The Sbr Of The Electromagnetic Scattering Of Complex Terminal Cavity And Fdtd Hybrid Method

The problem of analyzing scattering from cavity with a complex termination, such as jet inlet and exit of airplane, is one of the most important and challenging topics in the research area of aircraft stealth design. Calculating and reducing radar cross scattering of this kind of structure can improve stealth capability of aircraft. Starting with characteristics of cavities, SBR and FDTD methods are studied in detail in this paper, which are used to analyze the remaining front section of cavity and complex termination, respectively. Afterwards, the coupling between these two methods is discussed. Finally, the electromagnetic scattering of the overall cavity is obtained via termination reciprocity integral.On the aspect of theoretical study, the following research has been done: derivation of the expressions for the scattering from an arbitrarily shaped cavity using SBR method, reflection coefficients of coated cavity and approximate formula of the scattering factor. Z-buffer method in computer graphics was employed to overcome the problem of false point of intersection, thus a new technique of judging the relative position between the point and the patch was given. The basic theory of FDTD was illustrated and the ray solution was used as the excitation for FDTD. Therefore, absorbing boundary conditions were established for the two dimensional and three dimensional cavities in the hybrid method. Traditionally, backscattering of the termination is dependent on input angle, to overcome this dependency, the termination scattering matrix was applied.On the aspect of realization of the method, the program module has been written using SBR to analyze the circular PEC cavity with a planar termination. On the basis of the FDTD program which had been written priviously, program module has been done using hybrid SBR/FDTD method to analyze the parallel-plate cavity and circular PEC cavity with a cylindrical termination and a conical termination. The computed results of cavity with a cylindrical termination and a conical termination by hybrid SBR/FDTD method were validated compared with literatures.