US3864509A - Coaxial cable whose dielectric partly consists of air - Google Patents

Coaxial cable whose dielectric partly consists of air Download PDF

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Publication number
US3864509A
US3864509A US430789A US43078974A US3864509A US 3864509 A US3864509 A US 3864509A US 430789 A US430789 A US 430789A US 43078974 A US43078974 A US 43078974A US 3864509 A US3864509 A US 3864509A
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United States
Prior art keywords
filaments
central conductor
coaxial cable
conductor
tube
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Expired - Lifetime
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US430789A
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English (en)
Inventor
Hubertus Johannes Jose Gommans
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US Philips Corp
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US Philips Corp
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B11/00—Communication cables or conductors
    • H01B11/18—Coaxial cables; Analogous cables having more than one inner conductor within a common outer conductor
    • H01B11/1834—Construction of the insulation between the conductors

Definitions

  • ABSTRACT A longitudinally watertight coaxial cable whose dielec- [30] Foreign Apphcatwn Pnomy Dam tric consists partly of air, including spacer filaments of Feb. 2,1973 Netherlands 7301495 Synthetic resin which are located about the central conductor in accordance with spatial wavelines and [g2] :J.S.CCll 174/28, 174/36, 174/107 which are interconnected at regular spaces Over a lat. Short distance, and thus j y Surround the entire [58] Field of Search 174/28, 29, 16 B, 99 R, cumference of the conduct 4 Claims, 6 Drawing Figures P/JENTED 41975 3.864.509
  • the invention relates to a coaxial cable having a dielectric which consists partly of air, in which filaments of electrically insulating material serving as spacers surround the central conductor.
  • a tube of electrically insulating material may be present to support the outer conductor.
  • the cable may have one or more concentric outer conductors and furthermore an outer jacket of electrically insulating material and optionally an armor.
  • one or more filaments of synthetic resin spirally surrounding the central conductor serve as spacers.
  • the central conductor with the spacer is located within a tube of synthetic resin which tube is surrounded by the outer conductor.
  • Coaxial cables having filaments of synthetic resin serving as spacers spirally surrounding the central conductor can be manufactured in a continuous manner, that is to say, while moving the core at a constant rate the spacers and the further cable sections can successively be provided.
  • a drawback of this construction is, however, that the cable is not longitudinally watertight. Consequently, when leakage occurs, for example, due to a crack or break or at a connection, water may move unhampered over large distances through buried cables and cause discontinuity in the impedance and increase the damping of the cable. The properties of the cable thereby change over large distances in such a manner that the cable becomes unfit for use. if parts of a cable section have different temperatures, water vapor may condense in the part having the lowest temperature so that the electrical properties of the cable also are detrimentally influenced. This risk occurs, for example, in cable sections which are located partly within and partly outside a building.
  • An object of the invention is to provide a construction for a coaxial cable which is longitudinally watertight and can be manufactured in a continuous manner.
  • a coaxial cable satisfying this object has spacers consisting of at least two filaments of electrically insulating material which surround the central conductor in accordance with spatial wave lines and are interconnected at regular spaces over a short distance. In this manner the filaments jointly surround the entire circumference of the central conductor.
  • a spatial wave line is understood to mean a wave line which varies along and around a cylindrical surface preferably between two generatrices of a cylinder. Such a wave line is three-dimensional.
  • Each of the filaments thus surrounds only part of the conductor circumference as seen in a projection on a face at right angles to the central conductor.
  • the filaments jointly surround the entire circumference of the central conductor.
  • the spacers consist of two filaments which are located along the central conductor in accordance with spatial wavelines which are symmetrical with respect to a plane passing through the axis of the central conductor.
  • the filaments each surround half the circumference of the cylinder constituted by the central conductor, the filaments being connected together at the areas where they touch each other.
  • the space between the central conductor and the outer conductor or the tube of electrically insulating material which is surrounded by the outer con ductor is divided into a plurality of compartments bounded by filament pieces. Consequently water cannot move over large distances when leakages occur along the central conductor. The formation of disturbing quantities of water due to condensation of water vapor at areas of low temperature is prevented because the flow of water vapor to these areas is prevented.
  • the filaments serving as spacers in the cable according to the invention preferably consist of a thermoplastic synthetic resin having a low dielectric constant (E) and a loss angle (1,, 5).
  • Suitable synthetic resins are. for example, polypropylene. polyethylene. polystyrene. and polytetrafluoroethylene.
  • the filaments may be solid or hollow. lt is alternatively possible to use filaments of synthetic resin foam or of a composite structure (for example, with a core of synthetic resin foam surrounded by a solid jacket of the same or of a differ ent synthetic resin).
  • the filaments may have round, elliptical, rectangular or other cross-sections favourable for the envisaged object.
  • the filaments when they are connected together in such a manner that the space between the central conductor and the outer conductor or tube of electrically insulating material carrying the outer conductor is filled up as completely as possible at the area of connection. Particularly a moisture-tight engagement of the filaments to metal parts such as the central conductor is desirable.
  • the spacers according to the invention may be provided in different manners, for example, with the aid of two molding devices which carry out semicircular movements around the continuously moving central conductor while at the points of return of the movement the filaments which are still hot are melted together, if desired. under deformation by means of a device which moves along with the central conductor over a suitable distance.
  • the central conductor may be manufactured, for example, of copper, aluminum or copper-clad aluminum.
  • the outer conductor may likewise consist of these materials in the form of a braid of metal wires or a foil or a combination of both.
  • the outer conductor may be supported by a tube of synthetic resin for which the above-mentioned synthetic resins are likewise suitable. it is alternatively possible to give the outer conductor the form of a self-supporting tube.
  • FIG. I is a side elevational view of a central conductor provided with two filaments of synthetic resin serving as spacers.
  • FIG. 2 is a top view of the same part of the central conductor and filaments as in FIG. I after it has been rotated about the central axis.
  • FIG. 3 is a cross-sectional view of the device of HO. 2 at the area of a connection of the two filaments of synthetic resin.
  • FIG. 4 is a developed view of the spacers after a cut has been made parallel to a generatrix of the cylinder constituted by the central conductor.
  • FIG. 5 is a developed view of a spacer composed of 4 filaments.
  • FIG. 6 is a developed view of a spacer composed of 3 wire filaments.
  • FIG. I there is shown a central conductor 1, for example, of solid copper having two spacers, of which only the spacer 2 on the front side is visible.
  • the spacers in the embodiment shown consist of solid filaments of polyethylene.
  • FlG. 2 is a top view of the central conductor 1 and the spacers 2, 3, showing that the filaments 2 and 3 are connected together while being melted and deformed at 4, 5, 6 and 7. in this FIGURE the spatial character of the wavelines constituted by the filaments 2 and 3 can be seen.
  • FIG. 3 shows a cross-section of a complete cable taken on the line lll-lll of FIG. 2.
  • a tube 8 of a synthetic resin for example, consisting of the same material used for the wires filaments 2 and 3, surrounds the filaments.
  • An outer conductor 9 surrounds the tube 8.
  • This conductor may consist of a braid of metal wire such as copper wire, a metal tube, a metal foil folded about the tube 8 or a combination of a metal foil folded about the tube 8 and a braid of metal wire provided thereon.
  • the filaments 2 and 3 are jointly deformed at the areas 4 and 6 where they are melted together such that at that area the space between the central conductor 1 and the tube 8 is completely filled up.
  • the entire cable is provided with the outer jacket 10.
  • FIG. 4 shows the spacer after the connections between the filaments 2 and 3 are interrupted on one side of the central conductor (such as between 4' and 4" and between 5' and 5").
  • the references 6 and 7 denote the connections located behind the central conductor 1 in FIG. 2.
  • FIGS. 5 and 6 show spacers in a corresponding manner which are built up of 4 and 3 filaments, respectively, of synthetic resin.
  • the minimum number of filaments sufficient to permanently center the central conductor 1 within the tube 8 will be used. In practice this can generally be achieved with two filaments. The region of air in the space between the central conductor 1 and the tube 8 is then as large as possible for a given filaments diameter and wavelength of the wavelines constituted by the filaments resulting in a minimum damping in the cable.
  • the central conductor 1 consisted of copper and had a diameter of 3.6 mm.
  • Two filaments 2 and 3 of polyethylene were provided on the conductor 1 each with a diameter of 3mm and the tube 8 of polyethylene had a wall thickness likewise of 3 mm.
  • the outer conductor consisted of a copper foil folded about the tube 8 on which foil a copper wire braid was applied.
  • the outer jacket l consisted of polyethylene mixed with carbon black, and having a wall thickness of 2 mm.
  • connection points 4 and 5, and 6 and 7 were approximately 2.5 cm. This means that when a free space bounded by the filaments 2 and 3 and two connections between these wires located on the same side of the central conductor is completely filled up with water there is no noticeable increase in damping in the frequency range between l0 and L000 MHz.
  • a coaxial cable according to the invention has the advantage that the construction permits continuous manufacture while the cable is sufficiently longitudinally watertight to be used outside buildings and in a humid environment.
  • a coaxial cable having a dielectric which consists partly of air in which filaments of electrically insulating material serving as spacers around a central conductor, wherein the spacers consist of at least two filaments of electrically insulating material which surround the central conductor in accordance with spatial wavelines and which are interconnected at regular spaces over a short distance and thusjointly surround the entire circumference of the central conductor.
  • a coaxial cable as claimed in claim I wherein the spatial wavelines are symmetrical with respect to a plane passing through the axis of the central conductor, and each filament surrounds the cylinder constituted by the central conductor over half its circumference, the filaments-being connected together at the areas where they touch each other.
  • a coaxial cable as claimed in claim I wherein the filaments, consisting of thermoplastic synthetic resin, are deformed at the area of the connection so as to fill up the space between the central conductor and an outer conductor or tube of electrically insulating material which is surrounded by an outer conductor at the area of connection.

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  • Communication Cables (AREA)
  • Insulated Conductors (AREA)
  • Waveguide Aerials (AREA)
US430789A 1973-02-02 1974-01-04 Coaxial cable whose dielectric partly consists of air Expired - Lifetime US3864509A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
NL7301495A NL7301495A (ar) 1973-02-02 1973-02-02

Publications (1)

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US3864509A true US3864509A (en) 1975-02-04

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US430789A Expired - Lifetime US3864509A (en) 1973-02-02 1974-01-04 Coaxial cable whose dielectric partly consists of air

Country Status (13)

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US (1) US3864509A (ar)
JP (1) JPS49105990A (ar)
BE (1) BE810470A (ar)
CA (1) CA1006593A (ar)
CH (1) CH566061A5 (ar)
DE (1) DE2401559A1 (ar)
ES (1) ES422803A1 (ar)
FR (1) FR2216653B1 (ar)
GB (1) GB1458102A (ar)
IT (1) IT1007171B (ar)
NL (1) NL7301495A (ar)
NO (1) NO137622B (ar)
SE (1) SE394156B (ar)

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4011118A (en) * 1974-05-21 1977-03-08 U.S. Philips Corporation Method of manufacturing a coaxial cable, and coaxial cable made by this method
US5742002A (en) * 1995-07-20 1998-04-21 Andrew Corporation Air-dielectric coaxial cable with hollow spacer element
US6849799B2 (en) * 2002-10-22 2005-02-01 3M Innovative Properties Company High propagation speed coaxial and twinaxial cable
US20060254801A1 (en) * 2005-05-27 2006-11-16 Stevens Randall D Shielded electrical transmission cables and methods for forming the same
US20130281851A1 (en) * 2012-04-19 2013-10-24 Kenneth L. Carr Heating/sensing catheter apparatus for minimally invasive applications
US20140367143A1 (en) * 2013-06-17 2014-12-18 Hitachi Metals, Ltd. Coaxial cable
US20150179306A1 (en) * 2013-12-24 2015-06-25 Belden Inc. Semi-solid unbalanced audio cable
US9355755B2 (en) 2011-04-07 2016-05-31 3M Innovative Properties Company High speed transmission cable
US20160365174A1 (en) * 2013-12-24 2016-12-15 Belden Inc. Semi-solid balanced audio cable
US10839981B2 (en) 2011-04-07 2020-11-17 3M Innovative Properties Company High speed transmission cable

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2640083B1 (fr) * 1988-12-06 1991-05-03 Thomson Csf Support pour ligne de transmission hyperfrequence, notamment du type triplaque

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB460211A (en) * 1935-07-22 1937-01-22 Alexis Rene Grenfell Improvements in cables suitable for the transmission of high frequency electric currents
DE653669C (de) * 1935-04-16 1937-11-30 Hackethal Draht Und Kabel Werk Luftraumisolierte Hochfrequenzleitung
FR907582A (fr) * 1944-04-25 1946-03-15 Thomson Houston Comp Francaise Perfectionnements aux câbles électriques

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2348752A (en) * 1940-09-17 1944-05-16 Int Standard Electric Corp Electric cable
GB752408A (en) * 1954-06-04 1956-07-11 Ml Aviation Co Ltd Improvements relating to flexible electrical conductors

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE653669C (de) * 1935-04-16 1937-11-30 Hackethal Draht Und Kabel Werk Luftraumisolierte Hochfrequenzleitung
GB460211A (en) * 1935-07-22 1937-01-22 Alexis Rene Grenfell Improvements in cables suitable for the transmission of high frequency electric currents
FR907582A (fr) * 1944-04-25 1946-03-15 Thomson Houston Comp Francaise Perfectionnements aux câbles électriques

Cited By (19)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4011118A (en) * 1974-05-21 1977-03-08 U.S. Philips Corporation Method of manufacturing a coaxial cable, and coaxial cable made by this method
US5742002A (en) * 1995-07-20 1998-04-21 Andrew Corporation Air-dielectric coaxial cable with hollow spacer element
US6849799B2 (en) * 2002-10-22 2005-02-01 3M Innovative Properties Company High propagation speed coaxial and twinaxial cable
US20060254801A1 (en) * 2005-05-27 2006-11-16 Stevens Randall D Shielded electrical transmission cables and methods for forming the same
US9355755B2 (en) 2011-04-07 2016-05-31 3M Innovative Properties Company High speed transmission cable
US10354778B2 (en) 2011-04-07 2019-07-16 3M Innovative Properties Company High speed transmission cable
US10726970B2 (en) 2011-04-07 2020-07-28 3M Innovative Properties Company High speed transmission cable
US9799425B2 (en) 2011-04-07 2017-10-24 3M Innovative Properties Company High speed transmission cable
US10839981B2 (en) 2011-04-07 2020-11-17 3M Innovative Properties Company High speed transmission cable
US20140018697A1 (en) * 2012-04-19 2014-01-16 Meridian Medical Systems, Llc Heating/sensing catheter apparatus for minimally invasive application
US10987001B2 (en) 2012-04-19 2021-04-27 Applied ThermoLogic, LLC Heating/sensing catheter apparatus for minimally invasive applications
US20140012132A1 (en) * 2012-04-19 2014-01-09 Meridian Medical Systems, Llc Heating/sensing catheter appratus for minimally invasive applications
US20130281851A1 (en) * 2012-04-19 2013-10-24 Kenneth L. Carr Heating/sensing catheter apparatus for minimally invasive applications
US20140367143A1 (en) * 2013-06-17 2014-12-18 Hitachi Metals, Ltd. Coaxial cable
US20150179306A1 (en) * 2013-12-24 2015-06-25 Belden Inc. Semi-solid unbalanced audio cable
US9748022B2 (en) * 2013-12-24 2017-08-29 Belden Inc. Semi-solid balanced audio cable
US20160365174A1 (en) * 2013-12-24 2016-12-15 Belden Inc. Semi-solid balanced audio cable
US9455070B2 (en) * 2013-12-24 2016-09-27 Belden Inc. Semi-solid unbalanced audio cable
US9293239B2 (en) 2013-12-24 2016-03-22 Belden Inc. Semi-solid balanced audio cable

Also Published As

Publication number Publication date
CA1006593A (en) 1977-03-08
GB1458102A (en) 1976-12-08
IT1007171B (it) 1976-10-30
DE2401559A1 (de) 1974-08-15
FR2216653B1 (ar) 1977-06-10
NO137622B (no) 1977-12-12
ES422803A1 (es) 1976-05-01
NL7301495A (ar) 1974-08-06
BE810470A (fr) 1974-07-31
FR2216653A1 (ar) 1974-08-30
CH566061A5 (ar) 1975-08-29
AU6509574A (en) 1975-08-07
SE394156B (sv) 1977-06-06
JPS49105990A (ar) 1974-10-07
NO740288L (no) 1974-08-05

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