US2521829A

US2521829A - Adjustable length coaxial transmission line

Info

Publication number: US2521829A
Application number: US631182A
Authority: US
Inventors: James L Clark
Original assignee: Individual
Current assignee: Individual
Priority date: 1945-11-27
Filing date: 1945-11-27
Publication date: 1950-09-12
Anticipated expiration: 1967-09-12

Description

J. L. CLARK ADJUSTABLE LENGTH COAXIAL TRANSMISSIONr LINE sept., 12, 195o Filed Nov. 27, 1945 nvm-vwo@A `JAMES l.. CLARK Patented Sept. 12, .1950

James =L. lClark,l Cambridge, Mass., assigner to the United States of America as represcntedvby the Secretary of War Application November 27, 1945,.seria1fN0.-c31,1s2 7 This invention relates generallyto electrical apparatus and more particularly to coaxial transmission lines.

Often it is desirable to tune a coaxial transmission line by means of an associated coaxial transmission line` having an adjustable shorting plunger. `Such a tuning stub having a movable shortng plunger is usually arranged to permit the excursion of the shorting plunger to extend substantially the entire length of the coaxial transmission line tuning stub.

Such a required excursion of the shorting plunger is often mechanically undesirable.

The required excursion of such a shorting plunger can be substantially reduced by having the coaxial transmission line tuning stub adjuste able in length.

It is an object of the present invention to pro- Vide an adjustable length coaxial line.

More specically it is an object of the present invention to provide a means for changing the effectvie length of a coaxial transmission line whose overall dimension is determined by stacking several lines together and connecting the desired lengths by the use of a switching end plug.

`Several coaxial lines of different lengths are stacked together and at one end all lines terminate in a common plane which is at right angles to the longitudinal axes of the lines. At that end of the coaxial transmission lines there is provided a switching plug having terminals which connect together two or more lines, the total length of these connected lines being equal to the desired total length of line.

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 drawings in which:

Fig. 1 is an elevation of a device embodying the principles of this invention;

Fig. 2 is a side view of Fig. l

Fig. 3 is an elevation of a switching plug associated with the device shown in Figs. 1 and 2;

Fig. 4 is a side view of Fig. 3;

Fig. 5 is a schematic representation of the electrical circuit obtained by the use of the devices shown in Figs. 1, 2, 3, and 4; and

Fig. 6 is a schematic representation of an alternate electrical circuit obtained by the use of the devices shown in Figs. 1, 2, 3, and 4.

Referring now to Figs. 1 and 2, a framework IIl has four holes bored to receive and hold four 3 Claims. (Cl. 17E-44) coaxial transmission lines I I, I2, I3 and I4. Co- 55 i 2 l axial transmission lines II, I2, I3, an`d' I 4 terminate in a common plane determined by a' face of framework I0, o

' llt should be noted that the portions II and I2 formed from a'singlelength of line 22, terminate in framework I 0, and that coaxial transmission line I4 has a movable shorting plunger I5. Coaxial transmission line I3 is characterized by an inductive coupling loop IB which is formed from the inner conductor of that line where that. inner conductor breaks the confinement of its associated outer conductor. I

Referring now to Figs. 3 and 4, a switching plugl I'I has four terminals I8, I9, 20 and 2I,l respec tively, with terminals I8 and I9 electrically con-- nected 'and terminals 20 and 2l electrically connected. Terminals I8, I9, 20 and v2I are disposed at f-degree intervals about the circumference of a circle whose center coincides with the center of a face of switching plug I1.

In Figs. 1 and 2 coaxial transmission lines 22, I3, and I4 are similarly disposed in `framework I0 and the hollow inner conductors receive and make contact with the terminals of switching plug I'I of Figs. 3 and 4.

Fig. 5 shows the resulting circuit when switching plug II is inserted in framework I 0 such that terminals 20 and 2l connect together the inner conductors of coaxial transmission lines I3 and I4.

Fig. 6 shows the resulting circuit when switching plug I'I is rotated 90 degrees from the position assumed in the above paragraph. Under these conditions, terminals I8 and I9 of switching plug II connect together the inner conductors of coaxial transmission lines 22 and I3 and

terminals

20 and 2| of switching plug II connect together the inner conductors of coaxial transmission lines 22 and I4.

The apparatus shown in the drawings which embodies the principles of the invention herein disclosed is a means for extracting radio frequency energy from an open line type oscillator tank circuit and the presentation of that energy to an antenna or other load. For example, radio frequency energy may be coupled from a given source by means of coupling loop I 6 of line I3 and transmitted to any load (not shown) connected to one end of line I3. Lines 22 and I4 are connected to the other end of line I3 by means of a switching plug I'I, resulting in the circuit shown in Fig. 6. An alternate interconnection made possible by rotating switching plug I1 90 degrees, results in the circuit shown in Fig. 5 in which line I4 only is connected to line I3.

Under the latter conditions, line 22 forms no part of the operating circuit.

Depending upon the frequency o operation, either of the two above connections may be made by switching plug I1 and line I3 can be tuned by adjusting shorting plunger I5 in line I 4.

The ability to remove or add line 22 to the operating circuit by the simple method of removing switching plug I'I, rotating it 90 degrees, and then reinserting it, provides a means for effectivelyr changing the length of the tuning line associated with line I3.. Accordingly, the required excursions of shorting plunger I5 in line I 4 to accomplish tuning are substantially reduced even though the operating frequency range of the device is quite large.

It will be apparent that'there may be .deviations from the invention as described Which still vention.

Accordingly I claim all such deviations which.

fall fairly Within the spirit and scope of the invention as identied in the hereinafter appended claims.

What is claimed is:

1. An adjustable length coaxial line comprising a first coaxial transmission line. having an inner conductor and an outer conductor, means at one end for connecting said line to a load, means at an intermediate position along said line for connecting said line to a generator, a second coaxial transmission line having an inner conductor and an outer conductor, a movable shortingplunger in said second line, a third coaxial transmission line having an inner conductor and an outer conductor bent in a' generally U shape, said ylines being vstacked together with the endv of :said klines terminating in a common plane at right angles to thelongitudinal axes of said lines, and. lmeans including a switching plughaving four'terminals with pairs of said terminals electrically .connected for making the desired-interconnections .between .I

the inner conductors of said lines,v whereby vthe .4 effective length of said first coaxial transmission line is altered.

2. A n adjustable length coaxial line comprising a, rst coaxial transmission line having an inner conductor and an outer conductor, means at one end for connecting said line to a load, means at an intermediate position; along said line for. connecting said; line toa'generator, a second coaxial transmission line having an inner conductor and an outer conductor, a movable snorting plunger in said second lineI a third coaxial transmission line having an inner conductor and an outer conductor bent in a generally U shape.. and means including a switching plug'having four terminals with pairs of said terminals electrically connected for making the desired .interconnections between the inner conductors of said lines, whereby the effective length of said'iirst coaxial transmission line is altered.

3. An adjustable length coaxial line comprising a plurality of coaxial.transmission.line.s, each of said lineshaving an inner conductor., said lines being stacked in such a manner that an end of each of'said lines terminates in a common plane, .and means including a switching plugv having a plurality of terminals, said tern1i` nals electrically connected in pairs for interconenecting the .inner conductors of said lines, whereby the eiective length .0f said coaxial transmission lines is altered. y

JAMES L. CLARK.

REFERENCES CITEDy The following references are of record in the le of'this Vpatent:

y UNITED STATES PATENTS Kline Apr. 8,3 1947