Reflection and transmission by reinforced concrete - numerical and asymptotic analysis

To model the reflection and transmission properties of reinforced concrete, we develop a method of moments/Green's function (MoM/GF) model for a wire grid embedded in a lossy dielectric slab. Since the scattering by a wire grid is dominated by wires that are parallel to the incident electric field, a two-dimensional (2D) model with a grid of straight, parallel wires is used. The number of wires is finite, but can be large. The dielectric slab can be thin or thick, and it is of infinite transverse extent. The source and field points are in the near field. The wire currents are solved for by the MoM. Certain Green's functions for the dielectric slab are evaluated by two different methods: 1) exact numerical evaluation of Sommerfeld integrals (SI); 2) the high frequency asymptotic approximation, via the saddle point method, which yields the geometrical optics (GO) result. We explore the range dependence and angular dependence of the reflected and transmitted fields. The influence of surface waves and wire-wire interactions is also examined.