US2232592A - Modulation system - Google Patents

Modulation system Download PDF

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Publication number
US2232592A
US2232592A US219861A US21986138A US2232592A US 2232592 A US2232592 A US 2232592A US 219861 A US219861 A US 219861A US 21986138 A US21986138 A US 21986138A US 2232592 A US2232592 A US 2232592A
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United States
Prior art keywords
plates
source
circuit
transmission lines
current
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Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US219861A
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English (en)
Inventor
Gomer L Davies
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WASHINGTON INST OF TECHNOLOGY
WASHINGTON INSTITUTE OF TECHNOLOGY Inc
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WASHINGTON INST OF TECHNOLOGY
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
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Priority to US219861A priority Critical patent/US2232592A/en
Priority to GB20626/39A priority patent/GB531274A/en
Priority to CH230731D priority patent/CH230731A/de
Priority to FR857948D priority patent/FR857948A/fr
Application granted granted Critical
Publication of US2232592A publication Critical patent/US2232592A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • HELECTRICITY
    • H03ELECTRONIC CIRCUITRY
    • H03CMODULATION
    • H03C7/00Modulating electromagnetic waves
    • H03C7/02Modulating electromagnetic waves in transmission lines, waveguides, cavity resonators or radiation fields of antennas

Definitions

  • This invention relates, generally, to the modulation of radio frequency currents and, more particularly, is intended. to provide a method of and means for modulating currents transmitted at ultra-high frequencies.
  • Fig. 1 is a circuit diagram illustrating the application of my invention to a single line circuit
  • Fig. 2 is a circuit diagram illustrating an unbalanced input and balanced outputcircuit, which is generally similar to the circuit disclosed in Fig. 1;
  • Fig. 3 is a circuit diagram illustrating my invention as applied to a balanced line circuit
  • Figs. 4 and 5 are views illustrating forms of modulators which may be employed in carrying out my invention.
  • the present invention employs the modulating means disclosed in the aforesaid co-pending application for effecting the modulation of high frequency currents with carrier suppression.
  • a single line circuit for carrying out the invention is disclosed. in Fig. 1 of. thedrawing and it will be seen that the circuit there disclosed comprises a source of radio frequency current I and a load circuit 2, these being connected by transmission lines 3, 4 which are connected between the output terminals of the source and the input terminal of the load circuit.
  • the modulation of the radio frequency current output of the source I is efiected by alternately short-circuiting each of the transmission lines 3, 4 at any points B, B along the length thereof, which points are preferably spaced from the input ends of the lines by any distance which is a multiple of a quarter wave lengthof the current output of the source.
  • variable capacity coupling devices comprising fixed capacitatively related plates 6, 6, which are connected respectively to the conductor and grounded shield of transmission line 3, fixed capacitatively related plates 1, I which are connected respectively to the conductor and grounded shield of transmission line 4, and rotor 5.
  • the lines connecting the pairs of plates and the transmission lines are of known electrical length and, in order to avoid the necessity of exactly dimensioning these lines and the lines between the output of the source and the points B, B, additional loading circuits 8, 9 are connected to the transmission lines 3, 4, respectively, at the points B, B.
  • the aforesaid copending applicatiomthese loading circuits preferably take theform of short-circuited lines, the terminals of which are connected to the conductor and shield portions of each of the transmission lines 3, 4 respectively.
  • the lengths of the lines 8, 9 are so adjusted, as fully set forth in the aforesaid co-pending application, that the total combined length of each of lines 8 and 9 and the length of the line connecting the associated capacity device thereto will be such that the impedance across each transmission line at point B varies from zero to infinity.
  • the plates 6, 6 are capacitatively related, as are the plates 7, I, and the plates of the rotor 5 are so positioned that they may pass between the .platesof each pair as the rotor revolves, as illustrated in Figs. 4 and 5.
  • the two pairs of plates are so arranged with respect to each other that when the one plate of the rotor 5 is disposed between the plates of one pair,,the second rotor plate is entirely removed from the plates of the second pair, all as illustrated in Figs. 1, 4 and 5.
  • the operation of the rotor 5 will cause the capa-citative coupling between plates 6, 6 to vary from a maximum to a minimum value as one or the other of the rotor plates moves from a position completely covering these plates, as illustrated, to a position completely, removed therefrom.
  • the operation of the rotor causes the capacitance between plates 1, to vary from a, maximum to a minimum value.
  • the phase of the current in load circuit 2 will not change so long as line 4 passes more current than line 3, and the envelope of the resultant current in the load circuit will be a sine curve.
  • the rotor has moved .to a position in which one of the plates thereof equally covers the plates of pair 3, 6 and those of pair 1, 1, the currents passed by lines 3 and 4 will be equal and the resultant current in the load circuit will drop to zero.
  • the rotor has moved to a position at right angles to that illustrated in Fig.
  • a balanced output circuit may be employed in place of the unbalanced output circuit illustrated in Fig. 1 if an unbalanced input circuit is employed, and such a circuit is disclosed in Fig. 2, in which figure the parts are referred to by the same reference numerals as are used in Fig. 1.
  • a balanced line circuit for modulating radio frequency current with carrier suppression and supplying the side band frequencies to a load circuit, such as an antenna system.
  • a source of radio frequency current is'shown at 20 and a load circuit at 2
  • Each out of the output terminals of the source are connected to each of the terminals of the load circuit, terminal a of the source being connected to terminals 0 and d of the load through shielded transmission lines 22 and 23, respectively, while terminal b of the source is connected to terminals 0 and d of the load through shielded transmission lines 24 and 25, respectively.
  • Means are provided by the invention for modulating the radio-frequency current supplied by the source to the load 2
  • the plates 21, 21 are connected, respectively, to the two transmission lines 23, 24 at points B, B which are preferably spaced from the source 20 by an odd number of quarter wave-lengths of the output wave of the source, such connections being made by transmission lines 29, 30.
  • the plates 28, 28 are connected to the transmission lines 22, 25, respectively, at points C, C which are preferably spaced from the source 20 by an odd number of quarter wavelengths of the output wave of the source, such connection being made by transmission lines 3
  • a loading circuit 33 is connected between the transmission lines 23, 24, at the points B, B, and such circuit is so adjusted that the electrical length thereof plus the electrical length of the lines 29 and 30 will be such that the impedance of the transmission lines 23, 24 at points B, B will vary from zero to infinity.
  • a similar loading circuit 34 is connected across transmission lines 22 and 25 at points C, C and this circuit is so adjusted that the total electrical length of the circuit 34 and the lines 3
  • the loading circuits 33, 34 are inductive in nature and may be formed or short-circuited transmission line, as disclosed.
  • the envelopes of the two currents flowing in the load circuit will be sine curves. Regardless of whether this condition obtains, the resultant current in the load circuit will reverse in phase as the resultant current passes through zero.
  • Figs. 4 and 5 of the drawing are illustrated embodiments of variable capacity devices which may be employed in efiecting modulation according to the present invention.
  • Fig. 4 such a device comprising two pairs 40, 4
  • the plates are shaped as arcuate segments and the axis of one pair of plates is at right angles to the axis of the second pair.
  • Fig. 5 there is disclosed a second form which the variable capacity device may take.
  • this embodiment there are two pairs 50, 5
  • the stator plates are shaped as arcuate segments and theaxis of one pair is disposed at an angle of 135 to the axis of the second pair.
  • the rotor portion of this device is provided with. four radial arms each of which is spaced from adjacent arms and each of which is -provided,'at its outer extremity, with a circular plate, all of such plates being denoted by numeral 52 in the drawing.
  • the variable capacity device illustrated in Fig. 5 will provide'the same functions and effects as that illustrated in Fig.
  • of Fig. 5 correspond to the pairs of plates illustrated diagrammatically at 6, 6 and I, 1 in Fig. 1 and at 2121 and 28, 28 in Fig. 3.
  • a system for" supplying modulated radio frequency energy with carrier suppression to a load circuit comprising two shielded transmission lines connecting the terminals of a source of radio frequency energy to the terminals of the load circuit, variable capacity devices each connected across the conductor and shield of one of said lines, and means for inversely varying the capacities of said devices at a pre-determined rate to thereby cause the currents passed through said lines to be varied inversely at the pre-determined rate.
  • a ⁇ system for supplying modulated radio frequency energy with carrier suppression to a load circuit comprising two shielded transmission lines connecting the terminals of a source of radio frequency energy to the terminals of the load circuit, a variable capacity device and an inductive circuit connected between the con- 'ductor and shield of each of said lines, and means for inversely varying the capacities of said devices at a pre-determined rate to thereby cause the currents passed through said lines to be varied inversely at the pre-determined rate.
  • a system for supplying modulated radio frequency energy with carrier suppression from a source of radio frequency energy to a load circult comprising two pairs of variable impedance transmission lines connecting the terminals of the source to the terminals of the load circuit, two capacity devices each of which comprises two fixed plates which are connected across a different pair of said transmission lines, a rotary device associated with the plates of both said capacity devices and being operable to vary the capacitance between the plates of each of said .,devices, said capacity devices being so arranged with respect to each other that operation of the rotary device causes the capacitance of said devices to be substantially inversely varied, to
  • a system for supplying modulated radio frequency energy from a source of radio frequency energy to a load circuit comprising two transmission lines connecting the source and the load circuit and each having grounded shielding means, variable capacity means connected between each line and the shielding therefor, and means for continuously and inversely varying the capacities of said means to thereby continuously and inversely vary the currents passed through said lines.
  • a system for supplying modulated radio frequency energy with carrier suppression from a source of energy to a load circuit comprising at least two two-element transmission lines connecting the source and the load circuit, yariable impedance means connected across each of said transmission lines, and means for continuously and inversely varying said impedance means at a pre-determined rate to thereby continuously and inversely vary the energy passed through said transmission lines.
  • Asystem for supplying modulated radio frequency energy with carrier suppression from a source of radio frequency energy to a load circuit comprising two pairs of variable impedance transmission lines connecting the terminals of the source to the terminals of the load circuit, two capacity devices each of which is connected across a different pair of trassmission lines, means for continuously and substantially inversely varying the capacitance of said devices, to thereby continuously and substantially inversely vary the energy passed through each such pair of transmission lines.
  • each of the variable impedance means is connected across the associated transmission line at a point which is spaced from the source by a distance which is any quarter wavelength of the energy supplied by the source.

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  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Motorcycle And Bicycle Frame (AREA)
  • Amplitude Modulation (AREA)
US219861A 1938-07-18 1938-07-18 Modulation system Expired - Lifetime US2232592A (en)

Priority Applications (4)

Application Number Priority Date Filing Date Title
US219861A US2232592A (en) 1938-07-18 1938-07-18 Modulation system
GB20626/39A GB531274A (en) 1938-07-18 1939-07-15 Improvements in systems for modulation of radio frequency currents with carrier suppression
CH230731D CH230731A (de) 1938-07-18 1939-07-18 Modulationseinrichtung mit Trägerunterdrückung in einer Hochfrequenzanlage.
FR857948D FR857948A (fr) 1938-07-18 1939-07-18 Perfectionnements aux systèmes de modulation avec suppression de l'onde porteuse

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US219861A US2232592A (en) 1938-07-18 1938-07-18 Modulation system

Publications (1)

Publication Number Publication Date
US2232592A true US2232592A (en) 1941-02-18

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ID=22821064

Family Applications (1)

Application Number Title Priority Date Filing Date
US219861A Expired - Lifetime US2232592A (en) 1938-07-18 1938-07-18 Modulation system

Country Status (4)

Country Link
US (1) US2232592A (de)
CH (1) CH230731A (de)
FR (1) FR857948A (de)
GB (1) GB531274A (de)

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2416790A (en) * 1941-01-28 1947-03-04 Sperry Gyroscope Co Inc Transmission line bridge circuit
US2434917A (en) * 1943-11-06 1948-01-27 Standard Telephones Cables Ltd Mechanical modulator
US2444081A (en) * 1941-08-11 1948-06-29 Standard Telephones Cables Ltd Switching device for highfrequency circuits
US2479892A (en) * 1944-10-27 1949-08-23 Sadir Carpentier Radio direction finder
US2488419A (en) * 1943-06-30 1949-11-15 Rca Corp Antenna and lobe switcher
US2492138A (en) * 1940-02-23 1949-12-27 Int Standard Electric Corp Mechanical modulator for radio beacons utilizing two tones
US2514957A (en) * 1944-06-27 1950-07-11 Hazeltine Research Inc High-frequency tuning device
US3673516A (en) * 1971-02-08 1972-06-27 Itt Continuous phase shifter/resolver employing a rotary halfwave plate

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2492138A (en) * 1940-02-23 1949-12-27 Int Standard Electric Corp Mechanical modulator for radio beacons utilizing two tones
US2416790A (en) * 1941-01-28 1947-03-04 Sperry Gyroscope Co Inc Transmission line bridge circuit
US2444081A (en) * 1941-08-11 1948-06-29 Standard Telephones Cables Ltd Switching device for highfrequency circuits
US2488419A (en) * 1943-06-30 1949-11-15 Rca Corp Antenna and lobe switcher
US2434917A (en) * 1943-11-06 1948-01-27 Standard Telephones Cables Ltd Mechanical modulator
US2514957A (en) * 1944-06-27 1950-07-11 Hazeltine Research Inc High-frequency tuning device
US2479892A (en) * 1944-10-27 1949-08-23 Sadir Carpentier Radio direction finder
US3673516A (en) * 1971-02-08 1972-06-27 Itt Continuous phase shifter/resolver employing a rotary halfwave plate

Also Published As

Publication number Publication date
FR857948A (fr) 1940-10-05
CH230731A (de) 1944-01-31
GB531274A (en) 1941-01-01

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