A novel stochastic rough-surface scattering representation for ray-optical wave propagation modelling

A new method to include stochastic rough surface scattering into deterministic ray-optical wave propagation modelling is derived. It can be utilized in conjunction with the concept of ray launching. Similar to the Kirchhoff formulations, the approach is based on a tangential plane approximation, i.e. it is applicable to surfaces with gentle undulations, whose horizontal dimensions are large compared to the incident wavelength. However, in contrast to the Kirchhoff models, which are only valid for either slightly rough or very rough surfaces, the proposed stochastic scattering approach includes both the coherent and incoherent components at the same time. The purely deterministic ray-based modelling is expanded by a "stochastic" component, allowing for the first time to account for non-deterministic scattering in ray-optical wave propagation modelling.