| The development of computational electromagnetics has become an indispensable tool for antenna design and electromagnetic compatibility analysis.The finite element method has great advantages in dealing with electromagnetic problems with complex geometric structures and complex media properties,and has been widely used.Due to the complexity of the metal-medium composite target structure of the large-scale electric scale,there are many unknowns to be solved,and the traditional finite element method is often difficult to deal with such problems.The domain decomposition method combined with the finite element boundary integral method is an effective method to solve the electromagnetic characteristics of the electric large-scale metal medium composite target.The regional decomposition method uses the "divide and conquer" strategy to solve the problem of decomposing the original problem into several sub-regions,and the sub-regions are connected by transmission conditions,so that the problem solved after the partition is the same as the original problem.In this paper,based on the scattering problem,the realization process of the finite element boundary integral region decomposition method and the derivation of the system matrix are described in detail.The multi-layer fast multipole sub-algorithm is combined with the boundary integral equation.The relevant calculation examples illustrate the method.And the correctness of the program.Then,the research on the antenna radiation problem based on this method is discussed.The numerical simulation models of two commonly used antenna feeds in the finite element method are analyzed.The probe feed mode is simple and easy to implement,but it is only applicable to the model of the partial antenna.When the thickness of the substrate in the current direction increases,the accuracy of the calculation result is also affected.Subsequently,the numerical simulation model of the wave port feed mode is analyzed.The research and analysis of the coaxial line feed model are focused on,and the derivation of the system matrix is explained in detail.The model of the wave port feed is more complicated,and the programming implementation is relatively difficult,but it is suitable for the feeding mode of most antennas and has certain research value.Two calculation examples are provided based on the two feed models.The calculated circuit characteristics and radiation characteristics of the antenna are in good agreement with the commercial software,which proves the correctness of the method and program.In actual engineering,in order to protect the antenna from the external environment,a radome is added to the antenna system.While protecting the antenna,the radome also has a certain impact on the electrical performance of the antenna.Based on such problems,the classification model of the radome was studied and analyzed.Due to the traditional partitioning method,the excess unknown amount of air region between the radome and the antenna system is introduced.Therefore,the strategy of regional decomposition is improved and the finite element boundary integral region decomposition method is used to calculate the electrical performance changes of the antenna system before and after the radome..The numerical results of the compound expected results are consistent,which proves the correctness of the program and method. |
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