US2196392A - Ultra high frequency oscillator system - Google Patents

Description

April 9, c. HANSELL 2,196,392

ULTRA area FREQUENCY OSCILLATOR SYSTEM Filed Now). 28, 1934 AA/7510144 A 3 mW 0'\ 4 OUTPUT FC PEN ELL CLARE E .H .S lllllllllllllll BY ATTORNEY Patented Apr. 9, 1940 UNI-TED STATES.

ULTRA. HIGH. FREQUENCY OSCILLATOR SYSTEM Clarence W. HanselLJPort Jefferson, N. Y., as

signor to Radiocorporation of America,

poration of Delaware Application November 28, 1934, Serial No. 755,158"

18 Claims;

This invention relates tohigh frequency oscillation generators.

For the purpose of generating oscillations having frequencies-of the order of 300,000 kilocycles and: higher, there have commonlybeenusedsuch apparatuses the Barkhausen oscillator'and the magnetron. The. oscillations produced. in these oscillators are obtained/by. a sortof whistle effect wherein the electrons themselves produce. the

m:- oscillationswithout any control-element for-con-v trolling theiflow of electrons passing throughihe tube-in the manner commonly; employed in ordinary vacuum tubes. In. the .Barkhausen. oscillator there is a. pendulum orv to-and-fro motion of the electrons about the grid atthecenter point,

groups; of theseelectrons; being drawn. from "the. cathode toward the: grid. and. after passing. through the gridrreturning again to. it, some of.- these electrons returningto. the vicinity. of the cathode. The electronsreturningto the cathode. build up a dynamiclspace chargein: such manner as to control the emission.fromitheicathoder. in

much the same way as a negative'charge on..the gridcontrols the emission: from. thevcathodeof an ordinary vacuum tube. In. conSideringLthe.

Barkhausen. oscillator; it. should be noted that .a.

. negative charge exists inthe' space byvirtue only of the presence of theelectronsthemselves, since no control electrode is required. This phenom.-

enon, it has beeniound, is much more. successful. in producing ultra. high. frequency oscillations. than that employed in the ordinary. vacuum tube wherein controlelectrodes are used, for. the reasonv that the capacity current to thecontrol electrode in. the ordinary vacuum tube. becomes so.

enormous that the losses due tothis: currentprevent oscillations taking placeatextremely high.

a certain point is soon reachedbeyond which nofurther increase in frequency may be obtained by increasing the voltage, because of the necessity for the greater. spacing betweenelectrodes.

A.primary object of the invention is to. makeit.

possible to obtain relatively very high power by means of oscillators without a corresponding decreasein. the limiting frequencies which may be produced, particularly in the case of. oscillators functioning on, the. Barkhausen and magnetron principles.

An important feature of the present invention is the.-..so1id .type' of cylindrical plate. electrode used", which has.-anaperture or slot therein for enabling. groups: of electrons to pass through the ,plate electrode to a positive'charged anode spaced away from the plate and facing the aperture or slot.

- Although theprinciples underlying the inventionare described with special" reference to magnetron and Barkhausen oscillators, it is to be distinctly understood. that the. invention is not limited thereto, nor to the particular arrangement of parts shown, since other organizations of parts can be used without' departing from the "spiritiandlscope thereof.

Referring to the-drawing: I v Fig. 1 illustrates diagrammatically, the invention as appliedto a magnetron type of oscillation generator, and

Fig; 2 showsa Barkhausen oscillator system embodying the features of the invention.

. For the sake of simplicity and in order not to complicatethezdraWing, both figures show cross sectional views-of the oscillator tubes.

Fig." 1 illustrates, in general, an ultra short wave oscillation generator'intheform of a magnetron having 'within an envelope l, a cylindrical plate electrode 2, a cathode extending alongthe longitudinal axisof 'the=platecylinder, the whole being surrounded by-ia field will for producing an intense magnetic field inn-direction parallel to the axisof the filament. Since the method by which oscillations are produced in magnetronsis well known, and isadequately described in Japanese PatentNo: 7.55255,- granted January 25, 1928, to Kinjiro- Okabe; and 1 in my United States- Patents Nos. 2;037-",897"'and 2,0413%, granted April 21'and May 26, 1936, respectively, it will not-be described herein.

- According: to the present invention, the cylindrical plate 2 of the magnetron is provided with a slot 5, and facing thi's slot there is provided, within the envelope I, an anode ii which is maintained at a veryhighpositive potential by source l; wherebyd'uring' the operation of the magnetron and' wh'ile oscillations are being produced, those. portions'of the electrons'which approach the. area. of the. slot 5 and. comecwithin'. the electrostatic: fieldz of. the-anode 6 will be drawn to-.

ward the anode 6. In this manner groups or puffs of electrons are emitted through the slot and accelerated toward the anode 6, which groups of electrons constitute a fluctuating current having a frequency equal to the frequency of oscillations being produced by the magnetron oscillator.

Since the magnetic field causes the electrons to take a curved path, anode 6 is made suflicient- 1y large to extend to one side of the aperture so that the electrons do not miss it altogether. If desired, the anode may be positioned on one side of the aperture a suitable amount, as shown in Fig. 2, and not directly opposite the aperture.

Although it is preferred to use a slot in the plate 5, it will be quite evident that any suitable aperture having appreciable size will function as well.

As an illustration of the amount of power capable of being obtained by the oscillator of the invention, let it be assumed that the plate 2 of the magnetron oscillator is maintained by source l' at a positive potential of 2000 volts, and anode 6 at approximately 100,000 volts relative to the cathode. If the total plate current in the magnetron oscillator functioning to produce frequencies of the order of 1,000,000 kilocycles is approximately 0.5 ampere and the peak emission current permitted to escape through the slot in plate 2 is 0.1 ampere, then the R. M. S. value of the current through the slot to anode 6 will be approximately The efiective or R. M. S. alternating current voltage, available for internal drop and useful output to the output circuit connected to anode 6, will be 1oo,000 2=35,000 volts If it is assumed that the anode 6 is 100% efficient then the output will be 0.035 X 35,000=1225 watts In practice the anode 6 will be perhaps 40% efficient and provide an output of about 500 watts. The remaining power of about 625 watts will be lost in heat at the anode. It will be understood, of course, that the specific values herein mentioned are only given by way of example, since they happen to be approximately the values obtainable by types of magnetron oscillators commonly used in the field.

The anode circuit may, if desired, be tuned by a condenser 8, one of whose plates is connected to a movable slider 9 arranged to glide over the connection extending from the anode 8 to the source of potential 7. Any suitable utilization circuit, such as an antenna i0, may be connected to the anode circuit through a transmission line i I, which in turn is shown inductively coupled to the anode circuit by means of a straight wire lead I2. If desired, tuning elements such as trombone slides 13, M may be inserted in the transmission line circuit for tuning the line to the desired frequency. Telegraph key I5 is merely illustrative of any suitable means for modulating the oscillations produced.

Since radiation takes place directly from the pulsating electron stream made up of the groups of electrons which are accelerated toward the anode 6, it is preferred to use a reflector l5 instead of the transmission line antenna output circuit. Thus, by allowing radiation to take place directly from the electron stream there is obtained a sort of infra-red lamp which may be used in the focus of the reflector IS, the latter being designed to reflect the radio frequency waves in much the same way as a reflector of light. By positioning the tube in the reflector I 5 in any desired manner, advantage may be taken of the position for maximum radiation, although it will be noted that such maximum radiation from the pulsating stream of the electrons Will not ordinarily be at right angles to the axis of the tube.

Fig. 2 illustrates the application of the principles of the present invention to a Barkhausen oscillator. In this figure, the elements of the tube within the envelope are arranged similar to those in Fig. 1 except for the provision of a grid [6 which is shown to be positively charged by source 1, while the plate 2 is negatively charged by source H in order to obtain the desired pendulum motion of the electrons. As shown in the drawing, anode 6 is maintained at a much higher positive potential than grid [6 relative to the cathode. Portions of the electrons emanating from the cathode 3 and passing through the grid l travel out to the vicinity of the plate 2, some of which are subjected to the electrostatic field from the anode in the same manner as the electrons of the magnetron oscillator of Fig. 1. In this case also, radiation may be directly obtained from the pulsating electron system flowing to the anode 6, if desired, or the energy may be amplified in output circuit l 1, shown coupled to the anode lead.

From the foregoing it will be quite apparent that the invention is applicable to various types of oscillators such as the Gill-Morrell type of oscillator, and oscillators of the ordinary type wherein there is employed a vacuum tube of small dimensions capable of producing very high frequency oscillations in the same manner as low frequency oscillations are produced with the ordinary vacuum tube.

What is claimed is:

1. An ultra high frequency oscillation generator comprising a cathode, a substantially cyiindri cal electrode surrounding said cathode and apertured to permit the passage of electrons therethrough, means including connecting circuits so related to said cathode and said electrode as to constitute therewith a self-contained oscillator, an anode located outside said apertured electrode for receiving the electrons passing therethrough, and means including a source of potential for applying a positive potential to said anode for attracting electrons from said cathode toward said apertured electrode, whereby electrons escaping through said apertured electrode impinge on said anode.

2. An ultra high frequency oscillation generator comprising a cathode, an imperforate, substantially cylindrical plate electrode having an aperture in the side thereof surrounding said cathode, means for attracting electrons from said cathode toward said plate electrode, and an anode located outside said plate electrode and facing said aperture, means for producing electron oscillations within the hollow area of said plate electrode, and means for supplying a high positive potential to said anode with respect to said cathode for producing an electrostatic field in the vicinity of said aperture, whereby electrons escaping therethrough impinge on said anode.

3. An ultra high frequency oscillation generator metallic substantially cylindrical plate electrode I outside saidv cylinder but within said envelope surrounding said cathode and having a slot running through the entire length thereof, an anode facing said slot whereby electrons escaping therethrough impinge onsaid anode, means for producing electron oscillations within the hol low area of said cylindrical plate electrode including a source of potential for applying a positive potential on said plate and a relatively very high positive potential on said anodewith respect tosaidcathode. 1

4. An ultra high frequency oscillator comprising an envelope having within it a cathodeand a substantially cylindrical plate electrode surrounding said cathode, said plate electrode having an aperture in the side thereof for the escape therethrough of electrons emanating fromv said cathode, and an anode located within said envelope and outsidesaid plate electrode and directly-in'line with said aperture and cathode for receiving said electrons, means for maintaining said cylindrical plate ata positive potential and. said anode at a much higher positive potential N relative to said cathode, and a field coil surrounding said envelope for influencing the direction of travel of said electrons.

5. An electron discharge device comprising a cathode, a grid, and a cylindricalplate, means for supplying said grid with a high positive potential and said plate with a much lower potential relative to said cathode, said plate having an aperture for the escape of electrons therethrough emanating from said cathode and passing through said grid, and an anode facing said aperture for receiving said electrons after their escape through the aperture of said plate, and means for maintaining said anode at a positive potential which is much higher than that applied to said grid.

"6. In combination, an ultra high frequency oscillation generator comprising a cathode, an imperforate, substantially cylindrical plate electrode surrounding said cathode, said plate electrode having an aperture in the side thereof, means for attracting electrons from said cathode toward said plate electrode, means for producing oscillations within the hollow area of said cylindrical plate electrode, and an anode located outside said plate electrode and facing said aperture whereby tially cylindrical plate electrode surrounding said cathode substantially completely, said cylindrical plate having an aperture in the side thereof, means for attracting electrons from said cathode toward said plate electrode, means for producing electron oscillations within the hollow area of said plate electrode, and an anode located outside said plate electrode and facing said aperture, said anode beingpositively biased whereby electrons escaping through said aperture impinge on said anode.

8. An ultra high frequency oscillation generator comprising a cathode, a hollow, imperforate plate electrode substantially completely surrounding a portion of said cathode, said plate having an aperture in the side thereof, means including a source of potential for attracting electrons from said cathode toward said plate electrode, means for producing electron oscillations within thehollow areaof said plate electrode, an anode located outside said plate electrode and facing said: aperture,'and a connection from said anode to a positive terminal of said source whereby electrons escaping through said aperture are caused'to impinge on said anode. i

9. An electron discharge tube circuit comprising an electron emitting means, an anode, means relatively to said emitting means, and means forv causing an intermittent fiow of electrons from said emitting means to said'anode comprising additional electrodes and connecting circuits sorelated to said emitting means as to constitute therewith a braking field type of oscillator, said positive potential being such that the oscillatory energy available between said anode and said emitting means is large as compared with the braking field oscillatory energy. j I

10. An electron discharge tube circuit comprising, a'n electron emitting means, an anode separated from said emitting means only by etheric,

space, means for impressing a positive potential on said anode relatively to said emitting means,

and means for causing an intermittent flow of electrons from said emitting means to said anode comprising additional electrodes and connecting circuits so relatedto said emitting means as to anode and said emitting means is large'as compared with the braking field oscillator energy.

11. An electron discharge tube circuit comprising, an electron emitting means, means-for causing an intermittent flow of electrons from said emitting means comprising additional electrodes and connecting circuits so related to said emitting means as to constitute therewith a braking field type of oscillator, an anode, and means for impressing a positive potential on said anode relatively to said braking field oscillator electrodes, said positive potential being such that the oscillatoryenergy available between said anode and said emitting means is large as compared with the braking field oscillator energy.

12. An electron discharge tube circuit comprising an electron emitting means, an anode, means for impressing a positive potential on said anode relatively to said emitting means, and means for causing an intermittent flow of electrons from said emitting means to said anode comprising additional electrodes and connecting circuits so related to said emitting meansas to constitute therewith a self-contained positive grid triode oscillator, said positive potential being large asmeans for periodically impulsively energizing said 1 tuned circuit from said potential impressing means comprising additional electrodes and circuit means so related to said cathode as'to constitute therewith a self-contained positive grid triode oscillator, said positive potential being large as compared with the potentials used in said self-contained oscillator.

14. The oscillator circuit as specified in claim 13 in which said energizing means comprises said additional electrodes and circuit means adapted to cooperate with said cathode to constitute therewith a braking field type of oscillator circuit.

15. An electron discharge tube circuit compris- 5 ing, an electron emitting means, an anode separated from said emitting means only by etheric space, means for impressing a positive potential on said anode relatively to said emitting means, and means for causing an intermittent flow of m electrons from said emitting means to said anode comprising additional electrodes and connecting circuits so related to said emitting means as to constitute therewith a self-contained positive grid triode oscillator, said positive potential being 15 large as compared with the potentials used in said self-contained oscillator.

16. An electron discharge tube circuit comprising, an electron emitting means, an anode, means for causing an intermittent flow of electrons from 30 said emitting means to said anode comprising additional electrodes and connecting circuits so related to said emitting means as to constitute therewith a self-contained positive grid triode oscillator, and means for impressing a positive potential on said anode relatively to the intermittent electron flow means constituted by said oscillator electrodes, said positive potential being large as compared with the potentials used in said self-contained oscillator.

17. The oscillator circuit specified in claim 13 in which said tuned circuit is adjusted so that the whole circuit including said tuned circuit and the interelectrode capacitances of the electron discharge tube is tuned to the frequency of said periodic impulses.

18. The oscillator circuit specified in claim 13, in which said energizing means comprises said additional electrodes and circuit means so related to said cathode as to constitute therewith a braking field oscillator circuit and in which said tuned circuit is adjusted so that the whole circuit including said tuned circuit and the interelectrode capacitances of the electron discharge tube is tuned to the frequency of said periodic impulses.

CLARENCE W. HANSELL.

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