Wave Propagation Over Flat Earth

This chapter discusses how the simplest propagation scenario used in analytical modeling is the flat Earth with PEC surface under line‐source excitation. On the single knife edge problem, the ray summation approach is based on the construction of four different rays, related reflection, and diffraction coefficients using Fresnel integral. The parameters of the Fresnel integrals are derived by using the image source and receiver for the reflected waves. The 2D propagation scenario is completed by choosing the appropriate transverse and longitudinal BC. This problem has analytical exact solutions in terms of Airy functions for the range independent vertical refractive index. The specification of the number of numerical integration steps for the calculation of modal excitation coefficients is crucial. The code must adopt the number of integration steps automatically as the mode index increases.