Leaky feeder: Difference between revisions
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The leaky feeder system is used for underground mobile communication in [[mass transit]] [[railway]]s. In the [[Delhi Metro]], [[Rail transport in Hong Kong|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|date=June 2017}}{{Clarify|reason=Which example does this pertain to?|date=February 2021}} This gives emergency services seamless mobile communication from the underground to the surface. |
The leaky feeder system is used for underground mobile communication in [[mass transit]] [[railway]]s. In the [[Delhi Metro]], [[Rail transport in Hong Kong|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|date=June 2017}}{{Clarify|reason=Which example does this pertain to?|date=February 2021}} This gives emergency services seamless mobile communication from the underground to the surface. |
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[[London Underground]] uses a leaky feeder system for its internal communication network ''[[Transport for London#Connect project|Connect]]''.<ref>{{cite web|date=1 August 2003|title=Victoria line heads Metronet renewal|url=http://www.railwaygazette.com/nc/news/single-view/view/victoria-line-heads-metronet-renewal.html|access-date=6 March 2012|publisher=[[Railway Gazette International]]}}</ref> However, the communication used by the emergency services, [[Airwave Solutions|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.<ref>{{cite web|date=23 February 2012|title=Communications blamed in London bomb response|url=http://www.pcadvisor.co.uk/news/mobile-phone/6330/communications-blamed-in-london-bomb-response/|access-date=6 March 2012|publisher=PC Advisor}}</ref> 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,<ref>{{Cite press release |title=4G on Jubilee line tunnel section from March 2020|url=https://tfl.gov.uk/info-for/media/press-releases/2019/july/4g-on-jubilee-line-tunnel-section-from-march-2020|access-date=2021-03-12|website=Transport for London }}</ref> whilst the second cable provided coverage for the Home Office's [[Emergency Services Network]] (ESN),<ref>{{Cite |
[[London Underground]] uses a leaky feeder system for its internal communication network ''[[Transport for London#Connect project|Connect]]''.<ref>{{cite web|date=1 August 2003|title=Victoria line heads Metronet renewal|url=http://www.railwaygazette.com/nc/news/single-view/view/victoria-line-heads-metronet-renewal.html|access-date=6 March 2012|publisher=[[Railway Gazette International]]}}</ref> However, the communication used by the emergency services, [[Airwave Solutions|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.<ref>{{cite web|date=23 February 2012|title=Communications blamed in London bomb response|url=http://www.pcadvisor.co.uk/news/mobile-phone/6330/communications-blamed-in-london-bomb-response/|access-date=6 March 2012|publisher=PC Advisor}}</ref> 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,<ref>{{Cite press release |title=4G on Jubilee line tunnel section from March 2020|url=https://tfl.gov.uk/info-for/media/press-releases/2019/july/4g-on-jubilee-line-tunnel-section-from-march-2020|access-date=2021-03-12|website=Transport for London }}</ref> whilst the second cable provided coverage for the Home Office's [[Emergency Services Network]] (ESN),<ref>{{Cite magazine|last=Kobie|first=Nicole|date=2020-02-05|title=Inside the messy mission to bring 4G to the London Underground |magazine=Wired UK|url=https://www.wired.co.uk/article/london-underground-4g|access-date=2021-03-12|issn=1357-0978}}</ref> which is currently being rolled out to replace the ageing Airwave network.<ref>{{Cite web|title=Emergency Services Network: overview|url=https://www.gov.uk/government/publications/the-emergency-services-mobile-communications-programme/emergency-services-network|access-date=2021-03-12|website=GOV.UK }}</ref> 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. |
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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.<ref>{{cite news|last=Nally|first=Jonathan|title=Tunnel vision: getting New York talking|url=http://www.radiocomms.com.au/articles/63029-Tunnel-vision-getting-New-York-talking|archive-url=https://web.archive.org/web/20131001035850/http://www.radiocomms.com.au/articles/63029-Tunnel-vision-getting-New-York-talking|url-status=dead|archive-date=1 October 2013|access-date=8 March 2014|newspaper=CriticcalComms|date=30 September 2013}}</ref> |
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.<ref>{{cite news|last=Nally|first=Jonathan|title=Tunnel vision: getting New York talking|url=http://www.radiocomms.com.au/articles/63029-Tunnel-vision-getting-New-York-talking|archive-url=https://web.archive.org/web/20131001035850/http://www.radiocomms.com.au/articles/63029-Tunnel-vision-getting-New-York-talking|url-status=dead|archive-date=1 October 2013|access-date=8 March 2014|newspaper=CriticcalComms|date=30 September 2013}}</ref> |
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=== RFID === |
=== RFID === |
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Leaky feeders modified with metallic strips can be used as a [[Radio-frequency identification]] (RFID) antenna.<ref>{{cite journal |last1=Putaala |first1=Jussi |last2=Myllymäki |first2=Sami |last3=Kokkonen |first3=Mikko |last4=Jantunen |first4=Heli |title=Resonator‐enhanced radiating cable for UHF RFID readers |journal=Microwave and Optical Technology Letters |date=July 2021 |volume=63 |issue=7 |pages=1842–1847 |doi=10.1002/mop.32844}}</ref><ref>{{cite journal |last1=Kokkonen |first1=Mikko |last2=Myllymaki |first2=Sami |last3=Putaala |first3=Jussi |last4=Jantunen |first4=Heli |title=A Resonator Enhanced UHF RFID Antenna Cable for Inventory and Warehouse Applications |journal=IEEE Journal of Radio Frequency Identification |date=2022 |volume=6 |issue=1 |pages=128–133 |doi=10.1109/jrfid.2021.3135047}}</ref> |
Leaky feeders modified with metallic strips can be used as a [[Radio-frequency identification]] (RFID) antenna.<ref>{{cite journal |last1=Putaala |first1=Jussi |last2=Myllymäki |first2=Sami |last3=Kokkonen |first3=Mikko |last4=Jantunen |first4=Heli |title=Resonator‐enhanced radiating cable for UHF RFID readers |journal=Microwave and Optical Technology Letters |date=July 2021 |volume=63 |issue=7 |pages=1842–1847 |doi=10.1002/mop.32844|s2cid=233392835 |url=http://urn.fi/urn:nbn:fi-fe202103248166 }}</ref><ref>{{cite journal |last1=Kokkonen |first1=Mikko |last2=Myllymaki |first2=Sami |last3=Putaala |first3=Jussi |last4=Jantunen |first4=Heli |title=A Resonator Enhanced UHF RFID Antenna Cable for Inventory and Warehouse Applications |journal=IEEE Journal of Radio Frequency Identification |date=2022 |volume=6 |issue=1 |pages=128–133 |doi=10.1109/jrfid.2021.3135047|s2cid=245218056 }}</ref> |
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==See also== |
==See also== |
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Revision as of 01:02, 23 January 2023
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.
Principle
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]
Underground railways
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
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]
RFID
Leaky feeders modified with metallic strips can be used as a Radio-frequency identification (RFID) antenna.[15][16]
See also
References
- ^ "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 & 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.