US3500420A - Reflector for circularly polarized waves - Google Patents

Reflector for circularly polarized waves Download PDF

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Publication number
US3500420A
US3500420A US690920A US3500420DA US3500420A US 3500420 A US3500420 A US 3500420A US 690920 A US690920 A US 690920A US 3500420D A US3500420D A US 3500420DA US 3500420 A US3500420 A US 3500420A
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United States
Prior art keywords
reflector
circularly polarized
polarized waves
length
waves
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Expired - Lifetime
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US690920A
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English (en)
Inventor
Robert Pierrot
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Thales SA
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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
    • 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 reflector element for circularly polarized waves comprising a conductor, the length of which is equal to where )t is the Operating wavelength and N is an integer.
  • the conductor comprises a linear intermediate section parallel to the Wave propagation direction, of length equal to h A V 1 where n is an integer smaller than N, and two linear end sections of equal lengths, each section being perpendicular to the other two.
  • the present invention relates to semi-transparent electromagnetic systems.
  • it relates to elements which are resonant when they are excited by a wave having a circular polarization of a given direction, and are not resonant with a wave having a circular polarization of the opposite direction.
  • the invention also relates to reflecting systems comprising such reflectors, such as, for example, systems of the so-called Cassegrain type, aplanatic systems, reflecting systems without source shadow, and more generally systems based on the use of at least one semi-transparent reflector.
  • a reflector element for waves propagating along a given path with a circular polarization, the electric field vector of which rotates in a predetermined direction, said element being conductive and compromising an intermediate linear section, and two linear end sections, each section being perpendicular to both others, said intermediate section being parallel to said path, the total developed length of the element being equal to where N is an integer and A is the operating wavelength, the length of the intermediate section being equal to A A fi e where n is an integer smaller than N, and the two end sections having equal lengths.
  • FIG. 1 shows a resonant element according to the invention
  • FIGS. 2, 3, 4 and 5 are explanatory diagrams
  • FIG. 6 is a basic diagram of a reflector system according to the invention.
  • FIG. 7 is an example of an application of a reflector according to the invention.
  • a Wave linearly polarized parallel to a conducting wire, induces a current in this wire.
  • the wire excited in this way starts to resonate if its length is a multiple of M2, and behaves like a reflector relative to the wave.
  • the wire is perpendicular to the direction of polarization of the wave, the same is propagated without change, at least theoretically.
  • 'a circularly polarized wave may be regarded as the resultant of two component waves polarized in two mutually perpendicular directions and phase shifted by with respect to each other.
  • the element according to the invention shown in FIG. 1, comprises an intermediate section BC with a length d, parallel to the direction W of propagation of the wave and two end sections AB and CD having the same length, perpendicular to BC and perpendicular to each other.
  • One of the end sections is excited by the component of the electric field parallel thereto and the other by the other component.
  • the total length L of the element A B- C D must of course to a multiple N of M2 in order to be able to enter into resonance with the wavelength A, i.e.,
  • the current induced in the arm CD has the direction shown in FIG. 1, or the opposite direction for a right-hand circular polarization.
  • the choice of It depends substantially on the wavelength: the dimensions of the element must be both sufficiently small for the reflector according to the invention, shown in FIG. 6 and formed by a panel of elements of FIG. 1, not to be of prohibitive dimensions, and sufliciently large to permit easy manufacture at acceptable cost.
  • the spacings rs, and e between two consecutive ele ments, connected, respectively, to the first and last sections, must be small compared with the wavelength. Since they are, on the other hand, limited towards the smaller size by the length l of the end sections, it is preferably to give these elements minimum dimensions, i.e.,
  • the wire diameter will be small compared with the wavelength (of the order of The panel shown in FIG. 6 has the form of a parallelepiped. In practice, it can have any shape, provided that the radii of curvature are large compared with the dimensions of one single element.
  • FIG. 7 shows the diagram of an antenna with two reflectors operating with circular polarization according to the invention.
  • the primary source S radiates circularly polarized waves, for example, right hand polarized waves.
  • the front reflector R is formed by a semi-transparent panel according to the invention, transparent for waves with left-hand circular polarization and reflecting with regard to the waves with right-hand circular polarization.
  • the waves reflected by R without change in the direction of polarization are then reflected by the metal panel R with reversal of the direction of polarization, and pass then through the first reflector.
  • the use of the element and of the reflector is not limited to the application thereof given above.
  • the reflector according to the invention may be used equally well in systems with two reflectors, for example, of the type without source shadow and/or aplanatic reflectors described in the U.S. patent application, Ser. No. 536,880, filed Mar. 23, 1966, entitled Plural Reflector Antenna With Polarization Rotation to Minimize Feed Shadow, now Patent No. 3,430,246.
  • a semi-transparent reflector for circularly polarized waves comprising an array of identical reflector elements according to claim 1.
  • a reflector antenna system for circularly polarized waves comprising a radiating source for radiating, along a given path, waves with a predetermined type of circular polarization, a first reflector according to claim 2, positioned on said path, the elements of said reflector being reflective for said predetermined polarization, and a second reflector for reversing the sense of rotation of the field vector of circularly polarized waves incident thereon.

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  • Aerials With Secondary Devices (AREA)
US690920A 1966-12-30 1967-12-15 Reflector for circularly polarized waves Expired - Lifetime US3500420A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
FR89609A FR1512598A (fr) 1966-12-30 1966-12-30 éléments résonnants en polarisation circulaire et réflecteur semi-transparent composé de ces éléments

Publications (1)

Publication Number Publication Date
US3500420A true US3500420A (en) 1970-03-10

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US690920A Expired - Lifetime US3500420A (en) 1966-12-30 1967-12-15 Reflector for circularly polarized waves

Country Status (5)

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US (1) US3500420A (fr)
CH (1) CH510940A (fr)
FR (1) FR1512598A (fr)
GB (1) GB1167598A (fr)
SE (1) SE332019B (fr)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1992009118A1 (fr) * 1990-11-15 1992-05-29 Alenia - Aeritalia & Selenia S.P.A. Discriminateur de polarisation pour ondes electromagnetiques avec polarisation circulaire et surfaces dichroiques, et une multiplicite de tels discriminateurs
US9391374B2 (en) 2012-07-09 2016-07-12 Jasmin ROY Reciprocal circular polarization selective surfaces and elements thereof
US10224637B2 (en) 2012-07-09 2019-03-05 Jasmin ROY Reciprocal circular polarization selective surfaces and elements thereof

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2192308B (en) * 1977-12-16 1988-09-01 Elliott Bros Improvements in or relating to the reflectivity of metallic bodies
GB2192309B (en) * 1977-12-16 1988-05-25 Elliott Bros Energy reflectors

Citations (2)

* 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
US2867801A (en) * 1953-09-14 1959-01-06 Elliott Brothers London Ltd High frequency radio aerials

Patent Citations (2)

* 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
US2867801A (en) * 1953-09-14 1959-01-06 Elliott Brothers London Ltd High frequency radio aerials

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1992009118A1 (fr) * 1990-11-15 1992-05-29 Alenia - Aeritalia & Selenia S.P.A. Discriminateur de polarisation pour ondes electromagnetiques avec polarisation circulaire et surfaces dichroiques, et une multiplicite de tels discriminateurs
US9391374B2 (en) 2012-07-09 2016-07-12 Jasmin ROY Reciprocal circular polarization selective surfaces and elements thereof
US10224637B2 (en) 2012-07-09 2019-03-05 Jasmin ROY Reciprocal circular polarization selective surfaces and elements thereof

Also Published As

Publication number Publication date
FR1512598A (fr) 1968-02-09
SE332019B (fr) 1971-01-25
CH510940A (fr) 1971-07-31
GB1167598A (en) 1969-10-15

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