US2800634A - Radio frequency transmission waveguides - Google Patents

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Classifications

• • 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
  • H01P3/02—Waveguides; Transmission lines of the waveguide type with two longitudinal conductors
  • H01P3/08—Microstrips; Strip lines
  • H01P3/081—Microstriplines
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
  • H01B11/00—Communication cables or conductors
  • H01B11/18—Coaxial cables; Analogous cables having more than one inner conductor within a common outer conductor
  • H01B11/20—Cables having a multiplicity of coaxial lines
• • 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
  • H01P3/02—Waveguides; Transmission lines of the waveguide type with two longitudinal conductors
  • H01P3/08—Microstrips; Strip lines
  • H01P3/081—Microstriplines
  • H01P3/084—Suspended microstriplines
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01Q—ANTENNAS, i.e. RADIO AERIALS
  • H01Q13/00—Waveguide horns or mouths; Slot antennas; Leaky-waveguide antennas; Equivalent structures causing radiation along the transmission path of a guided wave
  • H01Q13/20—Non-resonant leaky-waveguide or transmission-line antennas; Equivalent structures causing radiation along the transmission path of a guided wave
  • H01Q13/26—Surface waveguide constituted by a single conductor, e.g. strip conductor
• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
  • H05K1/00—Printed circuits
  • H05K1/02—Details
  • H05K1/0213—Electrical arrangements not otherwise provided for
  • H05K1/0237—High frequency adaptations
  • H05K1/024—Dielectric details, e.g. changing the dielectric material around a transmission line
• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
  • H05K2201/00—Indexing scheme relating to printed circuits covered by H05K1/00
  • H05K2201/07—Electric details
  • H05K2201/0707—Shielding
  • H05K2201/0715—Shielding provided by an outer layer of PCB

Definitions

• One of the objects of this invention is to provide low loss transmission waveguide for use at ultra high frequencies.
• One of the features of this invention is the provision of an air space between the two conductors in order to obtain a high Q waveguide. This is accomplished by supporting the line conductor on the face of a strip of dielectric disposed in spaced parallel relation to the ground conductor. The supporting dielectric strip is in turn supported by beads or narrow strips of dielectric located laterally of the line conductor.
• Fig. 1 is a cross-sectional view of one form of transmission line in accordance with the principles of our copending application Serial No. 227,896;
• Fig. 2 shows in cross-section one embodiment of the present invention
• Figs. 3 and 4 are cross sectional views of additional embodiments of the invention.
• the radio frequency transmission waveguide illustrated is of the printed circuit type comprising a first or line condurtor 1 and a second or ground conductor 2 with a layer 3 of 2,800,634 Patented July 23, 1957 dielectric material therebetween.
• the conductive material may be applied to the layer of dielectric, such as polystyrene, polyethylene, 'Teflon (polytetrafluoroethylene) or other flexible insulation of high dielectric quality, in the form of conductive paint or ink, or the conductive material may be chemically deposited, sprayed through a stencil or dusted onto selected prepared surfaces of the dielectric according to known printed circuit techniques.
• the conductive strips may be cut and applied by a die-stamping operation.
• the insulation may be extruded and simultaneously or later provided on the two sides thereof with conductive material of the desired thickness and widths.
• the portions of the two layers that are to be retained may be coated with a chemically inert material exposing the parts to be removed, and thereafter passing the cable through an etching bath, whereupon the exposed portions of the layers are removed.
• the two conductive layers 1 and 2 are shown in cross-section to be substantially rectangular, they may comprise different shapes so long as the ground conductor 2 presents a wide extended surface with respect to the line conductor.
• the ground conductor should be from two to three times the width of the line conductor 1, although wider dimensions give still lower loss.
• the broken lines 4, 5 and 6 indicate, substantially the percentage of distribution of the electric field between the two conductors for a conductor relation wherein the ground conductor 2 is approximately three times the width of the line conductor, and the line conductor is wider than the spacing between conductors.
• the electric field concentrated within the lines 4 is from about to within the lines 5 it is from about to and within the lines 6 is is approximately 99%. From the foregoing it is clear that a narrow ground conductor may be used without much radiation loss, and where it can be three or more times the width of the line conductor an exceptionally low loss transmission line is assured.
• the loss is minimized by replacing at least part of the dielectric between conductors by an air space.
• the transmission line comprises conductors 1 and 2 as in Fig. 1 but the dielectric is made up of three parts, namely, two side strips '7 and 8 and a cover strip 9.
• the two side strips 7 and 8 are formed on conductor 2 and secured thereto along the outer edge portions thereof.
• the upper layer 9 is preferably formed with conductor 1 embedded therein or coated thereon as indicated in Fig. 3.
• the upper strip is then applied to the other assembly either as shown in Fig. 2 with the conductor on the surface thereof opposed to the conductor 2, or if desired, the conductor 1 may be on the outer surface of the layer 9. In either case, an
• air space 2i is provided between the conductors 1 and 2 thereby maintaining the dielectric coeificient of the overall region bounded by the opposed surfaces of the conductors 1 and 2 at a value close to the dielectric coefficient of air.
• a similar transmission line arrangement is provided with a relatively wide air space 11.
• the conductor 1 is provided with an extended layer of dielectric 12 which corresponds to the width of the conductor 2.
• the conductor 2 is likewise provided with a dielectric layer 13.
• Interposed in the assembly at the outer edges thereof are two dielectric beads 14 and 15, which may be rectangular or other shape in cross-section, thereby insuring a wide air space 11.
• the two dielectric layers 12 and 13 are interposed between the conductors 1 and 2.
• the upper layer 12 may be inverted so as to place the conductive coating 1 on the side thereof bounding the air space 11.
• a transmission waveguide for propagating radio frequency energy comprising a first conductor, a second conductor, and means supporting said first and second conductors in closely spaced substantially parallel relation, the spacing between said first and second conductors being a small fraction of the wavelength of the mid-frequency of said radio frequency energy and the width of said second conductor being larger than the width of said first conductor to present thereto a planar surface for wave propagation in a mode simulating approximately the TEM mode with the main electromagnetic field distributed between the opposed surfaces of said conductors, said supporting means being disposed outside the main field region leaving solely an air gap separating said opposed surfaces, said gap being substantially Wider than said first conductor.
• quency energy comprising a first conductor, a second conductor, and means supporting said first and second conductors in closely spaced substantially parallel relation, the width of said second conductor being greater than the width of said first conductor to present thereto a planar conducting surface for wave propagation in a mode simulating approximately the T EM mode with the main electromagnetic field distributed between the opposed surfaces of said conductors, and said means being of dielectric material in a form to provide solely an air space having a width substantially greater than the width of said first conductor disposed directly between the opposed surfaces of said conductors and throughout the main field region.
• a transmission waveguide for propagating radio frequency energy comprising a strip of dielectric material carrying a first strip of conductive material of a given width, a second strip of conductive material facing said first strip of conductive material and of a width sufficient- 1y greater than said given width as to present to said first conductive strip a planar conducting surface, and means supporting said dielectric strip in closely spaced parallel relation to the planar surface of said second conductive strip to provide solely a dielectric air space between the opposed surfaces of said strips of conductive material and to the sides thereof to provide a mode of propagation in which the main electromagnetic field is distributed between the opposed surfaces of said conductor in said air space, with said supporting means being disposed outside of said main field region.
• a transmission waveguide for propagating radio fre quency energy according to claim 3 wherein said strip of dielectric material extends laterally with respect to the side edges of said first conductive strip, and said supporting means includes a pair of narrow dielectric strips disposed laterally of said first conductive strip in supporting engagement between said first mentioned dielectric strip and said second conductive strip.

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• Engineering & Computer Science (AREA)
• Microelectronics & Electronic Packaging (AREA)
• Waveguide Aerials (AREA)

Description

Priority Applications (8)

Applications Claiming Priority (2)

Publications (1)

Family

ID=26928021

Family Applications (1)

Country Status (4)

Cited By (22)

Citations (3)

• 0
  • BE BE512499D patent/BE512499A/xx unknown
  • NL NLAANVRAGE7018785,A patent/NL170695B/xx unknown
• 1952
  • 1952-06-30 CH CH314176D patent/CH314176A/en unknown
• 1953
  • 1953-10-28 CH CH322497D patent/CH322497A/en unknown
• 1954
  • 1954-04-27 US US425852A patent/US2800634A/en not_active Expired - Lifetime

Patent Citations (3)

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