US2785398A - Radio antennae - Google Patents

Radio antennae Download PDF

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Publication number
US2785398A
US2785398A US297088A US29708852A US2785398A US 2785398 A US2785398 A US 2785398A US 297088 A US297088 A US 297088A US 29708852 A US29708852 A US 29708852A US 2785398 A US2785398 A US 2785398A
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United States
Prior art keywords
mirror
antenna
reflection
guide
strip
Prior art date
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Expired - Lifetime
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US297088A
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English (en)
Inventor
Jacobsen Bent Bulow
Thomas David Lane
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International Standard Electric Corp
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International Standard Electric Corp
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
Application filed by International Standard Electric Corp filed Critical International Standard Electric Corp
Application granted granted Critical
Publication of US2785398A publication Critical patent/US2785398A/en
Anticipated expiration legal-status Critical
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q19/00—Combinations of primary active antenna elements and units with secondary devices, e.g. with quasi-optical devices, for giving the antenna a desired directional characteristic
    • H01Q19/10—Combinations of primary active antenna elements and units with secondary devices, e.g. with quasi-optical devices, for giving the antenna a desired directional characteristic using reflecting surfaces
    • H01Q19/12—Combinations of primary active antenna elements and units with secondary devices, e.g. with quasi-optical devices, for giving the antenna a desired directional characteristic using reflecting surfaces wherein the surfaces are concave
    • H01Q19/13—Combinations of primary active antenna elements and units with secondary devices, e.g. with quasi-optical devices, for giving the antenna a desired directional characteristic using reflecting surfaces wherein the surfaces are concave the primary radiating source being a single radiating element, e.g. a dipole, a slot, a waveguide termination

Definitions

  • This invention relates to antenna arrangements of the type comprising a concave mirror having a co-operating antenna located at or adjacent to the focal point of the mirror. More particularly, it relates to arrangements of the said type in which the construction is such that one or more reflecting surfaces obstruct in part the mouth of the mirror and reflect back thereto some of the energy which would otherwise be radiated by the mirror into space.
  • the invention resides in a radio antenna arrangement comprising a concave mirror, a co -operating antenna located at or adjacent to the focal point of said mirror, and at least one member so located as to obstruct radiation from said mirror, characterised in this, that said obstructing member is so formed as to reduce the effect of reflection back to the mirror of radiation therefrom intercepted by said member.
  • Fig. 1A illustrates the undesired reflection phenomenon in an antenna arrangement which does not incorporate the present invention.
  • Fig. 18 illustrates an embodiment of the invention.
  • Fig. 1A of the accompanying drawing comprises a paraboloidal mirror 1 having at its focus "a co-operating antenna in the form of a horn 2 which is coupled to an energy translating device (not shown) such as a transmitter or receiver by means of an H-bend 3 followed by a linear wave guide 4 of rectangular crosssection, which wave guide lies radially across the mouth of the mirror with one wall of the guide parallel to but slightly spaced out from the aperture of the mirror.
  • One method of reducing the reflection-back is to provide an additional reflecting surface the reflection from which is equal in magnitude but opposite in phase to that just mentioned. This may be done, in one embodiment of the invention, by adding an auxiliary reflecting memby extending the wave guide linearly beyond its junction with the l-l-ben-d completely across the mouth of the mirror by means of a dummy portion of wave guide as illustrated at 6 in Fig. 1B, the dummy portion having a flat reflecting surface 7 facing the mirror, and of the same dimensions as the wave-guide proper, but displaced nearer the mirror by a distance of one quarter of the mean operating wavelength.
  • This displacement is conveniently obtained by the superposition of a conducting strip 8 on the wall of the dummy portion of waveguide, this strip being of the same width as the waveguide wall, and one quarter wavelength in depth. Since the reflecting surface of the waveguide proper and the spacing strip are equal and symmetrically located with respect. to the antenna horn, very effective cancellation of the reflected back energies is obtained.
  • the dummy portion of wave guide may also have a mechanical advantage in that it may be used as a member for improving the rigidity of the hornand-mirror assembly.
  • the dummy waveguide may be dispensed with, and a quarter wave strip applied over a sufficient length of the wave-guide proper to give cancellation between the reflection from the strip and that from the uncovered part of the wave-guide.
  • the spacing strip it is not necessary that the spacing strip be so much as one quarter wavelength thick; a thinner strip may be used provided that the mounting means is such that the proper spacing out from the reflecting surface, or from the plane thereof, is obtained.
  • the mounting mean may be made adjustable, and the shape of the strip need not be limited to one of the same width as the guide Wall, so long as the area of the strip is such that the total reflection therefrom balances the remaining reflection.
  • the strip may be divided into two efiective halves spaced respectively one quarter wavelength forward and one quarter wavelength backward from the plane of the offending surface, such disposition giving compensation over a very wide band.
  • the construction may be made such that the total reflection from an obstructing surface is small ab initio.
  • the obstructing surface may be coated with a layer of material of surface resistance such that the high frequency energy impingent thereon is absorbed instead of being reflected.
  • the surface may be so shaped that components of reflection from different points add in random phase instead of cophasally for example by using a curved surface instead of a flat one for the outer wall of the guide, or by curving the axis of the guide, in a plane through the axis of generation of the paraboloid.
  • a radio antenna arrangement comprising a paraboloidal mirror and a co-operating horn antenna located at or adjacent to the focal point of said mirror, a rectangular metal wave guide coupling said antenna to an energy translating device, a major part of said wave guide being linear and located in front of said mirror with one wall of greases the guide parallel to the aperture plane of the mirror, the surface of which Wall reflects energy radiated thereon by said mirror, and a collinear extension of said coupling wave guide beyond the junction with the horn and extending in front of said mirror, the external surface of said extension facing said mirror having a flat radiationreflecting surface in a plane parallel to that containing the reflecting surface of said one Wall but displaced therefrom by a distance of one quarter of the operating wavelength, whereby reflection from part of the surface of said dummy Wave guide cancels the reflection from a corresponding part of the surface of said one wall.
  • a radio antenna arrangement comprising a mirror, a cooperating antenna located in front of said mirror and adapted to radiate energy in the direction of said mirror, transmission means for feeding said antenna, a portion of said transmission means being located in front of said mirror and having a surface which reflects energy radiated thereon by said mirror, a reflecting member forming a collinear extension with said transmission means extending in front of said mirror, the reflecting member having a radiation-reflecting surface, spaced at a different distance from said mirror than said transmission means to cancel the effects of reflection from a corresponding part of said transmission means.
  • a radio antenna system comprising a curved mirror, an antenna positioned in front of said mirror substantially at its focus, a transmission means connected to said antenna and having a reflecting surface positioned in front of said mirror, whereby disturbing reflections back to said antenna are produced, and means for substantially cancelling the elfects of these disturbing reflections, comprising a reflecting means having substantially the same refleeting properties as said reflecting surface, positioned in front of said mirror and extending in a direction substantially symmetrically with respect to the transmission means, at a spacing from said mirror differing from the spacing of said transmission means by substantially the equivalent of a quarter wave length at the operating frequency.

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  • Aerials With Secondary Devices (AREA)
US297088A 1951-07-09 1952-07-03 Radio antennae Expired - Lifetime US2785398A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB310995X 1951-07-09

Publications (1)

Publication Number Publication Date
US2785398A true US2785398A (en) 1957-03-12

Family

ID=10317965

Family Applications (1)

Application Number Title Priority Date Filing Date
US297088A Expired - Lifetime US2785398A (en) 1951-07-09 1952-07-03 Radio antennae

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US (1) US2785398A (is")
BE (1) BE512707A (is")
CH (1) CH310995A (is")
DE (1) DE972294C (is")

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2429601A (en) * 1943-11-22 1947-10-28 Bell Telephone Labor Inc Microwave radar directive antenna
GB603676A (en) * 1945-10-27 1948-06-21 Eric Wild Improvements in ultra-high-frequency aerial systems or arrays
US2607010A (en) * 1945-04-23 1952-08-12 Bell Telephone Labor Inc Wave guide antenna system
US2671855A (en) * 1945-09-19 1954-03-09 Lester C Van Atta Antenna

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CH183565A (de) * 1934-10-15 1936-04-15 Emil Dr Huber Abschirmungsvorrichtung für Hochfrequenz führende Leiter.
FR802728A (fr) * 1935-02-19 1936-09-14 Meaf Mach En Apparaten Fab Nv Dispositif et procédé pour l'amélioration de dispositifs de production et de réception d'ondes électriques ultra-courtes

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2429601A (en) * 1943-11-22 1947-10-28 Bell Telephone Labor Inc Microwave radar directive antenna
US2607010A (en) * 1945-04-23 1952-08-12 Bell Telephone Labor Inc Wave guide antenna system
US2671855A (en) * 1945-09-19 1954-03-09 Lester C Van Atta Antenna
GB603676A (en) * 1945-10-27 1948-06-21 Eric Wild Improvements in ultra-high-frequency aerial systems or arrays

Also Published As

Publication number Publication date
BE512707A (is")
DE972294C (de) 1959-07-02
CH310995A (fr) 1955-11-15

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