EP1119079A1 - Coaxial cable and process and apparatus for forming - Google Patents
Coaxial cable and process and apparatus for forming Download PDFInfo
- Publication number
- EP1119079A1 EP1119079A1 EP00308800A EP00308800A EP1119079A1 EP 1119079 A1 EP1119079 A1 EP 1119079A1 EP 00308800 A EP00308800 A EP 00308800A EP 00308800 A EP00308800 A EP 00308800A EP 1119079 A1 EP1119079 A1 EP 1119079A1
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- EP
- European Patent Office
- Prior art keywords
- dielectric
- outer conductor
- cable
- bead
- 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.)
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Classifications
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01R—ELECTRICALLY-CONDUCTIVE CONNECTIONS; STRUCTURAL ASSOCIATIONS OF A PLURALITY OF MUTUALLY-INSULATED ELECTRICAL CONNECTING ELEMENTS; COUPLING DEVICES; CURRENT COLLECTORS
- H01R24/00—Two-part coupling devices, or either of their cooperating parts, characterised by their overall structure
- H01R24/38—Two-part coupling devices, or either of their cooperating parts, characterised by their overall structure having concentrically or coaxially arranged contacts
- H01R24/40—Two-part coupling devices, or either of their cooperating parts, characterised by their overall structure having concentrically or coaxially arranged contacts specially adapted for high frequency
- H01R24/42—Two-part coupling devices, or either of their cooperating parts, characterised by their overall structure having concentrically or coaxially arranged contacts specially adapted for high frequency comprising impedance matching means or electrical components, e.g. filters or switches
- H01R24/44—Two-part coupling devices, or either of their cooperating parts, characterised by their overall structure having concentrically or coaxially arranged contacts specially adapted for high frequency comprising impedance matching means or electrical components, e.g. filters or switches comprising impedance matching means
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01R—ELECTRICALLY-CONDUCTIVE CONNECTIONS; STRUCTURAL ASSOCIATIONS OF A PLURALITY OF MUTUALLY-INSULATED ELECTRICAL CONNECTING ELEMENTS; COUPLING DEVICES; CURRENT COLLECTORS
- H01R2103/00—Two poles
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01R—ELECTRICALLY-CONDUCTIVE CONNECTIONS; STRUCTURAL ASSOCIATIONS OF A PLURALITY OF MUTUALLY-INSULATED ELECTRICAL CONNECTING ELEMENTS; COUPLING DEVICES; CURRENT COLLECTORS
- H01R43/00—Apparatus or processes specially adapted for manufacturing, assembling, maintaining, or repairing of line connectors or current collectors or for joining electric conductors
- H01R43/28—Apparatus or processes specially adapted for manufacturing, assembling, maintaining, or repairing of line connectors or current collectors or for joining electric conductors for wire processing before connecting to contact members, not provided for in groups H01R43/02 - H01R43/26
Definitions
- the invention relates to a method of forming the ends of a coaxial cable, and especially to a method of securing together the ends of the outer conducting layer and the inner dielectric layer.
- a coaxial cable consists essentially of a center conductor, typically metal wire, a dielectric spacer, an outer conductor, typically of metal braid, and a protective jacket.
- the dielectric spacer may be made of unsintered or partially sintered polytetrafluoroethylene (PTFE).
- PTFE polytetrafluoroethylene
- the PTFE is commonly either extruded onto the center conductor or in the form of a tape wrapped around the center conductor, typically in 3 to 10 layers wrapped helically. All such unsintered or partially sintered PTFE dielectrics will be referred to hereinafter as "expanded PTFE" (ePTFE).
- the present invention proposes to sinter the different PTFE layers together at the end of the cable, so that they cannot move relative to one another, and to form the outer layer with a bead that engages the end of the metal braid, so that the PTFE cannot recede inside the braid.
- a method of forming an end of a coaxial cable comprising center and outer conductors separated by a dielectric.
- the dielectric is exposed beyond the end of the outer conductor.
- the exposed dielectric is compressed axially, while confining it radially.
- the dielectric is permitted to expand radially at a region adjacent to the end of the outer conductor so as to form a bead having an external diameter greater than the internal diameter of the outer conductor.
- a coaxial cable comprising center and outer conductors separated by a dielectric, wherein at least one end of the dielectric projects lengthwise beyond the corresponding end of the outer conductor and is formed with an encircling bead that projects radially adjacent the end of the outer conductor sufficiently to prevent the dielectric receding within the outer conductor.
- the step of permitting the dielectric to expand may comprise defining a gap between two axially-separated components and permitting the dielectric to expand into the said gap.
- the width of the gap may be determined by a spacer, and the bead is then preferably formed radially inside the spacer, with free space remaining between the formed bead and the spacer.
- One of the two said axially-separated components may be the outer conductor of the cable, and one of them may be a member that confines the exposed dielectric radially. The latter member may be a heated tool if the dielectric is thermoplastic.
- apparatus for shaping an end of a coaxial cable comprising: a shroud of refractory material dimensioned to fit over the outer conductor of the cable, and having at one end a spacer lip dimensioned to abut the end of the outer conductor while defining a radial clearance from the outer surface of the dielectric of the cable; and a heated tool having a blind bore dimensioned to fit snugly over the dielectric of the cable and dimensioned to abut the spacer lip of the shroud.
- the dielectric may be thermoplastic, especially PTFE, and may be heated sufficiently to soften it. If the dielectric is wound from tape or otherwise formed in layers, it is preferably heated sufficiently to fuse the layers in the exposed dielectric into a solid mass.
- the bead may be shaped after it is formed to reduce the effect of any change in impedance at the transition between fused and unfused layers of the dielectric.
- the effect of the transition with the shaped bead is less than, and is preferably no greater than half, the effect of a similar transition in impedance with no bead at all.
- Figure 1 is a side view, partly in section, of a cable, shroud, and sintering head ready for forming of one end of the cable.
- Figure 2 is a view similar to Figure 1, showing the shroud in position on the cable.
- Figure 3 is a view similar to Figure 2, showing the sintering head engaging the end of the cable.
- Figure 4A is a view similar to Figure 3, showing a later stage of the forming process
- Figure 4B is an enlarged view of the detail within the circle marked "Fig. 4B" in Figure 4A.
- Figure 5A is a view similar to Figure 4A, showing a final stage of the forming process.
- Figure 5B is an enlarged view of the detail within the circle marked "Fig. 5B" in Figure 5A.
- Figure 6A is a view similar to Figure 5A, showing the formed cable removed from the sintering head.
- Figure 6B is an enlarged view of the detail within the circle marked "Fig. 6B" in Figure 6A.
- Figure 7 is a view in longitudinal section of a coaxial cable connector fitted onto a cable formed as shown in Figures 1 to 6.
- Figure 8 is an enlarged view of the detail within the circle marked "Fig. 8" in Figure 7.
- the cable 10 consists essentially of a center conductor 12 of metal wire, a dielectric spacer 14 of several layers of helically wound or extruded ePTFE tape, an outer conductor 16 of metal braid, and a protective jacket 18.
- each layer is cut back to provide a clean end square to the length of the cable, and to expose a length of the layer within it.
- the braid 16 is stripped back to expose a substantial length of the ePTFE.
- a ceramic shroud indicated generally by the reference numeral 20 is slid over the prepared end of the cable 10.
- the main body of the shroud 20 consists of a cylindrical tube 22 that fits easily over the exposed braid 16.
- a shoulder 24 that fits more closely over the exposed braid 16, to ensure accurate centering of the shroud on the cable.
- a lip 26 that extends radially inward far enough to overlap the braid 16.
- the lip 26 does not extend far enough to contact the exposed dielectric 14, but rather leaves a substantial radial gap 28.
- the radial width of the gap 28 is normally at least 2% of the diameter of the braid 16.
- the shroud 20 is positioned so that the lip 28 abuts the cut end of the braid 16.
- a sintering head indicated generally by the reference numeral 30, consists largely of a cylindrical block of titanium with a heating element (not shown).
- the sintering head 30 has in one end a blind bore 32 that is of a suitable diameter to fit snugly over the exposed dielectric 14 of the cable 10. The depth of the bore 32 is approximately half the exposed length of the dielectric 14.
- the sintering head 30 also has an axial through bore 34, sufficiently wide to receive the center conductor 12 of the cable 10.
- a firing pin 36 is received in a radial bore in the sintering head 30, and can be advanced to a position where it clamps the center conductor 12, if the conductor is present in the bore 34.
- the sintering head 30 is preheated to a temperature of at least 375 °C (700 °F), and not more than 540 °C (1000 °F). As shown in Figure 3, the sintering head 30 is initially placed on the end of the cable 10 so that the cut end of the dielectric 14 abuts the bottom of the blind bore 32, and the tip of the center conductor 12 fits into the through bore 34.
- the sintering head 30 is then forced onto the end of the cable 10, compressing the dielectric 14.
- the cable 10 is gripped by at least one cable grip 35, which is set back at least 7 mm (0.25") from the exposed braid 16.
- the braid 16 fits over the dielectric 14 with sufficient tension to prevent the dielectric from being forced into the braid by the sintering head 30.
- the sintering head is advanced until it contacts the lip 26 of the shroud 20, as shown in Figure 4B.
- the gap 28 is now a closed, annular space, axially between the braid 16 and the sintering head 30, and radially between the dielectric 14 and the lip 26.
- the sintering head 30 is then clamped in place by tightening the firing pin 36 onto the center conductor 12. This also ensures good thermal contact between the sintering head 30 and the center conductor 12.
- the ePTFE forms a continuous mass 42.
- the ePTFE expands, filling the interior of the blind bore 34 within the sintering head. As the ePTFE presses against the surface of the blind bore, good heat transfer is ensured.
- the ePTFE then flows into the gap 28 to form a bead 40, shown in Figure 5B.
- the time for which the sintering head is left heated on the cable depends on the cable type, but is typically between 20 seconds and 3 minutes.
- the bead 28 does not fill the gap 28, but an air space is left outside it. This permits solder to flow completely around the circumference of the braid, so that a good solder fill can be obtained.
- the heat also erases any memory of previous shapes from the PTFE, ensuring that the bead will be permanent.
- the whole assembly is then allowed to cool, and the titanium sintering head 30 and the ceramic shroud 20 are then removed from the cable.
- the sintered PTFE mass 42 shrinks, but the bead 40 is still large enough to lock on the end of the braid.
- the braid is not embedded within the sintered PTFE, but the bead is too wide to slip inside the braid.
- the bead 40 may be shaped, as shown in Figure 6B, by providing a bevel 44 on the lip of the bore 32 in the sintering head 30, as shown in Figure 6A.
- the sintering of the ePTFE does, of course, alter the dielectric constant.
- dielectric constant there is a fairly sudden change in dielectric constant between the sintered ePTFE 42 of the endpiece and the only partially sintered ePTFE 14 within the braid 16. That change occurs approximately at the level of the bead 40, and can be compensated for by shaping the bead and/or by shaping the inside of a metal cable connector where it fits over the bead.
- the transition between partially-sintered and unsintered ePTFE 14 within the braid 16 is sufficiently gradual not to cause a serious effect on microwave transmission.
- the sintered ePTFE 42 of the endpiece may also be shaped for optimal fitting, both mechanical and electrical, into a connector.
- a conventional coaxial cable connector is shown mounted on the end of the cable 10.
- a sleeve 52 of the connector 50 is mounted on the cable 10, covering the exposed portion of the braid 16 and the end of the jacket 18.
- the sleeve 52 is secured mechanically and electrically to the braid 16 by soldering.
- a collar 54, with an external screw thread, is captive behind a shoulder 56 on the sleeve 52.
- a metal connector pin 58 fits over the exposed end of the center conductor 12 of the cable 10, and forms the center pin of the connector 50.
- the pin 58 is captive behind a shoulder on an insulating sleeve 60, which is captive behind a shoulder on an internally screw-threaded sleeve 62, which is screwed onto the collar 54.
- An internally screw-threaded collar 64 which forms the outer connection component of the connector 50, is held captive, but free to rotate, on the sleeve 62 by means of a spring ring 64.
- the bead 40 and therefore the transition from sintered dielectric 42 to only partially sintered dielectric 14, is aligned with the transition between the braid 16 and the connector sleeve 52.
- the bead 40 is machined to a profile that compensates for the transitions in the other components, so as to afford as nearly as possible an unimpeded propagation of the microwave signals along the cable 10 and through the connector 50.
Abstract
A method of forming an end of a coaxial cable to prevent the dielectric from
receding within the outer conductor is disclosed, together with a cable formed by the
method and an apparatus for carrying the method out. The cable comprises a central
wire conductor (12), a dielectric (14) formed of several layers of PTFE tape, and an
outer conductor (16) of metal braid. The outer conductor is cut away to expose a
substantial length of the dielectric. A shroud (20) is slid over the outer conductor. The
shroud carries a spacer lip (26) that abuts the end of the outer conductor, while leaving
a gap (28) between the lip and the exposed dielectric. The end of the cable is then
inserted into a blind bore (32) in a heated tool (30). The blind bore fits snugly around
the exposed dielectric, but is appreciably shorter. The tool is forced onto the cable,
compressing the dielectric, until the tool meets the spacer lip. The heat of the tool fuses
the layers of the PTFE together, and allows the PTFE to flow, forming a bead (40) in the
gap inside the spacer lip. The bead engages the end of the outer conductor, preventing
the dielectric from receding within the conductor.
Description
- The invention relates to a method of forming the ends of a coaxial cable, and especially to a method of securing together the ends of the outer conducting layer and the inner dielectric layer.
- A coaxial cable consists essentially of a center conductor, typically metal wire, a dielectric spacer, an outer conductor, typically of metal braid, and a protective jacket. The dielectric spacer may be made of unsintered or partially sintered polytetrafluoroethylene (PTFE). The PTFE is commonly either extruded onto the center conductor or in the form of a tape wrapped around the center conductor, typically in 3 to 10 layers wrapped helically. All such unsintered or partially sintered PTFE dielectrics will be referred to hereinafter as "expanded PTFE" (ePTFE).
- For many applications, flexible high performance microwave cables are required to operate through large temperature extremes, particularly in spaceflight. Because of power, multipaction, return loss (impedance mismatch), and phase matching concerns, it is important that cable and connector component locations remain stable and unchanged relative to each other. Any change in dimensions or dielectric constant can severely impact the microwave properties of the cable assembly. Due to the variety of materials used to manufacture these cable assemblies, it was impossible to guarantee no movement of the various layers of materials within the cable under extreme temperature changes. The movement primarily results from the large difference between the coefficients of thermal expansion of the ePTFE dielectric and the metallic conductors. With coaxial cable manufactured using ePTFE tape as the dielectric, in particular, there is a tendency for the dielectric to recede at the cable ends under repeated cycles of high and low temperature. The result is a gap between the dielectric of the cable and a dielectric block forming part of a connector on the end of the cable. The sudden change in dielectric constant at the ends of the gap severely disrupts microwave transmission along the cable.
- To prevent this potentially catastrophic problem, the dielectric must be mechanically captivated to the rest of the cable. Until now, there has been no simple method to do this without severe degradation of the high frequency electrical performance. The present invention proposes to sinter the different PTFE layers together at the end of the cable, so that they cannot move relative to one another, and to form the outer layer with a bead that engages the end of the metal braid, so that the PTFE cannot recede inside the braid.
- According to one aspect of the invention, there is provided a method of forming an end of a coaxial cable. The cable comprises center and outer conductors separated by a dielectric. The dielectric is exposed beyond the end of the outer conductor. The exposed dielectric is compressed axially, while confining it radially. The dielectric is permitted to expand radially at a region adjacent to the end of the outer conductor so as to form a bead having an external diameter greater than the internal diameter of the outer conductor.
- According to another aspect of the invention, there is provided a coaxial cable comprising center and outer conductors separated by a dielectric, wherein at least one end of the dielectric projects lengthwise beyond the corresponding end of the outer conductor and is formed with an encircling bead that projects radially adjacent the end of the outer conductor sufficiently to prevent the dielectric receding within the outer conductor.
- The step of permitting the dielectric to expand may comprise defining a gap between two axially-separated components and permitting the dielectric to expand into the said gap. The width of the gap may be determined by a spacer, and the bead is then preferably formed radially inside the spacer, with free space remaining between the formed bead and the spacer. One of the two said axially-separated components may be the outer conductor of the cable, and one of them may be a member that confines the exposed dielectric radially. The latter member may be a heated tool if the dielectric is thermoplastic.
- According to a further aspect of the invention, there is provided apparatus for shaping an end of a coaxial cable, comprising: a shroud of refractory material dimensioned to fit over the outer conductor of the cable, and having at one end a spacer lip dimensioned to abut the end of the outer conductor while defining a radial clearance from the outer surface of the dielectric of the cable; and a heated tool having a blind bore dimensioned to fit snugly over the dielectric of the cable and dimensioned to abut the spacer lip of the shroud.
- The dielectric may be thermoplastic, especially PTFE, and may be heated sufficiently to soften it. If the dielectric is wound from tape or otherwise formed in layers, it is preferably heated sufficiently to fuse the layers in the exposed dielectric into a solid mass.
- The bead may be shaped after it is formed to reduce the effect of any change in impedance at the transition between fused and unfused layers of the dielectric. Preferably, the effect of the transition with the shaped bead is less than, and is preferably no greater than half, the effect of a similar transition in impedance with no bead at all.
- Figure 1 is a side view, partly in section, of a cable, shroud, and sintering head ready for forming of one end of the cable.
- Figure 2 is a view similar to Figure 1, showing the shroud in position on the cable.
- Figure 3 is a view similar to Figure 2, showing the sintering head engaging the end of the cable.
- Figure 4A is a view similar to Figure 3, showing a later stage of the forming process
- Figure 4B is an enlarged view of the detail within the circle marked "Fig. 4B" in Figure 4A.
- Figure 5A is a view similar to Figure 4A, showing a final stage of the forming process.
- Figure 5B is an enlarged view of the detail within the circle marked "Fig. 5B" in Figure 5A.
- Figure 6A is a view similar to Figure 5A, showing the formed cable removed from the sintering head.
- Figure 6B is an enlarged view of the detail within the circle marked "Fig. 6B" in Figure 6A.
- Figure 7 is a view in longitudinal section of a coaxial cable connector fitted onto a cable formed as shown in Figures 1 to 6.
- Figure 8 is an enlarged view of the detail within the circle marked "Fig. 8" in Figure 7.
- Referring to the accompanying drawings, and initially to Figure 1, one form of coaxial cable for the transmission of microwave signals is indicated generally by the
reference numeral 10. Thecable 10 consists essentially of acenter conductor 12 of metal wire, adielectric spacer 14 of several layers of helically wound or extruded ePTFE tape, anouter conductor 16 of metal braid, and aprotective jacket 18. In a first step of the forming process according to the invention, each layer is cut back to provide a clean end square to the length of the cable, and to expose a length of the layer within it. In particular, thebraid 16 is stripped back to expose a substantial length of the ePTFE. - Referring now also to Figure 2, in a second step of the process a ceramic shroud indicated generally by the
reference numeral 20 is slid over the prepared end of thecable 10. As is shown in Figure 2, the main body of theshroud 20 consists of acylindrical tube 22 that fits easily over the exposedbraid 16. As is shown in more detail in Figure 4B, at the trailing end of the shroud is ashoulder 24 that fits more closely over the exposedbraid 16, to ensure accurate centering of the shroud on the cable. Beyond theshoulder 24 is alip 26 that extends radially inward far enough to overlap thebraid 16. Thelip 26 does not extend far enough to contact the exposed dielectric 14, but rather leaves a substantialradial gap 28. The radial width of thegap 28 is normally at least 2% of the diameter of thebraid 16. Theshroud 20 is positioned so that thelip 28 abuts the cut end of thebraid 16. - Referring now also to Fig. 3, a sintering head, indicated generally by the
reference numeral 30, consists largely of a cylindrical block of titanium with a heating element (not shown). The sinteringhead 30 has in one end ablind bore 32 that is of a suitable diameter to fit snugly over the exposed dielectric 14 of thecable 10. The depth of thebore 32 is approximately half the exposed length of the dielectric 14. The sinteringhead 30 also has an axial throughbore 34, sufficiently wide to receive thecenter conductor 12 of thecable 10. Afiring pin 36 is received in a radial bore in thesintering head 30, and can be advanced to a position where it clamps thecenter conductor 12, if the conductor is present in thebore 34. Thesintering head 30 is preheated to a temperature of at least 375 °C (700 °F), and not more than 540 °C (1000 °F). As shown in Figure 3, thesintering head 30 is initially placed on the end of thecable 10 so that the cut end of the dielectric 14 abuts the bottom of the blind bore 32, and the tip of thecenter conductor 12 fits into the throughbore 34. - Referring now to Figure 4A, the
sintering head 30 is then forced onto the end of thecable 10, compressing the dielectric 14. During this step thecable 10 is gripped by at least one cable grip 35, which is set back at least 7 mm (0.25") from the exposedbraid 16. Thebraid 16 fits over the dielectric 14 with sufficient tension to prevent the dielectric from being forced into the braid by thesintering head 30. The sintering head is advanced until it contacts thelip 26 of theshroud 20, as shown in Figure 4B. Thegap 28 is now a closed, annular space, axially between thebraid 16 and thesintering head 30, and radially between the dielectric 14 and thelip 26. - As shown in Figure 5A, the
sintering head 30 is then clamped in place by tightening thefiring pin 36 onto thecenter conductor 12. This also ensures good thermal contact between the sinteringhead 30 and thecenter conductor 12. Within the heated sintering head, the ePTFE forms acontinuous mass 42. The ePTFE expands, filling the interior of the blind bore 34 within the sintering head. As the ePTFE presses against the surface of the blind bore, good heat transfer is ensured. The ePTFE then flows into thegap 28 to form abead 40, shown in Figure 5B. The time for which the sintering head is left heated on the cable depends on the cable type, but is typically between 20 seconds and 3 minutes. As is shown in Figure 5B, thebead 28 does not fill thegap 28, but an air space is left outside it. This permits solder to flow completely around the circumference of the braid, so that a good solder fill can be obtained. The heat also erases any memory of previous shapes from the PTFE, ensuring that the bead will be permanent. - The whole assembly is then allowed to cool, and the
titanium sintering head 30 and theceramic shroud 20 are then removed from the cable. As is shown in Figure 6A, the sinteredPTFE mass 42 shrinks, but thebead 40 is still large enough to lock on the end of the braid. The braid is not embedded within the sintered PTFE, but the bead is too wide to slip inside the braid. Thebead 40 may be shaped, as shown in Figure 6B, by providing a bevel 44 on the lip of thebore 32 in thesintering head 30, as shown in Figure 6A. - The sintering of the ePTFE does, of course, alter the dielectric constant. In particular, there is a fairly sudden change in dielectric constant between the
sintered ePTFE 42 of the endpiece and the only partially sinteredePTFE 14 within thebraid 16. That change occurs approximately at the level of thebead 40, and can be compensated for by shaping the bead and/or by shaping the inside of a metal cable connector where it fits over the bead. The transition between partially-sintered andunsintered ePTFE 14 within thebraid 16 is sufficiently gradual not to cause a serious effect on microwave transmission. The sinteredePTFE 42 of the endpiece may also be shaped for optimal fitting, both mechanical and electrical, into a connector. - Referring now to Figures 7 and 8, a conventional coaxial cable connector, indicated generally by the reference numeral 50, is shown mounted on the end of the
cable 10. Asleeve 52 of the connector 50 is mounted on thecable 10, covering the exposed portion of thebraid 16 and the end of thejacket 18. Thesleeve 52 is secured mechanically and electrically to thebraid 16 by soldering. Acollar 54, with an external screw thread, is captive behind ashoulder 56 on thesleeve 52. Ametal connector pin 58 fits over the exposed end of thecenter conductor 12 of thecable 10, and forms the center pin of the connector 50. Thepin 58 is captive behind a shoulder on an insulatingsleeve 60, which is captive behind a shoulder on an internally screw-threadedsleeve 62, which is screwed onto thecollar 54. An internally screw-threadedcollar 64, which forms the outer connection component of the connector 50, is held captive, but free to rotate, on thesleeve 62 by means of aspring ring 64. - As may be seen from Figure 7, the
bead 40, and therefore the transition from sintered dielectric 42 to only partially sintered dielectric 14, is aligned with the transition between thebraid 16 and theconnector sleeve 52. As is shown in Figure 8, thebead 40 is machined to a profile that compensates for the transitions in the other components, so as to afford as nearly as possible an unimpeded propagation of the microwave signals along thecable 10 and through the connector 50. - Although the invention has been described with reference to an exemplary embodiment thereof, it will be understood by those skilled in the art that various changes, omissions, and additions may be made thereto without departing from the spirit and scope of the invention as recited in the attached claims.
Claims (17)
- A method of forming an end of a coaxial cable, comprising the steps of:providing a coaxial cable comprising center and outer conductors separated by a dielectric, with the dielectric exposed beyond the end of the outer conductor;compressing the exposed dielectric axially, while confining it radially; andpermitting the dielectric to expand radially at a region adjacent to the end of the outer conductor so as to form a bead having an external diameter greater than the internal diameter of the outer conductor.
- A method according to claim 1, wherein the step of permitting the dielectric to expand comprises defining a gap between two axially-separated components and permitting the dielectric to expand into the said gap.
- A method according to claim 2, wherein the width of the gap is determined by a spacer, and the bead is formed radially inside the spacer, with free space remaining between the formed bead and the spacer.
- A method according to claim 2 or 3, wherein one of the two said components is the outer conductor of the cable.
- A method according to claim 2, 3 or 4, wherein one of the two said components is a member that confines the exposed dielectric radially.
- A method according to any one of claims 1 to 5, wherein the dielectric is thermoplastic, and which comprises heating the dielectric sufficiently to soften it.
- A method according to claim 6, wherein the dielectric comprises PTFE.
- A method according to claim 6 or 7, wherein the dielectric is formed in layers, and which comprises heating the dielectric sufficiently to fuse the layers in the exposed dielectric into a solid mass.
- A method according to claim 8, which comprises shaping the bead to reduce the effect of any change in impedance at the transition between fused and unfused layers of the dielectric.
- A method according to any one of claims 6 to 9, which comprises inserting the exposed dielectric into a blind bore in a heated tool, the walls of which bore serve both to compress the dielectric axially and to confine it radially.
- A coaxial cable comprising center and outer conductors separated by a dielectric, wherein at least one end of the dielectric projects axially beyond the corresponding end of the outer conductor and is formed with an encircling bead that projects radially adjacent the end of the outer conductor sufficiently to prevent the dielectric receding within the outer conductor.
- A coaxial cable according to claim 11, wherein the bead has been formed by plastic flow of the dielectric.
- A coaxial cable according to claim 12, wherein the dielectric is thermoplastic and the bead has been formed by hot flow of the dielectric while heated sufficiently to soften it.
- A coaxial cable according to claim 13, wherein the dielectric is PTFE.
- A coaxial cable according to claim 13 or 14, wherein the dielectric is formed of layers, and the layers are fused together where the dielectric projects beyond the end of the outer conductor.
- A coaxial cable according to claim 15, wherein the bead is shaped to reduce the effect of any change in impedance at the transition between fused and unfused layers of the dielectric.
- Apparatus for shaping an end of a coaxial cable, comprising:a shroud of refractory material dimensioned to fit over the outer conductor of the cable, and having at one end a spacer lip dimensioned to abut the end of the outer conductor while defining a radial clearance from the outer surface of the dielectric of the cable; anda heated tool having a blind bore dimensioned to fit snugly over the dielectric of the cable and dimensioned to abut the spacer lip of the shroud.
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US48753900A | 2000-01-19 | 2000-01-19 | |
US487539 | 2000-01-19 |
Publications (1)
Publication Number | Publication Date |
---|---|
EP1119079A1 true EP1119079A1 (en) | 2001-07-25 |
Family
ID=23936142
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP00308800A Withdrawn EP1119079A1 (en) | 2000-01-19 | 2000-10-05 | Coaxial cable and process and apparatus for forming |
Country Status (3)
Country | Link |
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EP (1) | EP1119079A1 (en) |
JP (1) | JP2001238323A (en) |
CA (1) | CA2325208A1 (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US8800135B2 (en) * | 2006-06-27 | 2014-08-12 | Scientific-Atlanta, Inc. | Stinger cutting guide |
Families Citing this family (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN113488297B (en) * | 2021-07-08 | 2022-10-04 | 萍乡强盛电瓷制造有限公司 | High-strength suspension type porcelain insulator and processing method thereof |
Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3437960A (en) * | 1966-03-30 | 1969-04-08 | Amp Inc | Dielectric bead structure for coaxial connectors |
-
2000
- 2000-10-05 EP EP00308800A patent/EP1119079A1/en not_active Withdrawn
- 2000-11-02 CA CA002325208A patent/CA2325208A1/en not_active Abandoned
-
2001
- 2001-01-18 JP JP2001010879A patent/JP2001238323A/en active Pending
Patent Citations (1)
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US3437960A (en) * | 1966-03-30 | 1969-04-08 | Amp Inc | Dielectric bead structure for coaxial connectors |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US8800135B2 (en) * | 2006-06-27 | 2014-08-12 | Scientific-Atlanta, Inc. | Stinger cutting guide |
Also Published As
Publication number | Publication date |
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CA2325208A1 (en) | 2001-07-19 |
JP2001238323A (en) | 2001-08-31 |
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