The FEM–BIM approach using a mixed hexahedral finite element to model the electromagnetic and mechanical behavior of radiative microstrip antennas

This work is focused on the prediction of the impact of microstrip radiative antenna distortions on electromagnetic fields. In this way, a recent numerical tool, able to model the electromagnetic and mechanical behavior of a microstrip antenna, has been developed. Considering a weak coupling between electromagnetism and mechanical behavior, the mechanical equations are first solved. Then, from the mechanical strains results for the antenna, the electromagnetic fields are computed. To solve both problems, a 3D hexahedral finite element is used to discretize the structure, having both nodal mechanical and edges electromagnetic degrees of freedom. The weak electromagnetic formulation inducing integrals on an open infinite domain, a Boundary Integral Method (BIM) is used and applied to the strained structure. Three examples are considered. The simulations show that mechanical distortions can have major influence on the electromagnetic behavior of antennas.