radar images is growing.The use of electromagnetic computing methods to simulate targets can provide abundant data sources.For electrically large targets,high-frequency algorithm is the main means due to its advantages in calculation speed and computer memory.Therefore,fast imaging technology based on high-frequency method is of great meaning for target recognition.The acquisition of target characteristics is also a key technology for target classification and recognition.At high frequencies,the scattering field of the target can be regarded as the superposition of multiple strong scattering centers.People often gain the scattering signature of the target by studying the scattering centers.Because the scattering center model can give details of the scattering signature of the target concisely and accurately,its research and development also have great prospects.Therefore,this paper conducts research on fast imaging and scattering center parameterized modeling based on shooting and bouncing rays technology.Firstly,the fundamentals of radar imaging is briefly interpreted,including the imaging theory and mathematical analysis of the turntable model of the inverse synthetic aperture radar.In terms of electromagnetic calculation methods,the elementary knowledge of the shooting and bouncing rays method is expounded,consisting of ray path tracing,field strength tracing and Far-field integration.Secondly,fast imaging method based on shooting and bouncing rays technology is introduced.Starting from the traditional high-frequency imaging technology,the connection among the scattered field of the target received by the radar and the shape function is deduced.Due to the disadvantage that it takes longer time to obtain echoes by frequency and angle scanning for large-scale targets,the imaging technology based on unidirectional ray tracing is introduced.Establish the relationship between each ray and the target shape function to obtain the contribution of the ray to the two-dimensional image,and then superimpose the contribution of all rays to the image to obtain the imaging result of the entire target.Then speed up the calculation of this method for fast imaging.On this basis,a fast imaging method based on bidirectional ray tracing technology is proposed to further make the content of the image ampler and improve the accuracy.Some numerical experiments about fast imaging are conducted to verify the proposed method.Bidirectional ray tracing uses geometrical optics theory to track the incident direction and the reverse direction of observation direction.The contribution of all the rays obtained by two paths to two-dimensional imaging is superimposed,and the images based on bidirectional ray tracing are obtained.Finally,the parametric modeling of the scattering center based on shooting and bouncing rays technology is introduced.Firstly,starting with the geometric structure of the target,decompose the target into multiple components,and divide the rays irradiated on the target into multiple subsets through ray tracing and diversity technology.Each component corresponds to a ray subset.Use this method to separate the effects of each component on the scattered field.Calculate the scattering field carried by the rays in each ray subset,and screen out the stronger scattering source as the scattering center according to the size of the scattering field.Finally,based on the attribute scattering center model,obtain the various parameters of the scattering center through forward deduction,and establish parametric model,and give examples to illustrate its application scenarios.The scattering center parameters obtained in this way can directly correspond to the target,which has certain physical meaning.Moreover,this method does not need to obtain echo data,consumes less time,and reduce the pressure of computer storage. |
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