US3430246A - Plural reflector antenna with polarization rotation to minimize feedshadow - Google Patents

Plural reflector antenna with polarization rotation to minimize feedshadow Download PDF

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Publication number
US3430246A
US3430246A US536880A US3430246DA US3430246A US 3430246 A US3430246 A US 3430246A US 536880 A US536880 A US 536880A US 3430246D A US3430246D A US 3430246DA US 3430246 A US3430246 A US 3430246A
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United States
Prior art keywords
reflector
polarization
waves
axis
respect
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Expired - Lifetime
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US536880A
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English (en)
Inventor
Guy Le Parquier
Robert Pierrot
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Thales SA
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CSF Compagnie Generale de Telegraphie sans Fil SA
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Application filed by CSF Compagnie Generale de Telegraphie sans Fil SA filed Critical CSF Compagnie Generale de Telegraphie sans Fil SA
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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
    • H01Q19/18—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 having two or more spaced reflecting surfaces
    • 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
    • H01Q19/18—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 having two or more spaced reflecting surfaces
    • H01Q19/19—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 having two or more spaced reflecting surfaces comprising one main concave reflecting surface associated with an auxiliary reflecting surface
    • H01Q19/195—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 having two or more spaced reflecting surfaces comprising one main concave reflecting surface associated with an auxiliary reflecting surface wherein a reflecting surface acts also as a polarisation filter or a polarising device

Definitions

  • a centrally mounted feed faces a polarization selective first reflector which reflects all the waves to a polarization rotating second split reflector. The second reflector rotates the polarization of the waves and directs them back to the first reflector which is now transparent to the new polarization.
  • the present invention relates to antenna systems with two reflectors, for example of the Cassegrain type. More particularly, the invention relates to antennas wherein the polarization direction is not the same for the incident and the reflected signal.
  • the primary source casts a shadow on the reflecting surface. This adversely affects the antenna gain and increases the secondary lobes. This can be avoided at least in part by offsetting the primary source but the counterpart is that is that a dissymmetry is created.
  • an antenna system having an axis of symmetry comprising: a primary source located on said axis, for radiating waves having a given direction of polarization; a first reflector, positioned on the path of said wave, which is not transparent for the waves having said given direction of polarization and which is transparent for the waves having a different direction of polarization, said first reflector being symmetrical with respect to said axis; a second reflector positioned on the path of the waves reflected by said first reflector and which modifies the direction of polarization of waves incident thereon, said second reflector being symmetrical With respect to said axis; and a dioptric system, symmetrical with respect to said axis and positioned on the path of the waves reflected by said second reflector, said dioptric system making parallel the waves incident thereon.
  • the two reflectors build up an aplanatic system.
  • the system shown comprises a primary source 1, or an array of primary sources, normal to the plane of the fig- 3,430,246 Patented Feb. 25, 1969 ure; a first reflector which is not transparent for the polarization direction of the source 1 and which is formed by two identical paraboloid portions which have the same focus and are symmetrical with respect to the axis of the antenna system; a second reflector 3 formed by two plane reflector elements, also symmetrical with respect to the axis of the antenna system, and a double prism 4.
  • the second reflector is so built that it modifies the polarization direction of the incident signal.
  • the second reflector builds up, together with the first reflector, an aplanatic system.
  • the spherical wave which is generated by the primary source 1 is reflected by reflector 2 as two plane waves which propagate along the respective axes of the two paraboloids building up the reflector 2.
  • the polarization rotating reflector may comprise, as is well known, a reflecting metal surface, covered with a layer of dielectric, such as a resin, in which i incorporated a mesh of parallel wires which are spaced by at most half the maximum operating wavelength and inclined by 45 with respect to the polarization of the incident wave, all this being well known in the art.
  • the antenna system of the invention has an exit aperture without any-shadow or inactive surface portion, thus improving the antenna performance as to gain, secondary lobes and diffused radiations.
  • the standing wave ratio is improved since the waves reflected by reflector 2 do not interfere with the primary source.
  • the invention is not limited to the embodiment described and shown, since obviously the essential component parts of the antenna system according to the invention, namely the semitransparent reflector system, the reflector system which causes the polarization direction to change and the dioptric system used, may be of various types without departing from the spirit and scope of the invention.
  • An antenna system having an axis of symmetry comprising: a primary source located on said axis for radiating waves having a given direction of polarization; a first reflector positioned on the path of said wave which is not transparent for the waves having said given direction of polarization and which is transparent for the waves having a different direction of polarization, said first reflector comprising two parts symmetrical with respect to said axis, the two parts of said reflector being portions of respective surfaces intersecting each other on said axis, the planes respectively tangent to said surfaces on said axes being at an angle with respect to each other; a second reflector positioned on the path of the waves reflected by said first reflector and which modifies the direction of polarization of waves incident thereon, said second reflector being symmetrical with respect to said axis; and a dioptric system symmetrical with respect to said axis and positioned on the path of the waves reflected by said second reflector, said dioptric system making parallel the waves incident thereon.
  • said first reflector is formed by two adjacent identical paraboloid portions which have the same focus and are symmetrical respect to said axis, the axes of said paraboloids being at an angle with respect to each other and said second re- 15 4' flector is formed by two adjacent plane reflector elements, also symmetrical with respect to said axis, the planes of said elements being at an angle with respect to each other.
  • said first and second reflectors build up an aplanatic system.

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  • Aerials With Secondary Devices (AREA)
  • Variable-Direction Aerials And Aerial Arrays (AREA)
US536880A 1965-03-31 1966-03-23 Plural reflector antenna with polarization rotation to minimize feedshadow Expired - Lifetime US3430246A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
FR11338A FR1438482A (fr) 1965-03-31 1965-03-31 Antenne à double réflecteur sans ombre de source

Publications (1)

Publication Number Publication Date
US3430246A true US3430246A (en) 1969-02-25

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Family Applications (1)

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US536880A Expired - Lifetime US3430246A (en) 1965-03-31 1966-03-23 Plural reflector antenna with polarization rotation to minimize feedshadow

Country Status (5)

Country Link
US (1) US3430246A (enrdf_load_stackoverflow)
DE (1) DE1516741A1 (enrdf_load_stackoverflow)
FR (1) FR1438482A (enrdf_load_stackoverflow)
GB (1) GB1123951A (enrdf_load_stackoverflow)
NL (1) NL6604261A (enrdf_load_stackoverflow)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4011525A (en) * 1975-01-21 1977-03-08 Compagnie Generale D'electricite Gas laser generator
US4712111A (en) * 1984-12-26 1987-12-08 Sharp Kabushiki Kaisha Antenna system
US4823143A (en) * 1988-04-22 1989-04-18 Hughes Aircraft Company Intersecting shared aperture antenna reflectors
US20150022391A1 (en) * 2013-07-18 2015-01-22 Rohde & Schwarz Gmbh & Co. Kg System and a method for illumination and imaging of an object

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2736895A (en) * 1951-02-16 1956-02-28 Elliott Brothers London Ltd High frequency radio aerials

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2736895A (en) * 1951-02-16 1956-02-28 Elliott Brothers London Ltd High frequency radio aerials

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4011525A (en) * 1975-01-21 1977-03-08 Compagnie Generale D'electricite Gas laser generator
US4712111A (en) * 1984-12-26 1987-12-08 Sharp Kabushiki Kaisha Antenna system
US4823143A (en) * 1988-04-22 1989-04-18 Hughes Aircraft Company Intersecting shared aperture antenna reflectors
US20150022391A1 (en) * 2013-07-18 2015-01-22 Rohde & Schwarz Gmbh & Co. Kg System and a method for illumination and imaging of an object
US9658320B2 (en) * 2013-07-18 2017-05-23 Rohde & Schwarz Gmbh & Co. Kg System and a method for illumination and imaging of an object

Also Published As

Publication number Publication date
DE1516741A1 (de) 1969-06-26
GB1123951A (en) 1968-08-14
FR1438482A (fr) 1966-05-13
NL6604261A (enrdf_load_stackoverflow) 1966-10-03

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