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On wireless communication in tunnels

We review recent research work on wireless communication in straight and curved tunnels. Modal theory of fields in a circular tunnel excited by a linear source is given in detail. Closed form expressions for the propagation parameters of the dominant modes in circular and rectangular straight tunnels in the high frequencies are derived. We present field measurements in tunnels and interpret them in terms of the mode theory. The main characteristics of the dominant modes in a curved tunnel are studied.