| Chaff is the earliest passive jamming equipment,and is widely used in radar jamming,radar monitoring and other fields.Chaff jamming is the jamming to the signal of the real target caused by the explosion of chaff bomb or the scattering of aircraft,which forms a large number of metal scatterers scattered in the air,and the enemy radar receives the scattering of these scatterers to the incident wave.There are many jamming modes of chaff,including centroid jamming,dilution jamming and so on.Different jamming modes have different application ranges and delivery modes of chaff,and the delivery height in the atmosphere is also different.For different radars,different jamming scenarios,different types of chaff,the motion model and electromagnetic characteristics of cloud clusters will be different.The research work of this paper is mainly divided into three parts: motion model,electromagnetic model and combat scene simulation.In the first part,the motion models of typical cylindrical chaff and sheet chaff in dense atmosphere are studied,and a typical chaff jamming strategy is considered.The specific actual scene is the motion model of chaff cloud formed by Chaff explosion in the air.When studying the motion model of chaff cloud,the non ideal bending characteristics of chaff,the aerodynamic force and moment of chaff motion,the influence of atmospheric wind,and the delivery mode of chaff will affect the shape and distribution of chaff cloud.In this paper,the local coordinate system of each chaff is established.Through the simulation of six degrees of freedom and quaternion,the attitude transformation of the local coordinate system of the chaff in the global coordinate system is realized.When solving the differential equation of chaff motion,the dynamic square is integrated by Runge Kutta method.Finally,the complete simulation process of the motion model of chaff cloud in complex atmospheric environment based on Monte Carlo method is established,The complete movement state of chaff cloud from the moment of explosion to the end of falling is obtained.The second part is based on the six degree of freedom motion model of chaff cloud.According to the data of chaff cloud position,attitude angle,velocity and angular velocity obtained in the first part,the spatial positions of all chaffs in chaff cloud are divided into independent bounding boxes by using the generalized equivalent conductor method and octree subdivision.Each bounding box can be regarded as an equivalent continuous conductive medium,and the spatial density of chaff in the bounding box is used,And the induced equivalent current,considering the attenuation of the chaff cloud to the electromagnetic wave,the scattering cross sections of all the bounding boxes are superimposed to obtain the scattering cross sections of the chaff cloud.The change of RCS in the process of Cloud Diffusion with different number of chaff is studied,and the difference between the RCS solved by the method of moment and the generalized equivalent conductor method is compared.Finally,the polarization RCS of a single chaff under different attitude angles is studied,the distribution of chaff in pitch angle and azimuth angle is given,and the polarization scattering characteristics of the whole chaff cloud are analyzed.In the third part,the typical combat scenes are introduced.For the interference strategy of the actual scene,the simulation image is given.For the centroid interference,the RCS of the target and chaff cloud are compared,and the interference efficiency is solved.For diluted jamming,the influence of chaff cloud position change on penetration probability is analyzed.For corridor interference,the attenuation coefficient of electromagnetic wave passing through the corridor is solved,and the intensity distribution inside the corridor is given. |
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