A Ray Tracing Tool for Propagation Modelling in Layered Media: a Case Study at the Chip Scale

Nowadays, many wireless applications require the exchange of electromagnetic waves through propagation environments that look like to stratified media to some extent. This may concern both natural scenarios, e.g., air/vegetation/ground, and artificial structures, like meta-materials, photonic devices, solar cells or systems-on-chip. The characterization of the layered propagation channel is therefore important for the design and deployment of effective devices and systems. To this aim, the Dyadic Green Function method has been often leveraged, although its use is usually limited to simple sources, like short dipoles or current elements. Furthermore, it seems unsuited to assess the dispersive properties of the channel, which are known to become important when high data-rate must be conveyed. In this paper, a ray-based approach to propagation inside layers is proposed. As the layered environment can be quite reverberating, a great number of rays may be needed, to the extent that the corresponding computational burden might be hardly afforded by general purpose ray tracing tools. Therefore, the ray tracing engine here presented is specifically conceived for the layered case, and mostly relies on analytical formulation. The accuracy of the model is checked against measurement carried out at chip scale at optical frequency, as a reference study case.