Gap Electromagnetic Scattering Algorithm

Electromagnetic scattering from apertures in conducting bodies is a very important problem in the stealth technology field, and the apertures are very common in the electromagnetics, for example, the waveguide apertures antenna, EMC, etc.Multilevel Fast Multipole Algorithm (MLFMA) is an accurate and efficient algorithm to solve the electrically large objects, and its accuracy and efficiency have been proved. But the electrically small object, for example, apertures have especial characters, and if we directly use the MLFMA, the unknowns will be very large, at last the efficiency of the algorithm will be influenced. In the late years, the high order basis functions have been developed, and this basis function have merits when the object is slippery, but this basis function is not suitable to solve the electrically small object. It's important to research the electromagnetic character for the electrically large body with the electrically small feature.As a theory tools in the paper, the moment of method (MOM) algorithm is discussed, and it includes the basis function theory and the main steps. The RWG basis function and the maximally orthogonalized higher order basis functions are described separately. Then the electromagnetic scattering theory about the arbitrary shape aperture with finite scale perfect conductor is discussed particularly, and the accurate formulas are got. In order to prove the formula's accuracy, some objects are been calculated, and the results are compared with the MLFMA. At last the electromagnetic scattering theory by apertures which are very narrow and very long are discussed, and the equivalent current and the magnetic current are derived, so the original problems will be simpled, and the storage requirement and the CPU time are reduced.This paper discussed electromagnetic scattering by apertures systematical and simplify the special models, the accurate and efficient calculation is realized. This is very important for practical engineering problems.