Combination cable capable of simultaneous transmission of electrical signals in the radio and microwave frequency range and optical communication signals

• US 5,574,815 A
• Filed: 01/28/1991
• Issued: 11/12/1996
• Est. Priority Date: 01/28/1991
• Status: Expired due to Fees

• Current Assignee: Foster C. Kneeland
• Original Assignee: Foster C. Kneeland
• Inventors: Kneeland, Foster C.
• Primary Examiner(s): Lee, John D.
• Application Number:
  US07/646,229
• Time in Patent Office: 2,115 Days
• Field of Search: 350/96.23, 174/70 R, 174/74 R, 174/75 C, 174/88 C, 174/102 R, 174/107, 174/110 FC, 174/113 R, 174/120 R, 174/126.1, 174/126.4, 174/130, 385/100, 385/101, 385/75
• US Class Current: 385/101
• CPC Class Codes: G02B 6/3817 containing optical and electrical conductors cables including electrical and optical conductors H01B11/22; G02B6/3816 takes precedence
• CPC Class Codes: G02B 6/4416 Heterogeneous cables
• CPC Class Codes: H01B 11/1891 comprising auxiliary conductors
• CPC Class Codes: H01R 2103/00 Two poles
• CPC Class Codes: H01R 24/40 specially adapted for high frequency

Abstract

A compact, flexible, communications cable capable of electrical and optical signal propagation simultaneously is provided. The electrical signal is carried by coaxial inner and outer conductors of metal having suitable conductivity which surround and enclose a centrally disposed optical fiber conductor. The cable allows electrical signal propagation over a bandwidth from about 60 cycle D.C. or A.C. as well as radio frequency and microwave signals up to about 100 gigahertz without appreciable signal loss.

Claims

1. A signal communications cable capable of simultaneous transmission of radio and microwave frequency and optical signals characterized by an operating temperature of from about -65 degrees C. to about 250 degrees C. comprising:

(a) a core member comprising a single, circular-shaped optical fiber;

(b) a uniform layer of electrically conductive material on and coaxially surrounding the optical fiber core member providing an inner electrical conductor;

(c) a dielectric material on and coaxially surrounding the electrically conductive material layer; and

(d) a solid metal electrical conductor surrounding the dielectric material and coaxial therewith and with the inner electrical conductor and optical fiber core,

the signal communications cable having an overall diameter not greater than about 0.085 inches and the following radio frequency electrical characteristics;

space="preserve" listing-type="tabular">______________________________________ impedance 50 ohms;

frequency DC to 100 GHz;

______________________________________ average power attenuation watts, unity VSWR, db/100 ft @ 40 degrees C., frequency 20 degrees C.;

ambient;

______________________________________ 1 GHz 33.0 32 10 GHz 116.0 9 20 GHz 170.0 6.5. ______________________________________

2. A signal communications cable according to claim 1 having the following radio frequency mechanical characteristics:

inner electrical conductor (glass metal clad) having an O.D. (inch) about 0.0113;

dielectric of polytetrafluoroethylene having an O.D. (inch) about 0.037;

outer conductor is copper having an O.D. (inch) about 0.047,

said outer conductor having a wall thickness about 0.005 inches; and

optical characteristics are;

attenuation-about 1 db/km

bandwidth- about 100-1500 MHz/km

wavelength- about 850 through 1300 NM.

4. Method for the manufacture of a communications cable according to claim 2 wherein the optical fiber has an O.D. about 125 microns, the metal coated optical fiber is coated with a layer of aluminum and has an O.D. about 0.011 inches;

the dielectric material comprises polytetrafluoroethylene having an annular-shape and has an I.D. about 0.011 inches, an O.D. about 0.037 inches;

the outer conductor is a copper tube having an I.D. about 0.045 inches, an O.D. about 0.053 inches; and

the final assembly is reduced to a communications cable having an O.D. about 0.047 inches, said reduction being made incrementally in a plurality of steps, each step reducing the diameter of the assembly in an amount about 0.0001 inches, the resulting communications cable having approximately the ductility of the initial copper tube, and having an adhesion level between the outer electrical conductor and dielectric material of at least about 6 lbs. on a 6 inch long length of cable.

3. Method for providing a dual function communications cable capable of transmitting and receiving both electrical signals in the gigahertz frequency range and optical signals simultaneously comprising:

(a) first providing an optical fiber of suitable predetermined diameter having a layer of an electrically conductive metal of predetermined diameter coaxially surrounding and adhering to said optical fiber and defining an outer circumferential surface;

(b) extruding an annulus of dielectric material having a predetermined dielectric constant around said metal layer, said annulus having a predetermined outer and inner diameter and defining outer and inner circumferential surfaces, the inner circumferential surface of the said dielectric material coaxially surrounding and being in adhering contact with the said outer circumferential surface of the said metal layer;

(c) providing an annulus of an electrically conductive metal in surrounding relationship with said dielectric material, said metal annulus being a solid tubular-shaped metal member having predetermined outer and inner diameters; and

(d) drawing down the assembly formed in steps a, b, and c, in lengthwise direction to provide a communications cable of the desired outside diameter and to provide the metal layers in adhering contact with the circumferential surfaces of the dielectric material.

5. Method for providing a dual function communications cable capable of transmitting and receiving both electrical signals and optical signal simultaneously comprising:

(a) first providing an optical fiber of suitable predetermined diameter having a relatively thin layer of metal coaxially surrounding and adhering to said optical fiber and defining an outer circumferential surface;

(b) depositing a second layer of metal on the metal layer so as to coaxially surround the first metal layer, said second metal layer being electrically conductive and having a predetermined resistivity against the transmission of the electrical signals and defining a second outer circumferential surface;

(c) extruding an annulus of dielectric material having a predetermined dielectric constant around said second metal layer, said annulus having a predetermined outer and inner diameter and defining outer and inner circumferential surfaces, the inner circumferential surface of the said dielectric material coaxially surrounding and being in adhering contact with the said outer circumferential surface of the second metal layer;

(d) providing an annulus of an electrically conductive metal in surrounding relationship with said dielectric material, said metal annulus having predetermined outer and inner diameters and being characterized by a predetermined electrical resistivity; and

(e) drawing down the assembly formed in steps a, b, c and d in lengthwise direction to provide a communications cable of the desired outer diameter and to provide the metal layers on each side of the dielectric material in adhering contact with the circumferential surfaces of the dielectric material.

6. Means for connecting together two ends of a signal communications cable comprising the combination of a coaxial cable for transmission and reception of electrical signals and an optical fiber for transmission and reception of optical signals, said optical fiber having a predetermined diameter and being centrally disposed so as to form a core for the signal communications cable and comprising a solid, circular-shaped, elongated fiber, an inner, annular-shaped, electrical conductor coaxially surrounding said optical fiber core, and having predetermined inner and outer diameters, an outer, annular-shaped, solid electrical conductor coaxially surrounding said inner conductor and having predetermined inner and outer diameters, said outer conductor being radially, uniformly spaced from the outer diameter of the said inner conductor, and an annular-shaped dielectric material having predetermined outer and inner diameters and of a predetermined dielectric constant being located between the said inner and outer electrical conductors and coaxially surrounding the said inner conductor, said dielectric material maintaining the outer and inner electrical conductors in a desired uniform spatial relationship relative to one another and providing a desired uniform electrical impedance therebetween, the means for connecting comprising:

(a) a male plug housing comprising an annular-shaped coupling nut having a front end and a back end and being of predetermined inner and outer diameters defining inner and outer circumferential surfaces, a thread pattern being provided in the inner circumferential surface of the coupling nut from the front end of the coupling nut along at least a part of the length thereof, an elongated annular-shaped male plug member being located in the elongated opening provided by the inner circumferential surface of the coupling nut, said plug member being of predetermined inner and outer diameters less than the inner and outer diameters of the coupling nut and defining inner and outer circumferential surfaces, and means provided in operative association between the inner circumferential surface of the coupling nut and outer circumferential surface of the male plug member for retaining the two components in assembly together;

(b) an elongated tubular-shaped first electrical contact member open at both ends thereof and of predetermined length for location on an end of the communications cable and in surrounding, coaxial contact with the inner conductor, a length of outer conductor and dielectric material having been stripped from the cable of the same length as the predetermined length of the electrical contact member, said contact member having a lesser diameter at its front end for a predetermined length from the front end than the remainder of the contact member, said contact member being operatively associated with the male plug member;

(c) a second elongated tubular-shaped electrical contact member of predetermined length open at both ends thereof for location on another end of a communications cable in contact with the inner conductor, a length of outer conductor and dielectric material having been stripped from the cable of a somewhat lesser predetermined length than that of the second contact member, the inner diameter of the second contact member being somewhat greater at the front end of the contact member and for a predetermined length inwardly thereof equal to that of the lesser outer diameter of the first contact member;

(d) a jack member being operatively associated with the second electrical contact member comprising an elongated annular-shaped front member defined by front and back ends and inner and outer diameters defining inner and outer circumferential surfaces, a thread pattern being provided in the said outer surface of the front member complementary to that provided on the inner surface of the coupling nut, the outer diameter of the elongated front member of the jack member being such relative to the inner diameter of the coupling nut that these two members can be threadedly connected together and disconnected as desired, a circular-shaped receptacle being provided in the jack member and extending inwardly from the front end a predetermined distance and terminating in a radially disposed edge perpendicular to the length of the elongated member, said receptacle having a diameter and a predetermined length such that a predetermined length of the end of the male plug member can be located therein, the front edge of the male plug member being in contact with the said radially disposed edge and providing a block against further movement of the male plug member into the jack member when the jack member and male plug member are in operative assembly and the coupling nut is turned to bring those members in tight interface with one another, the front lesser diameter end of the first contact member being located in the front greater diameter end of the second contact member in male and female fashion, so that the ends of the optical fibers interface with one another and are in essentially the same plane.