US2596002A

US2596002A - Device for ultrahigh frequencies

Info

Publication number: US2596002A
Application number: US682986A
Authority: US
Inventors: Zaayer David
Original assignee: Hartford National Bank and Trust Co
Current assignee: Hartford National Bank and Trust Co
Priority date: 1943-02-22
Filing date: 1946-07-12
Publication date: 1952-05-06
Anticipated expiration: 1969-05-06
Also published as: FR912669A; BE454482A

Description

y 6, 1952 D. ZAAYER 2,596,002

DEVICE FORULTRAHIGHFREQUENCIES Filed July 12, 1946 INVENTOR. DAVID ZAA YER A7 TOPNFY Patented May 6, 1952 DEVICE FOR ULTRAHIGH FREQUENCIES David Zaayer, Eindhoven, Netherlands, assignor to Hartford National Bank and Trust Company, Hartford, Conn., as trustee Application July 12, 1946, Serial No. 682,986 In the Netherlands February 22, 1943 Section 1, Public Law 690, August 8, 1946 Patent expires February 22, 1963 Claims. 1

This invention relates to a device for ultra-high frequencies comprising at least one discharge tube, whose wall consists of insulating material and which has at least one anode and one cathode, at least the anode circuit including a resonator which is tuned to the operating frequency and consists of two coaxial conductors and is at least substantially closed on all sides.

In the construction of such a device one is confronted with various problems. To obtain a satisfactory efficiency it is necessary, for instance, that theconnecting leadsbetween the resonator and the electrodes of the discharge tube(s) should be very short, since these leads cause considerableradiation and conduction losses which are proportional to the length of the connecting leads.

A second problem one is faced with is related with the heating of the seals of the said connecting leadsi. e. those points of the wall of the tube, which may consist of glass, where the conductors conveying the high-frequency current are passed through this wall. This heating is due to the losses in the leads and may render the tube defective.

The present invention envisages a construction of the device referred to in the preamble, by which the aforesaid problems are solved satisfactorily. According to the invention this is achieved by means of a construction in which the inner conductor of the resonator is tubular, and one'en'd'of the inner conductor, which is not connected to the outer conductor, surrounds the discharge tube coaxially over a large part of the length of the anode in such a manner that the anode is capacitatively coupled to the inner conductor.

When making use of the construction accordingto the invention the connecting lead between anode and resonator, which lead causes the larger part of the losses because the voltages are a maximum at the anode, may be entirely dispensed with. Furthermore, since the tube is lodged at least for the greater part within the closed resonator, the radiation losses due to electromagnetic radiation from the electrode themselves are only smal1 and the remaining connecting leads conveying high-frequency current can also be kept short; in a suitable form of construction set out hereinafter the part of the grid lead outside the tubemay even be dispensed with completely.

In the construction according to the invention the seals are not heated or only to a slight degree,

since in this case the connecting leads for the electrodes, at least for the anode, passing through the insulating wall of the tube only serve for the supply of the feed voltages required for the electrodes, so that practically no losses occur in these leads.

In order that the invention may be clearly understood and readily carried into effect, it will now be described more fully with reference to the accompanying drawing which represents a preferred embodiment of a device according thereto in axial section.

The form of construction of a device according to the invention represented in the single figure of the drawing serves for the production of oscillations having the natural frequency of a resonator I which consists of a tubular inner conductor 3 and an outer conductor 5 surrounding the latter coaxially. The inner conductor 3 is connected at one end to the corresponding end of the outer conductor 5, through the intermediary of a conductive disc 1. The other end of the outer conductor is terminated by a conductive disc 9 so that the resonator is closed practically on all sides. The resonator l is included in the anode circuit of a discharge tube ll having an envelope I2 of insulating material. According to the invention the tube l l is lodged within the tubular inner conductor 3 and this tube is coaxially surrounded by the end of the inner con ductor 3, which is not connected to the outer conductor, over a great part of the length of the anode 13 in such a manner that the anode I3 is capacitatively connected to the inner conductor 3.

At the end of the inner conductor connected to the disc 1 a potential node occurs, whereas a potential loop appears at the end to which the anode is coupled.

For supplying the required feed voltage to the anode conveying a high-frequency voltage use is made of coaxial auxiliary conductor [5 having the same shape and substantially the same section as the inner conductor 3 and being incorporated in the tubular inner conductor 3 in such a manner as to be insulated therefrom. One end of this auxiliary conductor is connected through a short connecting lead to the anode 13, whereas the other end, which preferably slightly projects from the resonator I, is connected, through a connecting lead I! outside resonator, to a source of anode voltage I9. As a result of the short distance in this construction between the cylindrical surface of the auxiliary conductor 15 and the inner surface of the inner conductor 3 these conductors are tightly coupled capacitatively and constitute an assembly in electrical respect in regard to the operating frequency, so that the end of the conductor I projecting from the resonator and the lead I'I connected to this end does not have a high-frequency voltage relatively to earth.

The grid 2| of tube II is connected to the centre of the disc 9 through the intermediary of one or more connecting leads which are connected in parallel and are as short as possible. This centre and the end of the inner conductor 3 surrounding the anode constitute the electric terminals of the resonator. Consequently, the grid and the anode of the tube H are connected respectively to the electric terminals of the resonator.

The device represented in the drawing is of a type known per se, in which the resonant circuit is interposed between grid and anode and the cathode is connected to a point of a capacitative potentiometer connected in parallel with the resonant circuit and consisting of the cathodeanode capacity and the cathode-grid capacity. Between the cathode and the earthed outer wall of the resonator is included a circuit that is substantially tuned to the frequency of the oscillations to be generated and in the device shown in the drawing is constituted by a coaxial transmission line consisting of the

conductors

23 and 25.. The outer conductor 23 is connected to the earthed wall 9 of the resonator I in the proximity of the end facing the cathode, whereas the inner conductor 25 is earthed at the end of the resistance 3| remote from the cathode, which resistance serves for the obtainment of the required grid bias. The inner conductor 25, which serves at the same time for the supply of the required heating current, is tubular and contains the other heating lead which is insulated therefrom. The disc 9 is provided with a central aperture through which the two heating leads are connected to the cathode 21. The feed voltage for the cathode is supplied by a supply 29 one of whose terminals is earthed across the cathode resistance 3|. The resistance 3I is preferably not bridged by a short-circuit condenser so that a negative back-coupling is present for the low frequencies thus preventing the tube II from oscillating at the desired frequency and. at the same time at a low frequency.

The

transmission line

23, 25 is tunable by means of a short-circuit bridge 33 which is movable in an axial direction. In view of the fact that the outer conductor 23 is earthed in regard to direct current, whereas the inner conductor 25 has a positive direct voltage with respect to earth, the bridge 33 is realised in such a manner that there is no electrical connection in regard to direct current between the

conductors

23 and 25.

The device set out above generates oscillations whose frequency is determined by the natural frequency of the resonator I. The frequency of the generated oscillations is variable by means of a conductive piston 4| which is movable in an axial direction with the aid of a clasp 43 projecting from the resonator.

The generated oscillations may be taken from the resonator by means of a loop 45 coupled to the magnetic field within the resonator.

In order that the coupling between the inner conductor 3 and the anode I3 may be'controlled the inner conductor 3 is so realised as to be movable in an axial direction relatively to the tube II secured to the disc 9. With the aid of a screw 41 the inner conductor 3 can be fixed in the desired position.

The envelope I2 of tube II extending for the greater part of the high-frequency electric field between the anode I3 and .the end'of the inner conductor 3, use is preferably made of a tube II with an envelope of a material having low dielectric losses such as quartz.

For carrying off the heat dissipated by the anode I3 use is made of liquid cooling in the device shown in the drawing. To this end the inner conductor 3 has a double wall and is equipped with two partitions extending in a plane through the axis of the inner conductor and dividing the space between the two walls of the inner conductor 3 into two compartments which communicate with each other at the end of the inner conductor surrounding the anode. These partitions are normal to the plane of the drawing; for clarity, however, they have not been represented. The cooling liquid can be supplied through an inlet opening 49 at the end of the inner conductor remote from the anode I3 to one of the two compartments, and upon traversing the other compartment of the inner conductor it is carried off through an outlet opening 5|. To promote as much as possible the transfer of heat between the anode I3 and the inner conductor 3 preferably the inner side of the inner conductor 3 is coated with a black layer at the anode I3. When the tube I I is of the usual type, where the anode consists of carbon, an effective transfer of the heat to be dissipated is obtained in this manner by radiation.

In the device according to the invention cooling by air instead of liquid cooling may be used, if desired; in this case the cooling air may be blown through an aperture, for instance through the aperture through which pass the heating current conductors the air then passing between the wall of the tube II and the inner wall of the inner conductor 3 and escaping to the outside through the inner conductor What I claim is:

1. An ultra high frequency electronic device comprising an electron dis-charge tube having an insulating envelope with a cathode, a grid and an elongated tubular anode enclosed therein, said grid and said cathode being coaxially positioned within said anode, and a reentrant cavity resonator having a tubular outer conductor surrounding said tube and a tubular inner conductor coaxial with said outer conductor and connected to one end thereof, the other end of said outer conduotor being closed, said tube being received within said inner conductor to an' extent at which a portion of said anode is surrounded by said inner conductor to effect capacitive coupling" for high frequencies therebetween, said' envelope acting as a dielectric between said anode and said'inner conductor, said grid being connected to said closed end of said outer conductor.

2. An ultra high frequency electronic device comprising an electron discharge tube having an insulating envelope with a cathode, a grid and an elongated tubular anode enclosed therein, said grid and said cathode being concentrically ar ranged within said anode, a reentrant cavity resonator having a tubular outer conductor surrounding said tube and a tubular inner conductor coaxial with said outer conductor and connected to one end thereof, the other end of said outer conductor being closed, said tube being received within said inner conductor to an extent at which a portion of said anode is surrounded by said inner conductor to effect capacitive coupling for high frequencies therebetween, said envelope acting as a dielectric between said anode and said inner conductor, said grid being connected to said closed end of said outer conductor, a cylindrical conductor coaxially disposed within said inner conductor, and means to apply an energizing potential through said cylindrical conductor to the anode of said tube.

3. An ultra high frequency electronic device comprising an electron discharge tube having an insulating envelope with a cathode, a grid and an elongated tubular anode enclosed therein, said grid and said cathode being coaxially positioned within said anode, a reentrant cavity resonator having a tubular outer conductor surrounding said tube and a tubular inner conductor coaxial with said outer conductor and connected to one end thereof, the other end of said outer conductor being closed, said tube being received within said inner conductor to an extent at which a portion of said anode is surrounded by said inner conductor to effect capacitive coupling for high frequencies therebetween, said envelope acting as a dielectric between said anode and said inner conductor, said grid being connected to said closed end of said outer conductor, a cylindrical conductor coaxially disposed within said inner conductor, means to apply an energizing potential through said cylindrical conductor to the anode of said tube, and an annular shorting bridge slidably arranged between said inner and outer conductors.

4. An ultra high frequency electronic device comprising an electron discharge tube having an insulating envelope with a cathode, a grid and. an elongated tubular anode enclosed therein, said grid and said cathode being coaxially positioned within said anode, a reentrant cavity resonator having a tubular outer conductor surrounding said tube and a tubular inner conductor coaxial with said outer conductor and connected to one end thereof, the other end of said outer conductor being closed, said tube being received within said inner conductor to an extent at which a portion of said anode is surrounded by said inner conductor to effect capacitive coupling for high frequencies therebetween, said envelope acting as a dielectric between said anode and said inner conductor, said grid being connected to said closed end of said outer conductor, a cylindrical conductor coaxially disposed within said inner conductor, means to apply an energizing potential through said cylindrical conductor to the anode of said tube, an annular shorting bridge slidably arranged between said inner and outer conductors, a coaxial transmission line having one end of its outer lead secured to said closed end of said outer conductor and having the corresponding end of its inner lead connected to the cathode of said tube, a capacitive bridge interposed between said inner and outer leads for tuning said line, and a cathode resistor connected between the other end of said inner lead and the outer surface of said outer conductor.

5. An ultra high frequency electronic device comprising an electron discharge tube having a tubular insulating envelope with a cathode, a grid and an elongated tubular anode enclosed therein, said grid and said cathode being coaxially disposed within said anode, and a reentrant cavity resonator having a tubular outer conductor surrounding said tube and a tubular inner conductor coaxial with said outer conductor and connected to one end thereof, the other end of said outer conductor being closed, said tube being received coaxially within said inner conductor to an extent at which a portion of said anode is surrounded by said inner conductor to effect capacitive coupling therebetween, said envelope acting as dielectric between said anode and said inner conductor, said grid being connected to said closed end of said outer conductor.

DAVID ZAAYER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,278,210 Morton Mar. 31, 1942 2,284,733 Haefi June 2, 1942 2,312,723 Llewellyn Mar. 2, 1943 2,402,600 Chevigny et a1 June 25, 1946 2,408,355 Turner Sept. 24, 1946 2,408,927 Gurewitsch Oct. 8, 1946 2,409,640 Moles Oct, 22, 1946 2,412,998 Litton Dec. 24, 1946