US2431488A - Electron beam deflection system - Google Patents

Description

NOV. 25, 1947. Q C, LARSQN ELECTRON BEAM DEFLECTION SYSTEM Filed sept. 4',

INVENTOR vC.C. LARSON ATTORNEY Patented Nov. 25, 1947 ELECTRGN BEAM DEFLECTION SYSTEM Christian C. Larson, Fort Wayne, Ind., assignor, by mesne assignments, Vto Farnsworth Research Corporation, a corporation of Indiana Application September 4, 1944, Serial No. 552,626

12 Claims. 1

This invention relates to cathode ray apparatus and particularly to systems for deiiecting an electron beam of such apparatus. A Cathode ray devices wherein a cathode ray or a beam of electrons is deected over a target electrode have many uses such as oscilloscopes, television receivers, and in some cases as radiant energy receivers and/or converters. In the latter case it has been proposed to employ a tube of this general character as the sole means for receiving radiant energy at a relatively high carrier frequency and for demodulating this energy, Whereby thesignal-modulating component may be recovered and amplified suitably for impression upon a reproducing device.

Apparatus of this latter type generally comprises an apertured target electrode over which an electron beam is deflected at the received carrier frequency and at an amplitude or deflection magnitude in accordance with the intelligence signal modulated upon the carrier. In one form of such a device, Where it is desired to effect clemodulation of the received carrier, an electron multiplier is located behind the aperture of the target electrode in a position to receive, at the carrier frequency, a plurality of electronic impulses resulting from the beam deflection over the aperture. For demodulation purposes advantage is taken of the inherent characteristic of an electron multiplier whereby it is incapable of responding to frequencies above a predetermined cutoff frequency. Accordingly, in order for such a device to function as a demodulator it is necessary to effect the deflection of the electron beam over the aperture at a frequency which is greater than the cutoff frequency of the multiplier. If the beam deflection is controlled by the received signal, the carrier frequency of Which is greater than the cutoff freqeuncy of the multiplier, it is seen that the required conditions are fulfilled.

However, where a single tube receiver of the character described is to perform satisfactorily under substantially all conditions met in practice, the tube must have a deflection sensitivity of a relatively high order of magnitude. Even in strong signal areas the energy intercepted by a receiving antenna is quite small for use as the deiiectio-n voltage for an electron beam. The magnitude of the beam deflection depends upon a number of factors. One factor is the velocity of the beam. A much greater deflection by a given deiiection voltage may be effected of a relatively lovv velocity beam than of one of high velocity. A high velocity beam is one which frequently is termed a stiff beam; in other words, one which is not easily diverted from a given path. Hence, in a tube for use as `a so-called single tube receiver it is desirable to use a beam of a relatively low velocity. Where this is done the transit time of such a beam becomes relatively great. In such a case, however, it is possible to effect the desired defiection of the beam by a relatively weak field produced under the control of the received carrier frequency signals but one which extends for a considerable distance in the direction of the electron beam travel, In this manner the beam would be subjected to the infiuence of the deflecting field for a time sufficient to elect the desired deflection thereof.

But, Where the deflecting field is to be produced under the control of signal voltages of a frequency beyond the cutoff frequency of an electron multiplier, an extensive field of this character would reverse in polarity many times during the transit therethrough by a given portion of the beam by reason of the fact that the frequency of the deflecting voltage is so great in comparison with the electron transit time. Thus, instead of defle'cting the beam as desired, its deflection in traveling through such a field would be first in one sense and then in the other, so that upon emerging from the field it might not be deflected at all from its original path. In the most favorable case Where the emergence of the beam from the field occurs at a time when the field producing deflection voltage is at a maximum value and corresponds in polarity to the defiection voltage at the beginning of the field traversal by the beam, the resultant beam deection might still be too small for practical use for the reason that the deflection voltage even at its maximum instantaneous value Would necessarily be relatively small. It thus is apparent that, in order to avoid the transit time effects of the electron beam, it is necessary to provide deliection fields of relatively small extent so that the time required for the electron beam to travel through the field will correspond substantially with the time duration of a voltage maximum of the relatively high frequency carrier current signal. But as seen, such a field is in many cases not of suiiicient strength to effect the desired deflection of the electron beam.

It, therefore, is an object of the present invention to provide a novel deflection system for a cathode ray tube whereby to effect a relatively large beam deliection under the control of relatively small deflection voltages.

In accordance with this invention, there is prolthelmionic cathode 2.

vided a source of beam deection energy and a means including an electrical structure such as a transmission line for producing a time spaced distribution of the deflection energy. Also there is provided a means for utilizing the time distributed energy to produce successively a plurality of beam deflecting elds spaced along the path of the beam.V .,V.

In a so-called single tube receiver embodiment of the invention, more specifically there is prof vided a cathode ray tube having a source of an electron beam and, in spaced relation theretda target electrode. There also is provided means for producing a series of deflection fields within` the tube in the space intervening-between the` electron beam source andthe targetelectrode. The relatively high frequency carrier current signals to be used in this case as voltages` for controlling the plurality of deflecting clds are impressed upon one pair of terminals ,of a trans-r mission line which preferablyisterminated'in such a manner that it is resonant. o The transe mission line is tapped at pointsv located therealong at distances equal to a half a wave length of the radiant .carrierl frequency energy. The voltages developed at appropriate intervals at these tapped points of the transmission line thus are instantaneous maximum voltages of the energy'impressed thereon for the reasonthat they are developed at simultaneously produced antinodal or loop points of the voltage wave 4prepa-- gated along the rtransmission line. By impressing the voltages developed at the tapped points along the transmission line in suitable,` polarity upon the` respective eld producing means, itis possible to produce corresponding deectionuelds along the axis of the tube "so thatan electron beam traversing the successionof fieldsv at a suitable rate is subjected to a series Vof corresponding deflecting influences, eachA of'which increases the magnitude of the" beam deflection by a predetermined small amount.V The final result is that the beam emerges from the' last of the fields with a deflection of considerable magnitude which Vis the aggregate of all of the individual deflections imparted thereto. The spacing of the vmeans for producing theplurality of deecting elds along the axis of the tube isrrelated .to the velocity of the electron beam in such a manner that the time required for the beamto travel from one field to another is substantially equal to a half a wave length of the high frequencyn deflecting voltage. Y. I y

`'..-F0r a better understanding 'of the invention, togeth'erwith other and further Yobjects thereof, reference is had to the following description, `taken in connection with the accompanying drawig, and its scope will be pointed outV in the appended claims. Y ,Y

v The single figure of the drawing shows schematically a cathode ray device and associated deiiection control apparatus embodying the linvention in the form of a singletube radiant energy receiver.

Having reference now to the drawing, the cathode ray device consists of an 'evacuated envelope vor tube I. 'Adjacent one end of the tube there is provided an electron emitter such as a A The cathode may be heated for emission by any conventional means such as' an indirect heater element 3 which may ber'conlnected to any convenient sourcej of venergy such as the illustrated Vbattery 4. Adjacent'the cathode 2 there alsois provided'an intensity control element such as a grid 5. The elllQllSf .91@

4 accelerated initially and formed into a beam of the desired cross section by conventional means such as a beam forming accelerating electrode 6.

A pair .of vertically disposed plates 'l are provided adjacent the path of the electron beam emerging from the electrode 6. The function of these plates is to suitably control the beam in a fiorizontalrlaee as Viewdfll therwing- The voltage for producing the beam controlling field between the plates 'l may be derived from any convenient source such as a battery 8. In order to control the strength of the field produced betweenthe plates fI so as to properly locate `the horizontal position of the beam, there is provided apotentiometer. Sconnected in parallel with the battery.

'Still farther alongfthe path traveled by the electron beam there is located a plurality of horizontally disposed pairs of deflecting plates I0, II, I2 andi@ Alilaclfrof therespective pairs of plates II) to I3is located symmetrically relative to the central axis of the tube along` which the undelected electron beam"wo',ul d travel.` Each pair* of plates also is spacedA from an adjacent pair of plates longitudinally along the axis of the tube by a predetermined amount dependent upon the velocit'yrof the electron beam andthe frequency o f the deflection voltage to be employed.

Adjacent the right hand endoffthe tube I there is provided aV target electrodey I4 which embodies a centrally disposed small v*aperture I5 such position, for examplethatfitlies on the path of the undeflected beam. Behind, or as viewed in the drawing to the rightof,- the target electrode there ispmounted a multistage electron multiplier comprising a series arrangementiof a.'V plurality of secondary electronhemissive electrodes such as IB and I'I.V `The first'stage elec# trode I6 is mounted directly behind the aperture i5 lso that its sensitized secondary electronemis; sive surface is impinged by electrons passing through the aperture, An electron collecting electrode I8 is `located. adjacent thelast multif plier electrode I'I. U o

With the exception of the beam deflecting plates, the electrodes of thel tube and the electron multiplier have suitable fixed operating poten'- tials'impressed thereon which may be derived from any convenient source or plurality of sources of energy in accordance with wellknown practice. In the presentinstance the source of operating potentials for the tube is illustratedas a battery I9 provided with a plurality'of taps so that the potentials impressed upon the variouselectrodes may be made to correspond suitably to onemanother. The cathode 2.0i the electron' gun for producing the beam ofjelect'rons is lconnected to the' negative terminajlof the battery i9. `The control grid 5 isconnected to a potentiometer 2U which is connected between the negative terminal and a somewhat more positiverpoint of the battery, such as 2l. In a similar manner the accelerating anode E is connected to a potentiometer 22 `which is connected between the point 2l and a still more positive point 23 of the battery. The target electrode, which is electrically connected to the first multiplier electrode I5, and the rest oi the multiplier electrodes are connected to points oi the battery I9 which are increasingly more positive in accordance with conventional practice in devices of this character. The collector electrode I8 is connected through a load resistor 24 tothe grounded positive terminal of the battery lil. The signal voltages developed in the output resistor are impressed upon any desired utilization circuit connected across the output resistor.

The signal-modulated high frequency carrier Wave energy is intercepted by an antenna such as the dipole antenna 26 illustrated. The antenna 25 is coupled by condensers 21 to the two input terminals of a transmission line 28. This device may have any conventional electrical structure such as a coaxial cable, a Lecher wire system or the like. At suitable frequencies the transmission line may consist of a network of lumped circuit elements such as resistors, capacitors and inductors. In the case of a transmission line such asV aV coaxial cable, a Lecher wire system orthe like, the line will have considerable length, for the reason that the velocity of the electron beam of the cathode ray device is only a fraction of the velocity of the wave propagation along the transmission line. In order to conserve space it is contemplated that such a transmission line may be coiled or otherwise formed in any desired manner. However, for the purpose of simplifying the instant illustration, a transmission line of the Lecher wire type is shown as two substantially parallel linear conductors. It will be understood that there is no intention of implying that the length of the transmission line 28 or any parts thereof necessarily bear a relationship to the spacing of the deecting plates Il) to I3. These relationships depend, as will be apparent presently, upon the frequency of the deection voltage and the velocity of the electron beam.

The invention embodying a transmission line for the impression of deecting voltages upon the electrodes of the cathode ray device may be prac'- ticed by so terminating the transmission line that there will be produced either traveling waves or standing waves, as desired. Inasmuch as it is desired to develop maximum deflection voltages from relatively small quantities of received energy, it is preferred to terminate the transmission line in such a manner that there will be produced standing Waves. In this manner the maximum deflection voltages may be developed. Consequently, in the preferred embodiment of the invention illustrated the right hand terminals of the transmission line, as viewed in the drawing, are connected to an impedance device having a value considerably diierent from the characteristic impedance of the line. In such a case the terminals of the transmission line 28 are interconnected through relatively high impedance devices such as resistors 29. These resistors are of the order of several thousands of ohms so that they differ materially from the characteristic impedance of the transmission line. Consequently,

the energy which is propagated along the line from the antenna 26 to the other terminal is 'l reflected from this terminal for propagation back toward the terminal coupled to the antenna. It will be obvious to those skilled in the art that standing waves alternatively may be produced .either by short circuiting the line terminals or v Which are spaced from the input terminals of thetransmission line by substantially a half a wave length, there are provided connections from the respective transmission line conductors to the first pair of vertical deecting plates IIJ. Similarly, at points 32, which are spaced along the transmission line at a distance of a. half a wave length from the points 3|, connections are made to the pair of deflecting plates Il. In this case, however, it is noted that these connections are reversed from those made to the plates I0. In like manner, the plates I2 are connected to the respective transmission line conductors at points 33, which are located a half a wave length distant from the points 32. The polarity of the connections to the plates l2 is the same as that for the plates I0 inasmuch as the respective transmission line connecting points 3| and 33 are separated by a distance equal substantially to one full wave length. Similarly, the deiiecting plates i3 arenconnected, in like polarity to the plates Il, to pointsY 34 on the transmission/line conductors, which are removed from the points 33 at a distance of substantially a half a wave length. Obviously, as many pairs of deflecting plates and associated connections to a transmission line such as 28 may be provided as are required to eiect the desired magnitude of beam deection.

In order to secure stable operation of apparatus of the character described it is necessary to electrically correlate certain of the electrodes and auxiliary apparatus. Consequently, the focusing and accelerating electrode 6 is connected to one of the horizontal deflection plates 1 so that these two electrodes operate substantially at the same unidirectional voltage. For a similar reason the terminating resistors 29 for the transmission 28 may be connected to the accelerating electrode 6 as shown, or to a source of unidirectional energy of suitable voltage, whereby the terminating resistors and the accelerating anode are operated substantially at the same potential.

Referring now tothe operation of the described apparatus, assume that the cathode 2 is conditioned by heating, as illustrated, or otherwise as desired to eiect the emission of a copious quantity of electrons. A suitable number of the emitted electrons to form an electron beam of the intensity desired are permitted to pass through the intensity control grid 5 by suitably adjusting the rheostat 20. The electrons so passed are formed conventionally into a beam of the desired cross-sectional area by the electron optical conditions existing inside of and near the accelerating electrode E. Also, the desired velocity or relative stiifness of the electron beam so formed is secured by an appropriate adjustment of the potential with respect to the cathode which is applied to the accelerating anode E, This accelerating potential is subject to considerable variation by means of the potentiometer 22 for an adjustment purpose to be described presently. The beam is centered horizontally, or otherwis-e located as desired with respect to the aperture l5, under the control of the voltage impressed between the plates l which is susceptible of variation by means of the potentiometer 9. Once the horizontal location of the electron beam with respect to the aperture l5 is xed, further adjustment of the potentiometer 9 ordinarily will not be necessary.

The relatively high frequency carrier Wave energy which is modulated in amplitude in accordance with the intelligence signals is received 'by the dipole 'antenna 2S, and as a result a relatively small voltage varying in amplitude in'accordance with the modulated carrier wave is impressed upon the transmission line 23. Inasmuch as in the present instance the other terminals of this transmission line are connected to an impedance considerably greater than the characteristic impedance of the line; the energy which is prop- 7 aeated down thetlansiissoelins is; Subsieef tial-ly unabsorbed at. the right. handend.thereof1 as viewed in the drawing..v Thus, thisenergy is reiiected back along thetransrnission line. in the. direction ot the. input terminals. By proper. selection of the length of: the. transmission in. a. manner well known in. the art, the reiiected energy is in Fliese with the input-energy- AS a.

consequence, there is produced. along. the trans; mission line. a. standing wave. At the points. along the transmission lineA where antinodes; o the standing wave occur., there are developed maxi-4 mum.y voltage diierences. described, it isat. these points-that-thedelecting-plates. Il) ,to` I3 are. CQBHEQGG- Consider now the e'ec't. ot thevarious deecting fields produced by the plates. I Ilto L3V upon an electron bear-n; traveling from: left to right as. viewedy inj the. drawing between. successive pairs. oil vertical deiiecti-ng. plates.. While. a, given portion of the electrongbearn lSfI Passing; thronghthe i'iel'd produced between. the. mst, pair of deecting plates i8., assume. that tlievoltage. impressed be. tween these two. plates is atz an. instantaneous maximum negative vel-.ue as indcatedatihe point.. ?.^I. by the. broken line. curves. 311-.. The elctrons comprising this. portion ei, thebeam, therefore, will-.be deflected from the. straight `lin-e path be tween the anode Gand the. aperture. I5 by a predetermined smal-l amount, sayin an upward di. rection. as. viewed in the drawing..Y

This-group of electrons travels. from the.V plates, IIJ- to. the plates II- at.4 a. ratedetermined by. the acceleration imparted thereto. by the. anode 6.. By

suitable designand control. ofthe accelerating.

voltage the time required. for the. electron travel between plates l0 and II may be made substantially equa-l to the'. time required. for the relatively. high radio frequency voltage tovary through one hal-f a cycle; Thus, when this group, of electrons reaches the field of iniuence of the plates-v I I the energy in the. transmission line 28 will. have. reached a positive maximuminstantaneous, value such as indicatedv at the point` 3,2, By impressing this transmission line voltage upon the deflection. plates II in a polarity opposite to. that of. the plates I9., it is seen that. the eld producedbetween the plates II will: be substantially of. the. samer poe larity and magnitude as the field produced a short time earlier between the plates I il. Therefore, the same portion of. the electron beam is deiiected again upwardly by a small predetermined amount.A

The spacing-between the pair of plates l2 and. the pair of plates II and also that between the pairs of plates I3 and I2 is substantially the same as the spacing between the pairs of plates I I and. I0.. For this reason the considered portion of the electron beam requires substantially the Same time to travel between plates I I and I2, and subsequently between plates I2 and I3, as the time required for this portion of the beam to travel between the vpairs of plates Ill and Il. Then, by reason of the described connections of the plates I2 and I3 to the transmission line 28. atantinodal points of the standing wave, it is. seen that. the electron beam is successively deflected between. the pairs of plates I2 and I3 by small predetermined amounts in both cases and in the same sensev as the delectionthereoi imparted by the pairs of plates I0 and II. As a result, the beam emerging from the last pair of deiiectingY plates is displaced from the undeflected path of the e1ec tron beam by an amountsubstantially equal to four times that obtainable by the use of a single pair. of defletine elemente. .1e .this meneer itis toprovide a.V device Awhich is considerably easier tao'perate and control.

tionatthe plates I2f and I3.at the times when the sary timing of the electron travel between succes-V InV the construction of a device of this char-v acter. it isnecessary only to space the deecting. plates, III to I3` approximately, considering the Vealocity of the electron beam and to someextent the ferquency of the deflecting voltages to be eniployed. It is, however, desirable that the spacing 0f thedeflecting electrodes along the axis of the" tube` be as nearly uniform as possible so that, have` ingmadethe necessary` adjustmentsY to eiect the travel of a portion of the electron beam between the electrodes Ill` and. II,v for example, insubstanr-A tially the same time required for the deecting, voltage to go.thro u gh a half a cycle, the sameV ad;v justment will enable the arrival of the beam por-v voltages impressed upon these pairs of plates are at their respectivemaximum values.

-I-Ience., assuming a uniform spacing. between.

the. deflecting plates, in order to elect theneces:

sivey pairs of deflecting plates it merely is neces,- sary to adjust the voltage impressed upon the accelerating vanode 6 by a suitable manipulation of the potentiometer 22.. The greater the potentiall difference between the accelerating anodev Sand the cathode'2 the higher will be` the velocityv of theelectron beam which. is to traverse the iields created by the deecti'ng plates Ill to I3. It, therefore, is seen that this provides a relativelyl simple arrangement for adjusting a device of this. character for a certain. performance of the func-v tionfor which it is. intended.

While. there has been described what, at prese ent, is consideredv the preferred embodiment of the invention, it will be obvious to those skilled in the art. that various changes and modications may be made therein without departing from the invention, and therefore, it is aimed in the ape, pended claimsto cover all such changes and modi-v fications as fall within the true spirit and scope ef the invention.

What is claimed is:

l 1. An electron beam deflecting system for a cathode ray device. comprising, a source of beam deflection energy, a plurality of deecting field prodllng electrodes spaced along the path of said beam, and means including a vtransmission line connected at points spaced therealong to said electrodes for effectively connecting said. energy sgurce successively and in like polarity to said electrodes substantially coincidentally Vwith the travel of said beam past the electrodes.

2. An. electron beam deilecting system for a cathode ray device comprising, means energizabie tor. producing two beam deflecting nelds at points spaced along the path of. said beam'atA distances such that a' predetermined time is.y requiredfor the beam to travel between said fields, an. elec'f trical structure. of' such. character that electrical energy is propagated between two spaced points thereon in'said predeterminedtime,means. ier impressing periodic electrical energy upon s l d electrical .structure at a'predetermined. ireduen and, meansA for deriving. energy from.said two spaced electrical. Astructure pointsy to-energjiaein .like Poleiitr-Sad iwsld produei'eemeaes- 3. An 'electVv n beam deflecting system fora aihfide ray ,v e-Qomprisinameens for Drogue .a 91er.. 'ty ef beam defeating fieles. ai points uniformly spaced along the path of said beam at distances such that a predetermined time is required for the beam to travel between two successive 'defiecting fields, an electrical structure of such character that electrical energy is propagated between succ'essive ones of a plurality of uniformly spaced points thereon in said predetermined time, means for impressing periodic electrical energy upon said electricalstructure at a radio frequency, and means forconnecti'ng said plurality of spaced electrical structure points respectively to said plurality of field producing means'.

4. A system for deflecting an electron beam of a cathode ray device comprising, a plurality `of deflecting electrodes uniformly spaced along the Vundelected path -of said beam, a transmission line, means for impressing upon said transmission line energy at a' predetermined radio frequency, and means for connecting -successive pairs of said electrodes to points on said transmission line spaced therealong at distances substantially equal to a half a wave length of said radio frequency energy.

5. A system for deflecting an electron beam of a cathode ray device comprising, a plurality of pairs of beam denecting electrodes uniformly spaced along and symmetrically located relative to the axis of said device, a transmission line, means for impressing upon said transmission line alternating current energy of a predetermined frequency, means for connecting the successive pairs of said electrodes in opposite polarities to points of said transmission line spaced therealong at distances substantially equal to a half a wave length of said alternatingcurrent energy, and means for directing initially along the axis of said device an electron beam having an electron transit time between successive pairs of said deflecting electrodes corresponding substantially to the time of a half cycle of said alternating current energy.

6. Apparatus for 'defiecting the electron beam of a cathode ray device comprising, two pairs of deflecting electrodes mounted in said device in mutually spaced relationship and symmetrically located with respect to the axis of said device, a transmission line, means for impressing upon said transmission line alternating voltage having a predetermined frequency, means for connecting said pairs of deflecting electrodes to respective points on said transmission line spaced therealong to coincide with simultaneously developed antinodal portions of the alternating voltage propagated along said line, and means for directing an electron beam along the axis of said device at a velocity whereby the electron transit time between said two pairs of deflecting electrodes corresponds substantially to the time of a half cycle of said alternating current energy.

7. In a radiant energy receiving system, a cathode ray tube having two pairs of ray deecting electrodes spaced along the axis of said tube, a radiant energy intercepting antenna, a transmission line connected to said antenna, connections between respective pairs of said deflecting electrodes and points on said transmission line spaced therealong at a distance substantially equal to a half a wavelength of said radiant energy, said two pairs of deflecting electrodes being connected in opposite polarity to said transmission line, and means for directing along the axis of said tube an electron beam having an electron transit time between said two pairs of deecting electrodes corresponding substantially to the time of a half cycle of said radiant energy.

8. In a radiant energy receiving system, a cathode ray tube having two pairs of ray deecting electrodes spaced spaced along the vaxis of said tube, a radiantnergy intercepting antenna, a transmission line connected to said antenna, connections between respective pairs of said deilecting electrodesA and points on said transmission line spaced therealong at a distance substantially equal to a wavelength of said radiant energy, Ysaid two pairs of deflecting electrodes beingpcon'nected in the same polarity to said transmissionline, and means for directing along the axis of said tube an electron beam having an electron transit time between said two pairs of deflecting electrodes corresponding substantially to the time of a full cycle of said radiant energy.

i9. In 'a relatively high frequency radiant energy receiving system, a cathode ray tube having anelectrn gun for producing an electron Vbi'e'ar' and also having a plurality of pairs of beam reilecting plates uniformly spaced along the path of said electron beam, a radiant energy intercepting antenna, a transmission line connected to said antenna, connections between respective pairs of said deecting plates and points on said transmission line spaced therealong at distances substantially equal to a half a wavelength of said radiant energy, and means for controlling said electron beam so that the electron transit time between successive pairs of said delecting plates corresponds substantially to the time of a half cycle of said radiant energy.

10. In a relatively high frequency radiant energy receiving system, a cathode ray tube having an electron gun for producing an electron beam and also having a plurality of pairs of beam deflecting plates uniformly spaced along the path of said electron beam, a radiant energy intercepting antenna, a transmission line connected to said antenna, connections between respective pairs of said deecting plates and points on said transmission line spaced therealong at distances substantially equal to a. half a wavelength of said radiant energy, successive pairs of said plates being connected in opposite polarity to said transmission line, and means to impart to said electron beam a velocity such that the electron transit time between successive pairs of said deflecting plates corresponds substantially to the time of a half cycle of said radiant energy.

11. In a relatively high frequency radiant energy receiving system, a cathode ray tube having an electron gun including an accelerating electrode for producing an electron beam and also having a plurality of pairs of vertical beam delecting plates uniformly spaced along the path of said electron beam, a radiant energy intercepting antenna, a resonant transmission line having one terminal connected to said antenna, connections between respective pairs of said deflecting plates and points on said transmission line spaced therealong at distances substantially equal to a half a wavelength of said radiant energy, successive pairs of said plates being connected in opposite polarity to said transmission line, and means including said electron accelerating anode to impart to said electron beam a velocity such that the electron transit time between successive pairs of said deilecting plates corresponds substantially to the time of a half cycle of said radiant energy.

12. In a relatively high frequency radiant en- 11 rgy receiving system, a cathoderay tube -having `an electronv gun includingl an accelerating electrode for producing an electron beam,A a target electrode having an aperture, a pair of horizontal beam deecting plates and apluralityof pairs of Vertical beam deflecting plates uniformly spaced along they path of-said electron beam, a radiant energy intercepting antenna, a resonant transmission line having one terminal Connected to said antenna, connections between respective pairs of said vertical deeoting plates and points on said transmission line spaced therealong at distances substantially equal to a half a wavelength of Said radiant energy, successive pairs of' said Vertical deecting plates being connected inropposite polarity to said transmission line, means for impressing upon said pair of horizontal deflecting plates a potential suitable toV position said beam horizontally in alignment with said target electrode aperture, and means for impressing upon said electron acceleratingr anode a potential suitable to impart l2 to said eletron beam a Velocity suchrthatth electron transit timebetwen'-sccessive'pairs of' said vertical -deflectin-g platesj correspondssub stantially to the-time of ahalfA Cycle-of fsa'idra- 5 diant energy. Y .c, Y @CHRISTIAN C. LARSONL-...LL e REFR'ENC'S'QCTD Q1 The following references are of record in the 10 nie of this patent: f .I 1 UNITED sTA'rs PATENTS Number Name'y Date v 2,284,829 Ludi f June 2, 1942 15 2,233,126 Haef '"Feb.25,'1941 2,308,391 Roberts Jan. 12, 1943 2,074,478 Linder .l. i..LVMan 23, 1937Y l FOREIGNPATENTSV, f .920 Number Country Date;`

Great Britain Mar. 18, 193.8

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