US3110001A - Unwanted mode absorbing circular wave guide having circumferential gaps coupled, by intermediate dielectric, to external dissipative sheath - Google Patents

Unwanted mode absorbing circular wave guide having circumferential gaps coupled, by intermediate dielectric, to external dissipative sheath Download PDF

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Publication number
US3110001A
US3110001A US679929A US67992957A US3110001A US 3110001 A US3110001 A US 3110001A US 679929 A US679929 A US 679929A US 67992957 A US67992957 A US 67992957A US 3110001 A US3110001 A US 3110001A
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United States
Prior art keywords
jacket
helix
dielectric
wave
wave guide
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Expired - Lifetime
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US679929A
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English (en)
Inventor
Unger Hans-Georg
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AT&T Corp
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Bell Telephone Laboratories Inc
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Publication date
Priority to BE570125D priority Critical patent/BE570125A/xx
Application filed by Bell Telephone Laboratories Inc filed Critical Bell Telephone Laboratories Inc
Priority to US679929A priority patent/US3110001A/en
Priority to GB26325/58A priority patent/GB890800A/en
Priority to FR1209646D priority patent/FR1209646A/fr
Application granted granted Critical
Publication of US3110001A publication Critical patent/US3110001A/en
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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

  • 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 mode components, particularly of the TE and TE modes.
  • the finite size and spacing of the helix wires themselves create a capacitive grid between the propagating spurious mode wave energy within the wave guide and the external lossy jacket, thereby partly shielding the jacket from the Wave energy and permitting only partial penetration of the unwanted wave modes into the absorbing jacket.
  • a further object is to compensate the capacitive energy shielding eifect of the helix wires.
  • impedance-transforming radial transmission line means are inserted between the metallic helix wires and the outer lossy jacket of a helical transmission line.
  • the transformer means takes the form of an insulating layer of dielectric material.
  • Such a dielectric transformer presents an inductive reactance to the interior of the wave guide which acts in parallel with the helix Wire capacitance. By proper proportioning of the composition and thickness of this layer the capacitive shielding effect of the helix wires may be compensated.
  • the dielectric transformer serves to change the surface impedance of the lossy jacket as seen from the wave guide interior to a more favorable value as far as attenuation of the unwanted modes is concerned.
  • FIG. 1 is a cut away view of the end portion of a transmission line in accordance with the invention.
  • FIG. 2 is a perspective view of the form upon which the structure of FIG. 1 may be made.
  • FIGS. 3A and 3B are graphs illustrating the performance of the invention.
  • FIG. 1 a cut away cross sectional view of a 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 wire closely wound in a helix.
  • Conductor 11 may, for example, be an enameled or plastic insulated solid copper wire. Adjacent turns of the helix wires are electrically insulated rom each other, and this may be provided by a small air gap or by an insulating coating on the wire itself.
  • the pitch distance of the helix i.e., the distance between centers of adjacent turns, and therefore the pitch angle of the helix should be as small as is consistent with the insulating requirement. This distance in all events must be less than one-quarter wavelength and is preferably such that the gap between adjacent turns is less than the diameter of conductor 11.
  • Helix 11 is surrounded by successive annuli or jackets which will each be described in more detail hereinafter.
  • transformer jacket 12 which may comprise any insulating dielectric of moderate dielectric 3 constant.
  • the righthand 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 conductive 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. 1 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.
  • dielectric impedance transforming jacket 12 is formed in accordance with the present in- 'ventiom
  • this transformer is formed by laminating thin layers of a dielectric material.
  • the dielectric jacket acts much like a short radial transmission line, transforming the impedance of the lossy jacket presented to the longit-udinal cunrents through helix 11 to a more favorable value so far as attenuation of spurious modes is concerned.
  • the admittance of the lossy jacket as seen from the helix interior has a low inductive component.
  • adjacent turns of the helix wires themselves act as parallel plate capacitors and present a capacitive reactance which tends to shield the spurious mode wave energy from the lossy jacket and to prevent its absorption therein.
  • the impedance transforming effect of dielectric jacket 12 serves to increase the inductive component of the lossy jacket admittance. This inductive component acts in parallel .With the helix wire capacitance and eliminates its shielding effect, thereby permitting more complete penetration and absorption of the spurious mode wave energy into the lossy jacket than previously attainable.
  • Dielectric jacket 12 is preferably a material of low to medium dielectric constant.
  • the electrical thickness of the layer should be less than one-quarter wavelength of the highest operating frequency to be transmitted.
  • the spacing between adjacent turns of helix 11 is always less than one-quarter wavelength.
  • the spacing of the helix wires is kept as small as possible and is usually considerably less than 1/4.
  • the thickness of the dielectric jacket would be considerably greater than the helix wire spacing. That is to say, a helix wave guide employing insulated wire for the helix element wound (in such a manner as to have adjacent turns in continuous contact with each other may be said to have a dielectric layer on its outer surface of a thickness equal to half the spacing of the helix wires. Such a thickness of dielectric jacket, however, is insufiicient to provide the desired impedance transformation of the present invention.
  • transformer 12 may be any insulating dielectric of moderate dielectric constant, it is preferable that in addition to the proper electrical properties, it have desirable mechanical properties as well.
  • a particularly suitable material for such a structure may conveniently comprise glass fibers, reinforced plastic, or glass fibers impregnated with plastic.
  • a first cloth of Woven glass fibers having a length similar to the length of the helix is Wound over helix 11 While the plastic is applied between each turn.
  • a woven tape of woven glass fibers may be spirally wound down and back a plurality of times along the helix.
  • glass fiber roving comprising a loosely twisted cord containing in the order of 50 glass fibers is spirally wound down and back many times until the required thickness is built up. In the case of roving, 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 custom made short lengths while the use of tape or roving appears preferable for use With commercial winding machines.
  • the glass content of the glass lamination should be held at a high uniform value, perhaps of the order of between 50 and 75 percent, the higher ratios of glass appearing preferable.
  • plastic materials have been found suitable for the above purposes.
  • a preferred embodiment employs a suitable commercially available epoxide resin of the type that may be catalytically cured to form a thermosetting polymer.
  • FIGS. 3A and 3B illustrate, in graphical form, the
  • FIG. 3A shows the attenuation constant for the TM wave mode as a function of frequency for a helix wave guide both with and without a dielectric trans-
  • curve 31 shows the helix wave guide attenuation constant for the TM wave mode in the helix wire-lossy jacket structure. In such a structure the lossy jacket is contiguous to the helix itself.
  • Curve 32 illustrates the helix Wave guide attenuation constant for the TM wave mode in the helix wire-dielectric transformerlossy jacket structure in accordance with the invention. It is clear that the introduction of dielectric jacket 12 in FIG. 1 substantially increases the obtainable TM wave mode attenuation.
  • the TE wave mode attenuation constant is very small, of the order of 3 l0
  • the increase in the dilference in attenuation constants between the TE and TM wave modes provided by the invention is over 400 percent.
  • FIG. 3B shows, for the TE wave mode, the attenuation constant as a function of frequency for a helix wave guide with and without the dielectric transformer. Structures identical to those described above in conjunction with FIG. 3A were utilized to obtain the curves of FIG. 3B.
  • Curve 33 illustrates the TE attenuation constant of the plain helix wire-lossy jacket structure.
  • Curve 34 illustrates the same quantity for the helix wire-dielectric transformer-lossy jacket structure in accordance with the invention.
  • the II-3 wave mode attenuation constant is of the order of 3 l0- From this value and from FIG. 3B, it may be seen that at 55 kilomegacycles, for example, the increase in attenuation constants between the TE and TE wave modes provided by the invention is over 200 percent.
  • resistive layer 13 is formed.
  • homogeneous materials having isotropic electrical properties have been utilized for this layer. Oftentimes, however, these solid materials have mechanical properties unsuitable for some applications.
  • Kohman et a1. application a suitable material for this structure is laminated treated glass fibers.
  • the resistive layer is laminated employing plastics suitable for lamination purposes and glass cloth, tape or roving having an electrically conducting metallic oxide coating of the kind generally known as an iridized coating applied thereto.
  • Oxide coatings that have an electrical resistance and other characteristics suitable for the lossy jacket may be produced by using mixtures of the metal oxides of tin, titanium, cadmium, indium and antimony. In particular, the combination of the oxides of tin plus small quantities of the oxides of titanium and antimony have been found satisfactory.
  • the transmission line 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 1718 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 glass fiber roving and tape in these portions and to employ a resin having some resiliency and ductility to prevent chipping of these parts through use.
  • 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, as described in the principal embodiment of the invention, a substantially homogeneous, closely bonded 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 uniform,- ity through the line is necessary to ensure uniform serpentine deformation of the entire line in the event of ther- 6 mal expansion.
  • a Wall inch thick provides a sufiiciently large structural moment of inertia to offset the greater modulus of elasticity of the copper in a standard 2 inch inside diameter wave guide.
  • the completed guide is then cured according to stand ard 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 Wave mode comprising an elongated member of conductive material wound in a substantially helical form with adjacent turns electrically insulated from each other, dielectric spacing means having a low value of electrical dissipation and a minimum radial thickness substantially greater than one-half the separation between adjacent turns of the helical member but less than one-quarter Wavelength of said energy at the operating frequency surrounding said helix, and a sleeve of electrically lossy material having a value of electrical dissipation considerably greater than said low value surrounding said means.
  • a transmission medium for circular electric mode wave energy within a given frequency range comprising an elongated member of conductive material wound in a substantially helical form with a helix diameter greater than 1.2 free space Wavelengths of said energy with adjacent helix turns spaced apart a distance substantially less than one-quarter wavelength of said energy but electrically insulated from one another, a jacket of electrically dissipative dielectric material surrounding said helix and spaced away therefrom a distance substantially greater than one-half the spacing between adjacent helix turns, and a sleeve of dielectric material having a low value of electrical dissipation interposed between and contiguous to said helix and said jacket, said sleeve presenting an inductive reactance to radially propagating wave energy within said frequency range.
  • a transmission medium for wave energy in the circular electric wave mode within a given frequency range comprising an elongated member of conductive material wound in a substantially helical form with adjacent turns electrically insulated from each other, dielectric means for dissipating wave energy having current components parallel to the axis of said helically wound member surrounding said helix, and a sleeve of dielectric material exhibiting low electrical dissipation interposed between and contiguous to said helical member and said dielectric dissipating means to separate said dissipating means and said helical member a given distance substantially greater than one-half the spacing between adjacent helix turns, said sleeve presenting an inductive reactance to radially propagating wave energy within said frequency range.
  • a transmission medium for wave energy in the circular electric wave mode comprising a conductive means defining a low-1oss transmission path having a circular cross section in planes transverse to the transmission direction of said energy therethrough, a jacket of electrically lossy dielectric material surrounding said conductive means throughout its length, said conductive means and said lossy jacket being electrically coupled by a plurality of regularly spaced gaps in said conductive means, and means for spacing said jacket from said means comprising a substantially lossless dielectric sleeve interposed between and contiguous to said jacket and said means with a radial thickness substantially greater than one-half the longitudinal extent of said gaps between adjacent conductive portions of said conductive means but less than one-quarter wavelength of said energy.
  • a transmission medium for wave energy in the circular electric wave mode comprising a conductive means defining a low-loss transmission path having a circular cross-section in planes transverse to the transmission direction of said energy therethrough, a jacket of electrically lossy dielectric material surrounding said conductive means throughout its length, said conductive means and said jacket being electrically coupled by a plurality of regularly spaced gaps in said conductive means, and impedance transformer means interposed be- (3 tween and contiguous to said jacket and said conductive means for matching the impedance of said jacket to said low-loss transmission path, said transformer means consisting of a dielectric sleeve.

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US679929A 1957-08-23 1957-08-23 Unwanted mode absorbing circular wave guide having circumferential gaps coupled, by intermediate dielectric, to external dissipative sheath Expired - Lifetime US3110001A (en)

Priority Applications (4)

Application Number Priority Date Filing Date Title
BE570125D BE570125A (US06534493-20030318-C00166.png) 1957-08-23
US679929A US3110001A (en) 1957-08-23 1957-08-23 Unwanted mode absorbing circular wave guide having circumferential gaps coupled, by intermediate dielectric, to external dissipative sheath
GB26325/58A GB890800A (en) 1957-08-23 1958-08-15 Improvements in or relating to transmission media for electromagnetic wave energy inthe circular electric wave mode
FR1209646D FR1209646A (fr) 1957-08-23 1958-08-22 Transmission d'ondes électromagnétiques

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US679929A US3110001A (en) 1957-08-23 1957-08-23 Unwanted mode absorbing circular wave guide having circumferential gaps coupled, by intermediate dielectric, to external dissipative sheath

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US3110001A true US3110001A (en) 1963-11-05

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US (1) US3110001A (US06534493-20030318-C00166.png)
BE (1) BE570125A (US06534493-20030318-C00166.png)
FR (1) FR1209646A (US06534493-20030318-C00166.png)
GB (1) GB890800A (US06534493-20030318-C00166.png)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3678420A (en) * 1970-10-27 1972-07-18 Bell Telephone Labor Inc Spurious mode suppressing waveguide
US3771076A (en) * 1971-02-03 1973-11-06 British Insulated Callenders Combined electromagnetic waveguide and mode filter
US3771078A (en) * 1971-02-02 1973-11-06 British Insulated Callenders Mode filter for an electromagnetic waveguide
EP0024685A1 (en) * 1979-08-22 1981-03-11 Western Electric Company, Incorporated Hybrid mode waveguiding member and hybrid mode feedhorn antenna
US5202650A (en) * 1991-06-26 1993-04-13 The Johns Hopkins University Matched spurious mode attenuator and transition for circular overmoded waveguide
US5364136A (en) * 1991-11-12 1994-11-15 Alcatel Italia S.P.A. Flanges and bodies for microwave waveguides components
WO2023283167A1 (en) * 2021-07-06 2023-01-12 Quaise, Inc. Multi-piece corrugated waveguide

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR802728A (fr) * 1935-02-19 1936-09-14 Meaf Mach En Apparaten Fab Nv Dispositif et procédé pour l'amélioration de dispositifs de production et de réception d'ondes électriques ultra-courtes
US2538771A (en) * 1944-08-02 1951-01-23 Sperry Corp High-frequency attenuator
US2730649A (en) * 1950-02-04 1956-01-10 Itt Traveling wave amplifier
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 (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR802728A (fr) * 1935-02-19 1936-09-14 Meaf Mach En Apparaten Fab Nv Dispositif et procédé pour l'amélioration de dispositifs de production et de réception d'ondes électriques ultra-courtes
US2538771A (en) * 1944-08-02 1951-01-23 Sperry Corp High-frequency attenuator
US2779006A (en) * 1949-12-02 1957-01-22 Bell Telephone Labor Inc Spurious mode suppressing wave guides
US2730649A (en) * 1950-02-04 1956-01-10 Itt Traveling wave amplifier
FR1118560A (fr) * 1954-03-15 1956-06-07 Western Electric Co Dispositif de transmission d'ondes électromagnétiques
US2848696A (en) * 1954-03-15 1958-08-19 Bell Telephone Labor Inc Electromagnetic wave transmission

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3678420A (en) * 1970-10-27 1972-07-18 Bell Telephone Labor Inc Spurious mode suppressing waveguide
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
EP0024685A1 (en) * 1979-08-22 1981-03-11 Western Electric Company, Incorporated Hybrid mode waveguiding member and hybrid mode feedhorn antenna
US5202650A (en) * 1991-06-26 1993-04-13 The Johns Hopkins University Matched spurious mode attenuator and transition for circular overmoded waveguide
US5364136A (en) * 1991-11-12 1994-11-15 Alcatel Italia S.P.A. Flanges and bodies for microwave waveguides components
WO2023283167A1 (en) * 2021-07-06 2023-01-12 Quaise, Inc. Multi-piece corrugated waveguide
US11613931B2 (en) 2021-07-06 2023-03-28 Quaise, Inc. Multi-piece corrugated waveguide
US11959382B2 (en) 2021-07-06 2024-04-16 Quaise Energy, Inc. Multi-piece corrugated waveguide

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FR1209646A (fr) 1960-03-02
GB890800A (en) 1962-03-07
BE570125A (US06534493-20030318-C00166.png)

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