US2381320A - Electromagnetic apparatus - Google Patents

Description

Au 7, 1945, T G. 1.. TAWNEY 2381 320 ELECTROMAGNETIC APPARATUS I I Filed Nov. 28, 1940 Mumm- INVENTOR Gereld Zipbey. .BY

ATTORNEY WITNESSES? resonators is a difiicult matter.

Patented Aug. 7, 1945 2,381,320 ELECTROMAGNETIC APPARATUS 7 Gerald L. Tawney, Pittsburgh, Pa., assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application November 28, 1940, Serial No. 367,625

8 Claims.

My invention relates to apparatus for producing electromagnetic phenomena and has particular relation to systems for generating, modifying, or utilizing high-frequency electromagnetic waves.

Hollow body resonators perform an'important function in the production of phenomena involving a ultra-high-frequency radiation having a wave length of the order of decimeters. The dimensions of a resonator determine the wave length of the radiant energy with which it is resonant. If very high-frequency radiation is involved, a small resonator is, in accordance with the teachings of the prior art of which I am aware, used. The alignmentand mounting of small hollow bodies so that they function as Moreover, the frequency range over which hollow body resonators may be used is limited on the higher frequency side by the physical limitations involved in the construction of a. smallhollow body.

In the case of short wave electromagnetic radiation efficiency is also an important consideration. The efiiciency of a resonatoras a function of its dimensions is dependent on a quantity, Q, which may be computed from the relationship equation I 26fH dv I j'H ds where 6, (commonly called the skin depth) is a quantity determined from the thickness to which the field penetrates into the surface of theresonator, .H is the magnetic field vector, v is a volume coordinate and sis a surface coordinate. The efliciency of a hollow body resonator is thus roughly dependent on the ratio of the volume to the surface, and, therefore, decreases roughly as its linear dimension is decreased.

' It is, accordingly, an object of my invention to provide a resonator for the generation, modification or utilization of electromagnetic waves of very high frequency.

Another object of my invention is to provide an efflcient resonator, the .resonant frequency of which is very high- A specific object of my invention is to provide a generator or an amplifier for electromagnetic radiation of very high-frequency- More concisely stated, it is an objectof in body resonators are frequency determining; elements; 1 I

larity in the appended claims.

. invention to provide an eificient ultra-high-fre quency generator oramplifier inwhich hollow conducting barrier determining apotential node in a hollow body resonator having convenient dimensions. The frequency at which the resonator may be excited to oscillate thus corresponds to a harmonic of the fundamental frequencyof the resonator. A resonator of convenient dimensions with properly positioned node determining barriers may be excited to oscillate at a relatively high frequency. The Q function for a resonator of this type is dependent on the dimensions of the complete hollow body and, therefore, is substantial in spite of the fact that the resonant frequency may be high.

The novel features that I consider characteristic of my invention are set forth with particu- The invention, however, both as to its organization and its method of operation, together with additional objects and advantages thereof, will best be understood from the following description of specific embodiments when read in connection with the accompanying drawing, in which:

Figure 1 is a diagrammatic view partly in section and partly in perspective showing an embodiment of my invention;

Fig. 2 is a diagrammatic view partly in perspective and partly in section showing a modification of my invention; and

Fig. 3 is a view in perspective showing a portion of a resonator in accordance with a further modification of my invention. I

While my invention is shown in the drawing as applied to an ultra short wave oscillator, it is also applicable to an amplifier or'in any other device for modifying,'utilizing or generating high frequency electromagnetic radiation. The apparatus' shown in Fig. 1 comprises an evacuated cylindrical container 5 of insulating material within which a plurality of hollow cylindrical shells l and 9 of substantially the same dimensions is mounted. The shells 1 and 9 are mounted centrallywithin the container 5 with their axes coextensive and coincident with the axis of thecon'taine'r. The space within each shell is subdivided by a metal partition II which. extends along a central symmetric plane. The bases I3 and I 5 of the shells have centrally disposed circular openings on both sides of the partitions n and reentrant tubes |1,|9, 2|, '23, 25, 21, 29 and 3| extend into the opening Sp The internal ends of the tubes are spaced a relatively short distance and are covered by an openwork 33. The shellsv are so mounted that; the reentrant tubesll, I9, 25 and 21 and 2|, Z3, 29

line. They may, for example, trace acircle coaxial with the; cylinder or have any other configuration. The shells need not necessarily be subdivided by single partitions. circumstances several partitions may be inserted.

Under certain;

I, 9 The subdividing elements need not extend along and 53' ir'ithe'first shell 1 that the electrons are symmetric lines or symmetric planes of the shell. They should, however, coincide-with thesnatural nodes corresponding to the electromagneticharmonies of the resonator. While hollow shells are to be preferred, the space within the shells niayunder certain circumstances in part with a suitable insulating material.

"A plurality of electron emitting filaments 39 and are mounted in one end of the container 5. :In the'opposite end'of the container aplurality'of collectingelectrodes l3 and 45 is mounted. The geometric centers of one of the filaments 39 and one of'the electrodes 43 lie on the axes of oneset of aligned'reentrant tubes |1, |9, and 21 and the centers Of the other filament 4| and collecting electrode 45 lieon theaxes of the other set of tubes 2|,- 23, 29 and 3|. A potential is impressed between the collecting electrodes 43 and 45 and the filaments 39 and 4| from a source 49 and electron streams emitted from the filaments fiow through the reentrant tubes with which they are aligned. Preferably, fine electron streams are desired and for this reasonsuitable apertures and constricting grids are provided for each .of the-filaments 39 and 4|. Since the apertures and grids do not concern th present invention and are well-known in the cathode ray tube-art and the general electronic artythey are not shown and described in detail. Any suitable electron stream focusing system available in the cathode ray tube art may be used. Each electron stream passes through the open:- work ends 33 of the respectivereentrarit tubes 2| to 3l-with which it is aligned and issubl'ect to the electromagnetic field'sin the gaps 5| and 53, and 55 and 51"within the subdivisions of the shells 1 and 9, respectively, formed by thepartitions I I as it passes between the ends of the tubes |1 and |9.and 2| and 23, and 25 and 21-and 29 and 3|,respectively'.

1 The distance between the ends 33 of the 're-' entrant tubes 2| to 3l in each of'the'shells 1 and 9 is short compared 'to the wave length to which the subdivisions of the shellsare resonant.

i In passing through the gaps 5| and 53 of the? first shell 1 their path, the electron streams are subjected to the electric field vector of the high-frequency electromagnetic field with which the corresponding Subdivisions of the shell are resonant. "The field is periodic and has a frequency determinedby the'dimensions of thesaudivisions' of the resonator 1. Thespace' distribution of the field at any'instant is illustrated by the array of arrows 59 in the shell." The field has nodal regions in the external'wall of the'shell and in the partition." Between the nodal points the field varies as an oscillating function. The polarity of the field in one division of the shell is opposite to that in the adjacent subdivision;

ecause the reentrant tubes l1-and"|9 and 2|- and 23 are centrally mounted with respect'to the be filled wholly or the fields in the shell wall and the partition, the field is a maximum in the gaps 5| and 53.

As the streams pass through the gaps 5| and 53, the fields in the gaps impress a periodic component on the velocity of their electrons. Because the velocity of electrons leaving the gaps at different instants varies periodically, the electrons in each of thesstreams alternately accumulate in bunches and separate as: they advance'. The gaps 55 and 51 between the reentrant tubes 25 and 21 and 29 and 3|, respectively, of the second shell are so spaced from the corresponding gaps 5| grouped bunches when they pass through the i form p The field having the same frequency as the distance between the gaps 5| and 55 and 53 and ,51 is so related to the electron speed that when the electrons reach the gaps 55 and 51, gaps have a polarity such that they oppose the forward motion of the electrons. The fields in the gaps 55 and'51 absorb energy from the'electron streams. The energy may be radiated by an antenna 6| extending from loops 63 and 65' properly-oriented to be threaded by the magnetic field within the subdivisions of the shell 9'- Theloop's' 63'and65 in the two subdivisions or the shell face in opposite directions because the *magnetic fields by which they. are threaded are of opposite polarity and it is desired that the =electromotive forcesinduced in the. loops shall add and not counteract each: other. .Sufilcientenergy for modifying the electron speed is suppliedto the modulating shell-1 from theradiating' shell 9 by interconnected coupling loops 51 interconnected by a. conductor. I

Inaccordance-withthe preferred practice of my invention .anxelectron stream should beassociatedwitheacn of the subdivisions of the shells 1 and 9.11:1 lieu of.:a plurality of streams asingle stream may be used. For example, the lower filament 4b in thefoslcillator shown in maintained .deenergized and only the upper filament used tortransfer the energy frornthe source 49totheiantenna6l. v

jFilaments 59: and 1|, and collecting electrodes 13 'and 'fl5'may; also be disposed, atppposite ends of the container 5, as shown in Fig. 2. In this case each of the shells .1 and 9 functions both as a modulator for the: electron velocity and as an energy deriving device, one shell being a modulator' forv one stream and .1 an energy deriving resonator'for' 'the other while the-other shell is an energy. deriving resonator for ;the first stream and a'modulatorfor the second stream. Since therelisian interchange of ener ybetweenthe two shellsxthrough-the electron streams in the Fig. ,2 arrangement; no coupling loop need be utilized. In oscillators of the type'zshown in Fig; 2,, the subdividing barrier should preferably be ofithe type shown in Fig. 3 with the barsspaced closely. The close spacing ;-is desirable. becausev the velocity modulating energy should be relatively small and the energy of the absorbing: region relatively large. The bars when closely spaced permit willcient' leakage between: the. subdivisionsv of "each of the shells for modulating purposes.

'Although I have shown and described certain specific embodiments of my invention; 1 am fully aware that-many modifications thereof are possiblef' My invention, therefore, is-not to berestricted except insofar as is necessitated bytthe.

spirit of the appended-claims.

"I claim as my invention:

magnetic resonatorincluding "a first conducting Fig.1 may be shell having conducting means positioned therein subdividing the space bounded by said first shell, a plurality of electrodes mounted outside of said first shell for projecting a stream of electrical charges through one subdivision of said space bounded by said first shell, and a second electromagnetic resonator comprising a second conducting shell having second conducting means therein subdividing the space bounded by said second shell, one of the subdivisions of said second shell having the same resonant frequency as said one subdivision of said first shell, said second shell being mounted with said one subdivision thereof in the path of said stream between said first shell and one of said electrodes whereby said stream passes through said one subdivision of said second shell after it has passed through the subdivision of said first shell.

2. An electron tube comprising an electromagnetic resonator includin a conducting shell having conducting means therein subdividing the space bounded by said shell, a plurality of electrodes mounted outside of said shell for projecting a stream of electrical charges through one subdivision only of saidspace, said conducting means being positioned parallel to the path of said stream and means positioned along the path of said stream beyond said subdivision for producing an electromagnetic field in the path of said stream whereby said charges enter said field after passing through said subdivision.

3. An electron tube comprising a first electromagnetic resonator including a first conducting shell having a plane of symmetry and conduct: in means within said first shell and lying substantially in said plane subdividing the space bounded by said first shell, a plurality of electrodes mounted outside of said first shell for projecting a stream of electrical chargesthrough one subdivision of said space bounded by said first shell, said conducting means being parallel to the path of said stream and a second electromagnetic resonator comprising a second conducting shell having second conducting means therein subdividing the space bounded by said second shell, one of the subdivisions of said secondshell having the same resonant frequency as said one subdivision of said first shell, said second shell being mounted with said one subdivision thereof in the path of said stream between said first shell and one of said electrodes whereby said stream passes through said one subdivision of said second shell after it has passed through the subdivision of said first shell.

4. An electron tube comprising a first electromagnetic resonator including a first conducting shell having conducting means positioned therein subdividing the space bounded by said first shell, a plurality of electrodes mounted outside of said first shell for projecting a stream of electrical charges through one subdivision of said space, said conducting means being positioned parallel to the path of said stream, a second electromagnetic resonator comprising a second conducting shell having second conducting means therein subdividing the space bounded by said second shell, one of the subdivisions of said second shell having the same resonant frequency as said one subdivision of said first shell, said second shell being mounted with said one subdivision thereof in the path of said stream between said first shell and one of said electrodes whereby said stream passes through said one subdivision of said second shell after it has passed through said one subdivision of the first shell, and means connected to said shells electromagnetically coupling said one subdivision of the first shell and said one subdivision of the second shell whereby said first resonator introduces a periodic. change in the motion of said charges, said second shell being spaced from said first shell to receive the charges selectively and absorb energy from them.

5. An electron tube comprising an electromagnetic resonator including a conductin shell having conducting means therein subdividing the space bounded by said shell, first electrode means mounted outside of said shell for projecting a first stream of electrical charges through one of said subdivisions, said conducting means being positioned parallel to the path of said stream, second electrode means mounted outside of said shell for projecting a second stream of electrical charges through a second of said subdivisions, means positioned along the path of said first stream beyond said first subdivision for producing an electromagnetic field in the path of said first stream having a frequency resonant with said first subdivision, and means positioned along the path of said second stream beyond said second subdivision for producing an electromagnetic field in the path of said second stream having a frequency resonant with said second subdivision.

6.' An electron tube comprising an electromagnetic resonator including a conducting shell having conducting means therein subdividing the space bounded by said shell, electrode means mounted outside said shell for projecting a'stream of electrical charges through one subdivision only of the space bounded by said shell, said conducting means being positioned parallel to the path of said stream, and energy extracting means beyond said resonator and in the path of said stream coupled with the interior of said subdivision for producing an electromagnetic field therein having a frequency at which said subdivision is resonant to modulate the velocity of said stream of charges.

'7. An electron tube comprising an electromagnetic resonator including a conducting shell having a plane of symmetry and conducting means lying substantially in said plane within said shell subdividing the space bounded thereby, electrode means mounted outside said shell for projecting a stream of electrical charges through on subdivision only of said space, said conducting means being positioned parallel to the path of said stream, and energy extracting means positioned in the path of said stream beyond said resonator for elfecting the production of an electromagnetic field therein having a frequency at which said subdivision is resonant to modulate the velocity of said stream of charges.

8. An electron tube comprising an electromagnetic resonator including a conducting shell having a mode of oscillation and having apertures therein defining an electron path conducting bars positioned within said shell substantially parallel to the direction of said path and subdividing the space bounded by said shell, electrode means mounted outside said shell for projecting a stream of electrical charges along said path through One subdivision only of said space, and means positioned in the path of said stream beyond said resonator for efiecting the production of an electromagnetic field therein having a frequency at which said subdivision is resonant to modulate the velocity of said stream of charges.

GERELD L. TAWNEY.

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