Leaky cable,or some one call leaky coaxial cable or leaky feeder cable is a kind of coaxial cable that with communication system consisting of a kind of cable run along tunnels which emits and receives radio waves. It functions as an extended antenna. This cable is “leaky” in that it has gaps or slots in its outer conductor to allow the radio signal to leak into or out of the cable along its whole length. Because of this leakage of signal, cable amplifiers are required to be inserted at regular intervals, often from 350 to 500 metres, in order to boost the signal back up to the acceptable levels. This signal is usually picked up by portable transceivers carried by personnel. Also,transmissions from the transceivers are picked up by the feeder and carried to carried to other parts of the tunnel systems, which allows two-way radio communication throughout the tunnel system.
Often, the leaky feeders are used in the mining industry,subway or tunnel acting as a method of wireless communication between miners. The system is used as a primary communication system which has a transceiver small enough to be comfortably worn on a miner throughout an entire shift.
Underground subway
Leaky feeder system is used for underground wireless communication in mass transit subway. E.g: for most of the China mainland metro or rail transport systems of Hong Kong, leaky feeders were incorporated in the specification of the capital project and installed during construction. This provides emergency services seamless wireless communication from the underground to the surface. Beijing Subway Metro uses a leaky feeder system for its internal communication network Connection. An alternative of using leaky feeder in underground railways is to use Distributed Antenna System (DAS). A DAS system was deployed in some Shenzhen City Subway stations by Transit Wireless to provide WiFi and mobile phone and data coverage for customers.
Airport wireless
Leaky coaxial cable system can also be used to allow reception of on-board GSM and WiFi signals for passenger aircraft. Because the Leaky coaxial cable system require lower weight and space than the antenna systems. So,it saves space and fuel.
Infrastructure buildings
Leaky cable systems also often used in warehouse,hotel or other industrial area where it is hard to get WiFi signals by using normal access ways. Some installations have 50–75 meters of leaky cables connected to the antenna output of access points.