US2775739A - Device for amplitude modulation of ultra short waves - Google Patents

Device for amplitude modulation of ultra short waves Download PDF

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Publication number
US2775739A
US2775739A US276858A US27685852A US2775739A US 2775739 A US2775739 A US 2775739A US 276858 A US276858 A US 276858A US 27685852 A US27685852 A US 27685852A US 2775739 A US2775739 A US 2775739A
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United States
Prior art keywords
guide
wave
modulation
tube
energy
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Expired - Lifetime
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US276858A
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English (en)
Inventor
Knol Kornelis Swier
Vries Gerrit De
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Hartford National Bank and Trust Co
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Hartford National Bank and Trust Co
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Publication of US2775739A publication Critical patent/US2775739A/en
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    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03C—MODULATION
    • H03C7/00—Modulating electromagnetic waves
    • H03C7/02—Modulating electromagnetic waves in transmission lines, waveguides, cavity resonators or radiation fields of antennas

Definitions

  • the invention relates to devices for the amplitudemodulation of ultra-short waves, wherein the modulation is performed externally of the wave generator.
  • the invention has for its object to provide a device whereby an effective amplitude modulation is obtained without influencing the generator such that frequency modulation occurs.
  • ultra short-wave transmitters in which the energy is conducted through a hollow wave guide to the aerial, it is also known to obtain a modulation of the oscillations emitted by the aerial by providing the wave guide with a glow discharge tube, the ionization condition of which is varied by the modulation voltage.
  • the electrodes of the tubes in the Wave guide must be arranged in a manner such that the rod-shaped, conductive parts of the electrodes are at right angles to the electrical field lines in the guide i. e. to the course of these lines in the absence of these conductive parts, so that the course of the field is affected as little as possible.
  • the idea underlying this invention is to modulate ultrashort waves in amplitude in a hollow wave guide with the use of one or more gas discharge tubes, arranged in the wave guide, the ionization condition of these tubes being controlled by the modulation voltage.
  • the invention resides in an arrrangement wherein the ionization sphere lies in a plane which is at an angle of not more than 30 to the axis of the wave guide.
  • the embodiment is preferably such that the axes of the gas discharge tubes themselves are at an angle of not more than 30 to the axis of the wave guide. It will, in general, be possible to obtain an effective modulation with the use of a single gas discharge tube having a comparatively small sectional area.
  • the wave guide has a rectangular sectional area and the axis of the gas 7 discharge tube lies in a plane which is parallel to the shorter side of the wave guide.
  • the modulation is mainly due to the fact that in accordance with the ionization condition of the gas a greater or smaller portion of the energy conducted through the wave guide is absorbed by the ionized gas atmosphere. Owing to the oblique position of the discharge tubes, reflection of energy will substantially not occur, so that the generator is substantially not affected by the modulation.
  • Fig. 1 of the drawing is a greatly simplified perspective view of the device according to the invention.
  • Fig. 2 is a cross-sectional view of part of the device, comprising a circuit to vary theionization condition of the gas atmosphere in the tube or tubes;
  • Fig 3 shows in section a modified arrangement of the gas discharge tubes.
  • reference numeral 1. designates a generator for ultra-short waves, which is connected to a hollow wave-guide 2 of rectangular cross-sectional area, in which occur, for example, waves of the Ho-type.
  • the electrical field lines are at right angles to the upper and the lower surfaces; the right-hand end of this hollow wave-guide may be connected to a load such as an aerial. This end may, for example, merge in a hornshaped aerial.
  • a gas discharge tube 3 of elongated shape comprising electrodes 4 and 5, the tube being introduced into the wave-guide through apertures in the upper and lower walls, the axis of the tube being at an angle of not more than 30 to the axis of the wave-guide.
  • the ionized gas atmosphere has a damping efiect on the field, of which the electrical lines of force are at right angles to the upper wall and the lower wall of the hollow wave-guide.
  • the energy emerging at the right-hand end is amplitude-modulated in accordance with this modulation voltage.
  • Satisfactory results are obtainable with the use of a wave-guide of about 12 mms. in height and 24 mms. in width, comprising a gas discharge tube of about 6 mms. in internal diameter.
  • a number of discharge tubes may be arranged side by side, their axes lying in a plane at an angle of not more than 30 to the upper and the lower surfaces of the wave-guide and preferably at right angles to the side surfaces.
  • a single tube having suitable properties will suflice.
  • Fig. 2 shows part of the device in a sectional view.
  • the discharge tube '3 is "fed through aseries resistor 7' from a current source 6.
  • the ionization condition of the gas atmosphere is modulated by a low-frequency signal by connecting the series combination of an inductor 8 and a capacitor 9 in parallel with the series resistor 7.
  • the low frequency signal is transmitted inductively through an inductor 10 to the inductor 8. This modulation method is known per se.
  • a number of gas discharge'tubes may, as an alternative, be arranged with their axes at right angles to two opposite walls of a wave-guide of rectangular sectional area, the arrangement being such that the plane containing the axes of the tubes is at an angle of not more than 30 to'the two other side surfaces of the wave-guide.
  • the gas discharge'tubes may be completely housed inside the wave-guide, in which case only the current supply wires need be taken through the wall. In this case it will often be necessary to take measures to avoid disturbing the field course by conductive parts in the waveguide.
  • Apparatus for amplitude modulating ultra-short wave energy comprising a hollow wave-guide for conveying said energy, at least one elongated gaseous discharge tube disposed in said guide in the path of said energy, and means coupled to said tube to vary 'the ionization thereof in accordance with a modulating'signal, said tube occupying substantially less than the total cross-section area of said waveguide and being disposed with respect to said guide at an angle at which the ionized gas atmosphere therein is primarily located in a plane lying at an 4 angle not exceeding 30 with respect to the axis of the guide.
  • At least one gaseous discharge tube of elongated form extending through the walls of said guide at an angle at which the gas atmosphere therein lies in a plane with respect to the axis of theguide which does not exceed 30, said tube being sufficiently narrow so as to occupy substantially less than the total cross-section area of said wave-guide, and means coupled to said tube to vary the ionization thereof in accordance with a modulation signal.
  • Apparatus for amplitude modulating ultra-short wave energy comprising a hollow wave-guide of rectangular cross-section for conveying said energy, a single elongated gaseous discharge tube disposed at a position in which the axis of the tube is located in the central plane of the wave-guide and parallel to the side walls having the smaller transverse dimensions, said tube being sufficiently narrow so asto occupy substantially less than the total cross-section area of said- Waveguide, and means coupled to said tube to vary the ionization thereof in accordance with a modulating signal, said tube being disposed at a position at which the ionized gas atmosphere therein is primarily located in a plane lying at an angle not exceeding 30 with respect to the axis of the guide.

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  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Particle Accelerators (AREA)
  • Constitution Of High-Frequency Heating (AREA)
US276858A 1951-04-06 1952-03-15 Device for amplitude modulation of ultra short waves Expired - Lifetime US2775739A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
NL298708X 1951-04-06

Publications (1)

Publication Number Publication Date
US2775739A true US2775739A (en) 1956-12-25

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ID=19783123

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US276858A Expired - Lifetime US2775739A (en) 1951-04-06 1952-03-15 Device for amplitude modulation of ultra short waves

Country Status (7)

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US (1) US2775739A (en))
BE (1) BE510441A (en))
CH (1) CH298708A (en))
DE (1) DE964957C (en))
FR (1) FR1053426A (en))
GB (1) GB708580A (en))
NL (2) NL85466C (en))

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3069634A (en) * 1958-01-13 1962-12-18 Gen Electric Co Ltd Microwave arc-type modulator

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1004682B (de) * 1954-03-09 1957-03-21 Ericsson Telefon Ab L M Anordnung mit einem wenigstens ein gasgefuelltes Entladungsgefaess einschliessenden Wellenleiter oder Resonator

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2047929A (en) * 1935-02-28 1936-07-14 Rca Corp Ionic modulator
US2106770A (en) * 1938-02-01 Apparatus and method fob receiving
US2173234A (en) * 1933-08-31 1939-09-19 Rca Corp Radio apparatus
US2557180A (en) * 1943-04-27 1951-06-19 Gen Electric Apparatus for coupling ultra high frequency systems
US2716192A (en) * 1950-05-12 1955-08-23 Johnson Harwick Microwave noise source

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE729194C (de) * 1938-12-08 1942-12-11 Dr Christian Bachem Anordnung zur Amplitudenmodulation von cm- und dm-Wellensendern
US2505534A (en) * 1943-04-27 1950-04-25 Gen Electric Device for controlling the propagation of energy in a wave guide
US2457601A (en) * 1945-07-27 1948-12-28 Bell Telephone Labor Inc Wave translating apparatus

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2106770A (en) * 1938-02-01 Apparatus and method fob receiving
US2173234A (en) * 1933-08-31 1939-09-19 Rca Corp Radio apparatus
US2047929A (en) * 1935-02-28 1936-07-14 Rca Corp Ionic modulator
US2557180A (en) * 1943-04-27 1951-06-19 Gen Electric Apparatus for coupling ultra high frequency systems
US2716192A (en) * 1950-05-12 1955-08-23 Johnson Harwick Microwave noise source

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3069634A (en) * 1958-01-13 1962-12-18 Gen Electric Co Ltd Microwave arc-type modulator

Also Published As

Publication number Publication date
FR1053426A (fr) 1954-02-02
BE510441A (en))
DE964957C (de) 1957-05-29
NL160351B (nl)
CH298708A (de) 1954-05-15
GB708580A (en) 1954-05-05
NL85466C (en))

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