Modeling And Simulation Of Polarization Scattering Characteristics Of Complex Target

Polarization information is important to describe the scattering characteristics of targets,which can improve radar performances of target recognition and detection.In this thesis,the polarimetric scattering characteristics of typical military targets by modeling and simulation are studied.The dimensions of research include far-field,near-field and scattering center.The main research contents are as follows:(1)Since it is difficult to obtain fully polarimetric information of complex targets of millimeter wave accurately and quickly,the accuracy of Ray-Launching Geometrical Optics in calculating the scattering characteristics of targets with multiple reflection and wedge structure is verified.The results show that the algorithm is suitable for the rapid analysis of target scattering characteristics in engineering applications.Through theoretical derivation and simulation comparison,it is determined that dihedral corner reflector is a kind of typical geometric structure with strong cross-polarization scattering.The cross-polarization scattering of complex targets may be greater than the co-polarization scattering.In view of the different stealth performance of absorbing materials to targets under different polarization modes,the distribution and difference of far-field fully polarimetric radar cross section(RCS)of typical UAV and M1A2 targets under coated and uncoated conditions are compared.The causes of strong cross-polarization are analyzed.The results show that the cross-polarization component of the target is reduced more significantly by absorbing material,which is conducive to the stealth of fully polarimetric radar target detection.(2)The concept of generalized radar cross section(GRCS)is introduced for millimeter wave short-range detection system and electrically large complex target detection.The nearfield fully polarimetric scattering characteristics of trihedral corner reflector and tracked vehicle target in millimeter wave band are studied with the transmitting antenna in the far-field and the receiving antenna in the near-field.The results show that the closer distance between the target and the antenna,the greater influence of RCS.When the distance increases,the near-field GRCS approaches the far-field RCS gradually.The sensitivity of cross-polarization to distance is lower than that of co-polarization GRCS.It is proved that the ability of detecting near-field complex targets can be improved by changing the polarization mode.(3)The detailed geometric features of the target can be obtained by the wideband highresolution imaging of the target.The scattering center of the target is extracted to analyse wideband polarimetric scattering characteristics.The results show that in the full polarization mode,the Pauli decomposition can better identify the specific parts,the quantity,asymmetric component,odd-even scattering and the location of strong scattering points.The Inverse Synthetic Aperture Radar(ISAR)imaging simulation is carried out for the combined “SLICY”target composed of multiple reflectors and the tank “Stryker”.The results show that the copolarization image has significant mirror and multiple reflection effect,while the crosspolarization image is more sensitive to the structure with edge,wedge and large curvature.The cross-polarization image can be used as a favorable supplement to the co-polarization ISAR image.