A leaky feeder is a communications system used in underground mining and other tunnel environments.[1] Manufacturers and cabling professionals use the term "radiating cable"[2][3][better source needed][4] as this implies that the cable is designed to radiate: something that coaxial cable is not generally supposed to do.
A leaky feeder communication system consists of a cable run along tunnels which emits and receives radio waves, functioning as an extended antenna. The 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 entire length. Because of this leakage of signal, line amplifiers are required to be inserted at regular intervals, typically every 350 to 500 metres, to boost the signal back up to acceptable levels. The signal is usually picked up by portable transceivers carried by personnel. Transmissions from the transceivers are picked up by the feeder and carried to other parts of the tunnel, allowing two-way radio communication throughout the tunnel system.
The system has a limited range and because of the frequency it uses (typically VHF or UHF), transmissions cannot pass through solid rock, which limits the system to a line-of-sight application. It does, however, allow two-way mobile communication.
Due to the signal loss along the feeder, a leaky feeder is usually used for frequencies under 1 GHz. Above that frequency the losses require too many repeaters, thus making other options more effective. Antennas (omni, panel or bi-directional) or even Distributed antenna systems are more often used for higher frequency bands.
Applications
Mining
Leaky feeders are used in the mining industry 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.[5]
London Underground uses a leaky feeder system for its internal communication network Connect.[6] However, the communication used by the emergency services, Airwave, was not compatible and did not work below ground. The fact that this situation continued to exist after the 1987 King's Cross fire was criticized in the reports from the 7 July 2005 London bombings, where it hampered rescue efforts.[7] In March 2020, two additional leaky feeder cables were brought online in the Jubilee line tunnels between Canning Town and Westminster. One of these cables provided commercial 4G coverage for passengers, both in the tunnels and on station platforms,[8] whilst the second cable provided coverage for the Home Office's Emergency Services Network (ESN),[9] which is currently being rolled out to replace the ageing Airwave network.[10] This trial section is the first to be brought online as part of a project to provide both commercial 4G coverage and ESN coverage across the entire Tube network.
Leaky feeder antenna system can also be used to allow reception of on-board GSM and WiFi signals on passenger aircraft.[12][13] The weight and space requirements of leaky feeder systems are usually lower than comparable antenna systems, thus saving space and fuel. The even field strengths produced by runs of leaky feeders spanning the entire fuselage improve coverage while requiring less transmitting power.
Industrial buildings
Leaky feeders are used in hotels, warehouses and other industrial buildings where it is difficult to get WiFi coverage using normal access points. Some installations have 50–75 meters of leaky wire connected to the antenna output of access points.[14]
^"Times Microwave Radiating Cable Catalogue" (PDF). Times Microwave. Retrieved 12 March 2017.
^"Radiating Cable". CommScope. Retrieved 13 September 2014.
^. Radio Frequency Systems. Archived from the original on 30 August 2017. Retrieved 13 September 2014.
^"Basic Tutorial on Wireless Communication and Electronic Tracking: Technology Overview". Centers for Disease Control and Prevention. Retrieved 8 March 2014.
^Nally, Jonathan (30 September 2013). . CriticcalComms. Archived from the original on 1 October 2013. Retrieved 8 March 2014.
^ETSI White Paper No. 4 GSM operation onboard aircraft(PDF), January 2007
^W. L. Gore & Associates (15 October 2013), "Leaky Feeder Antennas for Airborne Wi-Fi", Microwave Journal
^"Leaky Feeder Communication and Installation Guide for Business". Wall to Wall Communications. 11 February 2019. Retrieved 12 March 2019.
^Putaala, Jussi; Myllymäki, Sami; Kokkonen, Mikko; Jantunen, Heli (July 2021). "Resonator‐enhanced radiating cable for UHF RFID readers". Microwave and Optical Technology Letters. 63 (7): 1842–1847. doi:10.1002/mop.32844. S2CID 233392835.
^Kokkonen, Mikko; Myllymaki, Sami; Putaala, Jussi; Jantunen, Heli (2022). "A Resonator Enhanced UHF RFID Antenna Cable for Inventory and Warehouse Applications". IEEE Journal of Radio Frequency Identification. 6 (1): 128–133. doi:10.1109/jrfid.2021.3135047. S2CID 245218056.
External links
IWT Wireless Communications and Tracking in Underground Mines - a wireless mesh alternative to leaky feeder
March 10, 2023
leaky, feeder, leaky, feeder, communications, system, used, underground, mining, other, tunnel, environments, manufacturers, cabling, professionals, term, radiating, cable, better, source, needed, this, implies, that, cable, designed, radiate, something, that,. A leaky feeder is a communications system used in underground mining and other tunnel environments 1 Manufacturers and cabling professionals use the term radiating cable 2 3 better source needed 4 as this implies that the cable is designed to radiate something that coaxial cable is not generally supposed to do Diagram of leaky feeder cable Contents 1 Principle 2 Applications 2 1 Mining 2 2 Underground railways 2 3 In flight wireless networks 2 4 Industrial buildings 2 5 RFID 3 See also 4 References 5 External linksPrinciple EditA leaky feeder communication system consists of a cable run along tunnels which emits and receives radio waves functioning as an extended antenna The 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 entire length Because of this leakage of signal line amplifiers are required to be inserted at regular intervals typically every 350 to 500 metres to boost the signal back up to acceptable levels The signal is usually picked up by portable transceivers carried by personnel Transmissions from the transceivers are picked up by the feeder and carried to other parts of the tunnel allowing two way radio communication throughout the tunnel system The system has a limited range and because of the frequency it uses typically VHF or UHF transmissions cannot pass through solid rock which limits the system to a line of sight application It does however allow two way mobile communication Due to the signal loss along the feeder a leaky feeder is usually used for frequencies under 1 GHz Above that frequency the losses require too many repeaters thus making other options more effective Antennas omni panel or bi directional or even Distributed antenna systems are more often used for higher frequency bands Applications EditMining Edit Leaky feeders are used in the mining industry 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 5 Underground railways Edit The leaky feeder system is used for underground mobile communication in mass transit railways In the Delhi Metro rail transport systems of Hong Kong and the Copenhagen Metro Danish CityRingen leaky feeders were incorporated in the specification of the capital project and installed during construction citation needed clarification needed This gives emergency services seamless mobile communication from the underground to the surface London Underground uses a leaky feeder system for its internal communication network Connect 6 However the communication used by the emergency services Airwave was not compatible and did not work below ground The fact that this situation continued to exist after the 1987 King s Cross fire was criticized in the reports from the 7 July 2005 London bombings where it hampered rescue efforts 7 In March 2020 two additional leaky feeder cables were brought online in the Jubilee line tunnels between Canning Town and Westminster One of these cables provided commercial 4G coverage for passengers both in the tunnels and on station platforms 8 whilst the second cable provided coverage for the Home Office s Emergency Services Network ESN 9 which is currently being rolled out to replace the ageing Airwave network 10 This trial section is the first to be brought online as part of a project to provide both commercial 4G coverage and ESN coverage across the entire Tube network An alternative to using leaky feeder in underground railways is to use Distributed Antenna System DAS A DAS system was deployed in some New York City Subway stations by Transit Wireless to provide WiFi and mobile phone and data coverage for customers 11 In flight wireless networks Edit Leaky feeder antenna system can also be used to allow reception of on board GSM and WiFi signals on passenger aircraft 12 13 The weight and space requirements of leaky feeder systems are usually lower than comparable antenna systems thus saving space and fuel The even field strengths produced by runs of leaky feeders spanning the entire fuselage improve coverage while requiring less transmitting power Industrial buildings Edit Leaky feeders are used in hotels warehouses and other industrial buildings where it is difficult to get WiFi coverage using normal access points Some installations have 50 75 meters of leaky wire connected to the antenna output of access points 14 RFID Edit Leaky feeders modified with metallic strips can be used as a Radio frequency identification RFID antenna 15 16 See also EditTunnel transmitter Through the earth mine communicationsReferences Edit Improvements coming soon to mine communications Kentucky New Era Associated Press 19 February 2007 Retrieved 6 March 2012 Times Microwave Radiating Cable Catalogue PDF Times Microwave Retrieved 12 March 2017 Radiating Cable CommScope Retrieved 13 September 2014 Radiating cable revealed Radio Frequency Systems Archived from the original on 30 August 2017 Retrieved 13 September 2014 Basic Tutorial on Wireless Communication and Electronic Tracking Technology Overview Centers for Disease Control and Prevention Retrieved 8 March 2014 Victoria line heads Metronet renewal Railway Gazette International 1 August 2003 Retrieved 6 March 2012 Communications blamed in London bomb response PC Advisor 23 February 2012 Retrieved 6 March 2012 4G on Jubilee line tunnel section from March 2020 Transport for London Press release Retrieved 2021 03 12 Kobie Nicole 2020 02 05 Inside the messy mission to bring 4G to the London Underground Wired UK ISSN 1357 0978 Retrieved 2021 03 12 Emergency Services Network overview GOV UK Retrieved 2021 03 12 Nally Jonathan 30 September 2013 Tunnel vision getting New York talking CriticcalComms Archived from the original on 1 October 2013 Retrieved 8 March 2014 ETSI White Paper No 4 GSM operation onboard aircraft PDF January 2007 W L Gore amp Associates 15 October 2013 Leaky Feeder Antennas for Airborne Wi Fi Microwave Journal Leaky Feeder Communication and Installation Guide for Business Wall to Wall Communications 11 February 2019 Retrieved 12 March 2019 Putaala Jussi Myllymaki Sami Kokkonen Mikko Jantunen Heli July 2021 Resonator enhanced radiating cable for UHF RFID readers Microwave and Optical Technology Letters 63 7 1842 1847 doi 10 1002 mop 32844 S2CID 233392835 Kokkonen Mikko Myllymaki Sami Putaala Jussi Jantunen Heli 2022 A Resonator Enhanced UHF RFID Antenna Cable for Inventory and Warehouse Applications IEEE Journal of Radio Frequency Identification 6 1 128 133 doi 10 1109 jrfid 2021 3135047 S2CID 245218056 External links EditIWT Wireless Communications and Tracking in Underground Mines a wireless mesh alternative to leaky feeder Retrieved from https en wikipedia org w index php title Leaky feeder amp oldid 1135165755, wikipedia, wiki, book, books, library,
