The Fast Electromagnetic Analysis And RCS Reducing Of Two Dimensional Complex Target

Radar scattering characteristic of the aircraft is an important factor for its survivability. Wings are one of the important scattering source on the aircraft. In order to reduce their RCS, the intense and powerful electromagnetic analysis are needed. For reducing the complexity, the wings can be viewed as a two dimensional large electric objects consisting of both conductors and inhomogeneous dielectrics. In this dissertation, we aim at a precision and efficiency method for numerical computing of two dimension objects. Moded wings and the RCS of the wings can be calculated in turn. The RCS results of different wing are compared and examined, and the stealth technology of wing are found out. Scattering mechanism are explained, which can give strong predictive power for stealth technology of aircraft. For reducing the RCS of metal wing, we choose three models those may have less backscatter RCS. Different electromagnetic analysis algorithms are applied. In order to compute on PC, all the algorithms have less computational complexity and resource occupy. Both the lossy material front edge of metal wing and lossy material coated metal wing can simply be treated as a target consist the large electric size conduct part and the lossy inhomogeneous dielectric part. In the first case, Fast multipole algorithm(FMM) and methods of moment(MM) are used to work out the scattering fields. In the second case, FMM and iterative technique and conjugate gradient method(CGM) are used to work out the scattering fields.Lossy material wing can simply treated as large electric size lossy inhomogeneous dielectric target. The generalize recursive aggregate T-matrix algorithm are used to solve this problem. In order to reduce the computing error when analyze the large electric size target, the dimensions of T-matrix are no longer invariable but turn bigger slowly during the recursive process. Lossy material wing with metal support staff can be treated as large electric lossy inhomogeneous dielectric target with conduct part. MM and Bi-orthogonal mode analysis are used to work out the T-matrix of conducting parts. when conduct part laid inside the dielectrics or in neighbour with the dielectrics, generalize recursive aggregate T-matrix algorithm or the method of divinding a large into parts are used to calculate the scattering field.Computer codes are designed and used to simulate the scattering of different wing models. Models of different structure with different lossy material are analyzed and the results are carefully examined. Under the condition of keeping the configuration and mechanical strength, different stealth methods are tested. Computation result shows that the lossy material front edged metal wing with a V shaped interface have a better effect to reduce the backscatter RCS, and the interior angle of interface have a very important role in this stealth effect. On the coated wing case, when the thickness d of dielectric layer is small enough(f=10G, d<2mm), the coated material wing have a little ability to reduce the backscatter RCS. Add the thickness of dielectric layer or add the imaginary parts of dielectric ( can both reduce the backscatter RCS. The lossy dielectric wing have a better stealth effect(f=2~10G). But if with a inside metal support staff, the backscatter RCS of the wing turn bigger. The shape of the staff's section affect the RCS strongly. As a basic research work for electromagnetic scattering of 2D complex target, this disseration provides the powerful way in rigorous modeling and effective solution. The informations given in the disseration can help the stealth technology of aircraft.