Hybrid finite element-Trefftz method for open boundary analysis

Electromagnetic field computation often involves open boundary analysis. Discretization of the exterior region by the finite element method (FEM) is cumbersome and computationally inefficient. This paper discusses a new hybrid finite element-Trefftz (1926) formulation to solve open boundary potential problems with an economic number of degrees of freedom. After the overview of literature, the paper describes the most important theoretical features of the proposed hybrid FEM-TRM formulation which is based on the synthesis of several proposed methods. Then it demonstrates the application of the formulation on a simple example which clearly shows its convergence behavior and reasonable precision both within the FEM region and very far from it. The verification has been carried out by a commercially available general purpose FEM package.