US2784379A

US2784379A - Switch for coaxial lines

Info

Publication number: US2784379A
Application number: US312758A
Authority: US
Inventors: Carl F Schunemann
Original assignee: Thompson Products Inc
Current assignee: Northrop Grumman Space and Mission Systems Corp
Priority date: 1952-10-02
Filing date: 1952-10-02
Publication date: 1957-03-05
Anticipated expiration: 1974-03-05

Description

March 5, 1957 c. F. SCHUNEMANN SWITCH FOR COAXIAL LINES Filed Oct. 2. 1952 ITZI E TZ'ZET United States Patent 6 F SWITCH FER CGAXIAL LINES Carl F. Schunemann, Cleveland, Ohio, assignor to Thompson Products, ind, Cleveland, @isic), a corporation of Uhio Application October 2, 1952, Serial No. 312,758 6 Claims. (Cl. 333-7) This invention relates to a switch for coaxial lines.

It is an object of the present invention to provide a switch for coaxial lines which will be simple and cheap in construction and reliable in operation.

it is a further object of the present invention to provide a novel switch for coaxial lines which will have a low voltage standing wave ratio and high power handling ability.

It is a further important object of the present invention to provide a novel switch for coaxial lines utilizing a ground plane conductor configuration for the radio frequency path in the switch.

it is a still further object of the present invention to provide, in a switch for coaxial lines, novel means to minimize contact resistance at switching points.

It is a still further object of the present invention to provide, in a switch for coaxial lines, a novel method and means for reducing discontinuity effects in the transition from a coaxial line to a ground plane conductor configuration.

Yet another object of the present invention is to provide a novel compact switch construction for switching co-axial lines.

It is another object of the present invention to provide a novel connector for coaxial lines utilizing a pair of plane, generally parallel, conducting paths.

The novel features which i believe to be characteristic of my invention are set forth with particularity in the appended claims. to its organization, manner of construction, and method or" operation, together with further objects and advantages thereof, may be best understood by reference to the following description taken in connection with the accompanying drawings, in which:

Figure l is a front elevational view of a switch for coaxial lines embodying the novel and distinctive characteristics of the present invention;

Figure 2 is a rear elevational view of the switch;

Figure 3 is an inside elevational view of the switch with the front panel and control knob removed; and

Figure 4 is an enlarged horizontal sectional view taken substantially along the line lV-lV of Figure 3.

The structural arrangement of one embodiment of the present invention is illustrated in detail in the drawings. More particularly, there is shown a box-like switch housing ll) having an operating knob 11 for controlling interconnection of a main coaxial line with a plurality of branch coaxial lines. As seen in Figure 2, a plurality of coaxial fittin s are provided at the rear of the switch housing for receiving the co-axial lines, the central upper fitting 3.3 constituting the main receptacle, while the

fittings

14, 15 and 1'6 constitute branch fittings for selective interconnection with the main fitting 13 by means of the switch knob 11.

l t will be observed from Figures 2 and 4 that the main fitting includes a connector ring 18 secured to the rear wall 19 of the housing coaxially with an opening 20 therein. An outer conductor tube 22 telescopes within My invention itself, however, both as,

2,7d l,37li

Patented Mar. 5, 1957 the ring 18 and is retained in assembly with the plate 19 thereby.

For positioning the inner conductor means 24 coaxially of the opening 20, a slab of dielectric 25 is secured at the inner face of the plate 3.9 with an opening 26 in the slab coaxial with the openings 20 in the plate 19. A cup or sleeve member 28 fits in the opening 26 and has a lip for abutting against the inner face of the slab 25 adjacent the openings 26. A sleeve holder 31 is press fit onto the outer periphery of the sleeve member 28 and, in turn, receives an inner conductor tube 33.

For selectively establishing continuity between the inner conductor of the main fitting 13 and one of the

branch fittings

14, 15 or 16, a switch blade 35 is provided. This blade 35 is provided with a sleeve element 36 of non-magnetic, conducting material for telescoping within the bore 37 of the sleeve member 28. For insuring good contact between the switch blade 35 and the tubing element 33, a permanent magnet 39 is secured within the bore 40 of the sleeve member 28. The sleeve 36 is interposed between the magnet 39 and the sleeve 28 It will be apparent that the blade 35 should be made of magnetic material of high permeability but low coercive force so as to be properly attracted by the magnet 39. The blade, which may be of steel, may be silver plated to afford good conductivity of the high frequency currents. The permanent magnet 39 may be of any suitable material having high coercive force, but preferably should be selected of a material which may also be silver plated for establishing good electrical contact with the switch blade, such, for example, as Ainico. The inner face of the lip 29 may also be silver plated for good contact with the switch blade.

Alternatively, a mixture, of 50% silver and 50% nickel can be used as an overlay for the permanent magnet 39 and lip 29 and also this material can be used as an insert in a brass switch blade to accomplish the magnetic contact pressure and good contact resistance desired. It has been found that the utilization of magnetic joints between the fittings and the switch blade reduces losses in the switch, and, therefore, increases its power handling capacity.

The branch fittings have permanent magnets 39' which are mounted similarly to the magnet 39. The space between the inner part of the sleeve member 28 and the permanent magnet 39' may be filled with solder as indicated at 45. The branch fittings are otherwise entirely similar to the main fitting 13, and corresponding primed reference numerals have been applied to corresponding parts.

An operating shaft 46 is secured to the blade 35 by means of a cup receptacle l7 and pin 48, and the knob 11 is connected to the front end of the operating handle 46 exteriorly of the housing 1 as shown in Figure 1.

Switching is thus accomplished by rotating the shaft 46 by means of the knob 11. to move the switch blade 35 selectively into contact at its free end with one of the ranch fitting permanent magnets 39'. It will be observed that the switch utilizes a ground plane conductor configuration for the radio frequency path in the switch.

Thus, the interior surface 56 of the conducting plate 19 acts as a ground plane while the switch blade 35 acts as a single conductor above the ground plane with the dielectric 25 interposed therebetween. It has been found that by proper proportioning of the width of the blade 35 and proper selection of the spacing of the blade from the ground plane 59 for the dielectric used, a characteristic impedance can be obtained which will match that of the coaxial lines.

It is additionally desirable that the efiects of the discontinuity in impedance at the transition from the coaxial line to the ground plane conductor be minimized. It has been found that this may be accomplished by utilizing a switch blade which will overhang at each end beyond the center conductor to'such an'e'xten't asto' overlie opposite portions of the outer conductor tubing such as 22. As seen in Figure 4, one end of theswitch blade 35 extends approximatelyto adjacent the edge of thelopening 20 in the plate 19 while the opposite end 52 extends to the opposite edge of the branch opening 20. With such an overhang, an extremely good VSWR characteristic is obtained.

For example, the voltage standing wave ratio does not exceed 1.1 in the range between 40 arid 500 megacycles forthe switch illustrated in the drawings. Versions of this switch modified for the type N connector havebeen operated up to 3000 megacycles with less'than 1.5

By way of example, in the switch illustrated in the drawings, the outer conductor of the coaxial lines has an outside diameter of 3 /s'inches and the inner conductor has an outside diameter of approximately 1.20 inches. With a polystyrenedielectric slab A1 inch thick, the switch blade Twas found to require a width of 1% inches to ob tain a characteristic impedance of 51.5 ohms and thus to match the coaxial lines. The overhang of the switch blade should be such as to extend across the diameter of the outer conductors of the'coaxial lines as illustrated in Figures 3 and 4, for minimizing discontinuity effects. The thickness of the dielectric is not extremely critical with the ground plane conductor configuration vbecause the characteristic impedance varies'rou'ghly with the square root'of the thickness dimension.

Because of the confining of the field to the area close to the blade in this switch, the metallic enclosure of the box-like housing has negligible effect if far enough removed from the dielectric and blade. In the switch illustrated, a box depth of approximately 5 inches and clearance from coaxial outlets of approximately 2 inches was found to yield excellent voltage standing wave ratio, substantially the same as without the metallic enclosure present.

Thus, in the embodiment illustrated, the front wall a of the housing is spaced approximately 5 inches from the rear wall 19, Figure l, and the

side walls

10b, 10c, 10d and 10e are spaced approximately 2 inches from the openings and 20', Figure 3.

It will be understood that modifications and variations may be effected without departing from the scope of the novel concepts of the present invention.

I claim as my invention:

1. A switch for coaxial lines comprising a conducting surface having a plurality ofv openings therethrough, ce-l axial fittings associated with said openings including outer conductors for continuity with said surface and inner conductors extending through said openings,'and a moyi ableconductor for selectively connectingthe inner conductors of said coaxial fittings, said conducting surface and said movable conductor together constituting a ground plane type energy transmission path, and said movable conductor when interconnecting a pair of inner conductors extending at both ends beyond the inner conductors to reduce discontinuity in the transition from the coaxial lines to the ground plane line.

"2. A switch for coaxial lines comprising a conducting plate having a plurality of openings therein, coaxial ,fit

ti'ngs on one side of said plate for receiving said coaster lines including outer conductor means in electricalcontinuity with said plate and extending axially of the respe'ctive openings in said plate and inner conductor means, said inner conductor means having a portion extending through therespective openings and projecting beyond the opposite side of said plate, and a movable switch blade having a flat elongated conducting surface for selective electrical continuity with said portions of said inner conductor meansfsaid plate and said conductingssurfacc togetherconstituting a ground plane type energy transmission path, and said switch blade when in electrical continuity with a pair of said inner conductor means overlying a di t o t e a o i ed o nin s in a d plate to reduce discontinuity effects.

3. A switch for coaxial lines comprising a conducting plate having a plurality of openings therein, coaxial fittings on one side of said plate for receiving said coaxial lines including outer conductor means in electrical continuity with said plate and extending axially of the respective openings in said plate and inner conductor means, said inner conductor means having a portion extending through the respective openings and projecting beyond the opposite side of said plate, a movable switch bladehaving a flat elongated conducting surface for selective electrical continuity with said portions of said inner conductor means, said conducting plate and switch blade conducting surface together constituting a ground plane type energy transmission path, said switch blade having magnetic material associated therewith, and permanent magnets disposed within said inner conductor portions for attracting said magnetic material of said switch blade to hold the conducting surface of the switch blade in good electrical continuity with said inner conductor portions.

4. In a switch for coaxial lines, a wall of conductive material having a plurality of openings therethrough, a plurality of coaxial line means including inner conductors and outer conductors surrounding said inner conductors and having terminal ends electrically joined to saidwall about said openings, and a switching conductor supported 'for movement in a path in spaced parallel relation to one surface of saidwalland arranged to selectively connect the terminal ends of said inner conductors,'said switching conductor and said one surface of said wall together constituting a ground plane type transmission line section which provides the sole coupling between said coaxial line means.

5, In a switch for. coaxial lines, a wall of conductive material having'a plurality of openings therethrough, a plurality of coaxial linemeans including inner conductors and outer. conductors surrounding said inner conductors and haying t erminal ends electrically joined to said wall about said openings, and a fiat blade switching conductor supported for movement in a path in spaced parallel relation to one. surface of said wall and arranged to selectively connectthe terminal ends of said inner conductors, said switching conductor and said one surface of said Well together constituting a ground plane type transmission. line section which provides the sole coupling between said coaxial line means.

'6. In" a s witch' for selectively interconnecting one co -V aboutithe axisof said one coaxial line in a path in spaced,

parallel relation to onersurfacefof said wall to selectively engage the other end of said conductor with the inner conductors of saidother coaxial lines, said switching conductor. and said one surface of said wall together con? stituting a ground plane'type' transmission line section which provides'the solecoupling between said coaxial lines.

References Cited in the fileof this patent UNITED STATES PATENTS 2,159,648; Alford May 23, 1939 2,324,22 Lamb July 13, 19.43 2,344,780 Kram et al. Mar. 21-, 1944- 2,443,635 Morris et al. June 22, 1948 2,498,907, Atwood et al.v Feb. 28, 19-50 2,6,11, '8-22 Bliss Sept. 23, 1952- 169176]: Charles Dec. 21, 1954