US2020310A - Ultra high frequency communication system - Google Patents

Description

Nov. 12, 1935. v R. GUNN 2,020,310

ULTRA HIGH FREQUENCY COMMUNICATION SYSTEM Filed July 26, 1952 r 2 Sheets-Sheet 1 INVENTOR Ross Gu 7272 ATTORNEY Nov. 12, 1935.

R. GUNN 'ULTRA HIGH FREQUENCY COMMUNICATION SYSTEM Filed July 26, 1932 2 Sheets-Sheet 2 nvun'u F 5/ v k L N INVENTOR Ross Gunn ATTORNEY Patented Nov. 12, 1935 UNITED STATES ULTRA HIGH FREQUENCY COMMUNI- CATION SYSTEM Ross Gunn, Chevy Chase, Md. Application July 26, 1932, Serial No. 624,877

6 Claims. (01. 250 36) (Granted. under the act of March 3, 1883, as amended April 30, 1928; 370 0. G. 757) This invention relates to high frequency communication systems, and more particularly to ultra high frequency communication systems and has for one of its objects to provide improved means for generating oscillations of high frequencies within the quasi-optical range. 7

Another object of this invention is to provide means for producing considerable amounts of power in theform of ultrahigh frequency oscillations.

Another object of this invention is to provide a system employing electronic oscillations wherein the electrons or ions oscillating within a tube are controlled as to phase whereby neutralizing effects of a multitude of electrons or ions oscillating in different phasesare avoided.

Another object of this invention is to provide 7 a receiver that is sensitive and highly selective to radiation of 'ultra high frequencies.

'Another object ofthis invention is to provide a means for concentrating, directing and scatter ing ultra high frequency radiation.

Another object of this invention is to provide electron discharge apparatus of novel construction that is particularly adapted for use in connection with the production and reception of ultra high frequency oscillations. I

With the above and other objects in view, the invention consists in the construction, combination and arrangement of parts as will be described more fully hereinafter. V

Oscillation generators of the conventional type employing negative resistance in combination with resonant circuits usually do not work well or at all in the ultra high frequency or quasi-' optical range. Generators of the so-called Barkhausen-Kurz or Gill-Morrell type employing electronic oscillations are found to work at quasioptical frequencies, but the output and efliciency of this type of generator has been extremely small. V

The present invention is concerned with improvements of systems employing electronic oscillations wherein their properties are greatly enhanced byproper adjustment of the phase of the moving particles.

receiver. type tube;

Fig. 3 is a diagrammatic showing of a transmitter employing a tube similar to the tube shown in Fig. 1; p

Fig. 4 is a diagrammatic showing of a receiver employing a tube similar to the. tube shown in 5 Fig. 2; Fig. 5 shows diagrammatically a beam transmitter with means to concentrate reflect, difiract and scatter ultra high frequency radiation.

Referring now to Fig. l, a filamentary cathode is shown at I00 mounted within an evacuated envelope 3 and provided with leads I and 2 for supplying heating current thereto. Displaced from the filament I09 within the envelope 3 are a plurality of tuned resonant systems 5-6, 'l8, IUI I, l2l3. Tuned conductors 56 and '|-B lying within the same plane are supported nodally at their midpointsby a conductor 4 which constitutes a lead for supplying the necessary direct current potential to these elements. Tuned conductors IUII and l2l3 are supported nodally at their midpoints by a conductor 9 which constitutes a lead for' supplying the necessary direct current potential to these elements. Leads I4 and 25 coupled to the resonant element 18 are for 25" the purpose of transferring the high frequency oscillations existing on this element to a tuned radiator of appropriate type. In Fig. 1, leads I 4 and I5 are shownassociated with tuned element 18, although it is to be understood that these 30 W The structure of the tube shown in Fig. 2 is identical with that of Fig. 1 except that tuned element IBI9 supported at its midpoint by a conductor 20, which serves as a lead thereto, has

been added. The tuned element l8--|9 occupies a position within the space generally surrounded by tuned elements 56, .18, lfll I, l2l3, and

is parallel thereto.

Because of the high voltages desirable for ultra frequencies, the tube structure must be quite rigid. It is desirable that the oscillating conduc- 45 tor tuned elements be supported at the node. Evidently the tuned elements 56, etc., can be approximately any number of half wave-lengths long or they can contain concentrated inductance or capacity values for securing special adjust- 50 ments of phase without departing from the basic ideas. It is evident, moreover, that arrays of tubes properly arranged in space will give rise to directive beams, etc.

Fig. 3 is a diagrammatic showing of the tube of Fig. 1 connected in circuit with appropriate sources of potential for the generation and radiation of high frequency oscillations. Coupled to the tuned resonant element 'I8 is a radiating system 5| located at an appropriate distance in front of a parabolic metallic mirror 50: Tuning devices 54 and 55 are connected in the coupling leads I6 and I1 between the radiating system 5! and the tuned resonant system 7-8 within the tube for adjusting the circuit for efficient transfer of energy to the radiating system. The battery 56 is connected to leads I and 2 so as to energize the filament I00. The battery 51 is connected between the filament and the tuned resonant system 5-6, etc., and is so poledthat the-tuned system is normally positive with respect to the filament. The battery 58 is connected between the filament and the radiating system II J -II,

etc., and is so poled that the tuned system Ill-4 I etc. is normally highly positive with respect to the filament. In the drawings, thepotential applied between the filament-I00 and the tuned system I0II is shown as being derived from batteries 51 and 58 in series although it is to be understood that a separate battery or other source of potential of proper value may be used instead of the two batteries connected in series.

A magnetic field is applied to the tube for use at the highest frequencies. This magnetic field may in general be applied by means of two-units, one designed to produce a very intense field, say- 5000 gauss, in a direction parallel to the electric field, the other of moderate value between 0 and 2000 gauss, depending on the frequency desired and the spacing of the elements, is applied in a direction at right angles to both the electric field and the oscillating dipole.

The units for applying magnetic fields to the tube 3 are shown in Fig. 1. (A showing of these units has been omitted from Fig. 3 for the sake of clarity.) Magnetizing coils 60 and BI are disposed on opposite sides of the tube 3 with their axes passing through the tube normal to the oscillating dipoles and the principal electric field within the tube. These coils are shown connected in series and provided with leads 62 and 63 which may be connected to an appropriate source of potential by way of a variable resistor. Magnetizing coils 64 and 65 are disposed on op- ;posite sides of the tube 3 with their axesparallel to the principal electric field within the tube. Coils 64 and 65 are shown connected in series, although it is to be understood that they'may be connected in parallel as may the coils 60 and 6|;

Coils 64 and 65'are provided with leads 66 and magnetic substances may be used for cores of these magnetizing coils.

The oscillations of ultra frequency, or ultra high frequency that we may expect in this system are:

(a) Electronic oscillations.

(b) Oscillations in tuned resonators as a result of electronic shock excitation.

(0) Phase oscillations.

In general, the electronic oscillations of Bark- 1hausen-Kurz are very feeble because there are a great many electrons in the tube and they have no definite phase relation to each other so tha the mutual radiation largely cancels out. 4 Consider in Fig. 1 a single electron from th hot filament connected to electrodes I and 2, and

suppose that it heads for the rod 'I8, passing midwaybetween the electrodes I 0I I and I2-I3. When the electron passes through the plane determined by I0I II2I3 it has its maximum energy and velocity which will be lost by the time it reaches the electrode 'I--8. The direction of the force reverses as it passes through the plane of electrodes I0'III2-I3 and therefore by proper positioning of the electrodes, the electric field on each side of the plane can be made roughly proportional to the distance from the plane. That is to say, the electric field is purposely made inhomogeneous.

Suppose the space charge is small and let this proportionality be expressed by v E=ky (1) where E is the electric field, y the distance of {the selected point from the plane and k the pro- 2 v=ef d Now the force F on the electron is F=Ee= ke1y where e is the electronic charge and 61 is its abso- U lute magnitude. Thus the electron executes simple harmonic motion of frequency This relation shows clearly that for extremely high frequencies the applied potential V must be moderately high and the spacing s kept as small as is consistent with structural difficulties. The operation of the system shown in Fig. 3, while not definitely understood, is believed to be as follows. The filamentary cathode I00 is heated by current from source of potential 56 and emits electrons. cathode I00 are transferred to the region be-. tween the tuned elements by the source of potential 51 operating via lead 4 and the element 5--6 which acts as a space charge electrode. The source of potential 51 is of such value that high current densities are not required. The electrons passing into the region between the tuned elements of the system are accelerated toward the plane formed by the anode elements Ill-II and I2I3 as a result of the electric field produced by the battery or other source of potential 58. Due to non-symmetry in the way the electrons initially come off, the. tuned resonant systems 5- -6, I0--II and I 2I3 individually and as a system are shock excited and resonate at their own natural frequency. The, electric field, due to the oscillating potential of the resonators, causes'the electric field between the filament I00 and parts of the resonator 5-6 to change with time; thus, when the end 5 is at a'higher positive potential with respect to the filament than its mean (steady) value, more electrons will come across at that end than at the end 6. One-half a cycle later more electrons will come across at the end 6, while the end 5 will be so charged as to block the flow of electrons adjacent thereto and the' phase of the electronic oscillations'willbe controlledby the varying potential on the ,dipole resonators and radiation from the electron The, electrons, emitted from.

with an auxiliary electrode similar to the tube shown in Fig. 2. The filament I00 is energized from battery 3| by means of the leads I and 2. Positive potential is applied to the tuned resonant system comprising elements 56, etc., from battery 32 connected to the filament I00 and lead 4. Positive potential is applied to the tuned resonant system comprising elements ill-4 l, etc., from battery 33 via lead 9. Thus far the receiver is identical with the transmitter except that the batteries 3| and 32 are of lower potential than are used in the transmitter in order that the electron emission be kept at a proper value for receiving purposes. The tuned resonant electrode l8|9 is connected at its midpoint by means of lead 20 to one end of the primary winding 34 of transformer 36. The other end of the winding 34 is adapted to be connected to the battery 32 at a point more positive than the filament. Coupled to the primary 34 is a secondary 35 which is connected to the filament 38 and grid 39 of a suitable thermionic amplifying device. A battery 31 is connected to the filament 38 for heating the same. A battery 43 is connected to the filament 3B and through the receiver 4| or other type of indicator to the anode or plate 40 of the tube. A condenser 42 is connected between the anode 40 and the filament. Coupled to the tuned system 1-- 8, etc., is a receiving antenna 26 located at the proper distance in front of a parabolic metallic mirror 25. Leads 21 and 28 between the antenna 26 and the tuned system 18 are provided with tuning condensers 29 and 30 for tuning the system to effect the most efficient transfer of energy therebetween.

The operation of the receiver, while not definitely understood, is believed to be as follows:

The radiated waves from the transmitter traverse the distance from the transmitter to the receiver where theyare converged or focused upon the receiving antenna 26 by the mirror 25. Antenna 2% then has induced therein high frequency oscillations of the frequency of the transmitted waves to which it is tuned. These high frequency oscillations are coupled by way of the condensers 29 and 30 to tuned resonant system 'l8, etc., which is caused to oscillate at the frequency of these waves. The total space current through the tuned system l8-l9 is controlled by these oscillations in some manner not well understood. This current controlled in accordance with the received oscillations passes through lead 20 to the transformer primary 34 and thence back to the battery 32 and filament I ill], inducing currents in the secondary to control the output of the amplifier tube in well known manner. Obviously, any type of amplifier could be used instead of the one shown, or the output of the receiving tube could be coupled directly to a receiver or other type of indicator instead of to the transformer winding 34. 1

The ultra frequencies have substantially optica properties and normally can be propagated only in straight lines. In general, a beam transmitter is used and the energy in the beam is very large and confined to a small area. Suppose it should be desired to transmit to stations A, B and C (Fig. 5), as well as station N. This may still be accomplished by placing a scatterer or director at the point L, say, which absorbs and emits or refracts some of the incident energy toward the desired stations A, B or 0. Many devices will serve to scatter or refract the waves, as for instance:

(a) Tuned resonant circuits or arrays of them. 7 (1)) Lens systems.

(c) Diffraction gratings of various kinds. (d) Metallic reflectors. This method of diffraction permits the transmission of the ultra frequency beyond the bulge of the earth around skyscrapers, bridges, etc. I

It is to be understood that any appropriate system of modulation may be used in connection with the above disclosed transmitter. The amplitude, frequency or phase or any combination of the three may be controlled by electrical means,

or the beam transmitted may be controlled di rectly by shutters in much the same way as is done with visible light in heliograph signaling systems.

The invention herein described may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalty thereon.

I claim:

1. In an oscillation generating system for generating oscillations of ultra-high frequency, an electron discharge device having a linear cathode, a tuned anode system comprising a pair of linear elements parallel to said cathode defining a plane displaced from said cathode and a tuned space charge electrode system comprising a pair of linear elements parallel to said cathode defining a plane that intersects the plane of said anode, each of said linear elements of said anode and space charge electrode being tuned to the ultrahigh frequency to be derived from said system, means for causing said cathode to emit electrons, means for causing some of the emitted electrons to be drawn toward the plane of said anode to execute Barkhausen-Kurz electronic oscillations, and means comprising said tuned space charge electrode and said anode for controlling the oscillation of electrons in accordance with the changing potential distribution existing on said tuned space charge electrode.

2. In an oscillation generating system for generating oscillations of ultra-high frequency, an electron discharge device having a linear cathode, a tuned anode system comprising a pair of linear elements parallel to said cathode defining a plane displaced therefrom and a tuned space charge system comprising a pair of linear elements parallel to said cathode defining a plane that inter sects the plane of said anode, each of said linear elements of said anode and space charge electrode systems being tuned to the ultra-high frequency to be derived from the system, means for heating said cathode, a source of high potential, means connecting the low potential side of said source to said cathode, means connecting the high potential side of said source to a potential nodal point on said anode system, and means for biasing the tuned space charge system at a potential intermediate the potential between said cathode and said anode system.

3. An ultra-frequency oscillation generating system, comprising an electron discharge device having a linear cathode, an anode system comprising a plurality of mutually parallel electrically resonant linear elements tuned to the ultra-frequency to be generated, an additional tuned electrode system comprising a plurality of mutually parallel electrically resonant linear elements tuned to the same said frequency and arranged parallel to each other and to said anode system and occupying a different plane therefrom, a source of high potential, means connecting the low potential side of said source to said cathode, and means connecting the high potential side of said source to a potential nodal point on each of the linear elements comprising said anode system, and means connectiong an intermediate potential point on said source to a potential nodal point on each of the linear elements comprising said additional electrode system.

4. An ultra-high frequency oscillation generator comprising a straight cathode, an anode system comprising a pair of straight parallel conductors defining a plane in which said cathode does not lie, said conductors being arranged parallel to said cathode and being of such length as to have an inherent resonant frequency approximating the frequency to be generated, means for impressing a high positive potential on said anode system with respect to said cathode, an additional electrode system comprising a pair of straight parallel conductors defining a plane intersecting the plane formed by said anode system, and means for applying a potential to said additional electrode system intermediate the potential of said cathode. and said anode.

5. An oscillation generator as claimed in claim 3 including means for applying an intense magnetic field to the electron discharge device in a direction parallel to the electric field between the elements thereof.

a 6. An oscillation generator as claimed in claim I 3 including means for applying a magnetic field along the vdirection of electron flow between cathode and anode.

ROSS GUNN.

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