The radio-coverage of ramway tunnels in the 460 MHz band

The railway radio systems take very important part in the railway communications. They provide transmission of command and control informations for Automatic Train Control System (ATCS) and other informations (mainly for passengers). The railway lines represent specific environments for radio-signals because of existence of longitudinal and punctual scatterers (such as vehicle, catenary, rails and other equipment) and high level of impulse disturbances. The most interesting parts of every railway line are tunnels, canyons and long iron bridges of "tunnel type". National Railways use several different systems for providing a radio-link, but the most used system up to now is a space-wave system in the 460 MHz band.