Diffusion of electromagnetic waves in multipath media

In this paper, we studied the diffusion behavior of 2-D multipath media. The effects of the area densities and obstacle shapes are explored. The results show that the obstacle area density of embedded objects is very crucial for determining the onset of diffusion. A system of reasonable size starts to behave diffusively at an area density around 5%, while the power-distance relationship of the EM waves follows a power law at low densities. When the area density is around or larger than 10%, analytical formulas derived from diffusion theory give very good estimations of the reality. The maximum error in excess loss is no larger than 3 dB in our results. Aside from increasing the number of objects, cylinders of non-circular shapes could also increase the amount of multiple scattering present in the system. These two factors together control the onset of diffusion of EM waves in disordered media.