Research On Fast Hybrid Method For Antennas Mounted On Stealth Electrically Large Platform

With the rapid development of science and technology,the importance of electromagnetic compatibility in complex weapon platforms such as aircrafts and warships is becoming more and more important,and it brings great challenges to computational electromagnetics.On the one hand,the weapon platforms are often electrically large in size,and due to the continuous improvement of the platform integration,the platforms usually contain complex fine structures;on the other hand,due to the needs of modern warfare,more and more radar absorbing materials are applied to the weapon platforms,which puts higher requirements on the calculation method.In summary,it is of great significance to study how to quickly and effectively analyze the electromagnetic characteristics of the antenna-loaded and stealth electrically large platform.In order to improve the inefficiency of the traditional stepping method and avoid the limitation of the impedance surface method to solve the coating problem,the Maxwell's equations and corresponding boundary conditions will be used to derive the reflection coefficient matrix of the multi-layer media coated on an infinite PEC plate.And based on this reflection coefficient matrix,the equivalent electromagnetic currents on the coated surface are derived.The Kd-Tree technique is used to accelerate the calculation efficiency of the hybrid algorithm,and the Bitmap method is used to reduce the storage space of the hybrid algorithm.Therefore,an efficient iterative method(EI-MOM/AIM-PO)that combines the method of moments(MOM)/adaptive integration method(AIM)and physical optics(PO)for complex coating problems is implemented to ensure computational accuracy and less computing resources at the same time.The main works are as follows:(1)According to Maxwell's equations and corresponding boundary conditions,the solution of the reflection coefficient matrix in multi-layer media coated on an infinite PEC plate is deduced and realized.The efficiency and correctness of the method are verified by numerical examples.Then by using the obtained reflection coefficient,the surface equivalent electromagnetic currents for solving the coating target by physical optics is deduced.Numerical examples are used to verify the efficiency and correctness of the method.(2)The additional excitation term formula of the equivalenmt electromagnetic currents in the PO zone to the MOM zone is derived,which improves the accuracy of the iterative hybrid algorithm in dealing with the coating problem in the PO zone.By introducing the Kd-Tree structure,the exploration process of the visible surface of the PO zone is accelerated and the computational complexity is reduced from O(N~2)to O(NlogN).At the same time,the illumination information storage space is reduced to 1/8 of the original structure by the Bitmap method,which greatly improves the calculation of the iterative hybrid algorithm for processing complex large-scale platforms.(3)Finally,the software implementation process of the algorithm is given.The operating environment,software workflow and related parameter configuration of the software are introduced in detail,and a clear explanation is given through the intuitive flow chart.