US2182134A - Radio directing and direction finding system - Google Patents

Radio directing and direction finding system Download PDF

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Publication number
US2182134A
US2182134A US130461A US13046137A US2182134A US 2182134 A US2182134 A US 2182134A US 130461 A US130461 A US 130461A US 13046137 A US13046137 A US 13046137A US 2182134 A US2182134 A US 2182134A
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United States
Prior art keywords
antenna
radiation
directing
radio
reflector
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Expired - Lifetime
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US130461A
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English (en)
Inventor
Perroux Georges Edme Marcel
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International Standard Electric Corp
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International Standard Electric Corp
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Publication date
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S1/00—Beacons or beacon systems transmitting signals having a characteristic or characteristics capable of being detected by non-directional receivers and defining directions, positions, or position lines fixed relatively to the beacon transmitters; Receivers co-operating therewith
    • G01S1/02—Beacons or beacon systems transmitting signals having a characteristic or characteristics capable of being detected by non-directional receivers and defining directions, positions, or position lines fixed relatively to the beacon transmitters; Receivers co-operating therewith using radio waves

Definitions

  • the present invention relates to improvements in radio direction finding or guiding systems, for example, systems for the blind landing of aeroplanes in fog, in which the distribution of the electromagnetic field is employed to guide the moving body which is provided with a device sensitive to the electromagnetic waves.
  • the object of the invention is the provision of means for eliminating the effect of parasitic influences which tend to alter the desired distribution of the electromagnetic field.
  • a directive antenna system comprises a central dipole antenna, a reflector dipole arranged parallel to the central dipole antenna on one side thereof and spaced therefrom a distance equal to a quarter of the operating wave length and a directing dipole antenna disposed on the other side of the central dipole antenna at a distance from it equal to one half of the operating wave length.
  • Fig. 1 represents a polar diagram of the distribution of the electromagnetic field in a horizontal plane such as is obtained with known antenna systems comprising a vertical dipole and associated reflector;
  • Fig. 2 represents a polar diagram in the horizontal plane of the electromagnetic field obtained by an antenna system according to the present invention
  • Fig. 3 represents one method of carrying out the invention for obtaining a radiation diagram similar to that of Fig. 2;
  • Fig. 4 shows schematically how the ground reflection of the waves is employed for guiding the moving body in a vertical plane
  • Fig. 5 represents a form of radiation diagram producing the same results without employing ground reflection
  • Fig. 6 shows in polar coordinates in the vertical plane the distribution of the electromagnetic field obtained by an antenna device according to the present invention.
  • a vertical antenna I is frequently employed associated with a vertical reflector 2 placed at a suitable distance from this antenna; this unit produces in the horizontal plane a diagram of field distribution of a form similar to that of curve l, 3, 4, 5 of Fig. 1.
  • the diagram of Fig. 2 which was obtained in the case of an antenna arrangement of the kind which will be described later, has two loops of secondary radiation I! and I2 whose maxima amplitudes in one embodiment were respectively 9 and 25 decibels above the radiation in the desired direction 9, X.
  • the secondary radiations H and I 2 have substantially the same angle of opening between their tangents to the origin so that wrong indications of direction obtained in the course of the manipulation represent field values far below the maximum amplitude of the smallest of the components, that is to say which is below 25 decibels with respect to the main marked axis I, X.
  • the transmission line !6, I7 is placed in the symmetrical axis of the antennae so that any disturbance caused by the line in the main field would be symmetrically produced during the successive periods of keying or manipulation and consequently would be eliminated. 7
  • reflectors such as 2 and t placed respectively at a quarter of the working wavelength from the antenna I. These reflectors 2 and 6 are employed to deform the radiation diagram in the rhythm of the keying by means of relays in known manner.
  • Fig. 4 shows a beam llVI emanating from an antenna and reflected by ground at the point M in the direction MP.
  • the field at the point P results from the superposition of the field directly transmitted. in accordance with the line IP and of the field reflected in accordance with MP.
  • the geometric position of the point P where the electromagnetic field has the same value is a curve shown as OX tangential to the ground at the point 0 situated vertically below the antenna I.
  • the effect is the same as if there were associated with the antenna its image l with respect to ground.
  • This known phenomenon has been employed in order to obtain a guiding path for a moving object such as P, in accordance with a constant field curve. It will, however, be seen that any irregularity in the reflection to ground will cause irregularities in the guiding trajectory OXP, and if objects such as houses, hangars, trees, etc., are situated at the point M, the disturbances of the trajectory may be considerable. These harmful efiects are largely avoided if a vertical radiation diagram such as that shown in Fig. 5 is employed. This diagram is characterized by the fact that the radiation in the direction of the ground is zero and that consequently irregularities of reflection are avoided, the guiding trajectory being only produced by the direct radiation of the antenna l towards the point P indicating the moving object to be
  • An antenna device similar to that of Fig. 3, permits a vertical radiator diagram to be obtained similar to that of Fig. 5.
  • the horizontal direction lA corresponds to a direction of zero radiation for the loop I l. Itfollows that the secondary effects produced by the radiation H! are negligible in the directions near the horizontal and only assume appreciable value for sufficiently large angles with respect to the horizontal. These angles correspond to the normal guiding trajectory ill, ll, to points very near the antenna i, that is to' say, in practice the reflection effects of the radiation l2 are entirely negligible.
  • the guiding indications prefferably supplied to the pilot by other means than the visual means, for example, by sound indications.
  • the intensity of the signals controls the frequency of an audio frequency oscillator, so that an increase of frequency is obtained when the electromagnetic field is greater than the normal value, that is to say, when the moving body is below the trajectory of vertical guiding. Conversely, a reduction of frequency characterizes too low an altitude.
  • This frequency variation may be shown by known visual apparatus such as frequency meters. If a sound indication be desired it is convenient to compare the variable frequency obtained by the above means with a frequency of fixed basis. It is possible, to employ as comparison frequency, the modulation frequency of the fixed ground transmitter.
  • the fixed frequency oscillator may be the heterodyne oscillator of the receiver if the latter comprises one.
  • a directive antenna system comprising a central dipole antenna, a reflector dipole antenna parallel to said central dipole and spaced therefrom a distance equal to a quarter of the operating wave length, a directing dipole antenna disposed on the opposite side of said central dipole at a distance therefrom equal to one half of the operating wave length, and a common transmission line for feeding said central and directing dipoles extending along the symmetrical axis of the three antennas.

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Remote Sensing (AREA)
  • Aerials With Secondary Devices (AREA)
  • Variable-Direction Aerials And Aerial Arrays (AREA)
US130461A 1936-04-09 1937-03-12 Radio directing and direction finding system Expired - Lifetime US2182134A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
FR2182134X 1936-04-09

Publications (1)

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US2182134A true US2182134A (en) 1939-12-05

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US130461A Expired - Lifetime US2182134A (en) 1936-04-09 1937-03-12 Radio directing and direction finding system

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US (1) US2182134A (en:Method)
BE (1) BE420576A (en:Method)

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BE420576A (en:Method)

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