Study On Layered Model Of Chaff Clouds Scattering

With the development of modern war from the land to space,information detection and information interference in space become one of the key points of competition in the war.The main way of information interference is to put some interference sources into space.As the most widely used passive information interference,the chaff is used to interfere the detection,which come from the enemy radar,of missiles and other targets through reflecting electromagnetic wave.When throwing the chaff into space,the space chaff is formed.Because of the special space environment,it is difficult to study the space chaff by experiment.therefore,it is more important to study the scattering model of chaff clouds in space.In this thesis,the radar scattering cross section of space chaff clouds is studied based on the space chaff scattering model based on layered structure.Firstly,The theory that the half wave dipole has the great RCS for the chaff in different size was verified in this thesis with the method of moments,Then,we carries on the stress analysis considering a single chaff as particle based on the theory of free molecular flow,simulate the state of motion of the chaff when throwing it from different height using statistical methods.Then we analyze the difference of the diffusion speed of chaff at different height through simulation,calculate the volume of the chaff clouds when throwing them from the different height and obtain the regularity that the diffusion velocity of the chaff is changed with the height.The above work lays the foundation for the study of the scattering model which is based on a layered structure.Next,we analyzed the distribution characteristics of chaff cloud forming chaff clouds.According the above analysis,we established the scattering model,which is a hierarchical structure,of the chaff clouds,presented a method to calculate the parameters that are required for hierarchical structure and analyzed the change of the chaff density of the hierarchical structure.The results show that the layered structure is feasible in the application of the chaff cloud model,Then,combining the theory of electromagnetic wave attenuation,we deduced the formula of chaff clouds RCS based on the layered structure,and analyzed the change of the RCS of the chaff clouds within the same time when throwing them from different height,The results shows that when the number of chaff is constant,the main factor that influence the change of RCS in chaff cloud were the change of cloud volume.Finally,the attenuation number of chaff in the radar unit is analyzed for the cover of the mid-trailing chaff on the trajectory,The results show that the main reason for the change of the RCS in the cloud is the change of the number in the radar unit.Then the chaff clouds RCS at different time is simulated based on the hierarchical structure model and the simple iterative coupling,.The results show that the results obtained by the scattering model of the layered structure are well consistent with the results obtained by the iterative coupling method.Then we compared the time took by the layered structure scattering model and the iterative coupling method in solving the chaff cloud RCS,The simulation results show that the time when using the scattering model based on hierarchical structure is obviously less than that of the iterative coupling method.