THEORETICAL AND EXPERIMENTAL-STUDY OF RADIO COVERAGE IN TUNNELS USINGRADIATING CABLES

The purpose of this paper is to study radiowave retransmission in conf ined areas using leaky coaxial cables. First, the theoretical approach determining the radiation of this type of structure is described. To show the tunnel walls' impact on electromagnetic field propagation, we give computed results for a cable in free space and in a tunnel. The study is conducted initially in the space domain to evaluate the varia tion of the electric field versus distance along the cable, and second ly in the time domain to estimate the spread or distortion of a short pulse due to reflection off the walls. Comparisons between theoretical and experimental results are also presented.