US2108900A - Ultrashort wave oscillation generator circuit - Google Patents

Description

Feb. 22, 1938. H. o. PETERSON ULTRASHORT WAVE OSCILLATION GENERATOR CIRCUIT Filed Nov. 8, 1934 2 Sheets-Sheet l JIICWPHO/YE INVENTOR H.O. PETERSON BY Q)- ATTORNEY Feb. 22," 1938. H. o. PETERSON 2,108,990

ULTRASHORT WAVE OSCILLATION GENERATOR CIRCUIT Fi led Nov. 8, 1934 2 Sheets-Sheet 2 +4.0. PETERSON BY guy-1M ATTbRNEY Patented Feb. 22, 1938 ULTRASHORT WAVE OSCILLATION GENER- ATOR CIRCUIT Harold Olaf Peterson, Riverhead, N. Y., assignor to Radio Corporation of America, a corporation of Delaware Application November 8, 1934, Serial No. 751,984

masts Claims.

This invention relates to a method of and apparatus for generating ultrashort wave oscillations, and in particular to a circuit arrangement wherein the principal elements of an oscillation generator tube constitute the conductors of a concentric transmission line.

Heretofore it has been the practice to generate ultrashort wave oscillations with circuits employing a tube and an associated oscillatory circuit connected to the elements of the tube but located externally of the tube envelope. One common form of such an oscillatory circuit is a transmission line operating with standing waves upon it.

It is known that if a conventional type of tube is connected to such a transmission line constrtuting an oscillatory circuit, that the capacities of the elements within the tube will cause a change of constants in the transmission line which might be sufficiently detrimental to prevent the circuit from functioning as a true transmission line. One of the objects of the present invention is to provide an improved form of tube, so constructed that the elements themselves form a uniform transmission line, and this is achieved, in the preferred form of the present invention, by the provision of cylindrical elements constructed as concentric transmission lines on which standing waves are developed.

Although elements of this form are preferred, it is to be distinctly understood that the invention is not limited thereto, since other shapes of transmission line may also be employed.

A better understanding of the invention may be had by referring tothe following detailed description, which is accompanied by drawings wherein Figs. 1-4, inclusive, show different embcdiments of the invention, and Fig. 1a shows a cross sectional view of the tube of Fig. 1.

Referring to Fig. 1 in more detail, there is shown a complete transmitting circuit arrangement employing a tube whose elements are constructed to form a transmission line one-quarter of a wave length long. In this tube, the elements of which are shown located within an evacuated envelope H), which may be of glass or other suitable material, there is shown a concentric transmission line which is one-quarter of a wave length long comprising an outer anode 4 and an inner grid 3, the latter of which is a perforated continuation of the inside conductor of the concentric transmission line. The outer conductor or anode 4 is connected at one end of the line through a capacity to the cathode 2, which is supplied with. heating current by transformer I in circuit with source of energy II, and at the other end thereof to the inside conductor through another by-pass capacity. Numeral 5 indicates the insulating dielectric of the capacities at both ends of the line. It will thus be seen that the grid 3 is at the high potential end of a one-quarter wave length resonator, the grid element 3 being well shielded by the anode element 4.

It is preferred to operate the tube as a Barkhausen type oscillator, wherein the grid is main tained at a high positive potential with respect to the cathode and the anode at a much lower potential, whereby pendulum motion of electrons emitted by the cathode is obtained about the grid. If desired, a constant magnetic field, such as is provided by coil 8 and unidirectional source of potential l4, may be employed to reduce the flow of electrons along the length of the conductor. For this purpose, unidirectional source of potential l2 supplies the grid with a high positive potential and source is supplies the anode with a much lower positive potential, although it will be understood that the anode may be at zero or negative potential with respect to the cathode.

If it is desired to modulate the oscillations, there maybe provided a modulation microphone 'l which impresses modulating currents upon an amplifier 6, in turn connected through a transformer 24 with the anode and cathode of the tube. Any suitable utilization circuit, such as an antenna 9, may comprise the output of the circuit and be connected to the inner'conductor of the concentric line, as shown.

Fig. 1a is a cross sectional view of the tube along the lines A, A.

Fig. 2 shows another embodiment of the invention, wherein the outside conductor of the concentric transmission line is made tobe the cathode, electron emission in this case being obtained at desired points, herein designated 2, 2, spaced onehalf wave length apart, by coating the inside of the outside conductor with suitable electron emitting material and supplying concentrated heat at the desired points through transformers l, I. The inside conductor 3 is the grid, which is maintained positive with respect to the cathode and is shown constructed in the form of a perforated cylinder. In this embodiment electrons.

nodal points of this transmission line is herein obtained by means of constant magnetic field coils 8. The potential curve is shown by the 'dotand-dash lines. The outputcircuits herein comprise dipole antennae l5, l5 connected with transmission lines l6, IE to the potential nodal points on the grids 3. A reflector ll serves to concentrate the radiation from the dipoles in any desired direction.

It will be noted that the magnetic fields are so polarized as to concentrate the flow of electrons to restricted sections of the length of the tube. Every other antenna feeder is reversed and so-connected that the antennae l5, l5 radiate cumulatively in the direction perpendicular to the axis of the reflector I1.

Fig. 3 shows still a third embodiment wherein the outer conductor has its inside coated with suitable electron emitting material at a desired point which is chosen to give proper loading of the one -quarter wave length resonator, as shown in the drawings. In this embodiment the concentric transmission line has an overall length of one-quarter wave length, and the distances at and b are so chosen as to give the proper loading. 1 V

Fig. 4 shows a still further modification utilizing a magnet yoke IT. The inside conductor of the concentric transmission line in this instance may comprise some magnetic material, such as nickel, in which casea highly concentrated magnetic field may be produced perpendicular to the axis of the concentric transmission line. The electron emitting material is herein shown at the top on the inside of the outer elements, the output being shown obtained from a tap at the bottom of the tube over lead 3. The magnetic field is so arranged as to concentrate the flow of electrons to a restricted section of the length of the tube. V

7 It will be understood, of course, that the invention is not limited to the precise details shown since various modifications may be 'made in the structure of the elements without departing from the spirit and scope of the appended claims, nor is the invention limited to the positive grid type of oscillation, inasmuch as the principles may also be applied in the type of oscillation circuit wherein the anode is made positive and the grid negative with respect to the cathode. 7

By the term multiple of one-quarter wavelengt used in the appended claims, is meant any multiple including one.

What is claimed is: 7

1. An ultrashort wave oscillation generator circuit comprising a multi-electrode electron discharge device having within its envelope an oscillatory circuit in the form of a concentric transmission line having inner and outer conductors of a length equal to a multiple of onequarter of the length of the operating wave, said conductors comprising electrodes of said devices, said inner conductor comprising a perforated grid over at least a portion of its length, said outer conductor having that part of its inside portion opposite the perforated grid coated with an electron einissive material, a source of energy for heating said electron emissive material for liberating electrons, means for applying suitable polarizing potentials to the electrodes of said device, and a utilization circuit coupled. to said inner conductor.

2. An ultrashort wave oscillation generator circuit comprising a multi-electrode electron discharge device having within its envelope an oscillatory circuit in the form of a concentric transmission line having inner and outer conductors of a length substantially a multiple of one-quarter of the lengthof the operating wave, said conductors comprising electrodes of said devices, said inner conductor comprising a perforated grid over at least a portion of the length of said conductor, said outer conductor having its inside coated with an electron emitting material at predetermined points throughout its length, said points being opposite perforations on said grid whereby the emission of electrons from said material enables said electrons to pass through the perforations in said grid, means for heating said electron emissive material and for applying suitable polarizing potentials to said electrodes, and means for obtaining oscillations from said device comprising a utilization circuit connected to a voltage nodal point on said grid.

3. A system in accordance with claim 2, characterized in this that said predetermined points on said outer conductor are spaced apart an even multiple of one-quarter the length of the operating wave, and said utilization circuit, comprises two antennae each connected to a voltage nodal point on said grid.

4. An ultrashort wave length oscillation generator circuit comprising a multi-electrode electron discharge device having within its envelope an oscillatory circuit in the form of a concentric transmission line having inner and outer conductors, said inner conductor comprising a perforated grid and said outer conductor comprising an anode, a source of electrons located within said grid, said anode: being capacitively coupled to said grid at one end of said line and capacitively coupled to said source at the other end of said line, means for maintaining said grid at a high positive potential relative to said source and anode, and means for producing a magnetic field within the length of said concentric transmission line.

5. A circuit in accordance with claim 4, includof a length substantially one-quarter of the.

length of the operating Wave and which are capacitively coupled together at one of their ends, said outer conductor comprising a cathode,

and said inner conductor the grid of said device,

means for causing said outer conductor to emit electrons at a point thereon removed from said one end of said transmission line, and an output circuit coupled to said grid.

7. An ultrashort wave oscillation generator circuit comprising a multi-electrode electron discharge device having within its envelope an oscillatory circuitformed of a concentric transmission line having inner and outer conductors capacitively coupled together at one of their ends, said inner conductor comprising a perforated grid and said outer conductor comprising a cathode arranged to emit electrons at the end opposite said one end of said line, means for applying a high positive potential to said grid relative to said cathode, and means for producing a uniform magnetic field in the length of said transmission line.

8. A circuit in accordance with claim 7, characterized in this that said means for producing said field comprise a coil surrounding said envelope for producing a constant magnetic field, and a magnet yoke having poles on opposite sides of said envelope, said inner conductor of said transmission line being made of a magnetic material.

9. An oscillation generator circuit comprising an electron discharge device having a pair of electrodes in the form of inner and outer concentric conductors having substantially uniformly distributed inductance and capacitance, said outer conductor being substantially an integral multiple including unity of one-quarter of the length of the operating wave and being an emitter of electrons in the form of a cylinder, means for maintaining said inner conductor at a positive potential relative to said outer conductor whereby said inner conductor is a collector of electrons, means for producing a constant magnetic field Within the lengths of said concentric conductors, and a utilization circuit directly connected to said inner conductor at a potential nodal point thereon.

10. An ultrashort wave oscillation generator circuit comprising a multi-electrode electron discharge device having within its envelope an oscillatory circuit in the form of a con centric transmission line having inner and outer conductors substantially one-quarter of the length of the operating wave, said conductors comprising electrodes of said device, said inner conductor comprising a perforated grid over at least a portion of its length, means for applying suitable polarizing potentials to said electrodes, said outer conductor comprising an emitter of electrons.

HAROLD OLAF PETERSON.

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