Wireless propagation in tunnels

In this article, we give a presentation of wireless electromagnetic propagation in tunnels. We discuss in depth the characteristics of multimodal propagation. We show analytical models whereby we are able to study electromagnetic fields in tunnels. To complement the analysis, we give an account of experiments performed in the Channel Tunnel between France and England, and the Massif Central in south-central France. We conclude with a discussion of the results, followed by some comments about bandwidth and the possibility of using multiple-input multiple-output (MIMO) systems to improve communication-channel capacity.