US2794848A - Transmission line - Google Patents
Transmission line Download PDFInfo
- Publication number
- US2794848A US2794848A US367916A US36791653A US2794848A US 2794848 A US2794848 A US 2794848A US 367916 A US367916 A US 367916A US 36791653 A US36791653 A US 36791653A US 2794848 A US2794848 A US 2794848A
- Authority
- US
- United States
- Prior art keywords
- spacers
- transmission line
- wires
- wire
- line
- 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
Links
- 230000005540 biological transmission Effects 0.000 title description 25
- 125000006850 spacer group Chemical group 0.000 description 25
- 239000012212 insulator Substances 0.000 description 12
- 238000004519 manufacturing process Methods 0.000 description 5
- 239000004793 Polystyrene Substances 0.000 description 4
- 239000000463 material Substances 0.000 description 4
- 229920002223 polystyrene Polymers 0.000 description 4
- 239000004033 plastic Substances 0.000 description 3
- 229920001169 thermoplastic Polymers 0.000 description 3
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 2
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 2
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 description 2
- 239000011248 coating agent Substances 0.000 description 2
- 238000000576 coating method Methods 0.000 description 2
- 229910052802 copper Inorganic materials 0.000 description 2
- 239000010949 copper Substances 0.000 description 2
- 230000001681 protective effect Effects 0.000 description 2
- 229910052709 silver Inorganic materials 0.000 description 2
- 239000004332 silver Substances 0.000 description 2
- 239000004416 thermosoftening plastic Substances 0.000 description 2
- 239000000919 ceramic Substances 0.000 description 1
- 239000004020 conductor Substances 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 210000003298 dental enamel Anatomy 0.000 description 1
- 235000012489 doughnuts Nutrition 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 239000011810 insulating material Substances 0.000 description 1
- 238000009413 insulation Methods 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 238000007747 plating Methods 0.000 description 1
- 239000011347 resin Substances 0.000 description 1
- 229920005989 resin Polymers 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 239000007858 starting material Substances 0.000 description 1
- 239000012815 thermoplastic material Substances 0.000 description 1
Images
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
- H01P3/04—Lines formed as Lecher wire pairs
Definitions
- TRANSMISSION LINE Filed July 14, 1955 IIE E w -zv B Y ,4 member of #1: firm nited States Patent TRANSMISSION LINE Application July 14, 1953, Serial No. 367,916 1 Claim. (Cl. 174-113)
- This invention relates to an open wire transmission line and the method of making the same.
- the transmission line of the present invention is particularly adapted for the carrying of ultra-high frequency electric currents, and as such finds its most common application as television lead-in wire, although many other uses will be apparent to those skilled in the art.
- Another object of this invention is to provide an air insulated transmission line having spacers wherein the spacers have a leakage path substantially longer than the distance between the two transmission wires.
- Still another object of this invention is to provide a simple and effective method of making an open wire transmission line having the above enumerated desirable characteristics.
- Figure 1 is a perspective view of a transmission line made in accordance with the present invention.
- Figure 2 is a cross-section of one of the spacers of the transmission line of Figure 1.
- FIGS 3 through 6 illustrate various embodiments of the spacers which may be used for transmission lines in accordance with the present invention.
- the wires 8 may be of any suitable material such as iron or copper and preferably have plated thereon a thin layer of a highly conducting material 14, such as silver. Tubing may be used instead of wire. Over the silver plating is preferably an outer coating of a protective material 16.
- the protective material 16 ordinarily serves to insulate the wire but, more important, makes the wire 2,794,848 Patented June 4, 1957 '2- corrosion-resistant. In this manner, the effects of weathering on the transmission lines are greatly lessened and the transmission line retains its original low attenuation for a long period of time, even when exposed to the elements.
- One particularly suitable coating 16 consists of Formvar, which is a polyvinylmethylal resin.
- the spacers 12 may be of any suitable insulating material such as plastic, ceramic or glass. However, because of the ease of fabrication, coupled with good electrical properties, we prefer to use a thermoplastic plastic such as polystyrene. Polystyrene is particularly suitable since it lends itself to an easy method of fabricating the line, as is set forth in more detail below.
- a preferred method of making the transmission line of the present invention is to first form an open wire transmission line having a spacing about twice the desired ultimate spacing, using straight spacers of a thermoplastic material such as polystyrene.
- the line which is used as a starting material may suitably be a transmission line having straight spacers, as illustrated in our pending patent application, Serial No. 280,416.
- the center of each of the plastic spacers may be heated until the central portion becomes somewhat softened.
- Each insulator may then be bent to the shape shown in Figure 2.
- the plastic insulators become rigid so that the line is left in the condition shown in Figure 1.
- polystyrene rod was employed as a spacing material, said rod having a diameter of A".
- the rod was cut into sections each about 1% long and No. 18 copper wires, which had been silver-plated and coated with Formvar enamel, were embedded in the ends of the spacer so that the spacing between the wires was about 1".
- the spacers were located about 6" apart on the wires.
- the centers of the spacers were then heated and the spacers bent into a U-shape, as illustrated in Figure 2, so that the wires were brought to a separation of about /2".
- a line formed in this manner has a surge impedance of slightly less than 400 ohms, has no substantial amount of dielectric, other than air, in the high intensity field between the wires, and the insulators have a much longer leakage path than would be obtained if straight insulators were used.
- the spacing of the insulators along the wire is not critical and distances of from 6" to 12 have been employed. It is often advantageous to not space the insulators at regular intervals, but to place them irregularly along the wire in orderthat resonances may be avoided.
- the spacers may be made in a variety of forms, but in each of the forms, the leakage path between the wires is much longer than if straight insulators were employed and there is no substantial amount of insulation between the wires in the high field portion.
- an insulator 18 is employed which is made in a rectangular U-shape.
- an insulator 20 is illustrated which is made in the form of a doughnut, the sides being slightly elongated.
- an insulator is illustrated made in the form of a sharp V.
- an insulator is illustrated wherein the insulator is in the shape of a U, with the sides of the U pressed outwardly.
- An open Wire transmission line comprising a pair of parallel spaced wires, said spaced Wires being held in a spaced relationship by a series of spacers thereon, said spacers being of a U-shaped configuration wherein the 3 .wires are gripped at the ends. of the U, the distancebetween said spacers along said transmission line being rela tively large as compared with the distance over which said spacers are in contact with the transmission line.
Landscapes
- Insulating Bodies (AREA)
Description
June 4, 1957 IIIE S J. D. GIULIE ETAL 2,794,848
TRANSMISSION LINE Filed July 14, 1955 IIE E w -zv B Y ,4 member of #1: firm nited States Patent TRANSMISSION LINE Application July 14, 1953, Serial No. 367,916 1 Claim. (Cl. 174-113) This invention relates to an open wire transmission line and the method of making the same. The transmission line of the present invention is particularly adapted for the carrying of ultra-high frequency electric currents, and as such finds its most common application as television lead-in wire, although many other uses will be apparent to those skilled in the art.
In recent years, it has been common practice to carry both high frequency and very high frequency electric currents on open wire transmission lines. One typical line consists of two No. 18 wires spaced about 1 apart and held in place by a series of thermoplastic spacers such as set forth in our patent application Serial No. 280,416, filed April 3, 1952. Such transmission lines are very effective for carrying very high frequency current, but have a higher attenuation when one attempts to carry ultra-high frequency currents on the lines. One reason for this is that the spacing of the wires becomes an appreciable fraction of a Wave length so that the wires tend to radiate. Further, since the dielectric spacers occupy the region of the most intense field, i. e., directly between the wires, the spacers introduce a further degree of attenuation.
If one attempts to remedy this situation by merely using shorter spacers, the spacers still occupy the most intense field and have a short leakage path.
It is an object of the present invention to provide a transmission line for the transmission of ultra-high frequency electric currents wherein the dielectric is substantially entirely air and only an inconsequential amount of solid dielectric appears between the two parallel lines.
Another object of this invention is to provide an air insulated transmission line having spacers wherein the spacers have a leakage path substantially longer than the distance between the two transmission wires.
Still another object of this invention is to provide a simple and effective method of making an open wire transmission line having the above enumerated desirable characteristics.
Referring to the drawings:
Figure 1 is a perspective view of a transmission line made in accordance with the present invention.
Figure 2 is a cross-section of one of the spacers of the transmission line of Figure 1.
Figures 3 through 6 illustrate various embodiments of the spacers which may be used for transmission lines in accordance with the present invention.
Referring to the drawings by reference characters, there is shown a transmission line having two parallel wires 8, which are held in spaced relationship by a spacer member 12. The wires 8 may be of any suitable material such as iron or copper and preferably have plated thereon a thin layer of a highly conducting material 14, such as silver. Tubing may be used instead of wire. Over the silver plating is preferably an outer coating of a protective material 16. The protective material 16 ordinarily serves to insulate the wire but, more important, makes the wire 2,794,848 Patented June 4, 1957 '2- corrosion-resistant. In this manner, the effects of weathering on the transmission lines are greatly lessened and the transmission line retains its original low attenuation for a long period of time, even when exposed to the elements. One particularly suitable coating 16 consists of Formvar, which is a polyvinylmethylal resin.
The spacers 12 may be of any suitable insulating material such as plastic, ceramic or glass. However, because of the ease of fabrication, coupled with good electrical properties, we prefer to use a thermoplastic plastic such as polystyrene. Polystyrene is particularly suitable since it lends itself to an easy method of fabricating the line, as is set forth in more detail below.
A preferred method of making the transmission line of the present invention is to first form an open wire transmission line having a spacing about twice the desired ultimate spacing, using straight spacers of a thermoplastic material such as polystyrene. The line which is used as a starting material may suitably be a transmission line having straight spacers, as illustrated in our pending patent application, Serial No. 280,416. After forming a transmission line using straight, thermoplastic spacers, the center of each of the plastic spacers may be heated until the central portion becomes somewhat softened. Each insulator may then be bent to the shape shown in Figure 2. Upon cooling, the plastic insulators become rigid so that the line is left in the condition shown in Figure 1.
In one typical operation, polystyrene rod was employed as a spacing material, said rod having a diameter of A". The rod was cut into sections each about 1% long and No. 18 copper wires, which had been silver-plated and coated with Formvar enamel, were embedded in the ends of the spacer so that the spacing between the wires was about 1". The spacers were located about 6" apart on the wires. The centers of the spacers were then heated and the spacers bent into a U-shape, as illustrated in Figure 2, so that the wires were brought to a separation of about /2".
A line formed in this manner has a surge impedance of slightly less than 400 ohms, has no substantial amount of dielectric, other than air, in the high intensity field between the wires, and the insulators have a much longer leakage path than would be obtained if straight insulators were used.
The spacing of the insulators along the wire is not critical and distances of from 6" to 12 have been employed. It is often advantageous to not space the insulators at regular intervals, but to place them irregularly along the wire in orderthat resonances may be avoided.
Although it is generally preferred to make the spacers in a U-shape, as is illustrated in Figures 1 and 2, the spacers may be made in a variety of forms, but in each of the forms, the leakage path between the wires is much longer than if straight insulators were employed and there is no substantial amount of insulation between the wires in the high field portion.
Thus, in Figure 3, an insulator 18 is employed which is made in a rectangular U-shape.
In Figure 4, an insulator 20 is illustrated which is made in the form of a doughnut, the sides being slightly elongated.
In Figure 5, an insulator is illustrated made in the form of a sharp V.
In Figure 6, an insulator is illustrated wherein the insulator is in the shape of a U, with the sides of the U pressed outwardly.
I claim:
An open Wire transmission line comprising a pair of parallel spaced wires, said spaced Wires being held in a spaced relationship by a series of spacers thereon, said spacers being of a U-shaped configuration wherein the 3 .wires are gripped at the ends. of the U, the distancebetween said spacers along said transmission line being rela tively large as compared with the distance over which said spacers are in contact with the transmission line.
References Cited in the fiIe of this patent UNITED STATES PATENTS 2,158,496 George May 16, 1939 4 2,428,052 Touraton Sept. 30, 1947 2,543,696 Krueger Feb. 27, 1951 FOREIGN PATENTS 947,544 France Jan. 10, 1949 665,239 Great Britain Jan. 16, 1952 OTHER REFERENCES
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US367916A US2794848A (en) | 1953-07-14 | 1953-07-14 | Transmission line |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US367916A US2794848A (en) | 1953-07-14 | 1953-07-14 | Transmission line |
Publications (1)
Publication Number | Publication Date |
---|---|
US2794848A true US2794848A (en) | 1957-06-04 |
Family
ID=23449145
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US367916A Expired - Lifetime US2794848A (en) | 1953-07-14 | 1953-07-14 | Transmission line |
Country Status (1)
Country | Link |
---|---|
US (1) | US2794848A (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
FR2615039A1 (en) * | 1987-05-05 | 1988-11-10 | Thomson Csf | Symmetric supply line, in particular for decametre waves |
Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2158496A (en) * | 1935-06-20 | 1939-05-16 | Rca Corp | Transmission line |
US2428052A (en) * | 1940-04-13 | 1947-09-30 | Int Standard Electric Corp | Antenna support |
FR947544A (en) * | 1947-06-05 | 1949-07-05 | Multiple electrical conductor and tool for bending this conductor | |
US2543696A (en) * | 1948-09-18 | 1951-02-27 | American Phenolic Corp | High-frequency transmission cable |
GB665239A (en) * | 1949-07-26 | 1952-01-16 | Bertrand Zucker | Improvements in or relating to electric cables |
-
1953
- 1953-07-14 US US367916A patent/US2794848A/en not_active Expired - Lifetime
Patent Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2158496A (en) * | 1935-06-20 | 1939-05-16 | Rca Corp | Transmission line |
US2428052A (en) * | 1940-04-13 | 1947-09-30 | Int Standard Electric Corp | Antenna support |
FR947544A (en) * | 1947-06-05 | 1949-07-05 | Multiple electrical conductor and tool for bending this conductor | |
US2543696A (en) * | 1948-09-18 | 1951-02-27 | American Phenolic Corp | High-frequency transmission cable |
GB665239A (en) * | 1949-07-26 | 1952-01-16 | Bertrand Zucker | Improvements in or relating to electric cables |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
FR2615039A1 (en) * | 1987-05-05 | 1988-11-10 | Thomson Csf | Symmetric supply line, in particular for decametre waves |
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