A leaky feeder is a communications system used in underground mining and other tunnel environments. Manufacturers and cabling professionals use the term “radiating cable as this implies that the cable is designed to radiate: something that coaxial cable is not generally supposed to do.
The leaky feeder communication network consists of a cable that runs along tunnels. It emits and receives radio signals, acting as an extended antenna. Cables are “leaky” because they have gaps or slots in their outer conductors that allow radio signals to leak in and out along their entire length. Line amplifiers must be installed at regular intervals (every 350-500 metres) to increase the signal to acceptable levels. Personal carry portable transceivers to pick up the signal. The feeder picks up the transmissions and carries them to other tunnel parts. This allows two-way radio communication through the tunnel system.
It has a limited range. Because of its frequency (typically UHF) transmissions cannot pass through solid rocks. This limits the system to a line–of-sight app. However, it allows two-way mobile communication.
A leaky feeder should be used when frequencies are below 1 GHz because of the signal loss from the feeder. Higher frequencies are more susceptible to losses, so it is better to use other options. For higher frequency bands, antennas (omni-, panel- or bidirectional) and even DAS systems are often more popular.
This post was written by Justin Tidd, Director at https://beckerwmsusa.com/ For over 15 years, Becker Communications has been the industry’s leader in increasingly more sophisticated electrical mining communication systems. As they expanded into surface mining, railroads, and tunneling they added wireless communication systems, handheld radios, tagging and tracking systems, as well as gas monitoring.