TRIANGULAR PRISMS FOR EDGE-BASED VECTOR FINITE-ELEMENT ANALYSIS OF CONFORMAL ANTENNAS

This paper deals with the derivation of the edge-based shape functions for the distorted triangular prism and their applications for the ana lysis of doubly curved conformal antennas in the context of the finite element method (FEM). Although the tetrahedron is often the element o f choice for volume tessellation, mesh generation using tetrahedra is cumbersome and central processing unit (CPU) intensive. On the other h and, the distorted triangular prism allows for meshes which are unstru ctured in two dimensions and structured in the third dimension. This l eads to substantial simplifications in the meshing algorithm, and many conformal printed antenna and microwave circuit geometries can be eas ily tessellated using such a mesh. The new edge-based shape functions are first validated by computing the eigenvalues of three different ca vities (rectangular, cylindrical, and pie-shell). We then proceed,vith their application to computing the input impedance of conformal patch antennas on planar, spherical, conical, and other doubly curved (ogiv al) platforms, where the FEM mesh is terminated using an artifical abs orber applied conformal to the platform. Use of artificial absorbers f or mesh termination avoids introduction of Green's functions and, in c ontrast to absorbing boundary conditions, a knowledge of the principal radii of curvature of the closure's boundary is not required.