Investigation of caustics region using physical optics for ray tracing simulation

In ray tracing simulations, curved surfaces and edges are difficult to handle. The approximation of dividing the curved surface into smaller flat plates is not so accurate as the size of smaller plates may not satisfy geometrical optics assumption, and the reflection point which satisfies Fermat´s principle may not exist. In this work, a new ray tracing method which models the reflection on the curved surface was implemented and the physical optics method was applied on the caustics region. To test this method, path gain simulation results for a square and horseshoe cross-section model are compared with measurements made inside an arched tunnel. To further improve the simulation results, the effect of rough surface is introduced, and the results are again compared with measurement.