US2432230A - Electrical apparatus - Google Patents

Description

Dtc. 9, 1947. A DQRNE 2,432,230

ELECTRICAL APPARATUS Filed March 29, 1946 l: IG. 2

`mwiwron ARTHUR ooRNE v y BY l "7W ifi/,Luna

AT TVQRNEY lPatented Dec. 9,1947

UNITED STATES PATENT OFFICE.,

ELECTRICAL APPARATUS States of America,

tary of War Arthur Dome, Freeport. N. Y., assigner to United as represented by the Secre- Appiication March 29, 1946, Serial No. 657,940

2 Claims.

ventional switches, operable at low radio frequencies, are unsatisfactory for use at high frequencies because of their geometrical configuration and electrical properties. Even the simple conventional single pole double throw switch,

representative of low frequency switching devices, presents an impedance mismatch tolines carryinghigh Ifrequency currents and has suiiicient capacitive coupling between elements to prohibit its"\i1se with high frequency circuits. This impedance mismatch and capacitive cou- .pling causes standing waves and undesirable cross talk in high frequency circuits.

The availability of aswitching device, operable at high radio frequencies, wouldr find wide' usage in electrical apparatus.

- It is an object of the present invention to provide-a switching device particularlyadapted for use in electrical circuits carrying high frequency currents.

It is another object to provide a single pole` double throw switch for use with electrical ciry cuits carrying high frequencyV currents.

It is also an object to provide an electrical switching device which has a low value of capacitance between switching elements and which has a value of characteristic impedance of the order of the characteristic impedance of common coaxial transmission lines.

An electrical switching device, which accomplishes the aforesaid'object consists of a rectangular block of metal with a single conventional coaxial transmission line connector attached to one end and with two similar connectors attached to the other end of the metallic y block. f v

Each of the three cable connectors are interconnected by tubular passages cut in the metallic block. These interconnecting passages intersect to form a Y, with the leg of the Y leading to the single connector at one end of the metallic block and with the arms of the Y leading to the pair of connectors at the other end of the metallic block The periphery of each of these passages forms the outer conductor of one of three intersecting coaxial transmission lines and each passage concentrically encloses a center conductor. Thus, three intersecting coaxial transmission lines are formed. Where the center conductors would normally intersect, a nonmetallic plunger is inserted in the metallic block and is fastened to each of the center conductors of the coaxial transmission lines forming the legs of the Y.

These two center conductors, which are fastened to the plunger, are arranged so that when one is in contact with the center conductor of the coaxial transmission line forming the leg of the Y, the other center conductor is grounded to its outer conductor. Longitudinal movement of the plunger reverses the condition of the twoA center conductors of the coaxial transmission lines forming the legs of the Y.

Other objects, features and advantages of this invention will suggest themselves to those skilled in the art and will become apparent from the following description of the invention taken in connection with the accompanying drawing in which:

Fig. 1 is a plan view of a device embodying the principles of this invention; and.

of the block and two similar coaxial transmis- Fig. 2 is an elevation of Fig. 1 with a portion cut away to show the internal mechanism.

Referring now to Fig. 1. a rectangular metallic block consisting of two similar halves, upper half I 0 and lower halt II, is held together by bolts such as I2. A conventional coaxial transmission line connector I3 is attached to one end sion line connectors .I4 and I5 respectively, are attached to the other end of the block.

Grooves having a semi-circular cross section are milled in each half I 0 and II of the metallic block. The grooves cut in half I0 coincide with the grooves cut in half I l, resulting in a passage whose total cross section is in the form of a circle. These passages interconnect the three connectors' I 3..I4 and I5, and intersect to form a Y with the leg of the Y leading to connector I3 and with th'e arms of the Y leading to connectors I4 and I5.

The periphery of each of these passages forms the outer conductor of a coaxial transmission line. A center conductor I 5 is coaxially contained in the passage leading to connector I3 and similarly, center conductors I6 and II are contained in the passages leading to` connectors Il and I5. These center conductors are held in place by spacers I8, I9 and 20. At the intersection of the passages, two spring'leaves 2| and 22 are attached to operating plunger 2:3. An end of leaf 2I is connected to center conductor I6 and an end of leaf 22 is connected to center conductor 3 I1. The other ends of leaves 22 and 22 are silver plated to reduce contact resistance.

Referring now to Fig. 2, it can be seen that longitudinal movement of plunger 2l forces the silver plated end of leaf 2i against the upper half I0 of the metallic block and that the silver plated end of leaf 22 is forced against conductor IU.

Longitudinal movement of plunger 2l in the opposite direction forces the silver plated end of leaf 2| in contact with conductor l5 and forces the silver plated end of leaf 22 in contact with the lower half il of the metallic block. The end of conductor It, which makes contact 4with leaves 2l and 22, is flattened and is also silver plated to reduce contact resistance. The principle of this device is similar to that of a single pole double throw switch. When plunger 23 is in one position, there is electrical continuity between connector I3 and connector I4, and at the same time, the inner conductor leading from connector I! is grounded. Consequently,` there can be no cross talk between the circuits associated with connector l5 and the circuits associated with the other two connectors.. When plunger 2l is in the other position, thre is electrical continuity between connector l and connector lli. and at the same time the in'ner conductor leading from connector I4, is grounded. Thus the eiect of any capacity existing between parts of the switching device is nulliiled.

Impedancel mismatches due to this switching device are minimized by the proper design of its components. The relative size of the inner and outer conductors of this switching device is proportioned to obtain a characteristic impedance which is comparable in value to the characteristic impedance of commonly used coaxial transmission lines.

A switching device constructed'according to the teachings of this specification has been found operable at frequencies as high as 5000 megacycles.

It will be apparent that there may be deviations from the invention as described which still fall fairly within the spirit and scope of the invention.

Accordingly all such deviations are claimed which fall fairly within the spirit and scope of the invention as identified in the hereinafter appended claims.

What is claimed is:

1. A switching device for use with high frequency electrical currents including a rectangular metallic block with three intersecting holes drilled in said block to form the periphery of the outer conductors of three coaxial transmission lines, two flexible center conductors each concentrlcally enclosed by one oi' said outer conductors of said transmission lines, one rigid center conductor concentrically enclosed by one of said outer conductorsl of said transmission lines and a nonconducting operating plunger inserted in said metallic block near the intersection of said transmission lines with said flexible center conductors attached to said plunger whereby movement of said plunger forces one of said flexible center conductors into electrical contact with said rigid center conductor and simultaneously the other ci said two flexible center conductors is forced into electrical contact with its outer conductor.

2. A switching device for use with high frequency electrical ciments including three intersecting coaxial transmission lines each comprising an outer conductor and a center conductor with two of said center conductors made of ilexibie material and with the other center conductor made of a rigid material, a control plunger inserted in said coaxial transmission lines at their intersection and attached to said two ilexible center conductors whereby movement oi' said plunger forces one of said two flexible center conductors into electrical and physical contact with its outer conductor and simultaneously the other of said two flexible center conductors is forced into electrical and mechanical contact with said rigid center conductor.

ARTHUR DORNI;

REFERENCES 0mm UNITED STATES PATENTS Name Date Schriener T- Nov. 25, 1941 Number

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