Analytical expressions for Fresnel reflection and transmission coefficients have been extensively used in ray-tracing simulation. Although these tools accurately predict the field for simple homogeneous wall structures, it is difficult, if not impossible, to extend such an analysis to find reflection and transmission coefficients for walls composed of dielectric and imperfectly conducting materials or complex, inhomogeneous structures. In principle, Fresnel theory is considered a high-frequency method, but in practical problems (such as walls with metallic rebars and similar applications), transmission does not monotonically decrease with incidence angle, and Fresnel theory does not apply. In this paper, we use the FDTD method to extend the theoretical Fresnel formulation to certain types of problems where Fresnel theory does not apply. We find that the presence of rebar affects transmission characteristics much more significantly than permittivity or wall depth. We initially verify the FDTD method with simple theoretical applications, and then we go further in more complicated cases; we furthermore extend our analysis to polarization effects that occur from such inhomogeneities
展开▼
