US3912850A - High frequency coaxial cable - Google Patents

High frequency coaxial cable Download PDF

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Publication number
US3912850A
US3912850A US40209673A US3912850A US 3912850 A US3912850 A US 3912850A US 40209673 A US40209673 A US 40209673A US 3912850 A US3912850 A US 3912850A
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United States
Prior art keywords
conductor
cable
detent
dielectric
arms
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Expired - Lifetime
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Saverio Thomas Bruno
Norbert Joseph Sladek
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Bunker Ramo Corp
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Bunker Ramo Corp
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Priority to US05402096 priority Critical patent/US3912850A/en
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Publication of US3912850A publication Critical patent/US3912850A/en
Priority claimed from US05/844,323 external-priority patent/USRE30194E/en
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    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01BCABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B11/00Communication cables or conductors
    • H01B11/18Coaxial cables; Analogous cables having more than one inner conductor within a common outer conductor
    • H01B11/1834Construction of the insulation between the conductors
    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01BCABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B11/00Communication cables or conductors
    • H01B11/18Coaxial cables; Analogous cables having more than one inner conductor within a common outer conductor
    • H01B11/1808Construction of the conductors

Abstract

A high frequency coaxial cable exhibiting a low insertion loss and a low reflection coefficient, and incorporating an improved construction providing for convenient adjustment of impedance.

Description

United States Patent Bruno et al.
[4 1 Oct. 14, 1975 [56] References Cited UNITED STATES PATENTS 2,189,091 2/1940 Unterbusch 174/106 R X HIGH FREQUENCY COAXIAL CABLE Inventors: Saverio Thomas Bruno, Danbury;
Norbert Joseph Sladek, Fairfield, both of Conn.
Assignee: Bunker Ramo Corporation, Oak
Brook, 111.
Filed: Oct. 1, 1973 Appl. No.: 402,096
US. Cl. 174/28; 174/102 D; 174/109;
174/126 CP; 333/95 R Int. Cl. HOlb 11/18 Field of Search 174/28, 29, 126 R, 126 CP,
174/128, 129 R, 129 B,130,113,119 R, 119 C, 102 D, 106 D, 106 R, 109; 333/95 R, 95
2,337,556 12/1943 Hosking 174/106 X 2,437,482 3/1948 Salisbury 174/28 X 3,271,506 9/1966 Martin et al. 174/28 3,585,270 6/1971 Trump 174/28 X 3,683,103 8/1972 Manlino 174/1 19 C FOREIGN PATENTS OR APPLICATIONS 43,423 6/1938 Netherlands 174/28 570,379 7/1945 United Kingdom 174/28 356,437 2/1938 Italy 174/106 D 841,517 5/1939 France 174/28 Primary ExaminerArthur T. Grimley Attorney, Agent, or Firm-Norton Lesser; F. M. Arbuckle ABSTRACT A high frequency coaxial cable exhibiting a low insertion loss and a low reflection coefficient, and incorporating an improved construction providing for convenient adjustment of impedance.
8 Claims, 3 Drawing Figures U.S. Patent Oct. 14, 1975 FIGJ HIGH FREQUENCY COAXIAL CABLE BACKGROUND OF THE INVENTION This invention relates generally to coaxial cables and more particularly concerns a coaxial cable with a low reflection coefficient and low insertion loss.
In the transmission of high-frequency signals, particularly in the gigahertz range, the structure of transmission cables is extremely critical. Moreover, such cables are often subject to flexure and other physical shocks which make the physical arrangement of the components even morecritical.
Thus, it is desired to provide a transmission line having low insertion loss and a low reflection coefficient (VSWR), in acable that will provide a stable VSWR and insertion loss under flexure and other shock conditions.
One of the problems constructing such a coaxial cable is meeting required critical electrical tolerances. For example, if it is desired to produce a coaxial cable with a characteristic impedance of fifty ohms plus or minus one ohm, it is often difficult to vary the conductors or dielectric to provide an impedance within that range. Accordingly with the present invention, while producing the cable, routine tests can be run and a detent can be varied slightly to correct the impedance to within the desired range. Thus, a detent can easily be pressed into corrugated outer conductor elements before assembly or an assembled cable without its protective wire mesh braid and plastic outer jacket can be further compressed to provide the desired characteristic impedance. I I
SUMMARY OF THE INVENTION A high frequency coaxial cable constructed in accordance with the invention includes a corrugated outer conductor with spaced interior convolutionspresenting flat inner surfaces, an inner conductor disposed axially within the outer conductor, a dielectric around the innerconductor with axially aligned arms extending to the outer conductor, and inwardly extending detents spaced along the flat inner surfaces of the outer conductor in compressive engagement with the arms of the dielectric member to lock the dielectric member in a desired position and to form a minimum inner diameter of the outer conductor.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a partial sectional view of a coaxial cable comprising one embodiment of the present invention;
FIG. 2 is a sectional view of the cable taken approximately along line 2-2 of FIG. I; and,
FIG. 3 is an enlarged view of an element of the cable, taken as indicated by outline 3-3 in FIG. 1.
DETAILED DESCRIPTION OF THE INVENTION FIG. 1 shows a coaxial cable constructed in accordance with one embodiment of the invention and comprising a corrugated outer conductor with interlock- .ing portions 11 and interior convolutions 12. Interior convolutions 12 have essentially flat inner surfaces which are better seen in FIG. 3. Along each of the inner surfaces is an inwardly extending detent 13, the importance of which will be described later. The interlocking portions 11 of the outer conductor 10 are connected by solder 14. The inside surface of the outer conductor is plated with a high conductivity metal such as silver or gold. The arrows A in FIG. 3 shows essentially where the inner surfaces are silver plated or plated with a high conductivity metal. To provide additional flexural strength, a wire mesh braid 15 and a plastic outer jacket 16 surround the outer conductor 10.
An inner conductor 20 is disposed coaxially within the outer conductor 10. A dielectric member 21 is molded around the inner conductor 20 and includes arms 22, 23 and 24 extending radially outwardly from the inner conductor and pressing against the outer conductor 10. Preferably, the dielectric member 21 is made of polytetrafluorothylene, though other dielectric materials can be used. The space 25 not occupied by 'the dielectric member 21 is filled with air, which also serves as a dielectric.
A feature of the invention is the inwardly extending detent 1 3, which is spaced along the flat inner surface 12 of the outer conductor 10. By varying or selecting the inward projection or radial position of the detent 13, the effective inner diameter of the outer conductor 10 will be varied and, accordingly, the impedance or electrical characteristic of the coaxial cable will be changed or controlled acccordingly.
Thus, as seen in FIGS. 1, 2 and 3, the outer conductor 10 comprises a series of spirally wound adjacent turns with the wall portion of each turn between opposite edges of each turn offset radially inwardly from the opposite edges. The opposite edges of each turn are in folded back overlapping radially spaced relationship with an adjacent portion of each edge for nestingly receiving there-between the edge of the adjacent turn to interlock the adjacent turns. Soldering the interlocked edges and silver plating the inner surfaces of the outer conductor provides a continuous metal or conductive path between turns. The spirally extending detent or detent means 13 is formed along the radially inwardly spaced surface of the outer conductor and it engages the radially outwardly spaced end surface of the axially and radially extending equi-circumferentially spaced arms 22, 23 and 24 of the dielectric member 21.
The outer conductor 10 provides a path which is continuous to RF signals. Preferably the center conductor 20 consists of silver plated stranded wire, though a solid conductor may be used if desired. The airpolytetrafluorothylene construction lowers the dielectric constant and decreases the dielectric losses of the cable.
In order to obtain optimum performance, the diameter of the outer conductor 10 should be consistent and the width of the convolutions should be equal.
The core dielectric member 21 is locked to the outer conductor 10 by means of mechanical compression. This procedure keeps the core and its center conductor 20 from moving relative to the outer conductor 10. This provides excellent alignment even when the cable is subjected to flexure or impact.
The impedance of the cable is controlled by the amount of compression of the outer diameter. The impedance of the coaxial cable is calculated from the equation:
138 DM fi gm ,T
where DM is the mean diameter of the outer conductor inner diameter, ID is the outer diameter of the inner conductor and E is the effective dielectric constant of the core components.
The insertion loss of the cable is computed by the summation of the inner conductor loss, the dielectric loss, and the outer conductor loss. The inner conductor loss and dielectric loss are computed by using standard microwave equations for insertion loss. The outer conductor loss is derived from standard equations, except that the added transmission line length due to the convolutions must be incorporated into the calculations. The cable provides a low reflection coefficient (VSWR), high electrical phase stability under stress, and high consistency in phase tracking. As an example of the low insertion loss, measurements of less than 0.35 dB per foot at 16 GHz, less than O.l4dB per foot at 8 ghz, and less than 0.065 dB per foot at 2 GHz have been recorded for a 50 ohm transmission line.
In production of a coaxial cable in accordance with one embodiment of the invention, the detent in the outer conductor can be formed prior to assembly to conform to calculated standards. An on-line assembly procedure includes, forming a corrugated outer conductor with spaced interior convolutions presenting flat inner surfaces, forming a dielectric core around an inner conductor, the dielectric core having a plurality of axially aligned arms, inserting the inner conductor and dielectric core axially within the outer conductor, and forming a plurality of inwardly extending detents spaced along the flat inner surfaces of the outer conductor to form a minimum inner diameter of said outer conductor.
The detents can be formed while forming the outer conductor or the detents can be added or varied after the inner conductor, outer conductor, and dielectic core are assembled. Thus, after assembly of these three elements, the impedance of the cable can be measured and the projection of the detent can be varied to vary the impedance to the desired range, the cable can then be enclosed in the wire mesh and plastic jacket. When silver plating the inside surface of the outer conductor, this step is preferably done before the assembly of the inner conductor, outer conductor, and dielectric core.
We claim:
1. A high frequency coaxial cable, comprising;
an outer conductor with spaced interior convolutions presenting inner surfaces;
at leastone inner conductor disposed axially within the outer conductor;
a dielectric member around the inner conductor with a plurality of axially aligned arms extending to the outer conductor; and.
at least one inwardly extending detent spaced along the inner surfaces of the outer conductor in compressive engagement with the arms of the dielectric member to lock said member in a desired position with the radial position of said detent selected in accordance with a desired electrical characteristic of said cable to control said electrical characteristic.
2. A cable as in claim 1 wherein said outer conductor is corrugated and said detent extends around the perimeter and axially along said outer conductor surface.
3. A cable as in claim 1 wherein said inner conductor includes a plurality of silver coated strands of wire.
4. A cable as in claim 2 wherein said outer conductor includes interlocked portions and is silver plated on its inner surface.
5. A cable as in claim 2 wherein said corrugated outer connector includes interlocking portions and is soldered at its interlocking portions.
6. A cable as in claim 5 wherein said outer conductor is enclosed by a wire mesh braid and a plastic outer jacket.
7. A coaxial cable for use in transmitting high frequency electrical signals comprising:
at least one inner conductor;
an outer conductor encircling said inner conductor and spaced radially outwardly of said inner conductor;
a dielectric member extending axially of said inner and outer conductors secured to said inner conductor and having a plurality of axially extending circumferentially spaced arms extending radially toward said outer conductor; and
detent means on said outer conductor extending radially inwardly from said outer conductor in movement restraining relationship to said arms for holding said dielectric member and inner conductor against movement relative said outer conductor with the radial position of said detent means located for controlling an electrical characteristic of said cable.
8. The coaxial cable claimed in claim 7 in which said outer conductor is formed in a series of continuous turns having interlocked opposite edges and a wall portion in each turn intermediate said opposite edges is offset radially inwardly of said opposite edges with said detent means being formed in said wall portion for engaging the radially outward end of each of said arms. l l=

Claims (8)

1. A high frequency coaxial cable, comprising; an outer conductor with spaced interior convolutions presenting inner surfaces; at least one inner conductor disposed axially within the outer conductor; a dielectric member around the inner conductor with a plurality of axially aligned arms extending to the outer conductor; and, at least one inwardly extending detent spaced along the inner surfaces of the outer conductor in compressive engagement with the arms of the dielectric member to lock said member in a desired position with the radial position of said detent selected in accordance with a desired electrical characteristic of said cable to control said electrical characteristic.
2. A cable as in claim 1 wherein said outer conductor is corrugated and said detent extends around the perimeter and axially along said outer conductor surface.
3. A cable as in claim 1 wherein said inner conductor includes a plurality of silver coated strands of wire.
4. A cable as in claim 2 wherein said outer conductor includes interlocked portions and is silver plated on its inner surface.
5. A cable as in claim 2 wherein said corrugated outer connector includes interlocking portions and is soldered at its interlocking portions.
6. A cable as in claim 5 wherein said outer conductor is enclosed by a wire mesh braid and a plastic outer jacket.
7. A coaxial cable for use in transmitting high frequency electrical signals comprising: at least one inner conductor; an outer conductor encircling said inner conductor and spaced radially outwardly of said inner conductor; a dielectric member extending axially of said inner and outer conductors secured to said inner conductor and having a plurality of axially extending circumferentially spaced arms extending radially toward said outer conductor; and detent means on said outer conductor extending radially inwardly from said outer conductor in movement restraining relationship to said arms for holding said dielectric member and inner conductor against movement relative said outer conductor with the radial position of said detent means located for controlling an electrical characteristic of said cable.
8. The coaxial cable claimed in claim 7 in which said ouTer conductor is formed in a series of continuous turns having interlocked opposite edges and a wall portion in each turn intermediate said opposite edges is offset radially inwardly of said opposite edges with said detent means being formed in said wall portion for engaging the radially outward end of each of said arms.
US05402096 1973-10-01 1973-10-01 High frequency coaxial cable Expired - Lifetime US3912850A (en)

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Application Number Priority Date Filing Date Title
US05402096 US3912850A (en) 1973-10-01 1973-10-01 High frequency coaxial cable

Applications Claiming Priority (11)

Application Number Priority Date Filing Date Title
US05402096 US3912850A (en) 1973-10-01 1973-10-01 High frequency coaxial cable
SE7411909A SE405427B (en) 1973-10-01 1974-09-23 HIGH FREQUENCY COAXIAL CABLE INCLUDING A CORRUGATED EXTERNAL LEADER AND PROCEDURE FOR ITS PRODUCTION
DE19742445565 DE2445565A1 (en) 1973-10-01 1974-09-24 HIGH FREQUENCY COAXIAL CABLE AND METHOD OF ITS MANUFACTURE
IT2780374A IT1022389B (en) 1973-10-01 1974-09-27 High frequency coaxial cable
JP49112667A JPS5077888A (en) 1973-10-01 1974-09-30
CA210,374A CA1015417A (en) 1973-10-01 1974-09-30 High frequency coaxial cable
FR7432940A FR2246948A1 (en) 1973-10-01 1974-09-30
NL7412874A NL7412874A (en) 1973-10-01 1974-09-30 High frequency coaxial cable.
GB4256974A GB1487755A (en) 1973-10-01 1974-10-01 High frequency coaxial cable
CH1322174A CH589919A5 (en) 1973-10-01 1974-10-01
US05/844,323 USRE30194E (en) 1973-10-01 1977-10-11 High frequency coaxial cable

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US05/844,323 Reissue USRE30194E (en) 1973-10-01 1977-10-11 High frequency coaxial cable

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US3912850A true US3912850A (en) 1975-10-14

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JP (1) JPS5077888A (en)
CA (1) CA1015417A (en)
CH (1) CH589919A5 (en)
DE (1) DE2445565A1 (en)
FR (1) FR2246948A1 (en)
GB (1) GB1487755A (en)
IT (1) IT1022389B (en)
NL (1) NL7412874A (en)
SE (1) SE405427B (en)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5451718A (en) * 1993-04-08 1995-09-19 Southwire Company Mechanically bonded metal sheath for power cable
US6180877B1 (en) * 1996-09-09 2001-01-30 Thomson-Csf Communications Electrical conductor protected against electromagnetic interference exceeding a threshold
WO2004013870A1 (en) * 2002-08-06 2004-02-12 Ube-Nitto Kasei Co., Ltd. Thin-diameter coaxial cable and method of producing the same
US20140299348A1 (en) * 2013-04-08 2014-10-09 Nexans Data transmission cable intended for the aeronautical industry

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2428895B1 (en) * 1978-06-13 1981-08-07 Fileca
FR2747832B1 (en) * 1996-04-23 1998-05-22 Filotex Sa METHOD AND DEVICE FOR MANUFACTURING A VENTILATED SHEATH IN AN INSULATING MATERIAL AROUND A CONDUCTOR, AND COAXIAL CABLE EQUIPPED WITH SUCH SHEATH
JP2006108030A (en) * 2004-10-08 2006-04-20 Mitsubishi Cable Ind Ltd Coaxial cable

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2189091A (en) * 1935-12-02 1940-02-06 Felten & Guilleaume Carlswerk Flexible high frequency cable
US2337556A (en) * 1939-02-03 1943-12-28 Composite Rubber Products Corp Cable
US2437482A (en) * 1942-12-07 1948-03-09 Nasa High-frequency electrical transmission line
US3271506A (en) * 1964-03-25 1966-09-06 Siemens Ag Coaxial high-frequency cable with internal spacers
US3585270A (en) * 1968-07-31 1971-06-15 John George Trump Gas-insulated transmission line
US3683103A (en) * 1971-07-07 1972-08-08 J & J Equity Co Multi-strand electrical conductor

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2189091A (en) * 1935-12-02 1940-02-06 Felten & Guilleaume Carlswerk Flexible high frequency cable
US2337556A (en) * 1939-02-03 1943-12-28 Composite Rubber Products Corp Cable
US2437482A (en) * 1942-12-07 1948-03-09 Nasa High-frequency electrical transmission line
US3271506A (en) * 1964-03-25 1966-09-06 Siemens Ag Coaxial high-frequency cable with internal spacers
US3585270A (en) * 1968-07-31 1971-06-15 John George Trump Gas-insulated transmission line
US3683103A (en) * 1971-07-07 1972-08-08 J & J Equity Co Multi-strand electrical conductor

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5451718A (en) * 1993-04-08 1995-09-19 Southwire Company Mechanically bonded metal sheath for power cable
US6180877B1 (en) * 1996-09-09 2001-01-30 Thomson-Csf Communications Electrical conductor protected against electromagnetic interference exceeding a threshold
WO2004013870A1 (en) * 2002-08-06 2004-02-12 Ube-Nitto Kasei Co., Ltd. Thin-diameter coaxial cable and method of producing the same
US20050230145A1 (en) * 2002-08-06 2005-10-20 Toku Ishii Thin-diameter coaxial cable and method of producing the same
US20140299348A1 (en) * 2013-04-08 2014-10-09 Nexans Data transmission cable intended for the aeronautical industry

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Publication number Publication date
CH589919A5 (en) 1977-07-29
NL7412874A (en) 1975-04-03
CA1015417A1 (en)
JPS5077888A (en) 1975-06-25
SE405427B (en) 1978-12-04
GB1487755A (en) 1977-10-05
FR2246948A1 (en) 1975-05-02
IT1022389B (en) 1978-03-20
SE7411909L (en) 1975-04-02
CA1015417A (en) 1977-08-09
DE2445565A1 (en) 1975-04-10

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