US2966643A - Electromagnetic wave guide structure - Google Patents

Electromagnetic wave guide structure Download PDF

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Publication number
US2966643A
US2966643A US679835A US67983557A US2966643A US 2966643 A US2966643 A US 2966643A US 679835 A US679835 A US 679835A US 67983557 A US67983557 A US 67983557A US 2966643 A US2966643 A US 2966643A
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US
United States
Prior art keywords
jacket
helix
glass
wave
wave guide
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
US679835A
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English (en)
Inventor
Girard T Kohman
Stewart E Miller
Charles F P Rose
Jr James A Young
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.)
AT&T Corp
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Bell Telephone Laboratories Inc
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Priority to NL121090D priority Critical patent/NL121090C/xx
Priority to BE570083D priority patent/BE570083A/xx
Priority to NL230209D priority patent/NL230209A/xx
Application filed by Bell Telephone Laboratories Inc filed Critical Bell Telephone Laboratories Inc
Priority to US679835A priority patent/US2966643A/en
Priority to DEW23938A priority patent/DE1111688B/de
Priority to FR1209645D priority patent/FR1209645A/fr
Application granted granted Critical
Publication of US2966643A publication Critical patent/US2966643A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01P—WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE
    • H01P3/00—Waveguides; Transmission lines of the waveguide type
    • H01P3/12—Hollow waveguides
    • H01P3/13—Hollow waveguides specially adapted for transmission of the TE01 circular-electric mode

Definitions

  • This invention relates to electromagnetic wave trans-.
  • the TE mode may have a substantially difierent phase constant from the TM mode thereby providing decoupling between these modes.
  • the helix is surrounded by a jacket of electrically dissipative material which introduces a large difference in the attenuation constants presented to the spurious modes and the TE mode and that by virtue of this difference, degeneration is reduced whether or not there is a difference in phase constant without a substantial amount of energy being actually lost in the dissipative material.
  • the dissipative jacket is in turn surrounded by a sheath to give mechanical strength and protection to the structure.
  • Such a transmission medium is ideally suited for long distance transmission of wide band signals since the attenuation of the TE mode decreases with increasing frequency.
  • the helical wave guide serves to negotiate both accidentally and intentionally introduced bends and turns.
  • the helical guide serves as a filter to purify the TE energy and to remove spurious components, particularly of the TB and TE modes.
  • the lossy jacket comprises a suitable plastic or dielectric material in which small particles of resistive material are suspended.
  • the resistive material is carbon or similar material
  • an attempt to more densely impregnate the plastic material to increase the concentration of the resistive particles and lower the resistance is unsatisfactory because it is accompanied by a physical weakening of the material substantially before a resistivity of 10 ohm centimeters can be reached.
  • this apparent lack of a suitable resistance material is overcome by employing as the lossy jacket strands of dielectric material that are coated with a thin metallic semiconductive or resistive film and then laminated with a suitable dielectric plastic. While the real ohmic resistance of the film so employed is much below the usable range, it will be shown that the efiective resistance presented by the laminated structure to the spurious mode energy can be readily controlled by the ratio of resistive to dielectric material in the laminated structure.
  • fibrous glass material is coated with a thin metallic oxide and then laminated with a synthetic resin such as epoxide. This structure has desirable electrical properties, is easy and economical to fabricate by commercial processes.
  • additional layers of fibrous glass and plastic may be built as a homogeneous structure upon the lossy jacket layer to produce a protective sheath that has dimentional accuracy, that has moisture, corrosion, and deterioration resistance to a high degree, and that has a bending stilfness that can duplicate that of a connected metallic-type wave guide.
  • a dielectric layer between the helix and the resistive jacket may be added by this construction for the purpose and in accordance with the teachings of H. G. Unger in his copending application Serial No. 679,929, filed August 23, 1957.
  • Fig. 1 is a cut-away view of a small end portion of a transmission line in accordance with the invention.
  • Fig. 2 is a cross-sectional view of the form upon which the structure of Fig. 1 may be made.
  • a cut-away cross-sectional view of a small section of transmission line contemplated for use in a circular electric mode wave transmission system is shown as an illustrative embodiment of the present invention.
  • This line comprises an elongated conductive member 11 of relatively fine insulated wire closely wound in a helix.
  • Conductor 11 may, for example, be a number 37 size, enameled or plastic insulated solid copper wire (0.005 inch overall diameter). A uniform and appropriate spacing between successive turns is provided by the insulation.
  • Helix 11 is surrounded by successive layers or jackets which will each be described in more detail hereinafter.
  • a dielectric jacket 12 of glass fibers impregnated with a plastic or resinous material is followed by a lossy jacket 13 of glass fibers covered with a film of metallic oxide and similarly impregnated with plastic.
  • Jacket 13 is in turn surrounded by an outer jacket 14 of impregnated glass fibers.
  • the right-hand portion of jacket 14 includes a connector comprising an internally threaded region 15 for connecting to an adjoining section of wave guide, an internally smooth portion 16 of larger diameter which facilitates thread alignment when inserting the adjoining section, and a larger diameter section 18 forming a seat 17 to receive a suitable washer for sealing with the adjoining section.
  • a copper ring 19 between helix 11 and threaded portion 15 that has an inside diameter equal to the inside diameter of helix 11 terminates the ends of the helix and forms a conductive abutting surface for the adjoining wave guide.
  • Fig. 2 shows the mandrel upon which the structure of Fig. l is formed.
  • Portion 21 represents a smoothly polished member upon which helix 11 is wound and portion 22 represents a typical one of a pair of end molds suitably fastened by threads 23 to either end of portion 21.
  • Portion 22 includes an externally screw threaded portion 24, a smooth portion 25 and a seat forming portion 26.
  • Such a mandrel of the desired length together with its end molds is mounted for axial rotation between the chucks of a suitable winding machine after rings 19 have been located in place.
  • mandrel 21 and end mold 22 After a suitable mold release agent has been applied to mandrel 21 and end mold 22, the mandrel is rotated and helix 11 is closely Wound between rings 19. It may be wound with a single strand, or it may be wound with a plurality of strands being simultaneously fed in parallel.
  • this jacket provides a transformation of the surface impedance that the lossy jacket 13 presents to the longitudinal currents through helix 11 and acts as an inductance in parallel with the capacitance of the helix to compensate for the shielding effect of the helix upon the spurious modes.
  • this jacket provides a transformation of the surface impedance that the lossy jacket 13 presents to the longitudinal currents through helix 11 and acts as an inductance in parallel with the capacitance of the helix to compensate for the shielding effect of the helix upon the spurious modes.
  • the material of jacket 12 comprises plastic reinforced with glass fibers or glass fibers impregnated with plastic.
  • plastic reinforced with glass fibers or glass fibers impregnated with plastic Several methods of building up this layer have each been found satisfactory. According to a first, cloth woven of glass fiber having a length similar to the length of the helix is wound over helix 11 while the plastic is applied between each layer. Alternatively, a tape woven of glass fibers may be spirally wound down and back a plurality of times along the helix. Similarly, glass fiber roving comprising a loosely twisted cord containing in the order of 15 to 50 glass fibers is spirally wound down and back many times until the required thickness is built up.
  • the loosely twisted fibers tend to flatten out so that each turn increases the layer by only the thickness of a few fibers.
  • the material may first be passed through a container of fluid plastic before winding or the plastic may otherwise be suitably applied between turns.
  • the use of woven cloth appears preferable for handmade or custom made short lengths while the use of tape or roving appears preferable for use with commercial winding machines.
  • the glass content ofthe glass lamination should be held at a high uniform value perhaps of the order between 50 and 75 percent, the higher ratios of glass appearing preferable.
  • a preferred embodiment employs a suitable commercially available epoxide resin of the type that may be catalytically cured to form a thermosetting polymer.
  • a suitable catalyst is usually either an amine, amide, or a combination of both. It is preferred that a fast enough catalyst be employed that the exothermic heat aids in producing the cure. However, it has been found that the reaction may be hastened without undesirable shrinkage if the exothermic cure is also accompanied by moderate external heat. Specifically, 20 parts per 100 by weight of the curing agent metaphenylene diamine has proven satisfactory. Alternatively, one of the several less expensive thermoplastic polyester resins may be employed. In
  • the resistive layer is laminated employing plastics of the types described and glass cloth, tape or roving having an electrically conducting metallic oxide coating of the kind generally known as an iridized coating applied thereto.
  • an electrically conducting metallic oxide coating of the kind generally known as an iridized coating applied thereto.
  • composition and thickness of the film thus formed may be defined more clearly after the function that the resistive jacket plays in the transmission line has been examined;
  • circular electric TE mode energy is excited within helix 11 by its connection to a solid pipe guide or other component in the system in which the helix is to be used either as a filter or as a transmission medium for circular electric wave energy.
  • a major component of the circular current of this wave is conducted along the helical path by each turn. Since the pitch of the helix is small, this component constitutes substantially the entire current of the wave.
  • the wave is presented with only a small reactance by the discontinuity between adjacent turns which changes the phase velocity of the wave only slightly. Very little of the total TEo current will pass through the resistive material-of jacket 13 and, therefore, the attenuation constant of the TEm, wave is also substantially unchanged.
  • the TM mode has a predominantly longitudinal current flow along, the wave guiding path and will be seriously affected by the discontinuity between adjacent turns of helix 11. Not only is the phase constant of this mode increased by the reactance of each discontinuity, but the longitudinal currents are forced to flow through the dissipative material of jacket 13'. Thus, the attenuation constant for the TM mode becomes very different from the attenuation constant for the TE mode and its degeneration into this spurious mode is reduced. With the TE and TE modes, however, there is only a limited range of values of resistivity of jacket 13 for which these modes exhibit a preference for the jacket and are subject to its attenuation to a much greater extent than the TE mode. Calculations leading to this conclusion are fully set forth in the first above-identified publication. This range includes a resistance presented to the wave energy in these modes of approximately 1 to 10 ohm centimeters.
  • the resistance presented'to the wave energy is not the same as the measurable resistance of the metallic films upon the glass.
  • the latter will therefore be referred to as the ohmic resistivity and the resistance presented to the wave as the effective resistivity.
  • the parameters of a preferred embodiment may be given by way of example. It is desired to produce an effective resistivity in the order of 2 ohm centimeters having a dielectric constant in the order of 10. This is done by Winding 0.005 inch thick laminations (the thickness of the glass fibers material) having a metallic oxide coating applied thereto of material having an ohmic resistivity of approximately 0.002 ohm centimeters to a total thickness of 0.04 inch.
  • the metallic oxide coating in such an embodiment may be in the order of 3,000 angstroms in thickness which gives it a surface resistivity of approximately 50 ohms per square.
  • Equivalent parameters for other embodiments may be determined empirically or they may be calculated using the equations derived for multilayer transmission line structures by E. I. Hawthorne in an article Electromagnetic Shielding With Transparent Coated Glass appearing in the Proceedings of the Institute of Radio Engineers, vol. 42, page 548, March 1954.
  • the transmission line in accordance with the invention is completed by adding the protective sheath 14 and the connectors at each end thereof.
  • Portions of the connector comprising threaded portion 15, aligning portion 16 and seat portion 17-18 are formed by being filled in and built up to the outside diameter of ring 19 in a wound or laminated construction by a process similar to that described for dielectric jacket 12. It is preferable to employ roving of glass fibers and tape of glass fibers in these portions and to employ a resin having some resiliency and ductility to prevent chipping of these parts through use. Therefore, in accordance with a preferred embodiment of the invention, an epoxide resin cured by a mixture of parts per 100 metaphenylene diamine and 32 parts per 100 polyamide may be employed.
  • sheath 14 is wound over resistive jacket 13 and over the formed threads and seats of parts 15, 16, 17 and 18. Except for its greater thickness, sheath 14 may be identical to dielectric jacket 12. If preferred, somewhat larger fibers of glass may be used however. Because of the identical mechanical nature of jackets 12, 13 and 14, a substantially homogeneous, closely bounded structure is obtained. Thus, the thickness of sheath 14 is built up so that the total thickness of the laminated structure has a bending stiffness comparable to that of the solid wall metallic wave guide employed in the same system: Such structural uniformity through the line is necessary to insure uniform serpentine deformation of the entire line in the event of thermal expansion. Otherwise, a concentrated bend would occur at the weakest point introducing undesirable mode conversion. In a particular embodiment, a wall /6 inch thick provides a sufiiciently large structural moment of inertia to oifset the greater modulus of elasticity of the copper in the standard 2 inch inside diameter wave guide.
  • the completed guide is then cured according to standard plastic handling processes while mandrel 21 continues to rotate. Slight elevations in temperature have been found permissible to hasten the curing. End molds 22 may then be removed and mandrel 21 withdrawn.
  • a transmission medium for electromagnetic wave energy in the circular electric mode comprising an elongated member of conductive material wound in a substantially helical form with adjacent turns electrically insulated from each other, a first jacket surrounding said helix for presenting an effective resistivity of a given value to wave energy having current components parallel to the axis of said helix, said jacket comprising glass fibers coated by an iridized film of metallic oxide, said film having a value of ohmic resistivity substantially lower than said given value, said coated fibers being bound together in a laminated structure by a plastic material, a second jacket surrounding said first jacket comprising further glass fibers being bound together in a laminated structure by a plastic material.
  • a sec tion of conductive metallic walled wave guide connected to one end of said medium, the laminated jackets of said medium having a total thickness suflicently greater than the thckness or the metallic wall of said wave guide sec tion so that said medium has a bending stiffness substantially equal to the bending stiffness of said Wave guide section.
  • a transmission medium for electromagnetic wave energy in the circular electric mode comprising an elongated member of conductive material wound in a substantially helical form with adjacent turns electrically insulated from each other, and a jacket surrounding said helix for presenting an efiective resistivity of a given value to wave energy having current compo nents parallel to the axis of said helix, said jacket comprising fibers of glass with iridized coatings of metallic oxide, said iridized coatings having values of ohmic resistivity substantially lower than said given value of efiective resistivity and being separated in a laminated construction by dielectric material at least a part of which c0mprises a plastic material impregnating said glass fibers the amount of separation raising the value of effective resistivity presented to said component to said given value.

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  • Insulating Bodies (AREA)
US679835A 1957-08-23 1957-08-23 Electromagnetic wave guide structure Expired - Lifetime US2966643A (en)

Priority Applications (6)

Application Number Priority Date Filing Date Title
NL121090D NL121090C (pl) 1957-08-23
BE570083D BE570083A (pl) 1957-08-23
NL230209D NL230209A (pl) 1957-08-23
US679835A US2966643A (en) 1957-08-23 1957-08-23 Electromagnetic wave guide structure
DEW23938A DE1111688B (de) 1957-08-23 1958-08-20 Wendelfoermig gewickelter Hohlleiter zur UEbertragung elektromagnetischer Wellen mit zirkularem elektrischem Feld
FR1209645D FR1209645A (fr) 1957-08-23 1958-08-22 Structure de guide d'ondes électromagnétiques

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US679835A US2966643A (en) 1957-08-23 1957-08-23 Electromagnetic wave guide structure

Publications (1)

Publication Number Publication Date
US2966643A true US2966643A (en) 1960-12-27

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US679835A Expired - Lifetime US2966643A (en) 1957-08-23 1957-08-23 Electromagnetic wave guide structure

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US (1) US2966643A (pl)
BE (1) BE570083A (pl)
DE (1) DE1111688B (pl)
FR (1) FR1209645A (pl)
NL (2) NL121090C (pl)

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3176249A (en) * 1959-11-30 1965-03-30 Marconi Co Ltd Waveguide impedance matching transitions while maintaining effective cross-section unchanged
US3257630A (en) * 1961-04-07 1966-06-21 Post Office Variable phase shifter, utilizing extensible helical waveguide, for circular te modes
US3599126A (en) * 1969-10-08 1971-08-10 Bell Telephone Labor Inc Circular waveguide formed from a flexible ribbon carrying a conductor pattern
US3748606A (en) * 1971-12-15 1973-07-24 Bell Telephone Labor Inc Waveguide structure utilizing compliant continuous support
US3771078A (en) * 1971-02-02 1973-11-06 British Insulated Callenders Mode filter for an electromagnetic waveguide
US3771076A (en) * 1971-02-03 1973-11-06 British Insulated Callenders Combined electromagnetic waveguide and mode filter
US4066987A (en) * 1974-03-29 1978-01-03 Bicc Limited Electromagnetic waveguides
US5495218A (en) * 1994-04-20 1996-02-27 Thermo Instrument Controls Inc. Microwave waveguide seal assembly

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1213021B (de) * 1962-10-29 1966-03-24 Siemens Ag Verfahren zur Herstellung eines Hohlleiters fuer die UEbertragung elektromagnetischer Wellen

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2564709A (en) * 1950-11-24 1951-08-21 Corning Glass Works Electrically conducting coating on glass and other ceramic bodies
US2745074A (en) * 1951-01-11 1956-05-08 Ralph E Darling Electrically equipped oxygen hose
US2746018A (en) * 1951-10-02 1956-05-15 Sichak William Microwave phase shifter
FR1118560A (fr) * 1954-03-15 1956-06-07 Western Electric Co Dispositif de transmission d'ondes électromagnétiques
US2779006A (en) * 1949-12-02 1957-01-22 Bell Telephone Labor Inc Spurious mode suppressing wave guides

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2779006A (en) * 1949-12-02 1957-01-22 Bell Telephone Labor Inc Spurious mode suppressing wave guides
US2564709A (en) * 1950-11-24 1951-08-21 Corning Glass Works Electrically conducting coating on glass and other ceramic bodies
US2745074A (en) * 1951-01-11 1956-05-08 Ralph E Darling Electrically equipped oxygen hose
US2746018A (en) * 1951-10-02 1956-05-15 Sichak William Microwave phase shifter
FR1118560A (fr) * 1954-03-15 1956-06-07 Western Electric Co Dispositif de transmission d'ondes électromagnétiques

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3176249A (en) * 1959-11-30 1965-03-30 Marconi Co Ltd Waveguide impedance matching transitions while maintaining effective cross-section unchanged
US3257630A (en) * 1961-04-07 1966-06-21 Post Office Variable phase shifter, utilizing extensible helical waveguide, for circular te modes
US3599126A (en) * 1969-10-08 1971-08-10 Bell Telephone Labor Inc Circular waveguide formed from a flexible ribbon carrying a conductor pattern
US3771078A (en) * 1971-02-02 1973-11-06 British Insulated Callenders Mode filter for an electromagnetic waveguide
US3771076A (en) * 1971-02-03 1973-11-06 British Insulated Callenders Combined electromagnetic waveguide and mode filter
US3748606A (en) * 1971-12-15 1973-07-24 Bell Telephone Labor Inc Waveguide structure utilizing compliant continuous support
US4066987A (en) * 1974-03-29 1978-01-03 Bicc Limited Electromagnetic waveguides
US5495218A (en) * 1994-04-20 1996-02-27 Thermo Instrument Controls Inc. Microwave waveguide seal assembly

Also Published As

Publication number Publication date
NL121090C (pl)
FR1209645A (fr) 1960-03-02
BE570083A (pl)
NL230209A (pl)
DE1111688B (de) 1961-07-27

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