US2596539A - Circuit for transmitting or generating electrical oscillations of ultrahigh frequency - Google Patents

Description

May 13, 1952 G. DIEMER CIRCUIT FOR TRANSMITTING OR GENERATING ELECTRICAL OSCILLATIONS 0F ULTRAHIGH FREQUENCY Filed April e, 1948 INVENTOR. GESINl/IS DIEMER QQAWM AGENT.

Patented May 13, 1952 CIRCUIT FOR TRANSMITTING OR GENER- AfljlNq ELECTRICAL os'cmLArIoNs" F ULTRAHIGH FREQUENCY Gesinus Diemer, Eindhoven, Netherlands, as-

slgnor to Hartford National. Bank and Trust Company, Hartford, Conn., as trustee Application March 6 1948, Serial N0..1 3,356

In the Netherlands April 9, 1947 6 Claims. (01. 119 -171) The invention relates to a circuit-arrangement for transmitting or producing ultra-highfrequency electrical oscillations less than 3 meters comprising a discharge tube having at least a cathode, a control-grid whose potential slightly differs from the cathode potential and preferably is slightly negative with respect to the latter potential, an electrode (anode) having a positive potential with respect to the cathode and a secondary-emission electrode having, with respect to the cathode, a considerably lower positive potential in the said order of succession, the oscillations to be transmitted or the oscillations derived from the electrical oscillations produced being operative between the control-grid and the cathode.

The invention has for its object to provide a circuit-arrangement such that for a wide band of frequencies a high. energy amplification is obtainable.

The invention primarily consists in that the control-grid is connected to the secondary-emission electrode through a capacitativ connection exhibiting a low impedance for the oscillations to be transmitted or produced and that the output circuit is connected between the anode and the secondary-emission electrode or control-grid, the said capacitatively interconnected electrodes being connected to a point of constant or substantially constant potential (earth).

In order to minimize the influence exerted by the self-inductance of the supply conductors leading to the said electrodes on the said capacitative connection, the latter is preferably provided within the tube.

With circuit-arrangements comprising a discharge tube having a cathode, a control-grid, an anode and, moreover, a secondary-emission electrode a damping-reducing feedback may be obtained, as is well-known, by connecting the secondary-emission electrode through a capacity to the control-grid. The circuit-arrangement according to the invention differs from this known circuit-"arrangement inthat the capacity between the secondary-emission electrode and the controlgrid is such that for allfrequencies required to be transmitted the said electrodes the same high-frequency voltage, that is to say that in the subject-matter of the invention the capacity present between the said electrodes must be high with respect to all other electrode capacities occurring in the tube. A further diiference from the known circuit-arrangement is that with the latter the output circuit is connected between the-anode and the cathode, whereas it is essential have substantially to the invention that the output circuit shoul'dlbe located between the anode and the control-grid conductors leading to the various electrodes are,

ingeneral, taken through the wall-of the tube so as to be parallel or substantially parallel to one" another, a number of leading-through pins concentrically arranged with respect to one another being provided for each. electrode inorder .to reduce the so-called pin damping. Here the said capacity between the control-grid. and the secondary-emission.electrode may be .obtained by providing the cylindrical control-grid at one end with a flange-shaped extension, which forms one electrode or at least part of one electrode of acondenser, the other electrode of which is connected to the secondary-emission electrode. The said flange-shaped extension. may act, in addition, as a screening member between the anode and the cathode.

A further advantage of. the invention is that without any harmful results the secondary-emissionelectrode may be provided with cooling fins, for since this electrode is earthed. these cooling. fins do not increase the parasitic capacity. When using such cooling fins it is furthermore possible to obtain in a simple manner therequired capacity between the control-grid and the secondary-emis'sion electrode by providin the afore-. said flange-shaped extension of the control-grid with condenser electrodes which are separated from the cooling fins by a thindielectric of. for example, mica, the fins serving also as condenser electrodes.

The invention will be described more fully with reference to the drawing, in which Fig. 1 shows,- by way of example, .a circuit-arrangement accord-- ing tothe invention and Figs. 2 and 3 show dia-- grammatically the manner in which the-capacity between the control-grid and the secondary? emission electrode may be obtained.

In Fig. 1 referencenumeral l denotes atube comprising a cathode 2, a control-grid 3, a secondary-emission electrode 4 and an anode 5. The cathode 2 and the control-grid 3 have connected between them an' input circuit 6, across; whichis l developed the votlageto be transmitted. It it is control-grid 3 is connected, through a capacity 8, V

to the secondary-emission electrode i, this capacity being so high with respect to the other tube capacities that the said electrodes have substantially the same high-frequency voltages for the frequencies to be transmitted. It is preferred to make this capacity so high as is compatible with the space available in the tube and with the properties of the materials. In practice, a value of 50 micro-microfarads suihces in general, this value being readily obtainable.

The output circuit l is connected between the secondary-emission electrode and the anode 5. The output voltage may be taken from terminals 9.

It has been found that with the circuit-arrangernent shown a very satisfactory energy amplification may be obtained for a wide band of frequencies. Thus, for example, for a wavelength of 40 cms. an energy-amplification factor of 50 has been obtained for a band width of 28 mc./s., whilst for a wavelength of 100 cms, even an energy-amplification factor of 225 was measured for a band width of 3.5 mc./s., a factor of 1-69 being measured for 12 mc./s.

Fig. 2 shows diagrammatically the construction of the electrode system of a tube adapted to be advantageously used in a circuit-arrangement according to the invention. In this Figure 1 denotes the glass wall of a tube, the cathode 2 of which is arranged in the axial direction. The cathode is entirely surrounded by a control-grid 3, which is provided at one end with a cap 28 acting as a screening member with respect to the other electrodes and at the other end with an extension l5 exhibiting the shape of an annular metal disc. This disc acts not only as a screening member between the cathode and the other electrodes and as a conductive transition between the pins and the grid body, but also as one of the electrodes of a condenser by means of which the capacity required between the control-grid and the secondary-emission electrode is obtained. The dielectric of this condenser is formed by an annular disc is of mica, whereas the second electrode is constituted by a metal ring H, which is connected to the secondaryemission electrode 4. The anode 5 is formed by a plurality of bars; the secondary-emission electrode may also consist of bars which are preferably profiled. The control-grid 3 is connected to a plurality oi leading-through pins H arranged 6n the circumference of a circle. The leadingthrough pins for the cathode are designated by It. The anodebars 5 are also taken through the wall, the leading-through points being likewise located on the circumference of a circle. There may be, for example, four anode bars. The bars of the secondary-emission electrode 4 are provided with cooling fins I8 which are connected preferably in a manner similar to the connection between the control-grid and the associated pins, by means of a disc to pins 12, which are taken through the wall of the tube and are again arranged according to a cylindrical 4 surface. Instead of using leading-through pins use may be made at least for the control-grid and the secondary-emission electrode, of a socalled disc-seal. Outside the tube the leadthrough pins maybe connected to Lecher systerns in the form of concentric tubes l3, M.

Fig. 3 illustrates how the capacity between the control-grid and the secondary-emission electrode may be obtained by using the cooling fins as condenser electrodes. This figure is a sectional view at right angles to the axis of the electrode system of the tube. Here again 2 designates the cathode and 3 the grid, which may consist of a wire helically wound on supports 2|. The anode bars are designated by 5 and are arranged in the electron shadow of auxiliary conductors 22 which are connected to the control-grid. The two bars of the secondary-emission electrode are each provided with a cooling fin [8, on either side of which mica plates are provided which constitute the dielectric of the condenser. The other electrodes are constituted by metal plates 23 which are connected to the control-grid. This connection may, for example, be formed by the flange I5 shown in Fig. 2 and serving as a screen.

The circuit-arrangement described may be used not only for the amplification, but also for the production of oscillations, in which event regenerative feedback between input and output circuits must be provide d.

What I claim is: i

1. An ultra-high-frequency system comprising an electron discharge tube having a cathode, a control grid, a secondary emitting electrode, and an anode, an input circuit coupled between said cathode and said grid for applying ultrahigh-frequency oscillations to said system, an output circuit coupled between said electrode and said anode to produce an output voltage in accordance with the current flow between said electrode and said anode, means to maintain said grid at a ground potential, means to maintain said electrode at a positive potential with respect to said cathode, means to maintain said anode at a positive potential with respect to said cathode having a magnitude which is high relative to the positive potential on said electrode, and a capacitance connected between said electrode and said grid, said capacitance having an impedance value. at which within the frequency range of oscillations applied to said'systern said electrode and said grid are at substantially the same high-frequency potential.

2. An ultra-high-frequency system comprising an electron discharge tube having a cathode, a control grid, a secondary emitting electrode. and an anode, an input circuit coupled between said cathode and said grid for applying ultrahigh-frequency oscillations to said system, an

output circuit coupled between said electrode and said anode to produce an output voltage in accordance with the current fiow between said electrode and said anode, means to maintain said grid at a ground potential, means to maintain said electrode at a positive potential with respect to said cathode, means to maintain said anode at a positive potential with respect to said cathode having a magnitude which is high relative to the positive potential on said electrode, a capacitance connected between said electrode and said grid, saidcapacitance having an impedance value at which within the frequency range of oscillations applied to said systemsaid electrode and said grid are at substantially the same high-frequency potential, and means to ground said grid.

3. An ultra-high-frequency system comprising an electron discharge tube having a cathode, a control grid, a secondary emitting electrode, and an anode, an input circuit coupled between said cathode and said grid for applying ultrahigh-frequency oscillations to said system, an output circuit coupled between said electrode and said anode to produce an output voltage in accordance with the current flow between said electrode and said anode, means to ground said grid, means to maintain said grid at a ground potential, means to maintain said electrode at a positive potential with respect to said cathode, and means to maintain said anode at a positive potential with respect to said cathode having a magnitude which is high relative to the positive potential on said electrode, said grid and said electrode possessing an inter-electrode capacitance therebetween having an impedance value at which within the frequency range of oscillations applied to said system said grid and said electrode are at substantially the same highfrequency potential.

4. An ultra-high-frequency system comprising an electron discharge tube having in successive arrangement a cathode, a cylindrical control grid surrounding said cathode, an anode and a secondary emitting electrode, said cylindrical control grid being provided at one end with a flange-shaped extension constituting one element of a condenser, a portion of the secondary emission electrode being disposed in proximity to said grid extension to constitute the other element of said condenser, an input circuit coupled between said cathode and said grid for applying ultra-high-frequency oscillations to said system,

an output circuit coupled between said electrode and said anode, means to ground said grid, means to maintain said grid at a negative potential with respect to said cathode, means to maintain said electrode at a positive potential with respect to said cathode, and means to maintain said anode at a positive potential with respect to said cathode having a magnitude which is high relative to the positive potential on said electrode, said condenser having an impedance value at which within the frequency range of oscillations applied to said system said electrode and said grid are at substantially the same high-frequency potential.

5. An arrangement, as set forth in claim 4, wherein said secondary emission electrode is provided with cooling fins.

6. An arrangement, as set forth in claim 5, further including a dielectric member interposed between said grid extension and one end of said cooling fins to constitute said condenser.

GESINUS DIEMER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS

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