US2520152A

US2520152A - Radiant energy receiving device

Info

Publication number: US2520152A
Application number: US510714A
Authority: US
Inventors: Christian C Larson
Original assignee: Farnsworth Research Corp
Current assignee: Farnsworth Research Corp
Priority date: 1943-11-18
Filing date: 1943-11-18
Publication date: 1950-08-29
Anticipated expiration: 1967-08-29

Description

Aug. 29, 1950 c. c. LARSON RADIANT ENERGY RECEIVING DEVICE 2 Sheets-Sheet 1' Filed Nov. 18, 1943 Gumm 44206 momDom mw Om hum Em NEOI mm m VN mm INVENTOR CHRISDTIAN c. LARSON ATRNEY Aug. 29, 1950 c. c. LARSON 2,520,152

RADIANT ENERGY RECEIVING DEVICE Filed NOV. 18, 1943 2 Sheets-Sheet 2 VERT.

DEFLECT INYENTOR CHRISTIAN 0. LARSON BYW ATTORNEY Patented Aug. 29, 19 50 UNITED STATES PATENT OFFICE RADIANT ENERGY RECEIVING DEVI-CE Christian C. Larson, Fort Wayne, Indz, assignor, by mesne assignments, to Farnswortli Research Cor'poration, a corporation of Indiana Application November 18, 1943, Serial N5. 5109214 11 Claims.

This invention relates to radiant energy receivers in general and more particularly to ultra-ultra high frequency radiant energy receivers such as those adapted to receive signals in the range between 30 and 300 megacycles.

Conventional radiant energy receivers adapted to receive ultra-ultra high frequency radio signals are of the superheterodyne type which require radio frequency channels, intermediate frequency channels and audio or video signal amplifiers or both. The channels and amplifiers not only require a multiplicity of vacuum tubes but they also require a large number of circuit elements such as resistors, inductance coils, condensers and transformers. Circuits utilizing these various circuit elements are necessarily complex in nature and expensive to design and assemble. Furthermore, such complex circuits introduce distortion of various Sorts, the correction of which adds to the complexity of the entire circuit.

7 The principal object of this invention is to provide a novel electronic tube adapted to constitute a substantially complete radiant energy receiving device.

A further object of this invention is to proi'ride a simple and efificient radiant energy receiver adapted toreceive carrier modulated signals in the ultra-ultra high frequency range.

' In accordance with this invention, there is providd an electron tube comprising electron gun "apparatus adapted to generate an electron beam of a sharply defined cross-section together with tuneable deflecting means arranged to receive ultia ultra high frequency radio signals and dee fleet the electron beam in accordance with such signals. There is illustrated purely by Way of example an initial electrode of an electron multiplier in the path of the electron beam. There is provided in the electrode an aperturefor passing electrons to the secondary emissive surface on the interior of the electrode. The beam may nor-- mally be positioned by the deflecting electrodes adjacent one edge of the aperture and deflected accordance with signals to pass varying num bers' of electrons in accordance with the received signal. The multiplier also includes successive stages for additionally multiplying the primary electrons in the electron stream thereby to provide' a high factor of amplification. It is not intended, however, that this invention shall be lim ited to the use of an apertured electrode. For example, the inner surface of the initial electrode of the electron multiplier may be partially covered with carbon black and thebeam directed to f, this hon emissive surface. Deflection of the beam in accordanc with received signals from the non-emissive surface to the emissive surface would provide secondary emission of electrons in accordance with received signals. It is also within the scope of this invention to provide a shield electrode between the vertical deflecting electrodes and the initial stage of the multiplier whereby the death may be normally blocked by the shield and deflected with respect to one edge of the shield in accordance with received signals. These are only a few examples of many barriers that may be provided for controlling the flow of electrons into the multiplier.

Since the electron multiplier has rectifying properties and, moreover, has a definite frequency cutoff, it willactas a detector or rectifier of modulated carrier signals in the ultra-ultra high frequency range beyond the multiplier cutoif point. Therefore, the electron beam inthe tube may be deflected in accordance with modulated carrier signals in this frequency range and the flow of electrons through theapertured electrode is in accordance with themodulated carrier signals. However, since the multiplier does not respond to carrier frequencies of this order, they disappear and only the signal itself is transmitted through the multiplier. Thus there is obtained a rectified intelligence signal of sufficient strength to directly energize a reproducing device such as a picture reproducing tube or sound reproducing loud speaker. v I

It is also within thscopeof this invention to provide, instead of a deflecting system, a signal F grid for varying the electron current in the beam emitted by the electron gun. Thus by providing a tuneable antenna and suitable connections to the grid, the tube provided by thisinvention may be utilized as a c inplete ultra-ultra high frequency radio receiver.

For a better understanding of the invention,

together with other and further objects thereof,

reference is made to the following description, taken in connection with the accompanying drawings, and its scope will be pointed out in the appended claims.

In the accompanying drawings:

Fig, l is a plan view in cross-section of an electron tube receiver together with circuits for energizing it as provided in accordance with this invention. V

Fig. 2 is a graphillustrating a typical frequency response characteristic of the electron tube of Fig. 1. v

Fig. 3 is a plan view in cross-section of a modification of the receiver shown in Fig. 1.

Referring to the drawings, there is provided an electron tube consisting of an envelope l in which is supported an electron gun assembly comprising a cathode heater element 2, a cathode 3 and

beam control electrodes

4 and 5. Electrodes 2, 3, i and 5 are energized in accordance with well known practice from power source l8 as illustrated in the drawings. Adjustable resistors l5 and It may be adjusted to provide the proper potentials on

electrodes

4 and 5 for forming an electron beam.

Electrostatic deflection plates 6 energized by a horizontal deflection potential derived from source Hi control the horizontal path of the electron beam in accordance with the setting of resistor 20. Vertical deflection of the beam is controlled by tuneable electrodes 7 in accordance with carrier signals received on antennae 8. The vertical deflection of the beam is controlled by electrodes 7 in accordance with a potential derived through a circuit consisting of the electrodes 1, plates 2| and 22 of the tuning element, inductors 24 connected thereto, potentiometer 25 and battery 26. For insulating plates 2| and 22 with respect to one another, there is provided an insulator disc 23. By varying the setting of potentiometer 25, the beam may be directed by electrodes 1 in a predetermined plane.

For obtaining electron multiplication, there is provided an electron multiplier comprising an initial secondary emissive stage it havin an aperture H. Successive stages 12 in the electron multiplier provide progressive multiplication of electrons until the stream finally impinges on the collector electrode I4.

Output electrode Id of the electron multiplier is connected to a load or signal translating device such as an audio frequency loud speaker or a cathode ray picture reproducing tube whereby received signals may be reproduced.

As explained hereinbefore, the electron tube may be utilized as a detector and an amplifier by reason of the fact that the electron multiplier has rectifying properties and inherently has a frequency cutoff in the ultra-ultra high frequency range beyond which it does not respond.

The electron gun structure consisting of cathode 3 and

control electrodes

4 and 5 generates an electron beam in a manner well known to .be impressed on electrodes 6 a potential from source is sufficient to normally deflect the elec- .trode beam into vertical alignment with aperture l I. Electrodes I may be tuned by moveable plates 2! and 22 to receive from the antennae 8 the desired ultra-ultra high frequency modulated carrier signal for deflecting the electron beam in a vertical plane from its normal position into overlapping relation with respect to aperture ii. The electron beam is deflected in varying degrees in accordance with the received modulated carrier signals whereby a varying number of electrons penetrate the aperture H.

The electron multiplier consisting of electrodes HJ, I2 and Hi amplifies the space current flowing therein in accordance with well known theory. However, as mentioned hereinbefore, the carrier components of the received signal disappear in the electron multiplier because of its inherent rectifying and frequency response characteristics.

Thus on electrode hi there appears the modulation signal which may be fed to a utilization device of the general character of television or sound reproducing devices. Such devices are schematically indicated in the drawing as a load connected to the output electrode M.

The typical frequency response characteristics of the multiplier may be best illustrated by a graph such as illustrated in Fig. 2 of the drawings. When the response of the multiplier is plotted against frequency of the signals passing through the multiplier, a curve such as A is obtained which shows that maximum response occurs at zero frequency and minimum response occurs at a frequency of, for example, 100 megacycles. It is thus apparent that a modulated carrier signal of 100 megacycles or more in frequency may be rectified by reason of the fact that the multiplier does not' respond to frequencies over 100 megacycles, whereas frequencies of less than 100 megacycles corresponding to a modulation signal are amplified.

The frequency cutoff of a multiplier is not necessarily 100 megacycles as the cutoff point depends upon the spacing of multiplier stages with respect to one another and the voltage between successive stages. Furthermore, it is believed that a, change in the multiplier electrode geometry would also change the cutoff characteristics of the multiplier. If it is desired to increase the cutoff frequencies, it is believed that an increase in voltage between certain multiplier stages or between all multiplier stages would increase the cutoff frequency. Similarly a change in the spacing between respective multiplier stages would change the frequency cutoff characteristic. For example, an increase in the spacing would increase the electron travel time between stages and therefore would decrease the cutoff frequency. It is believed that such changes in the parameters of the multiplier as mentioned above may vary the frequency cutoff characteristics of an electron multiplier over the range extendin from 30 megacycles to 300 megacycles.

Fig. 3 of the drawings illustrates a modification of this invention comprising a tube having similar structure generally to that shown in Fig. 1. Similar parts are indicated by identical reference characters, and since these parts are obvious from inspection it is not deemed necessary to describe them in detail. Whereas the receiving tube illustrated in Fig. 1 is provided with a deflection means for varying the electron current in the beam, such variation is obtained in this modification by the use of a control grid 29 which may be disposed between cathode 3 and auxiliary control electrode 4. For controlling the grid to cathode potential, there is provided a pair of ultra-ultra high frequency conductors 30 which may be'suitably connected to these electrodes. Dipole antennae 8 are connected to conductors 30 for receivingradiant energy. For tuning the receiving circuit, there is provided a slider bar 3| which may be operated in a well known manner to tune the circuit to receive a desired carrier signal.

In this modification of the invention, the defiection electrodes 6 create an electrostatic field under the control of resistor 20 and potential source I 9 to control the path of the electron beam in a horizontal plane whereby to direct the beam through aperture ll of multiplier electrode Ill. The path of the beam in a vertical plane is controlled by deflection plates 32 energized from assess-r2 source 34 through variable resistor 33. As

the modification illustrated in Fig. l, the electron iic'w impinging on the surface of electrode HI represents the modulated carrier signal received on the antennae. As explained hereinbefore, the signal is then rectified and amplified in the multiplier to derive the modulation signal.

It is not intended that this invention shall be limited to the specific embodiments illustrated here-in, As mentioned hereinbefore, it is not necessary to utilize an apertured electrode for receiving the electron beam. The initial multiplier stage may be entirely open on the side facing the electron gun, and a portion of the interior surface "of the electrode may be coated with carbon black to provide a non-emissive surface or shield. The electron beam normally may be directed to impinge on the carbon black surface and may be deflected by received signals to impinge in varying degrees on the secondary emissive surface to provide electron flow in the multiplier varying in accordance with modulation signals, Various types of shield electrodes may also beu'tili'zed in the space between the electron gun and the initial multiplier stage. plate or shield may be so disposed as normally to intercept theelectron beam whereby deflection of the beam with respect to one edge of the plate may provide variable flow of electrons in accordance with received signals.

"It will be obvious to those skilled in the art that having obtained a rectified signal, it is only necessary to provide a suflicient number of multiplier stages to obtain the desired degree of ampliflcation. Thus Signals may be fed directly to a utilization device such as a loud speaker or a picture reproducing tube. Distortion of the rectified signals is substantially completely eliminat'ed, and the numerous components of the conventional radiant energy receivers are entirely dispensed with.

While there has been described what is at present considered the preferred embodiment of the invention, it will be obvious to those skilled in the art that various changes and modifications may be made therein without departing from the invention, and it is, therefore, aimed in the appended claims to cover all such changes and modifications as fall within the true spirit and scope of the invention.

What is claimed is:

l. A signal receiver comprising means for generating a beam of electrons, electron multiplier means in the path of said beam of electrons having a predetermined frequency cutoff characteristic, an electron barrier, a source of carrier modulated signals the carrier frequency of which is beyond the frequency cutoff of said electron multiplier and the signal modulations thereof are below the cut-off frequency of said multiplier, beam control means responsive to said carrier modulated signals for deflecting the flow of electrons of said beam with respect to said barrier, and tunable means for applying carrier modulated signals from said source to said beam control means.

2. A signal receiver comprising means for generating an electrcn beam, electron multiplier means having a predetermined frequency cutoff characteristic and including a secondary electron emissive surface disposed to be impacted by said beam, an electron barrier, a source of modulated carrier signals the carrier frequency of which is beyond the frequency cutofi of said electron multiplier and tuneable means including an elec- For example, a

6 trode coupled to said source of signals for deflect ing the electron beam with respect to said bar rier and said secondary emissive surface in accordance with received signals.

3; A signal receiver comprising an electron gun for generating a beam of electrons, electron multiplier means having a predetermined frequency cutoff characteristic and including a sec- 'ondary electron emissive surface, a non-emissive surface, a source of carrier modulated signals the frequency of which is beyond the frequency cutoff of said electron multiplier and tuneable means connected to said source of si nals for deflecting said electron beam between said non-emissive surface and said emissive surface in accordance with said signals whereby said multiplier rectifies and amplifies said signals.

4. A signal receiver comprising means for generating a beam of electrons, means disposed in the path of said beam for normally blocking it, electron multiplier means adjacent said blocking means having a predetermined frequency cutofi characteristic, a source of carrier modulated signals the frequency of which is beyond the frequency cutoff of said electron multiplier and tuneable means connected to said source of signals for deflecting said electron beam with respect to said blocking means in accordance with said signals whereby said multiplier amplifies said signals.

5. A signal receiver comprising means for generating a stream of electrons, electron multiplier means having a predetermined frequency cutoff characteristic and including a secondary electron emissive surface, means for normally rendering said electron stream ineffective with respect to said electron multiplier means, a source of modulated carrier signals the frequency of which is beyond the frequency cutoff of said electron multiplier and tuneable means including a control grid coupled to said source of signals for rendering said stream of electrons effective with respect to said electron multiplier in variable degree in accordance with said signals.

6. A signal receiver comprising means for generating an electron beam, electron multiplier means having a predetermined frequency cutoff characteristic and including a secondary electron emissive surface disposed to be impacted by said beam, an electron barrier, a source of modulated carrier signals the frequency of which is beyond the frequency cutoff of said electron multiplier and tuneable means including a grid electrode adjacent said beam generating means and coupled to said source of signals for deflecting the electron beam with respect to said barrier and. said secondary electron emissive surface in accordance with received signals.

'7. A method of detecting and amplifying a signal in an electron multiplier comprising the steps of receiving a modulated carrier signal the frequency of which is beyond the cutoff frequency of said multiplier, generating an electron beam, deflecting said beam in accordance with said modulated carrier signal to vary the electron flow in said beam and electronically multiplying said electron beam to rectify said carrier signal and derive an amplified modulation signal.

8. A method of detecting and amplifying a signal comprising the steps of receiving an ultraultra high frequency modulated carrier signal, generating an electron beam, deflecting said beam with respect to an electron barrier to effect a variation in the electron flow in said beam in accordance with said modulated carrier signal,

7 and simultaneously rectifying and multiplying the varying portion of said electron beam to derive an amplified modulation signal. 1

9. A signal receiver comprising an electron gun for generating a beam of electrons, a shield disposed in the path of said beam for normally blocking it, beam deflecting means including source of potential for normally directing said beam to impinge on said shield, electron multiplier means adjacent said shield having a predetermined frequency cutoff characteristic, a source of carrier modulated signals the frequency of which is beyond the frequency cutoff of said electron multiplier, beam deflecting conductors coupled to said source of carrier modulated signals for deflecting said electron beam with respect to saidshield to a degree controlled by said signals and means for tuning said last mentioned deflecting means to receive a predetermined carrier modulated signal wave.

10. A signal receiver comprising an electron gun for generating a beam of electrons, a shield including an aperture disposed in the path of said beam for normally blocking it, beam deflecting means including a source of potential for normally directing said beam to impinge on said shield, electron multiplier means? adjacent said shield having a predetermined frequency cutoff characteristic, a source of carrier modulated sig nals the frequency of which is beyond the frequency cutoff of said electron multiplier, beam deflecting conductors coupled to said source of carrier modulate-d signals for deflecting said electron beam into overlapping relation with respect to said aperture to a degree controlled'by said signals and means including a movable capacitor for tuning said last mentioned deflecting means to receive a predetermined carrier modulated signal wave.

11. A signal receiver comprising an electron gun for generating a beam of electrons, a shield disposed in the path of said beam for normally blocking it, beam deflecting means including a source of potential for normally directing said beam in a first plane to impinge on said shield, electron multiplier means adjacent said shield having a predetermined frequency cutoff characteristic, a source of carrier modulated signals the frequency of which is beyond the frequency cutoff of said electron multiplier, beam deflecting conductors coupled to said source of carrier modulated signals for deflecting said electron beam with respect to said shield to a degree controlled by said signals, a source of potential coupled to said conductors for normally directing said beam in a second plane to impinge on said shield and means for tuning said last mentioned deflecting means to receive a predetermined carrier modulated signal wave. v

CHRISTIAN C. LARSON.

REFERENCES CITED The following references are of record indth flle of this patent:

UNITED STATES PATENTS Larson Nov. 25, 1947 OTHER REFERENCES Proceedings of IRE, November 1941, pages 587 to 598, Electrostatic Electron Multipliers, by Malter.