EP0582013B1 - Method for making a flexible coaxial cable and resultant cable - Google Patents

Method for making a flexible coaxial cable and resultant cable Download PDF

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Publication number
EP0582013B1
EP0582013B1 EP19920401998 EP92401998A EP0582013B1 EP 0582013 B1 EP0582013 B1 EP 0582013B1 EP 19920401998 EP19920401998 EP 19920401998 EP 92401998 A EP92401998 A EP 92401998A EP 0582013 B1 EP0582013 B1 EP 0582013B1
Authority
EP
European Patent Office
Prior art keywords
accordance
dielectric
starting material
shaped
coaxial cable
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.)
Expired - Lifetime
Application number
EP19920401998
Other languages
German (de)
English (en)
French (fr)
Other versions
EP0582013A2 (en
EP0582013A3 (enrdf_load_stackoverflow
Inventor
William T. Pote
Roger Johansen
Thomas Pote
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.)
Flexco Microwave Inc
Original Assignee
Flexco Microwave Inc
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Filing date
Publication date
Application filed by Flexco Microwave Inc filed Critical Flexco Microwave Inc
Publication of EP0582013A2 publication Critical patent/EP0582013A2/en
Publication of EP0582013A3 publication Critical patent/EP0582013A3/xx
Application granted granted Critical
Publication of EP0582013B1 publication Critical patent/EP0582013B1/en
Anticipated expiration legal-status Critical
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B13/00—Apparatus or processes specially adapted for manufacturing conductors or cables
    • H01B13/06—Insulating conductors or cables
    • H01B13/18—Applying discontinuous insulation, e.g. discs, beads
    • H01B13/20—Applying discontinuous insulation, e.g. discs, beads for concentric or coaxial cables
    • H01B13/208—Applying discontinuous insulation, e.g. discs, beads for concentric or coaxial cables by mechanically removing parts of a continuous insulation
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B13/00—Apparatus or processes specially adapted for manufacturing conductors or cables
    • H01B13/06—Insulating conductors or cables
    • H01B13/18—Applying discontinuous insulation, e.g. discs, beads
    • H01B13/20—Applying discontinuous insulation, e.g. discs, beads for concentric or coaxial cables
    • H01B13/206—Applying discontinuous insulation, e.g. discs, beads for concentric or coaxial cables by forming a helical web

Definitions

  • the present invention relates to improvements in the methods of making flexible coaxial cables and the resultant cables made by such methods.
  • Coaxial cables such as for microwave transmission
  • the electrical characteristics of the cable are critical and any variation therein will yield unsatisfactory transmissions via such cables.
  • corrugated outer conductors such as disclosed in U.S. Pat. Nos. 3,582,536; 3,173,990 and 2,890,263 have been utilized.
  • a method in accordance with claim 1 for making a flexible coaxial cable having an inner conductor to which a dielectric material is secured to form a dielectric core for the coaxial cable, and a flexible outer conductor, such as a convoluted outer conductor formed from a strip helically wound conductor employs a solid dielectric starting material, such as a spline dielectric, or a cylindrical dielectric, or an expanded dielectrics which is controllably cut, such as by saw blades, using a desired cutting angle and blade width, in order to cut away a predetermined amount of the solid dielectric starting material to provide a shaped dielectric core, such as a spiral or helix, from the solid dielectric starting material.
  • a solid dielectric starting material such as a spline dielectric, or a cylindrical dielectric, or an expanded dielectrics which is controllably cut, such as by saw blades, using a desired cutting angle and blade width, in order to cut away a predetermined amount of the solid dielectric starting material to provide a
  • the resulting shaped core such as single or double helix, has a resultant predetermined pitch which provides a desired predetermined velocity of propagation and impedance for the coaxial cable.
  • the resulting helically shaped core is inserted into the convoluted outer conductor to produce a fast cable without any locking of the core to the outer conductor.
  • the core may be locked to the outer conductor by any of numerous locking methods, such as by way of example, the mechanical crimping method of the type described in prior U.S. Patent Nos. 3,797,104 and 4,758,685, or the threadable locking method of the type described in the U.S. Patent No 5,196,078.
  • various parameters such as impedance, velocity of propagation or phase length, attenuation, and VSWR, associated with the resulting flexible coaxial cable, may be readily controlled using the method of the present invention.
  • a spiral or helix type dielectric core for a flexible coaxial cable enables the velocity of propagation, by way of example, to be readily controlled during manufacture in accordance with the pitch of the helix, which also affects the impedance of the dielectric core.
  • the method employed in U.S. Patent No. 4,758,685, for providing this dielectric core involves the use of a heat shrinkable dieletric tubing over a helically wound dielectric beading which can result in a non-uniform dielectric core. As shown and preferred in FIGS.
  • the spiral or helix dielectric core 30 in the present invention is formed from a solid dielectric starting material 32 which is preferably cut by adjustable saw blades 34 at a predetermined cutting angle ⁇ , using saw blades 34 of a predetermined cutting width ⁇ which effectively determines the web width ⁇ for the resultant spiral dilectric core 30.
  • the solid dielectric starting material 32 is preferably initally provided with a conventional inner conductor 36 which comprises the center conductor 36 for the resultant flexible coaxial cable 38.
  • the solid dielectric starting material 32 is secured to the inner conductor 36, such as by bonding during the extrusion process, so that it is locked to the inner conductor 36.
  • the solid dielectric starting material 32 is cylindrical in shape although it can be any desired shape such as, for example, triangular, and may even comprise a spline 40, such as shown in FIG. 11, which is then cut to provide the spiral or helix dielectric core 30 which is comprised of the spiral web 42 of web width ⁇ , by way of example, of a predetermined pitch determined by the cutting angle ⁇ and cutting width ⁇ .
  • These parameters determine the amount of dielectric material which is cut away or removed from the solid dielectric 32 which effectively changes the impedance Z and the velocity of propagation V, as well as the VSWR and attentuation, such as shown in FIGS. 13-21 to be described in greater detail hereinafter.
  • the resultant impedance of the spiral dielectric core 30a is controllably changed to 50.9 ohms by employing the method of the present invention by utilizing a cutting width ⁇ of 3.3 mm (0.128 inches) for the saw blades 34, adjusted at a cutting angle ⁇ of 36°10', to provide a web width ⁇ of 12.7 mm (0.50 inches), with a pitch of 5.4 mm (0.214 inches) and a pitch diameter of 2.4 mm (0.095 inches).
  • FIGS. 17 and 20 shows a lower VSWR after the controlled spiral cut (FIG. 20) than before (FIG. 17).
  • a double shaped spiral or helix 30b such as illustrated in FIG.3, can be employed in place of the single spiral 30a of FIG. 2 for the spiral cut dielectric core 30.
  • the method of the present invention is still basically the same with the saw blades 34 instead being adjusted to cut a double helix 30b from the solid dielectric starting material 32.
  • FIG.3 using the same diemeter dielectric starting material 32 as in FIG.
  • the resultant impedance of the double helix spiral dielectric core 30b is controllably changed to 51.5 ohms by employing the method of the present invention by utilizing a cutting width ⁇ ' of 1.9 mm (0.075 inches) for the saw blades 34, adjusted at a cutting angle ⁇ ' of 45°30', to provide a web width ⁇ ' of 1.2 mm (0.046 inches), with a pitch of 7.5 mm (0.297 inches) and a pitch diameter of 2.7 mm (0.108 inches).
  • the saw blades 34 are preferably circular jewelers saw blades which may be used to cut a solid dielectric starting material of Teflon, TFE, FEP or polyolefin, by way of example, and are conventionally motor driven by a motor 40, such as at a rate of approximately 3600 rpm, while the solid dielectric starting material 32 is rotated and driven or pushed or pulled past the rotating saw blades 34 in the direction of arrow 42 through holder 44 to provide the spiral cut dielectric core 30.
  • the cutting angle ⁇ may readily be adjusted by adjusting the angle ⁇ of the saw blades 34 with respect to the holder 44 longitudinal axis 46 along which the dielectric starting material 32 is pulled or driven as it is rotated past the saw blades 34.
  • spiral dielectric core 30 is shown and presently preferred, other variations of shapes and styles may be produced using the method of the present invention which will transmit RF energy efficiently while increasing the velocity of propagation and adjusting the impedance. This may be accomplished by changing the amount of blades 34 and their respective widths and the space there between.
  • the spiral cut dielectric core 30, containing the inner conductor 36 is preferably inserted into a flexible outer conductor, such as a convoluted outer conductor 50, such as one preferably composed of a corrugated main conductive member 52 which has been corrugated to produce peaks 54 and valleys 56 in the conductive member 50 at a predetermined pitch, such as the outer conductive member described in the commonly owned U.S. Patent Nos. 3,797,104 and 4.758,685,or a corrugated type conductor in which the flexible outer conductor is manufactured from a seamless or seamed tube.
  • a flexible outer conductor such as a convoluted outer conductor 50, such as one preferably composed of a corrugated main conductive member 52 which has been corrugated to produce peaks 54 and valleys 56 in the conductive member 50 at a predetermined pitch, such as the outer conductive member described in the commonly owned U.S. Patent Nos. 3,797,104 and 4.758,685,or a corrugated type conductor in which the flexible outer
  • a helically wound conductive strip 58 preferably composed of the same conductive material as the main conductive member 52, is preferably helically wound about the main conductive member 52 so as to have the strip wound conductor 58 be helically wound about the peaks 54 of the corrugated main conductive member 52.
  • the conductive strip 58 is preferably secured to these peaks 54, such as by soldering, so as to form a single unitary composite conductive member, such as disclosed in U.S Patent Nos. 3,797,104 and 4,758,685, wherein the peaks 54 are accentuated by the helically wound strip 58 so as to increase the flexibility of the outer conductor 50.
  • the convolutions in the flexible outer conductor 50 are shown as helical, they can be angular instead without departing from the present invention.
  • additional electrical stability may be provided for the resultant flexible coaxial cable 38 by locking the convoluted outer conductor 50 to the inserted spiral cut dielectric core 30, if such additional stability is not needed, such as if a change of 15 degrees in phase were tolerable, then the outer conductor 50 need not be locked to the inserted spiral cut dielectric core 30 and the resultant flexible coaxial cable 38 can still be a fast cable without locking.
  • the convoluted outer conductor 50 is preferably locked to the spiral cut dielectric core 30 by any desired locking method such as, by way of example, the mechnical locking method disclosed in commonly owned U.S. Patent Nos. 3,797,104 and 4,758,685 and illustrated in FIGS.
  • the locked cable 38 is then preferably temperature cycled in a conventional temperature chamber 60 over a temperature range of -60 degrees C to + 150 degrees C for 48 hours, by way of example, to provide temperature stability for the locked cable 38.
  • the outer conductor 50 is preferably mechanically crimped to the inserted spiral cut dielectric core 30 in the manner described in commonly owned U.S. Patent Nos. 3,797,104 and 4,758,685, in accordance with the desired characteristic impedance of the resultant cable 38 such as by using a conventional time domain reflectometer 62 and mechanical crimping means 64, with the crimping points preferably being in the valleys 56 of the outer conductor 50.
  • the mechanical locking may be enhanced by the webs 42 filling additional voids in the interior of the outer conductor 50 between adjacent valleys 56, since the inside diameter of the outer conductor 50 is preferably substantially the same as the outermost outside diameter of the inserted cut dielectric core 30.
  • the outermost diameter d 3 of the spiral cut dielectric core 30 is larger than the inside diameter d 2 of the convoluted outer conductor 50 with the peak-to-peak of the webs 42 preferably being 2/1000-5/1000 larger than the inside diameter d 2 of the outer conductor 50.
  • the spiral cut dielectric core 30 is then threaded into the outer conductor 50, as shown in FIG. 8, or vice versa, which locks the core 30 and the outer conductor 50 together as shown in FIGS. 9 and 10, by way of example, with FIG. 9 illustrating the locking of the core 30 to the outer conductor 50 when both have the same pitch, and with FIG.
  • the user can controllably change not only the shape and pitch of the spiral, but also the quantity of dielectric which is removed. As shown in FIGS. 13-21, this enables control over the velocity of propagation, the impedance, the attenuation, the phase length, and the VSWR of the resultant cable 38. For example, as shown in FIGS. 13-15, if the velocity of propagation of a coaxial cable with a solid dielectric is at 73% (FIG. 14) it can readily be controllably raised to 85% (FIG.
  • FIG. 13 shows the graphs of FIGS. 13 and 14 superimposed on each other.
  • FIGS. 16 and 19 comprise additional impedance traces for a different dielectric core 30 in which FIG 16 illustrates the impedance trace for the solid dielectric starting material 32 before cutting in which the velocity of propagation is at 71% and the resultant impedance is 45.3 ohms, and FIG. 19 illustrates the impedance trace of the resultant cable 38 after the solid dielectric starting material 32 has been controllably cut to produce a spiral cut dielectric core which has a velocity of propagation of 85% and a resultant impedance of 50.1 ohms.
  • FIG. 17 illustrates a VSWR before cutting at 1.333 with the frequency of the highest VSWR at 14.82275 GHz
  • FIG. 18 illustrates an attentuation of 58db/30.48 m (100ft.) or -2.03db at 18GHz before cutting.
  • FIG. 20 illustrates a desired lower VSWR after cutting of 1.2822 with the frequency of the highest VSWR being at 15.89675GHz
  • FIG. 21 illustrates a desired lower attentuation of 47db/30.48 m (100ft) or -1.64db at 18GHz after cutting.
  • the presently preferred method of the present invention allows various electrical parameters of the resultant cable 38, such as impedance, velocity of propagation or phase length, attenuation and VSWR to be determined in advance of manufacture, and to be readily achieved from a solid dielectric starting material 32 by a controlled cutting of this material 32 to any desired shape and configuration to provide a spiral cut dielectric core 30, having an inner conductor 36 which may readily be assembled with a convoluted outer conductor 50 to provide a fast cable which is a stable flexible coaxial cable 38 which may be rendered even more stable by locking the core 30 to the outer conductor 50.
  • Teflon is presntly preferred as the dielectric starting material
  • other dielectric materials such as polyethylene, TFE or FEP can also readily be shaped and cut in accordance with the method of the present invention.
  • portions of the solid dielectric 32 which may be a spline dielectric or an expanded dielectric, may also be cut out in order to introduce more air into the cable 38.
  • a solid dielectric starting material having a bonded center conductor is controllably cut with saw blades to a desired pitch and shaped by varying the cutting angle and the cutting width, the spiral cut dielectric core is then inserted into the convoluted outer conductor and, assuming additional stability is desired, is locked to the outer conductor and the resultant locked cable is temperature cycled to provide temperature stability for the cable.
  • the dielectric constant (Ke) can be lowered, the dielectric losses or attenuation can be lowered, the VSWR can be lowered, the electrical length can be decreased and the velocity of propagation can be increased.
  • a larger center conductor may be employed thereby decreasing conductor losses and attenuation.

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  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Communication Cables (AREA)
EP19920401998 1991-07-09 1992-07-09 Method for making a flexible coaxial cable and resultant cable Expired - Lifetime EP0582013B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US72758991A 1991-07-09 1991-07-09
US727589 1992-07-09

Publications (3)

Publication Number Publication Date
EP0582013A2 EP0582013A2 (en) 1994-02-09
EP0582013A3 EP0582013A3 (enrdf_load_stackoverflow) 1994-04-13
EP0582013B1 true EP0582013B1 (en) 1999-05-12

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EP19920401998 Expired - Lifetime EP0582013B1 (en) 1991-07-09 1992-07-09 Method for making a flexible coaxial cable and resultant cable

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EP (1) EP0582013B1 (enrdf_load_stackoverflow)
DE (1) DE69229172D1 (enrdf_load_stackoverflow)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5674394A (en) * 1995-03-24 1997-10-07 Johnson & Johnson Medical, Inc. Single use system for preparation of autologous plasma
DE102007047741B4 (de) * 2007-10-05 2010-05-12 Kathrein-Werke Kg Mobilfunk-Gruppenantenne

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
NL70908C (enrdf_load_stackoverflow) * 1946-01-18
GB616303A (en) * 1946-05-14 1949-01-19 Telegraph Constr & Main Co Improvements in and relating to electric cables
CH438695A (fr) * 1965-04-20 1967-06-30 Little Inc A Procédé pour former un filet hélicoïdal dans la surface d'un cylindre allongé en matière thermoplastique et appareil pour la mise en oeuvre de ce procédé
DD136780A1 (de) * 1978-02-16 1979-07-25 Reinhold Hennicke Verfahren zur herstellung koaxialer hochfrequenzkabel mit genauem wellenwiderstand
US4758685A (en) * 1986-11-24 1988-07-19 Flexco Microwave, Inc. Flexible coaxial cable and method of making same

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Publication number Publication date
EP0582013A2 (en) 1994-02-09
DE69229172D1 (de) 1999-06-17
EP0582013A3 (enrdf_load_stackoverflow) 1994-04-13

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