GB2235336A - Leaky cable antenna - Google Patents

Leaky cable antenna Download PDF

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Publication number
GB2235336A
GB2235336A GB9013909A GB9013909A GB2235336A GB 2235336 A GB2235336 A GB 2235336A GB 9013909 A GB9013909 A GB 9013909A GB 9013909 A GB9013909 A GB 9013909A GB 2235336 A GB2235336 A GB 2235336A
Authority
GB
Grant status
Application
Patent type
Prior art keywords
tube
cable
transmission system
system according
housing
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
GB9013909A
Other versions
GB2235336B (en )
GB9013909D0 (en )
Inventor
David Vaughan Bartram
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Hunting Engineering Ltd
HUNTING ENG Ltd
Original Assignee
* HUNTING ENGINEERING LIMITED
HUNTING ENG LTD
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date

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Classifications

    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01QANTENNAS, i.e. RADIO AERIALS
    • H01Q13/00Waveguide horns or mouths; Slot antennas; Leaky-waveguide antennas; Equivalent structures causing radiation along the transmission path of a guided wave
    • H01Q13/20Non-resonant leaky-waveguide or transmission-line antennas; Equivalent structures causing radiation along the transmission path of a guided wave
    • H01Q13/203Leaky coaxial lines

Abstract

A communication system comprises a leaky feeder cable 1 disposed within a housing 8 which provides a discontinuous RF shield. The housing is preferably made of stainless steel, and the discontinuities, which may be apertures 9 are preferably arranged to establish a regular pattern on signals received or transmitted. As an alternative the discontinuities can be provided by a series of separate tubes (Fig 2a). Such a tube may be made with the discontinuities of RF transparent material or may be a continuous RF transparent tube with areas of RF shielding, coating or sheathing. The tube may be notched (Fig 2b). Instead of a circular tube, square or other cross-section tube may be used. Instead of terminating in resistance 2 the ends of the cable 1 can be coupled (Fig 3) to enhance received signals. The leaky feeder may be used for voice, remote control and video communication. The leaky feeder may be used for mobile to mobile communication (Fig 4). A mesh network such as used in buildings is described (Fig 5). <IMAGE>

Description

COMMUNICATION VIA LEAKY CABLES This invention relates to communications systems and in particular but not exclusively to communication systems in which leaky cables are utilised to enhance communication with a mobile transmitter or receiver.

There are various environments such as large buildings or industrial works, docks, mines, airports, railways, tunnels and so forth where communication between a base station and mobile vehicles or personnel ('mobiles') or between two mobiles is necessary. Full radio communication using significant power broadcasting presents problems in some environments due to potential hazard and in others, in terms of channel availability and regulatory conditions. More serious difficulties are encountered when wideband signals such as video signals are to be transmitted; and are aggravated by changes in geometry. It is known to provide distributed low power transmission from or reception by a leaky feeder cable which extends from a base station. A leaky feeder cable of the known type comprises a coaxial cable which has deliberately imperfect screening.

One problem that arises in a variety of circumstances is a need to shield the feeder physically while permitting propagation in the manner of a leaky feeder and particularly to enable servicing of the feeder for very long periods of time.

The present invention provides a transmission system comprising a feeder cable disposed within a housing that provides discontinuous RF shielding in which the discontinuous RF shielding comprises a plurality of intervals in the screening arranged to define a pattern on transmitted or incident RF signals.

The invention is now described by way of example with reference to the accompanying drawings in which : Figure 1 is a schematic drawing of an installation according to an embodiment of the invention; Figure 2 shows alternative embodiments of tube housings; Figure 3 is an embodiment for enhancing received signals; Figure 4 illustrates mobile to mobile communication; Figure 5 illustrates an embodiment utilising a network of leaky cables, and Figure 6 illustrates a typical single station arrangement configured for a mobile vehicle controlled from a base station.

In buildings or sites communication between a base and a vehicle may be required not only for voice but also for remote control and in many instances communication in both directions is required although not necessarily always of the same type of signals. For example in robotic systems such as in warehouses directional instructions are transmitted to the robot and video and/or other positioning signals may be transmitted back from the robot to the remote operator. Frequently the remote operator will be located at a base station, but in some instances may also be mobile.

Thus two way communcation is desirable both between stations and mobiles and between mobiles.

Referring now to Figure 1, a schematic embodiment of the invention shows a leaky feeder cable 1 that is connected to a terminating resistance 2. Signals are launched into the feeder cable 1 from a transmitter 3, and signals in the cable are picked up by a receiver 4. The transmitter 3 and receiver 4 are connected to the cable and isolated from each other by a directional coupler, which may be a low-loss frequency sensitive coupler 5. Typically the transmitted data comprises low bandwidth control data at 25KHz on a 30MHz carrier. With a leaky feeder cable externally generated RF radiation will penetrate the imperfect screening at the cable and then propagate in the cable in both directions, and this can be utilised to receive signals from an external mobile, such as mobile 6.

However, a typical rate of propagation in cable is 0.8 times the free space velocity, thus a signal such as a video picture at normal TV rates on a substantially plane wavefront 7 that impinges on a leaky cable 1 over a distance of say 6 metres will suffer multi-path distortion, in the example of a video picture blurring it over 100ns and reducing the line resolution by a factor of 2.

In the present invention it is proposed to provide an additional component comprising a member such as a metal tube 8 having spaced apart apertures 9. Where the tube is solid it acts as an RF screen preventing both egress and entry of radiation, but at the apertures radiation leaked from cable 1 is emitted as if from a series of point sources, and likewise impinging external radiation enters the cable only in the vicinity of the apertures.

The effect of the radiation being transmitted from a series of apertures rather than along a continuous length is of negligible effect in that the apertures, over the route of the leaky feeder cable, effectively constitute a near randomly distributed pattern of secondary sources. Very close to the tube (i.e. within a few centimetres) there may be voids in the transmitted signals, but this can be overcome by providing spaced apart multiple antennae for reception at the mobile.

With respect to the externally generated radiation the effect of the apertured tube is of more significance. In this instance the image blurring is quantised into periodic time-delayed elements, instead of a continuum of blurring, and this periodic blurring can be removed by adaptive filter techniques. The particular spacing and arrangement of the apertures can be selected to suit the filtering arrangement.

The use of an apertured tube in this way is significantly less expensive and less complex than the alternative of installation of directional transmission antennae on to the mobile stations. Additionally, the metal tubing has the practical advantage of providing a rugged housing for the feeder cable.

The apertured tube illustrated in Figure 1 could be replaced by alternative structures, the basic concept being to provide an RF shield with interruptions or discontinuities at particular intervals. Figure 2 shows some alternative exemplary structures: (a) a series of discrete tubes, for example 6 metre lengths separated by a 0.02 metre interval.

Such a tube may be fabricated with the discontinuities of RF transparent material so as to maintain continuous ruggedisation, or be a continuous RF transparent tube with areas of an RF shielding, coating or sheathing. Figure 4(b) illustrates a notched tube, with 0.2m width notches at intervals of 2 to 12 metres along the tube. Square or other cross-sections of tubes may also be used.

An important advantage of the present invention is that the tube, which may be, for example, of stainless steel, provides physical protection for the cable and yet does not significantly impair propagation of signals to or from the cable. Moreover, the invention allows for long-term servicing of the cable. In particular the tube may extend around a region in which are deployed mobile transmitters and/or receivers, such as may be incorporated in remotely operated vehicles. The cable may be withdrawn from the sheath or tube for inspection or replacement. A new cable may be inserted into the sheath or tube without any need for human entry into the region around or in which the sheath or tube extends.

When an externally generated signal enters the cable 1 it divides and propagates in opposite directions. With the arrangement shown in Figure 1, the far end of the leaky feeder is terminated in a load to minimise distortion from reflected signals returning back along the cable. An alternative embodiment is shown in Figure 3, in which the end of the leaky feeder is connected to a low loss coaxial cable (which could of course be a continuation of the same cable but with full rather than leaky sheathing) and the low loss coaxial cable is then connected back to the base station, so that the signals in the low loss cable are combined with the signals that propagated along the leaky cable. In this way the signal strength can be improved at the receiver which, instead of receiving from only half of the input energy transmitted along a leaky cable, also receives signals that propagated in the opposite direction.

Such an arrangement may further minimise the risk of voids as well as signal loss in the effective field pattern.

Mobile station to mobile station communication may be achieved by the technique illustrated in Figure 4.

In Figure 4 a first mobile station 10 transmits a signal f, that is picked up by the leaky cable 1 in apertured tube 8.

This signal is passed by the leaky cable to the receiver 4 where it is amplified, passed to transmitter 5 and retransmitted as signal f2 along the leaky cable. It can then be picked up by any other appropriately tuned mobile such as mobile 11.

In Figure 5 a mesh network is illustrated. Such an arrangement, incorporating the discontinuously shielded leaky cable, may be utilised in buildings or large vehicles or vessels. The leaky cables define a network of local cells coupled together and communicating with transmitters and receivers. Such an arrangement may be utilised to provide mobile to mobile communication without the attendant propagation delay and attenuation associated with remote base stations.

Figure 6 schematically illustrates a one station arrangement configured for a mobile vehicle controlled from a base station. One or more video channels may be transmitted at UHF or higher frequencies from mobile to the cable.

Telemetry data from the vehicle may be combined with video signals or, more preferably, separately transmitted.

Command data is sent from.

A modification of the invention would be to establish discrete discontinuities (or zones of imperfect screening) in the screening of the cable with 'perfect' screening between the discontinuities so that the leak pattern from the cable itself adopted the pattern described in relation to the tube.

Claims (8)

1. A transmission system comprising a feeder cable disposed within a housing that provides discontinuous RF shielding in which the discontinuous RF shielding comprises a plurality of intervals in the screening arranged to define a pattern on transmitted or incident RF signals.
2. A transmission system according to claim 2 in which the intervals comprise a regular pattern of interruptions in the shielding.
3. A transmission system according to claim 1 or claim 2 in which the feeder cable comprises a leaky feeder cable and is disposed within a tube having a plurality of regularly spaced intervals in its screening.
4. A transmission system according to claim 3 in which the tube comprises a series of spaced apart tubes.
5. A transmission system according to claim 3 in which the tube has a series of apertures.
6. A transmission system according to any preceding claim in which the housing is metal.
7. A transmission system according to any preceding claim in which the housing comprises a screening layer disposed over a supporting member.
8. A transmission system according to any preceding claim in which the far end of the feeder cable is connected via a low loss cable back to a receiver.
GB9013909A 1989-06-23 1990-06-22 Communication via leaky cables Expired - Fee Related GB2235336B (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
GB8914399A GB8914399D0 (en) 1989-06-23 1989-06-23 Apparatus for remote control
GB9013909A GB2235336B (en) 1989-06-23 1990-06-22 Communication via leaky cables

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB9013909A GB2235336B (en) 1989-06-23 1990-06-22 Communication via leaky cables

Publications (3)

Publication Number Publication Date
GB9013909D0 GB9013909D0 (en) 1990-08-15
GB2235336A true true GB2235336A (en) 1991-02-27
GB2235336B GB2235336B (en) 1994-05-11

Family

ID=26295524

Family Applications (1)

Application Number Title Priority Date Filing Date
GB9013909A Expired - Fee Related GB2235336B (en) 1989-06-23 1990-06-22 Communication via leaky cables

Country Status (1)

Country Link
GB (1) GB2235336B (en)

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4335345A1 (en) * 1993-10-16 1995-04-20 Sel Alcatel Ag Mobile base station and antenna arrangement to provide radio coverage for a tunnel
DE19732503A1 (en) * 1997-07-29 1999-02-04 Alsthom Cge Alcatel HF signal transmission, radiation and reception device
DE19905595A1 (en) * 1999-02-11 2000-09-14 Motorola Inc Radio system enabling communication inside tunnel or building, comprises monitoring circuit which feeds in monitoring signal when first or second radio feed fails through which breakdown is indicated
GB2407914A (en) * 2003-11-05 2005-05-11 Esl Defence Ltd A Cable with low radar reflections
EP1609251A1 (en) * 2003-02-06 2005-12-28 Hamilton Sundstrand Corporation Multi-receiver communication system with distributed aperture antenna
EP1770594A2 (en) 2002-06-04 2007-04-04 Mineral Lassen LLC Transponder communication using leaky cable antenna
WO2010107440A1 (en) * 2009-03-20 2010-09-23 Innovative Wireless Technologies, Inc. Method and apparatus for reliable communications in underground and hazardous areas
US8253636B2 (en) 2005-11-28 2012-08-28 Bae Systems Plc Improvements relating to antenna arrays
US9179475B2 (en) 2009-03-20 2015-11-03 Innovative Wireless Technologies, Inc. Distributed ad hoc mesh network protocol for underground mine and hazardous area communications

Citations (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1327864A (en) * 1970-02-18 1973-08-22 Iniex Wireless telecommunication system for confined spaces
GB2062359A (en) * 1979-10-31 1981-05-20 Bicc Ltd Aerials
GB1597125A (en) * 1977-08-24 1981-09-03 Bicc Ltd Radiating cables
GB2076226A (en) * 1980-05-13 1981-11-25 Tanaka Hiroki Antenna
GB2127621A (en) * 1982-09-20 1984-04-11 Control Data Canada Method of manufacturing a leaky coaxial cable
EP0122497A2 (en) * 1983-04-15 1984-10-24 Times Amphenol Canada Ltd. Method of producing leaky coaxial cable
EP0141961A1 (en) * 1983-09-15 1985-05-22 LES CABLES DE LYON Société anonyme dite: Radiating coaxial cable
GB2152290A (en) * 1982-03-26 1985-07-31 Thomson Csf A slotted-waveguide antenna
EP0300147A1 (en) * 1987-07-20 1989-01-25 KABEL RHEYDT Aktiengesellschaft Leaky coaxial cable radio frequency transmission device
GB2212985A (en) * 1987-12-01 1989-08-02 Alison Microsystems Limited Slotted antenna
EP0375840A2 (en) * 1988-12-30 1990-07-04 KABEL RHEYDT Aktiengesellschaft Apparatus for transmitting high-frequency signals

Patent Citations (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1327864A (en) * 1970-02-18 1973-08-22 Iniex Wireless telecommunication system for confined spaces
GB1597125A (en) * 1977-08-24 1981-09-03 Bicc Ltd Radiating cables
GB2062359A (en) * 1979-10-31 1981-05-20 Bicc Ltd Aerials
GB2076226A (en) * 1980-05-13 1981-11-25 Tanaka Hiroki Antenna
GB2152290A (en) * 1982-03-26 1985-07-31 Thomson Csf A slotted-waveguide antenna
GB2127621A (en) * 1982-09-20 1984-04-11 Control Data Canada Method of manufacturing a leaky coaxial cable
EP0122497A2 (en) * 1983-04-15 1984-10-24 Times Amphenol Canada Ltd. Method of producing leaky coaxial cable
EP0141961A1 (en) * 1983-09-15 1985-05-22 LES CABLES DE LYON Société anonyme dite: Radiating coaxial cable
EP0300147A1 (en) * 1987-07-20 1989-01-25 KABEL RHEYDT Aktiengesellschaft Leaky coaxial cable radio frequency transmission device
GB2212985A (en) * 1987-12-01 1989-08-02 Alison Microsystems Limited Slotted antenna
EP0375840A2 (en) * 1988-12-30 1990-07-04 KABEL RHEYDT Aktiengesellschaft Apparatus for transmitting high-frequency signals

Cited By (20)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4335345A1 (en) * 1993-10-16 1995-04-20 Sel Alcatel Ag Mobile base station and antenna arrangement to provide radio coverage for a tunnel
DE19732503A1 (en) * 1997-07-29 1999-02-04 Alsthom Cge Alcatel HF signal transmission, radiation and reception device
US6671463B2 (en) 1997-07-29 2003-12-30 Alcatel Arrangement for transmitting, radiating and receiving high-frequency signals
DE19905595A1 (en) * 1999-02-11 2000-09-14 Motorola Inc Radio system enabling communication inside tunnel or building, comprises monitoring circuit which feeds in monitoring signal when first or second radio feed fails through which breakdown is indicated
DE19905595C2 (en) * 1999-02-11 2001-03-15 Motorola Inc Radio system and method of providing a portion with a radio signal
US7970353B2 (en) 2002-06-04 2011-06-28 Mineral Lassen Llc Reflective communication using radio-frequency devices
US7844221B2 (en) 2002-06-04 2010-11-30 Forster Ian J Reflective communication using radio-frequency devices
US7697946B2 (en) 2002-06-04 2010-04-13 Forster Ian J Reflective communication using radio-frequency devices
EP1770594A2 (en) 2002-06-04 2007-04-04 Mineral Lassen LLC Transponder communication using leaky cable antenna
EP1770594A3 (en) * 2002-06-04 2007-07-11 Mineral Lassen LLC Transponder communication using leaky cable antenna
US7630684B2 (en) 2002-06-04 2009-12-08 Forster Ian J Reflective communication using radio-frequency devices
EP1609251B1 (en) * 2003-02-06 2010-08-18 Hamilton Sundstrand Corporation Multi-receiver communication system with distributed aperture antenna
EP1609251A1 (en) * 2003-02-06 2005-12-28 Hamilton Sundstrand Corporation Multi-receiver communication system with distributed aperture antenna
GB2407914B (en) * 2003-11-05 2007-01-24 Esl Defence Ltd A cable with low radar reflections
GB2407914A (en) * 2003-11-05 2005-05-11 Esl Defence Ltd A Cable with low radar reflections
US8253636B2 (en) 2005-11-28 2012-08-28 Bae Systems Plc Improvements relating to antenna arrays
WO2010107440A1 (en) * 2009-03-20 2010-09-23 Innovative Wireless Technologies, Inc. Method and apparatus for reliable communications in underground and hazardous areas
US8885559B2 (en) 2009-03-20 2014-11-11 Innovative Wireless Technologies, Inc. Method and apparatus for reliable communications in underground and hazardous areas
US9179475B2 (en) 2009-03-20 2015-11-03 Innovative Wireless Technologies, Inc. Distributed ad hoc mesh network protocol for underground mine and hazardous area communications
US9258722B2 (en) 2009-03-20 2016-02-09 Innovative Wireless Technologies, Inc. Method and apparatus for reliable communications in underground and hazardous areas

Also Published As

Publication number Publication date Type
GB2235336B (en) 1994-05-11 grant
GB9013909D0 (en) 1990-08-15 grant

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Legal Events

Date Code Title Description
PCNP Patent ceased through non-payment of renewal fee

Effective date: 20010622