Electromagnetic Wave Propagation Modeling for Finding Antenna Specifications and Positions in Tunnels of Arbitrary Cross-Section

Electromagnetic wave propagation in confined environments, such as mine, road or railway tunnels, has inadmissible quality due to multi-path and high scattering effects of receivable signals. The ever-increasing work difficulties and the large demand for systems operating in these scenarios, requires more and more innovative wireless systems to guarantee a reliable communication. From the radiating element point of view, some investigations have been given over to the development of novel technologies to provide radio communication in these environments. In 1956, a paper [46] disclosed what is now generally known as the leaky-feeder principle for propagation of VHF or UHF signals through a tunnel. Leaky coaxial cables (LCXs) have been employed since then [18, 38]. Nevertheless, high cost, maintenance and installation difficulties are the main disadvantages of leaky feeders. These problems are easily solved in short tunnels, but in the case of longer tunnels the leaky feeder solution becomes too expensive. For these reasons, solutions that are based on the use of distributed antennas are becoming more interesting [6].