Electromagnetic forward scattering by large objects

The increase of the computational power as well as the development of advanced numerical methods during the last decades has enabled the deterministic analysis of larger electromagnetic problems. The rapid and accurate simulation of the interactions of the electromagnetic waves with the environment is particularly important for the development of modern communication systems, for example. However, depending on the targeted application, some approximations are still necessary for the reduction of the problem computational complexity. In this work, we investigate different classes of numerical methods for modelling the forward scattering mechanisms. In other words, we are interested in the behavior of the electromagnetic waves behind large radiating structures. This problem is addressed using methods of decreasing order of complexity, from full-wave methods towards the asymptotic physical optics approach and ray-based techniques. Assuming identical sub-domains, the complexity of full-wave techniques is reduced using Green’s function decompositions in multipoles and inhomogeneous plane waves. In a more general case, we propose a modified version of the physical optics based on electric and magnetic currents which increases significantly the accuracy of the scattered fields in the forward direction. Coupled within an iterative scheme, this approach is particularly attractive for multiple scattering scenarios. Finally, a practical application of the forward scattering is studied and consists in modelling the human blockage at mmWaves for indoor scenarios. Simplified geometrical models and a ray-tracing approach with a very low computational complexity provide results in very good agreement with the actual measurements.