US2244756A - Modulation system - Google Patents

Modulation system Download PDF

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Publication number
US2244756A
US2244756A US288134A US28813439A US2244756A US 2244756 A US2244756 A US 2244756A US 288134 A US288134 A US 288134A US 28813439 A US28813439 A US 28813439A US 2244756 A US2244756 A US 2244756A
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US
United States
Prior art keywords
impedance
network
energy
modulation
transmission line
Prior art date
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
US288134A
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English (en)
Inventor
Alford Andrew
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
INTERNAT TELEPHONE DEV CO Inc
INTERNATIONAL TELEPHONE DEVELOPMENT Co Inc
Original Assignee
INTERNAT TELEPHONE DEV CO Inc
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
Priority to BE456046D priority Critical patent/BE456046A/xx
Application filed by INTERNAT TELEPHONE DEV CO Inc filed Critical INTERNAT TELEPHONE DEV CO Inc
Priority to US288134A priority patent/US2244756A/en
Priority to FR867296D priority patent/FR867296A/fr
Application granted granted Critical
Publication of US2244756A publication Critical patent/US2244756A/en
Priority to CH262004D priority patent/CH262004A/de
Priority to ES176814A priority patent/ES176814A1/es
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H7/00—Multiple-port networks comprising only passive electrical elements as network components
    • H03H7/48—Networks for connecting several sources or loads, working on the same frequency or frequency band, to a common load or source
    • H03H7/487—Networks for connecting several sources or loads, working on the same frequency or frequency band, to a common load or source particularly adapted as coupling circuit between transmitters and antennas
    • 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

  • New York, N. Y., a corporation of Delaware My invention relates to radio beacons and more particularly to arrangements for coupling to radio beacon antennae to prevent intermodulation of signals.
  • radio beacons are often arranged so that the antennae are energized over branch transmission lines from a signal carrier source.l
  • a commo'n dimculty is that which may be termed crossmodulation.
  • the impedance of one line is changed, not only does the current in the particular antenna to which it is connected become modulated, but the resultant load impedance is also varied lation is transferred to the other antenna.
  • the modulation in the second antenna is reflected into the rst antenna so that there is quite an amount of cross-modulation. Since the modulation frequencies commonly used are in the order of 90 cycles per second and l0() cycles per second, the impedance cannot oe coordinated with ,the minimums of desired wav and the cross-modulation cannot be completely prevented. This-results in a course beam which is less definite than would otherwise be obtained and is more subject to extraneous eects.
  • balancing network is interposed between the source of energy and the transmission lines connected to the antennae to which the modulators are coupled, so that cross-modulation is prevented.
  • the network used for preventing cross-modulation is designed so as' to Working condition so that a very small percentage of energy is wasted.
  • FIG. 2 diagrammatically illustrates' a particular preferred embodiment of my invention
  • Figs. S'and d illustrate modulation arrangements that may be utilized to ⁇ attain these desired results in accordance with the systems of my invention.
  • an energy source it@ is shcwneonnected over a transmission line lili :to a network indicated generally-at H02.
  • Network it?? is a special form of the high frequencybridge such. as illustrated in .my prior United States Patent No. 2,147,809 of February 21, 1939.
  • This network is made in the form o' reentrant loops having e.. phase changing arrangement such. as .the trans- DOSition shown at
  • the network is formed with four arms of substantially equal. electrical length so that the whole arrangement has the appearance of a bridge.
  • a balancing network tilt At the intersection ci.' two of the arms, such as
  • This balancing impedance network has preferably an 1inpedance substantially equal to the surge impedance of the load looking into it at the point of connection to the bridge.
  • Across the other diagonally related junction point of the bridge network are connected transmission lines iii, to the terminals of which. are connected high frequency loads M2, till, which may constitute directive antennae.
  • the arrangement described above may also be used for transmitting from two separate sources placed in relative positions such as shown in loads IIZ. H3, connected to a single load arrangement at a point such as I I without causing cross-modulation between the sources. This is clear from the general reciprocity law Jrelating to such circuits.
  • junction point b is bridged by an open quarter
  • an additional half wavelength of transmission line may be added, or any other well known form of.
  • phase shifter may be provided. lThese various forms of phase Shifters are disclosed in my previously mentioned Patent 2,147,809.
  • Fig. ⁇ 2 is illustrated a preferred embodiment of my invention applied to a radio beacon circuit.
  • 00 terminates in a tuned output circuit 200, which is dcoupled over a tuned secondary circuit to transmission line
  • 02 are each made equal to a quarter wavelength of the operating frequency or an odd multiple thereof in length.
  • the network I 08 has an impedance Zo equal to the surge impedance of .the load looking into at point a..
  • the four junction points of the bridge network are designated a, b, c, d, as shown.
  • the modulating networks IM, IIE comprise sections of transmission line coupled to the antenna leads I I0, III and provided with rotatable condenser plates 203, cut so as to give a diiferent modulation to the energy transmitted from each or antennae H2, H3.
  • These networks are tuned by their respective condensers so as to he in resonance with the carrier frequency they act as cut-olf filters producing an apparent open circuit inthe line.
  • a common driving motor 204 connected by means of a shaft, as shown by broken lines to the condenser rotors, serves to drive these condensers so as to modulate energy at two different frequencies, for example, at frequencies 90 and 100 cycles, respectively.
  • I3 as seen from points b and d, respectively, may be so related as to be equal to one-half Zn. Then, since arms
  • the modulating arrangements are located at such a distance from the junction points c and d, that the portion of the lines 0, III between points c and d and the modulator point, where the apparent open'circuit occurs when the networks are tuned to stop the ilow of current in lines IIO, III is made equal to an odd multiple of a quarter wavelength.
  • the following operational characteristics will be observed:
  • quarter wave line has the same effect to the energy as if a short circuit across the network at point b. Therefore, arm
  • 01 acts as a short circuited quarter wavelength line across point c and does not eiect the impedance network. Since antenna H3 and transmission line has an effective impedance equal to one-half Zu and a network
  • the oscillator would carry such highy current as to probably result in a burning out of the oscillator.
  • the modulation arrangement must be of a type which will produce an effective opening of the circuit of lines
  • several types of arrangements may be utilized.
  • Figs. 3 and 4 I have illustrated two types of arrangements suitable for use in this arrangement. Referring rst to Fig, 3, two transmission line conductors 302 are shown. These may be the conductors of a line such as H0, of Figs. l and 2. Mounted close to these transmission line conductors is provided a transmission line section .303, closed at .one end and open circuited at the other.
  • the frequency of the modulation signals may be determined by the speed of rotation of the condenser disc 330, and the number of notches provided therein. Thus, any desired modulation frequency may be produced.
  • a trough section such as 308 mounted around the transmission line conductors and carrying the shaft
  • a cover plate may be provided over the trough 308.
  • Fig. 4 is shown another type of arrangement for producing the desired modulation effect.
  • is bridged across the transmission lines 30
  • This condenser plate isV 'I'his network may be tuned to the operating frequency and detuned therefrom. When properly tuned it may operate so as to produce a virtual short circuit across the transmission line. Since, as stated above, this section may be spaced at a distance equivalent to a half wavelength from ⁇ the junction point of the bridge arm andmay be made equal to a half wavelength long, it is lclear that at this time the effect will be the same as .though the transmissionline were short circuited at a point a half wavelength distant from the junction. This will be effectively equivalent to a short circuit at the junction point, for example, at a point such as b in the arrangement f shown in Fig. 2.
  • a high frequency system comprising a reentrant loop circuit, a high frequency energy source having a given surge impedance coupled to a point on said reentrant loop circuit, a network having substantially the same impedance as said surge impedance coupled to said loop circuit at another point, said coupling points dividing said loop into two parts, one of said parts being electrically a half wavelength or an odd multiple of a half wavelength longer than the other of said parts, high frequency loads of substantially equal impedance values coupled to said l loop substantially midway between the points of connection of said source and said network, and means for differently modulating the energy delivered from said source to respective ones of said loads.
  • a high frequency system wherein said arms of said reentrant loop formed by connection of said source, said loads said ioop circuit at a xed point and a high frequency impedance network having an impedance substantially equal to the impedance of said source connected at another point of said loop, said connecting points dividing said loop into two parts, one of said parts being electrical/ly substantially a half wavelength or an odd multiple thereof longer than the other of said parts, and means for connecting each said load to said loop at points substantially equi-distant electrically between the points of connection of said source and said impedance network.
  • a high frequency transmission system comprising a source of high frequency energy, two high frequency loads of substantially equal impedance, a network for interconnecting said source and said loads and providing a conjugate relationship between said loads comprising, a reentrant bridge circuit having four arms of substantially equal electrical length, one of said arms having transposition therein, means for coupling said source to the junction point of two of said arms.
  • a high frequency impedance means means for coupling said impedance means to the Junction point of said vbridge circuit diagonally related to said rst named junction, means for coupling said loads respectively to the other junctions of the arms of said bridge, f
  • a high frequency transmission system wherein the arms of said reentrant bridge circuit are each equal to a quarter wavelength of the operating frequency or an odd multiple thereof, said means lfor coupling said loads to said bridge each comprising transmission line sections, and said modulating means each comprising arrangements for varying the impedance of the transmission line from normal value to a very high impedance value, said modulating means being located at a point in said transmission line a quarter of a wavelength or an odd multiple of a quarter wavelength from the connection point of said load coupling means and said bridge.

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  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Transmitters (AREA)
US288134A 1939-08-03 1939-08-03 Modulation system Expired - Lifetime US2244756A (en)

Priority Applications (5)

Application Number Priority Date Filing Date Title
BE456046D BE456046A (en)van) 1939-08-03
US288134A US2244756A (en) 1939-08-03 1939-08-03 Modulation system
FR867296D FR867296A (fr) 1939-08-03 1940-09-24 Systèmes de transmission à fréquence élevée
CH262004D CH262004A (de) 1939-08-03 1947-01-20 Ubertragungsanordnung für Hochfrequenzschwingungen, mit zwei zu entkoppelnden Hochfrequenzvorrichtungen, die mit einer dritten Hochfrequenzvorrichtung verbunden sind.
ES176814A ES176814A1 (es) 1939-08-03 1947-02-15 Mejoras en sistemas de transmisión de alta frecuencia

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US288134A US2244756A (en) 1939-08-03 1939-08-03 Modulation system

Publications (1)

Publication Number Publication Date
US2244756A true US2244756A (en) 1941-06-10

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Family Applications (1)

Application Number Title Priority Date Filing Date
US288134A Expired - Lifetime US2244756A (en) 1939-08-03 1939-08-03 Modulation system

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US (1) US2244756A (en)van)
BE (1) BE456046A (en)van)
CH (1) CH262004A (en)van)
ES (1) ES176814A1 (en)van)
FR (1) FR867296A (en)van)

Cited By (22)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2415242A (en) * 1943-02-25 1947-02-04 Rca Corp Switching in wave guide transmission system
US2415932A (en) * 1943-04-21 1947-02-18 Rca Corp Antenna system
US2416790A (en) * 1941-01-28 1947-03-04 Sperry Gyroscope Co Inc Transmission line bridge circuit
US2425328A (en) * 1944-08-01 1947-08-12 Frederic A Jenks Switching and modulation system
US2426992A (en) * 1942-05-27 1947-09-09 Sperry Gyroscope Co Inc Glide path transmitter
US2439255A (en) * 1942-09-09 1948-04-06 Gen Electric Capacitor switch
US2449451A (en) * 1944-09-28 1948-09-14 Westinghouse Electric Corp High-frequency dielectric heating apparatus
US2473535A (en) * 1941-04-04 1949-06-21 Sperry Corp Switching and modulation system
US2492138A (en) * 1940-02-23 1949-12-27 Int Standard Electric Corp Mechanical modulator for radio beacons utilizing two tones
US2531777A (en) * 1945-10-24 1950-11-28 John N Marshall Variable directive coupler
US2594409A (en) * 1943-07-27 1952-04-29 Bell Telephone Labor Inc Directive antenna
US2602887A (en) * 1948-10-04 1952-07-08 Rca Corp Radio transmitter
US2632108A (en) * 1949-07-28 1953-03-17 Rca Corp Diplexer arrangement
US2660709A (en) * 1951-11-10 1953-11-24 Standard Telephones Cables Ltd Mechanical modulator
US2735982A (en) * 1956-02-21 Radio frequency power comparator
US2959659A (en) * 1957-08-19 1960-11-08 Alford Andrew Electromagnetic heating unit
US3113314A (en) * 1960-09-01 1963-12-03 Forrest G Yetter Radio guidance and landing system
DE976983C (de) * 1942-12-31 1964-10-15 Western Electric Co Kopplungseinrichtung fuer Wellenuebertragungssysteme
DE977019C (de) * 1942-12-31 1964-12-23 Western Electric Co Kopplungsanordnung fuer Wellenuebertragungssysteme
US3516025A (en) * 1968-12-19 1970-06-02 Adams Russel Co Inc Wide band hybrid coupler having an open end transmission line section coupled to each part
US4721929A (en) * 1986-10-17 1988-01-26 Ball Corporation Multi-stage power divider
US9088063B1 (en) 2015-03-11 2015-07-21 Werlatone, Inc. Hybrid coupler

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
NL191136A (en)van) * 1953-10-01
US2831168A (en) * 1954-01-04 1958-04-15 Gen Electric Coupling device for wave transmission systems
GB770317A (en) * 1954-07-15 1957-03-20 Gen Electric Co Ltd Improvements in or relating to electric hybrid devices

Cited By (22)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2735982A (en) * 1956-02-21 Radio frequency power comparator
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
US2473535A (en) * 1941-04-04 1949-06-21 Sperry Corp Switching and modulation system
US2426992A (en) * 1942-05-27 1947-09-09 Sperry Gyroscope Co Inc Glide path transmitter
US2439255A (en) * 1942-09-09 1948-04-06 Gen Electric Capacitor switch
DE977019C (de) * 1942-12-31 1964-12-23 Western Electric Co Kopplungsanordnung fuer Wellenuebertragungssysteme
DE976983C (de) * 1942-12-31 1964-10-15 Western Electric Co Kopplungseinrichtung fuer Wellenuebertragungssysteme
US2415242A (en) * 1943-02-25 1947-02-04 Rca Corp Switching in wave guide transmission system
US2415932A (en) * 1943-04-21 1947-02-18 Rca Corp Antenna system
US2594409A (en) * 1943-07-27 1952-04-29 Bell Telephone Labor Inc Directive antenna
US2425328A (en) * 1944-08-01 1947-08-12 Frederic A Jenks Switching and modulation system
US2449451A (en) * 1944-09-28 1948-09-14 Westinghouse Electric Corp High-frequency dielectric heating apparatus
US2531777A (en) * 1945-10-24 1950-11-28 John N Marshall Variable directive coupler
US2602887A (en) * 1948-10-04 1952-07-08 Rca Corp Radio transmitter
US2632108A (en) * 1949-07-28 1953-03-17 Rca Corp Diplexer arrangement
US2660709A (en) * 1951-11-10 1953-11-24 Standard Telephones Cables Ltd Mechanical modulator
US2959659A (en) * 1957-08-19 1960-11-08 Alford Andrew Electromagnetic heating unit
US3113314A (en) * 1960-09-01 1963-12-03 Forrest G Yetter Radio guidance and landing system
US3516025A (en) * 1968-12-19 1970-06-02 Adams Russel Co Inc Wide band hybrid coupler having an open end transmission line section coupled to each part
US4721929A (en) * 1986-10-17 1988-01-26 Ball Corporation Multi-stage power divider
US9088063B1 (en) 2015-03-11 2015-07-21 Werlatone, Inc. Hybrid coupler

Also Published As

Publication number Publication date
CH262004A (de) 1949-06-15
FR867296A (fr) 1941-10-10
ES176814A1 (es) 1947-03-16
BE456046A (en)van)

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