US2044580A - Transmission line - Google Patents

Description

June 16, 1936. LEACH TRANSMISSION LINE Filed Feb. 28, l934- h Q e rm m E m e VdN n .5 6

I Patented June '16, 1 93.6

UNITED STATESPATENT oFF c i- 2.044.580 V TRANSMISSION LINE New York Application February 28, 1934, Serial No. 713,408

1 Claims. (or. 173-265)} time is so constructed that it may be readily.

disassembled for repair purposes and the like.

A further object the invention is to provide a transmission line having the above advantages and which at the same time includes means .whereby expansion and contraction of the conductors of the line may occur without injury or displacement of the line. v

The novel features which I believe to be characteristic 01- my invention are set forth with particularity in the accompanying claims. My

, invention itself however, both as to its organization and method or operation, together with further objects and advantages thereot may best be understood by reference to the accompanying drawing in which Fig. 1 illustrates an embodiment of my invention; Fig. 2 shows a cross section, in part, 'of the transmission line illustrated in Fig. 1;

thereof. 1

Referring to the drawing, I have indicated at I in Fig. 1 an antenna which is supplied with high frequency oscillations through a transmission line 2 from a transmitter, 8 which may be located'at any desired distance from the antenna. Transmitter I, for example, may be located'in a transmitter building the wall of which is indicated at Q, while the antenna I is located 5 in proximity to a second building the wall of which is'indicated at 5, the latter of which buildings may house any desired lineterminating or tuning equipment which may be employed in connection with the antenna, such for example as the elements 8 and I showmin the drawing,

and later to be described. The element 6 comprises an inductance which is connected between the antenna and the transmission line for tuning purposes. It will be observed that it is connected to a central conductor 8 which extends throughout the length or the transmission line and into the transmitter l'where it is of course connected to the output high potential circuits of the transmitter.

by means of an outer grounded concentric conductor of large diameter which is supported from the earth by means of supports 9. c

The transmission line "comprising these concentric conductors is made up in a plurality of sections it and H. The mechanical construction and Figs. 3 and 4 illustrate details This conductor is shielded of the line 'is better illustrated in Fig. 2 which shows a cross section in part of a portion of the line including, for example, sections. l8 and II of Fig. 1. It will be seen that the outer conductor of each section comprises a large conducting cylinder l2 and that the adjacent ends of adjoining sections of the cylinder l2 are connected by means of a collar l3 which slides over the outer surfaces of the two ends and forms an electrical connection between the two adjacent 10 sections of the conductor. This collar is slitted at l4 to allow it to be easily mounted over the ends of tubes l2, and additional slits, as indicated at H, are out from one edge of the collar l8. A band I5 is placed about the edge 15 of the collar opposite the slits l4, whereby the collar-may be securely clainped to one of the Y adjacent ends of the cylinder I2; for example, to the, right end of the cylinder of section M of the transmission line. The left end of the cylinder i2 of the section H of the-transmission line 20 by reason of the slits I4 is free to slide within the collar II. The sections of the inner conductor 8 are of equal length with the outer conductor and are likewise joined at the ends therecTf by means of 25 a sliding connection. This connection comprises a conducting collar I6, arranged within the collar l8, and which is securely attached, as by a'screw thread, to the 'end of one of the conductors 8, as for example to the right end of the conductor 8 of section II), and slidingly receives the adjacent end of the conductor 8 of section II. This collar I6 is supported from the collar 13 by'means of non-conducting supports 35 i1 and I8 which are better illustrated in Figs.

3 and 4.

Fig. 3 is a sectional'view taken along the line 3-8 of Fig. 2 and in the direction indicated by the arrow. In this figure the insulating support-. 40 ing members ll and'lB for the collar ii are shown extending as chords across the endof the cylinder 12 and-abutting against the inner surface of the outer collar B, the collar l8 being supported between the two non-conducting sup- 45 ports. I! and i8. In this figure the outer band l5 illustrated in Figs. 1 and 21s somewhat more clearly illustrated; this bang? being provided upon one side by projections l8 which are connected together by means of a bolt 20 whereby 9 this band is tightly drawn against the outer periphery of the collar I3 andcausing the collar 13 securely to grip the adjacent end of the conductor". u

electrostatic gradients which would produce co-= rone. between the non-conducting and lug surfaces.

The sections of the transmission line may con= veniently be about 10 feet in' length and since the outer conductor is supported at its middle point practically any see at the ends of the re== spectlve sections is svoidedfTheconnections described whereby adjacent sections are joined allow for expansion of the various sections as well as for quick removal of any section ior repair. That is, the distance between the adjacent ends of the conductor H of adjacent sections to end ii is sufliciently great to receive the supporting conductmembers If! and I8 and to allow sufficient space.

to accommodate any expansion which may take place due for example to temperature variation.

Similarly, the sliding fit between the collars i8 and the conductors 3 also allows for such expansion.

- If it be desired at any time to remove e. section of the transmission line, for example, for repairs, it is only necessary to-release the bolt 20, slide the collar 3 to the-left, remove the non-conducting members i! and i8, and thence grasp the collar I6, forcing it to the left until itclears the conductor d with which it slidingly engages. When this has been done the collar it and attached conductor t may be withdrawn from the section. It is thus seen that the transmission line is very readily assembled and discs sembled.

Fig. 4 which is' a view from line 4' of Fig. l,

shows one of the supportsjor the transmission Y line.

This supporting structure comprises. the supports 9 on either side of the transmission line provided with the cross bar 28 upon which the transmission line is mounted by means of the metallic band 23 which extends around the cylindrical member l2 and which is drawn downwardly by means of the clamps 22. T6 avoid any deformation of the cylinder l2 near the point of engagement of the cross bar M an additional metallic strip .24 .is provided betweenthe cylinder l2 and the support 2!, this member being formed to fit the outer periphery of the cylinder l2 and to engage the inner surfaces of the strip 23.

The line may be adjusted laterally by movement of the clamps 22 along the support M. It

may also be adjusted in the vertical plane by raising or lowering the support 2| upon the verticals 9 by means of clamps 25. These adjustments facilitate the alignment of the transmission line during construction.

If desired the top portions of the vertical supports may be interconnected by stringer members, 3 which are attached to the vertical supports by clamps 3 I 'As thus constructed it will be seen that the transmission line may be readily assembled and disassembledand that it, at thesame time, is adapted to accommodate any expansion and contraction which may occur due to temperature or metal employed being elunnnum.

c eeses weather variations without any likelihood of buckling or other injury to the line. The inner conductor is suiiiciently insulated from the outer conductor to withstand any high voltage which it may be desired to transmit through the line. 5

In one applicatioriof my invention the line has beenlused to transmit substgntlally 500 kw. or energy at a. frequency within the broadcast bend over a distance of opprommetely $00 feet. In this transmission. line the sections are about 10 feet in length and. the spacing between the ad- .iocent ends of the oliflerent conductor sections is 'such that approximately is inches is allowed for expansion of the verious conductors, the

15 lln this application the transmission line was demgned to have s. surge impede-nee approximately equal to the radio ireuuency resistance of the antenna. In the event of any variation of the antenna resistance from that of the surge 2Q impedance or the line one or more condensers B may be employed between the antenna and ground, thereby-to alter the apparent resistance to such an extent as to cause the=lmpedance oi the line to match that of the antenna circuit. 29. The condensers l are shown as comprinng oppov sitely extending cylinders 26 and 21 which are adjustably joined together by collars 28 thereby to constitute one plate of the condenser the opposite plate of which is a small conductor 29 extending along the axis of the cylinder. The capacitance produced'by these condensers may be varied by varying the number 01' condensers and by adjustment of the spacing between cylinders 26 and 21 by movement of the cylinders either outwardly or inwardly. The outer ends 01' the cylinders 26 and 21 are flared upwardly to form corona shields. v

While I have shown a particular embodiment of my invention it will of course be understood that 1 do not wish to be'linnted theretosincc difierent modifications may be made. 'I contemplate by the'appended claims to /cover any such modifications as fall within the true spirit and scope ofmy invention. I

What I claim as new and desire to secure by Letters Patent of the United States, is:

1. The combination, in a. high frequency transmission line, of a cylindrical conductor comprismg a. plurality of end to end sections extending throughout the length of said line, a-second conductor comprising a plurality of sections or substantially equal length with said sections of said first conductor, means to support said second conductor within saidflrst conductor with the ends ofJzhe' inner conductor sections in proximity to the ends of the outer conductor sections, said means comprising separate supports extending across adjacent ends of the outer conductor and supporting the .two adjacent ends offthe inner to conductor fori'ree longitudinal movement centrally of the outer conductor, and a. collar about adjacent ends of said outer conductor engaged by said supports whereby upon removal of said last collar said separate supportsand inner conductor 65 of an adjacent section may be readily removed while other sections of said line are maintained in normal condition.

2. A transmission line comprising a plurality of sections, each section comprising an outer con- 70 du'ctive shield and an inner conductor, the ends 01' said conductive shield and the inner conductor being adjacent, means to support each end or the inner conductor from the end of the outer conductive shield and to permit free longitudinal,

movement of one of said ends due to expansion and contraction 0! said conductor, said means comprising supports extending across an end of said outer conductive shield and supporting the adjacent end of said inner conductor and a collar about theaend of said outer conductor and engaged by said supports, and means to support the outer conductive shield at a point intermediate its ends while permitting the ends to move longitudinally due to expansion and contraction.

3. A transmission line comprising a plurality of sections, each section comprising an outer conductive shield and an inner conductor, the ends of said conductive shield and inner conductor being adjacent, a removable band about the external peripheries of each pair of adjacent ends of said outer conductive shields, a plurality oi non-conductive members extending transversely of each of said bands and supported thereby between the ends of adjacent sections or said outer, shield, said members being so shaped that they are removable upon removal of the associated supporting band, and means including said members for supporting said inner conductors within said outer conductive shields.

4. A transmission line comprising a plurality of sectionsg'each section comprising an outer conductor, the ends of said outer conductive shield and inner conductor being adjacent, means to insulate said inner conductorirom the outer conductor, said means comprising a band about the outer peripheries of adjacent ends of the outer conductive shield, a plurality of non-conductive members extending transversely of said band and supported thereby between adjacent ends of said outer conductive shield, a conductive member supported by said non-conductive members' centrally of said outer shield, said conductive member supporting said inner conductor and having conductive surfaces gradually departing from said non-conductive members to form a corona shield.

5. A transmission line comprising a plurality of sections, each section comprising a pair oi. concentric conductors oi! substantially equal length, the adjacent ends of adjoining sections being yieldingly connected by a pair 01' conducting collars, one of said collars being attached to one end of the outer conductor of one section and arranged slidingly to receive the adjacent end of the outer conductor of an adjoining sec- 5 tion and the other of said collars being attached to one end of the inner conductor of one section and arranged slidingly to receive the adjacent end or the inner conductor oi. the adjoining section, a plurality of non-conducting supporting strips extending as chords across said outer collar and abutting against the inner surface thereot. said strips supporting between them said inner collar, the spaces between the adjacent ends of the outer conductor being sufiicient to receive the ends of said strips and to allow. for expansion of said conductors and the space within the inner collar between the" ends of the inner conductor being sufllcient to allow for expansion of said inner conductors.

6. A transmission line comprising a plurality of sections of concentric conductors, each section being supported at a point intermediate its ends and being unsupported at its ends, both the outer and inner oi. said concentric conductors being 25 connected by sliding collars to corresponding conductors of adjoining sections, the sliding collar for thednnerconductor at each connection beingsupported from the sliding collar of the outer conductor, by means 0! non-conducting strips extending as chords across and within said outer collar, said strips supporting between them the collar of the inner conductor.

'7. A transmission line including a pair of sections having adjacent ends, each section com- 3 prising an outer conductive shield and an inner conductor, the ends of said conductive shield and saidconductor being adjacent, andmeans for supporting the adjacent ends of the inner conductor sections from the adjacent ends of the outer conductive sections, said means including an expansion joint comprising a conductive member mounted on an end of one of said inner conductors and slidably connected to the adjacent end of the other of said inner conductors.

EDWARD A. mach.

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