US3828352A - Antenna system employing toroidal reflectors - Google Patents

Antenna system employing toroidal reflectors Download PDF

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Publication number
US3828352A
US3828352A US00277670A US27767072A US3828352A US 3828352 A US3828352 A US 3828352A US 00277670 A US00277670 A US 00277670A US 27767072 A US27767072 A US 27767072A US 3828352 A US3828352 A US 3828352A
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reflector
axis
rotation
reflectors
generatrix
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S Drabowitch
B Daveau
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Thales SA
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Thomson CSF 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

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  • I ABSTRACT A microwave antenna consists of two toroidal reflectors turning their concave sides toward a common axis of rotation, i.e., a main reflector farther from that axis and an ancillary reflector closer thereto.
  • the main reflector has a parabolic generatrix with a focal point situated on a point between the axis and the vertex of the ancillary reflector in a common equatorial plane of the two reflectors; the ancillary reflectorhas a hyperbolic generatrix whose foci substantially coincide with the focal point and with the vertex of the para- 3 Claims, 7 Drawing Figures ANTENNA SYSTEM EMPLOYING TOROIDAL REFLECTORS BACKGROUND OF THE INVENTION
  • the present invention relates to improvements in microwave antennas and more particularly to antennas including a toroidal reflector, with a view to reducing some aberration.
  • Antennas with toroidal reflectors whose surface is generated by a curve known as a generatrix, situated in a plane rotating about a straight line contained within this plane, are known and possess certain important and interesting properties which have been put to good use in certain constructions.
  • the surface is a torus in the strict sense of the term. If the center of the circle is a point on the straight line taken as the axis of revolution, the torus is a sphere.
  • a spherical reflector The properties of a spherical reflector are known and are recalled in what follows. Whatever the angle of incidence of a plane wave may be, it is focused, at least approximately, near a point situated on the straight line parallel to the direction of incidence and passing through the center of the sphere, half way between this center and the point atwhich that line intersects the sphere. The locus of the focal points is therefore a sphere of radius approximately half the radius of the sphere forming the reflector.
  • Such a reflector allows an aerial to be constructed with multiple beams or with a beam scanning a very large angle in all spatial directions.
  • a reflector of suf ficiently large radius for the sphere has been used, in a first approximation, equivalent to a paraboloid.
  • a second means of compensating for spherical aberration has been to operate directly on the primary sources or to provide correcting lenses.
  • a third means is to alter the surface of a paraboloid by deforming it in steps approaching the shape of a sphere. In this case the spherical aberration is reduced.
  • a transverse cross-section of the reflector thus obtained shows a staircase profile with steps of the order of half the operating wavelength.
  • a reflector of this type introduces diffraction on the steps and the bandwidth is relatively small.
  • the generatrix is a parabolic arc rotating around an axis parallel to the directrix of the parabola, a parabolic torus is obtained.
  • the reflector should be so designed that the geometric focus of the parabolic arc coincides with the optimum point of focus, i.e., the center of the straightline segment joining the center of the torus to the apex of the parabolic arc.
  • the locus of the primary sources to be considered is then a circle of radius equal to half the length of that line segment situated in a plane perpendicular to the axis and passing through the center of the torus. In this case focusing is improved in every plane containing the axis of revolution of the toroidal reflector and the direction of incidence. Nevertheless,
  • this toroidal reflector with parabolic generatrix always shows a certain spherical aberration.
  • Another drawback of toroidal reflectors is the poor accessibility of the primary sources, especially if the assembly'is of large size.
  • the installation of the sources also brings with it certain drawbacks. For example, in an installation situated on the surface of a planet, if the directions of incidence are situated above the horizon, the primary sources are necessarily oriented below the horizon and are exposed to the risk of receiving, on account of the overspill effect, the planetary thermal noise coming from directions outside the periphery of the reflector.
  • the object of our present invention is to remedy the defects which have been cited.
  • An antenna structure comprises a first and a second toroidal reflector centered on a common axis of rotation, each reflector having a surface which isconcave toward that common axis and has a vertex located in a common equatorial plane perpendicular thereto.
  • the surface of each reflector has a generatrix which is substantially in the form of a segment of a conic section having a focal point located, within the equatorial plane, between its vertex and the axis.
  • the two generatrices have a common focal point lying between the axis and the vertex of the smaller, ancillary reflector disposed closer to that axis.
  • the generatrix of the other, main reflector preferably has a parabolic curvature whereas the generatrix of the ancillary reflector is hyberbolically curved, the second focus of the hyperbola substantially coinciding with the vertex of the parabola.
  • FIG. 1 represents an antenna structure according to the invention
  • FIG. 2 represents a section through the structure of FIG. 1, in the equatorial plane
  • FIG. 3 represents a section through the structure of FIG. 1 in the equatorial plane in the case of a beam divergent from the axis of that structure;
  • FIG. 4 represents a structure according to the inven tion in a system with three-dimensional axes
  • FIG. 5 represents a structure according to the invention with a mobile exploratory beam
  • FIGS. 6 and 7 represent illumination patterns in elevation and azimuth obtained with an aerial according to the invention.
  • the object of the invention is to establish a class of antennas operating at microwave frequencies which possess the advantages inherent in toroidal reflectors and avoid their disadvantages, in particular spherical aberration which ought to be reduced as far as possible.
  • twin-reflector antennas which may be described as conventional are different from that conforming to our invention.
  • a conventional twinreflector antenna is produced by the rotation of two coaxial curves around their common axis and not around an axis perpendicular to this common axis.
  • FIG. 1 shows the structure of a system of reflectors according to the invention.
  • the two curves 1, 2 perform the role of generatrices for the system obtained by rotating the two curves around a straight line 4 which is situated in their common plane and perpendicular to their common axis 3. It is worth noting that the axis of revolution 4 lies on the concave side of these curves.
  • curves 1, 2 By rotating around the axis 4, curves 1, 2 generate two coaxial toroidal surfaces SH and ST2.
  • Surface STl forms what may be termed the outside or main reflector and surface ST2 defines the inside or auxiliary reflector.
  • the generatrices 1 and 2 have curvatures compatible with the desired properties as regards the focusing in any plane passing through the axis of revolution of the system.
  • curves are conic sections each having a focal point, namely to point F, located before the axis of revolution 4 and the corresponding vertex S, S, in a common equatorial plane of surfaces ST, and ST
  • the curve 1 may be a parabolic arc and the curve 2 a hyperbolic arc.
  • the focus F of the parabola 1 coincides approximately with one of the foci of the hyperbola 2, while the other focus F 1 of the hyperbola is near the apex S of the parabolic arc.
  • the primary source is situated at this focus P, which in practice merges with the apex S of the parabola.
  • FIG. 2 shows a section through the structure of FIG. 1 in the equatorial plane, i.e., the plane orthogonally intersecting the axis of rotation 4 of the system and containing the common axis 3 of the reflectors.
  • the beams emitted from the point S or impinging thereon diverge sufficiently from the axis for the Gauss approximation to be no longer valid, it may be advantageous to slightly modify the ratio of the two reflectors r/R if it is desired that the aberrations be kept at an acceptable minimum level for a given aperture (scanning angle) of the system.
  • FIG. 3 shows a plot of the aberrations in the equatorial plane.
  • an axis S-X passes perpendicularly to the axis S-P through the apex S, and the projection of the point P of the main reflector on this axis S-X is designated T.
  • T the projection of the point P of the main reflector on this axis S-X.
  • the line P-V is no longer parallel to the horizontal axis but diverges from it by an angle equal to 2s-t and the extension of line 0-? intersects the axis S-X at point Q.
  • An aberration parameter D is then given by:
  • D is a fourth order function of s if r 2/3 R, in which case D 2/5 R s.
  • SQ ST 2 Rs X from which D (5/32) (XIR)
  • twin-reflector system enables, in comparison with a single reflector of the same size, the phase error to be reduced by a considerable proportion.
  • this proportion has been found to be of the order of 1.6.
  • FIG. 4 shows the system which makes this study possible. However, the detailed calculations will not be made here.
  • the calculation of the pathlength difference D (SM MP PT) 2 (SS1) requires that the hyperbolic meridian d and the parabolic meridian d be determined to calculate the coordinates of the various points M, M P.
  • phase-error as a function of t and s may be stated as E (t,s) [360 D (t,s)/)t] in degrees where A is the operating wavelength and D('t,s) is the difference in path length as a functionof the angles s and t.
  • the class of antennas according to the invention offers a certain number of advantages derived both from the properties of antennas with toroidal reflectors and from antennas with twin reflectors.
  • the primary sources become accessible, being situated behind the main reflector, and they are directed towards the sky, which shields them from the disturbances of terrestral radiation.
  • an antenna has been produced capable of exploring in a given azimuth an area of space included within a considerable angle of elevation, of the order of 40.
  • the sweep is carried out by means of a mobile beam whose angular width corresponds to a radiation aperture of the order of 30 m and whosewavelength is 30 cm (1,000 Mhz).
  • the antenna is formed by two coaxial toroidal reflectors, i.e., a main reflector 5 and an auxiliary reflector 6 (FIG. 5).
  • the primary source is situated in the vertical plane of symmetry of the system, near the main reflector 5.
  • FIG. 5 shows in schematic fashion such an antenna system with two extreme positions 7 and 8 of the primary source and the directions of the beams in these cases.
  • the polar diagrams (illumination laws) may be plotted according to the main elevation and azimuth diagrams.
  • FIG. 6 gives the illumination pattern in elevation
  • FIG. 7 gives the illumination pattern in azimuth from which it will be noticed that there is a masking efiect due to the auxiliary reflector; this effect does not exist in elevation, where it would be a good deal more inconvenient.
  • An antenna structure for the focusing of microwaves comprising a first toroidal reflector and a second toroidal reflector centered on a common axis of rotation, each of said reflectors having a surface which is concave toward said axis of rotation and has a generatrix substantially in the form of a segment of a conic section having a focal point located between said axis of rotation and a vertex of the respective surface in a common equatorial plane of said reflectors perpendicular to said axis of rotation; said second reflector lying between said axis of rotation and said first reflector, the generatrix of said first reflector being a segment of a parabola, the generatrix of said second reflector being a segment of a hyperbola having a focus substantially coinciding with the vertex of said parabola, said parabola and hyperbola having a common focal point between said second reflector and said axis of rotation.
  • An antenna structure for the focusing of microwaves comprising a first toroidal reflector and a second toroidal reflector centered on a common axis of rotation, each of said reflectors having a surface which is concave toward said axis of rotation and has a generatrix substantially in the form of a segment of a conic section having a focal point located between said axis of rotation and a vertex of the respective surface in a common equatorial plane of said reflectors perpendicular to said axis of rotation; the surface of said first reflector following a great circle of radius R in said equatorial plane and the surface of said second reflector following a great circle of radius r in said equatorial plane, said radii substantially satisfying the relationship r 2R/3.

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US00277670A 1971-08-09 1972-08-03 Antenna system employing toroidal reflectors Expired - Lifetime US3828352A (en)

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Cited By (22)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3922682A (en) * 1974-05-31 1975-11-25 Communications Satellite Corp Aberration correcting subreflectors for toroidal reflector antennas
US3995275A (en) * 1973-07-12 1976-11-30 Mitsubishi Denki Kabushiki Kaisha Reflector antenna having main and subreflector of diverse curvature
US4145695A (en) * 1977-03-01 1979-03-20 Bell Telephone Laboratories, Incorporated Launcher reflectors for correcting for astigmatism in off-axis fed reflector antennas
US4339757A (en) * 1980-11-24 1982-07-13 Bell Telephone Laboratories, Incorporated Broadband astigmatic feed arrangement for an antenna
US4343004A (en) * 1980-11-24 1982-08-03 Bell Telephone Laboratories, Incorporated Broadband astigmatic feed arrangement for an antenna
US4482898A (en) * 1982-10-12 1984-11-13 At&T Bell Laboratories Antenna feed arrangement for correcting for astigmatism
US4491848A (en) * 1982-08-30 1985-01-01 At&T Bell Laboratories Substantially frequency-independent aberration correcting antenna arrangement
US4535338A (en) * 1982-05-10 1985-08-13 At&T Bell Laboratories Multibeam antenna arrangement
US4631545A (en) * 1984-11-16 1986-12-23 At&T Bell Laboratories Antenna arrangement capable of astigmatism correction
WO2002005385A1 (en) * 2000-07-10 2002-01-17 Wavefrontier Co., Ltd Reflector antenna
US6703980B2 (en) 2000-07-28 2004-03-09 Thales Active dual-polarization microwave reflector, in particular for electronically scanning antenna
RU2598401C1 (ru) * 2015-04-22 2016-09-27 Федеральное Государственное Унитарное Предприятие Ордена Трудового Красного Знамени Научно-Исследовательский Институт Радио (Фгуп Ниир) Многолучевая двухзеркальная антенна со смещенной фокальной осью
US20170025736A1 (en) * 2011-12-05 2017-01-26 CLARKE William McALLISTER Aerial inventory antenna
RU2620875C1 (ru) * 2016-07-15 2017-05-30 Федеральное Государственное Унитарное Предприятие Ордена Трудового Красного Знамени Научно-Исследовательский Институт Радио (Фгуп Ниир) Многолучевая диапазонная зеркальная антенна
RU2629906C1 (ru) * 2016-11-09 2017-09-04 Самсунг Электроникс Ко., Лтд. Зеркальная антенна с двойной поляризацией и широким углом сканирования
RU2664792C1 (ru) * 2017-11-20 2018-08-22 Федеральное государственное унитарное предприятие Ордена Трудового Красного Знамени научно-исследовательский институт радио Многолучевая комбинированная неосесимметричная зеркальная антенна
RU2664751C1 (ru) * 2017-12-06 2018-08-22 Анатолий Михайлович Сомов Многолучевая диапазонная двухзеркальная антенна с вынесенным облучением
RU2664753C1 (ru) * 2017-12-06 2018-08-22 Анатолий Михайлович Сомов Многофокусная офсетная зеркальная антенна
RU2664870C1 (ru) * 2017-11-20 2018-08-23 Федеральное государственное унитарное предприятие Ордена Трудового Красного Знамени научно-исследовательский институт радио Ненаклонная многолучевая диапазонная двухзеркальная антенна
RU2665747C1 (ru) * 2017-12-06 2018-09-04 Анатолий Михайлович Сомов Офсетная тороидально-параболическая зеркальная антенна (варианты)
RU2673436C1 (ru) * 2017-11-20 2018-11-26 Федеральное государственное унитарное предприятие Ордена Трудового Красного Знамени научно-исследовательский институт радио Ненаклонная многолучевая двухзеркальная антенна вынесенного излучения
RU2776722C1 (ru) * 2021-06-29 2022-07-26 Федеральное государственное казенное образовательное учреждение высшего образования "Академия Федеральной службы безопасности Российской Федерации" (Академия ФСБ России) Осесимметричная многодиапазонная многолучевая многозеркальная антенна

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3317912A (en) * 1963-07-29 1967-05-02 Kenneth S Kelleher Plural concentric parabolic antenna for omnidirectional coverage
US3406401A (en) * 1966-08-25 1968-10-15 Bell Telephone Labor Inc Communication satellite system
US3414904A (en) * 1966-05-16 1968-12-03 Hughes Aircraft Co Multiple reflector antenna

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR1392013A (fr) * 1964-01-31 1965-03-12 Nouveaux aériens pour micro-ondes

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3317912A (en) * 1963-07-29 1967-05-02 Kenneth S Kelleher Plural concentric parabolic antenna for omnidirectional coverage
US3414904A (en) * 1966-05-16 1968-12-03 Hughes Aircraft Co Multiple reflector antenna
US3406401A (en) * 1966-08-25 1968-10-15 Bell Telephone Labor Inc Communication satellite system

Cited By (24)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3995275A (en) * 1973-07-12 1976-11-30 Mitsubishi Denki Kabushiki Kaisha Reflector antenna having main and subreflector of diverse curvature
US3922682A (en) * 1974-05-31 1975-11-25 Communications Satellite Corp Aberration correcting subreflectors for toroidal reflector antennas
US4145695A (en) * 1977-03-01 1979-03-20 Bell Telephone Laboratories, Incorporated Launcher reflectors for correcting for astigmatism in off-axis fed reflector antennas
US4339757A (en) * 1980-11-24 1982-07-13 Bell Telephone Laboratories, Incorporated Broadband astigmatic feed arrangement for an antenna
US4343004A (en) * 1980-11-24 1982-08-03 Bell Telephone Laboratories, Incorporated Broadband astigmatic feed arrangement for an antenna
US4535338A (en) * 1982-05-10 1985-08-13 At&T Bell Laboratories Multibeam antenna arrangement
US4491848A (en) * 1982-08-30 1985-01-01 At&T Bell Laboratories Substantially frequency-independent aberration correcting antenna arrangement
US4482898A (en) * 1982-10-12 1984-11-13 At&T Bell Laboratories Antenna feed arrangement for correcting for astigmatism
US4631545A (en) * 1984-11-16 1986-12-23 At&T Bell Laboratories Antenna arrangement capable of astigmatism correction
WO2002005385A1 (en) * 2000-07-10 2002-01-17 Wavefrontier Co., Ltd Reflector antenna
US6703980B2 (en) 2000-07-28 2004-03-09 Thales Active dual-polarization microwave reflector, in particular for electronically scanning antenna
US20170025736A1 (en) * 2011-12-05 2017-01-26 CLARKE William McALLISTER Aerial inventory antenna
US9780435B2 (en) * 2011-12-05 2017-10-03 Adasa Inc. Aerial inventory antenna
RU2598401C1 (ru) * 2015-04-22 2016-09-27 Федеральное Государственное Унитарное Предприятие Ордена Трудового Красного Знамени Научно-Исследовательский Институт Радио (Фгуп Ниир) Многолучевая двухзеркальная антенна со смещенной фокальной осью
RU2620875C1 (ru) * 2016-07-15 2017-05-30 Федеральное Государственное Унитарное Предприятие Ордена Трудового Красного Знамени Научно-Исследовательский Институт Радио (Фгуп Ниир) Многолучевая диапазонная зеркальная антенна
RU2629906C1 (ru) * 2016-11-09 2017-09-04 Самсунг Электроникс Ко., Лтд. Зеркальная антенна с двойной поляризацией и широким углом сканирования
RU2664792C1 (ru) * 2017-11-20 2018-08-22 Федеральное государственное унитарное предприятие Ордена Трудового Красного Знамени научно-исследовательский институт радио Многолучевая комбинированная неосесимметричная зеркальная антенна
RU2664870C1 (ru) * 2017-11-20 2018-08-23 Федеральное государственное унитарное предприятие Ордена Трудового Красного Знамени научно-исследовательский институт радио Ненаклонная многолучевая диапазонная двухзеркальная антенна
RU2673436C1 (ru) * 2017-11-20 2018-11-26 Федеральное государственное унитарное предприятие Ордена Трудового Красного Знамени научно-исследовательский институт радио Ненаклонная многолучевая двухзеркальная антенна вынесенного излучения
RU2664751C1 (ru) * 2017-12-06 2018-08-22 Анатолий Михайлович Сомов Многолучевая диапазонная двухзеркальная антенна с вынесенным облучением
RU2664753C1 (ru) * 2017-12-06 2018-08-22 Анатолий Михайлович Сомов Многофокусная офсетная зеркальная антенна
RU2665747C1 (ru) * 2017-12-06 2018-09-04 Анатолий Михайлович Сомов Офсетная тороидально-параболическая зеркальная антенна (варианты)
RU2776722C1 (ru) * 2021-06-29 2022-07-26 Федеральное государственное казенное образовательное учреждение высшего образования "Академия Федеральной службы безопасности Российской Федерации" (Академия ФСБ России) Осесимметричная многодиапазонная многолучевая многозеркальная антенна
RU2776725C1 (ru) * 2021-06-29 2022-07-26 Федеральное государственное казенное образовательное учреждение высшего образования "Академия Федеральной службы безопасности Российской Федерации" (Академия ФСБ России) Многолучевая многодиапазонная многозеркальная антенна

Also Published As

Publication number Publication date
DE2239228C3 (de) 1983-12-01
DE2239228B2 (de) 1980-04-24
SE377633B (ja) 1975-07-14
DE2239228A1 (de) 1973-03-01
FR2148341A1 (ja) 1973-03-23
FR2148341B1 (ja) 1977-01-28

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