US2097519A - Signal transmission system - Google Patents

Description

Nov. 2, 1937. J. c. GABRIEL ET AL 7 SIGNAL TRANSMISSION SYSTEM Filed Sept .J.C. GABRIEL /NV;//7'ORS. G. ROOM/V 'qq eqe e" Walla 14mg ATTORNEY Patented Nov. 2, 1937 UNITED STATES PATENT OFFICE SIGNAL TRANSMISSION SYSTEM Application September 8 Claims.

This invention relates to signal transmission systems and more particularly to tuning devices for such systems adapted for use at ultra-high frequencies.

One object of this invention is to facilitate the tuning of a high frequency transmission system.

Another object of this invention is to simplify the structure and to increase the stability of operation of tuning devices for transmission systems.

In one illustrative embodiment of this invention, a tuning device comprises a metallic tubular member having a substantially semi-cylindrical plate at one end thereof. Disposed within the tubular member is a metallic rod, which preferably is coaxial with the tubular member and is rotatable about its longitudinal axis. The rod has slidably mounted thereon a short-circuiting member or plug which contacts with the rod and the tubular member and forms an electrical connection therewith. One or more plate members are mounted on the rod and are disposed adjacent and parallel to the semi-cylindrical plate at one end of the tubular member and form a o condenser therewith.

The rod constitutes an inductive element, the active length, and hence the inductance, of which may be varied by sliding the short-circuiting member or plug along the rod. The plate and plate members constitute a condenser in shunt with the inductive element, the capacitance of the condenser being variable by rotation of the rod and hence of the plate members carried thereby. Although some distributed capacitance may exist between the metallic rod and the tubular member, because of the relatively short length of the rod and member, this capacitance is substantially negligible in comparison with the capacitance of the condenser formed by the plate and the plate members. The tuning device in accordance with this invention thus is similar to a resonant circuit of lumped constants.

In a modification of the embodiment described above, the tubular member may be en compassed by another tubular member, the two members being spaced by a dielectric material such, for example, as a sheet of mica, and forming a fixed condenser which may be used, for example, as a by-pass condenser to ground.

The invention and the features thereof will be understood more clearly and fully from the following detailed description with reference to the accompanying drawing in which:

Fig, l is a perspective view of a tuning device 5, 1935, Serial No. 39,280

constructed in accordance with this invention, a portion of the tubular member being broken away to show details of structure more clearly;

Fig. 2 is a perspective view of a modification of the tuning device illustrated in Fig. 1, portions of the outer tubular member being broken away, and

Fig. 3 illustrates one typical application of tuning devices constructed in accordance with this invention, as an interstage coupling unit, the tuning device being shown partly in cross-section.

Referring now to the drawing, the tuning de- Vice shown in Fig. 1 comprises an elongated tubular or cylindrical member ID having an apertured closure member H at one end and a substantially semi-circular plate l2 at the other end. The tubular member is of a metal having good electrical conductivity, such, for example, as copper or aluminum. Disposed within the tubular member ID and coaxial therewith is a rod l3, which also may be of aluminum or copper. A cylindrical metallic member or plug I4 is slidably mounted on the rod I3 and slidably engages the inner wall of the cylindrical or tubular member ID. A set screw l5 may be provided for fixing the plug M in a particular position on the rod l3. Another rod 16, preferably of insulating material, is coupled to the rod l3 by a sleeve connector I1 and carries a knob l8 for facilitating rotation of the rods I3 and I5.

The rod 13 carries a pair of semi-cylindrical metallic plate members l9 which are disposed on opposite sides of the plate [2 and form a condenser therewith. An electrical connection to the rod l3 may be established through a metallic strip 20, preferably of copper, which is provided with a slot 2| having arcuate surfaces engaging a reduced extension 22 on the rod l3 and is provided also with an integral tab or lug 23 to which a conductor may be secured as by soldering. The strip 20 is supported from an insulating bushing 24 carried by a bracket 25 mounted on the tubular member ID, the bushing 24 having threaded taps for receiving screws 26.

In another embodiment of this invention illustrated in Fig. 2, the cylindrical or tubular member I0 is encompassed by a similar member 21, the two cylindrical or tubular members It! and 21 being spaced by a dielectric material, as for example, by a sleeve 28 of mica.

As shown in Fig. 3, tuning devices constructed in accordance with this invention may be used as an interstage coupling unit, each stage comprising an electron discharge device 29 including, for example, a heater type cathode 30, a

control'grid 3|, an anode '32, and a screen grid 33. Suitable batteries are provided as shown for applying the requisite potentials to the various electrodes. The tubular member H1 is connected to the cathodes 3G and the strip 26 is connected by a conductor 35 to the conductor connecting the anode 32 of one'electron discharge device 29 to the grid 3| of the electron discharge device in the next stage. The outer cylindrical or tubular member 2? may be connected to ground as shown.

It will be clear from Fig. 3. that'the rod I 3 constitutes an inductance and that the plate l2 and plate members l9 form a condenser in shunt with the inductance. The cylindrical or tubular members I U and 21, together with the mica sleeve 28, form a by-pass condenser. The in-' ductance of the rod 53 may be varied by sliding the plug member 14 along the rod to 'vary the efiective length thereof. The capacitance of the condenser formed by the plate I2 and plate members l9 may be varied by rotating the rod 13. In the operation of the tuning device, the plug I4 may be fixed upon the rod IS in a predetermined position, for'example, approximately one-eighth Wave length of the frequency it is desired to transmit, and the device .may then;

' be'tuned to this frequency by rotating the rod J3.

It will be apparent that this invention provides a simple and compact tuning device which is. structurally rigid and, therefore, insures stable operation.

Furthermore, it maybe noted that the cylindrical o-r tubular members Hand 21 provide substantially complete shielding of. the

inductance element I3 so that faithful transmission between stages is assured.

Although specific embodiments of the invenf tion have been shown' and described, it will be understood, of course, that modifications may be made therein without departing from the scope and spirit of this invention as defined in theappended claims. 1

' a What is claimed is:

1. 'A'tuning device comprising a pair of conductors disposed one within the other, the inner of said members constituting an inductance element, a metallic member ,slidably mounted on the inner of said conductors, said metallic member contacting with and electrically connecting said conductors, and plate members carried by and electrically connected to said conductors and forming a condenser.

' 2. A tuning device comprising a pair of conductors disposed onewithin the otherand' one of which constitutes the inductive element of the device, means for varying the effective length of said one conductor, and means including members'integral 'with' said conductors forming a variable condenser in shunt with said inductive element.

3. A tuning device comprising a tubular metallic member having a laterally extending plate portion, a metallic rod within said tubular memher and constituting an inductive element, a metallic member slidably mounted onsaid rod and electrically connecting said rod to said tubular member, and a rotatable plate member mounted on and electrically connected to said rod, said plate member beingdisposed in juxtae position to said plate portion and forming a condenser therewith.

. 4. A tuning device comprising a pair of coaxial ment, means on said conductors forming a condenser, and means adjacent one of said con-' ductors and forming another condenser therewith, said means being insulated conductors. V W

6. A tuning device comprising a pair of-coaxial conductors the inner of which constitutes an inductance, means for varying the efiective lengthof said inner conductor, means on said conductors forming a variable condenser, and

another conductor forming another condenser withthe outer of said coaxial conductors.

Q 7. A tuning device comprising a pair of icoaxial conductors the inner of which'is rotatable and constitutes an inductance, means for varying the efiective length of said inner conductor,

a plate on the outer of said'conductors, a plate i member carried by said inner concluctorand ro-' tatable therewith, said plate and plate member being in juxtaposition and forming, a condenser, and a tubular conductor encompassing the outer and forming a conof said coaxial conductors denser therewith.

8. A tuning device comprising a' tubular nietallic member, a rod within said member, said rod constituting an inductive element, adjustable means electrically connecting said. rod and from both said said member for varying the eifective length'of.

said rod, means carried by said rod and cooperating with'a portion of said member to form a variable condenser in shunt with'said inductive element, and another tubular metallic member encompassing said first tubular member and forming a condenser therewith. 7

.JOHN C. GABRIEL.

GEORGE RODWIN DISCLAIMER 2,097,519.J0hn 0. Gabriel, New York, and George Roalwin, Randall Manor, N. Y.

SIGNAL TRANSMISSION SYSTEM. Patent dated November 2, 1937. Disclaimer filed March 24, 1939, by the assignee, Bell Telephone Laboratories, Incorporated.

Hereby enters this disclaimer to claim 1 of said Letters Patent.

Hereby disclaims from the scope of claim 2 of said Letters Patent any tuning device as therein defined except such device wherein the means forming a variable condenser in shunt with the inductive element consists of members integral with the conductors disposed one within the other.

[Ofiicial Gazette April 18, 1989.]

DISCLAIMER 2,097,519.Joh'n, 0. Gabriel, New York, and George Rod'win, Randall Manor, N. Y.

SIGNAL TRANSMISSION SYSTEM. Patent dated November 2, 1937. Disclaimer filed March 24, 1939, by the assignee, Bell Telephone Laboratories,

Incorporated. Hereby enters this disclaimer to claim 1 of said Letters Patent.

Hereby disclaims from the scope of claim 2 of said Letters Patent any tuning device as therein defined except such device wherein the means forming a variable condenser in shunt with the inductive element consists of members integral with the conductors disposed one within the other.

[Oficz'al Gazette April 18, 1939.]

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