US3797020A - Microwave antenna structure with aperture blocking elimination - Google Patents

Microwave antenna structure with aperture blocking elimination Download PDF

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Publication number
US3797020A
US3797020A US00286407A US3797020DA US3797020A US 3797020 A US3797020 A US 3797020A US 00286407 A US00286407 A US 00286407A US 3797020D A US3797020D A US 3797020DA US 3797020 A US3797020 A US 3797020A
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Prior art keywords
reflector
polarization
plane
antenna structure
array
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Expired - Lifetime
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US00286407A
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English (en)
Inventor
J Roger
C Aubry
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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
    • H01Q25/00—Antennas or antenna systems providing at least two radiating patterns
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q15/00—Devices for reflection, refraction, diffraction or polarisation of waves radiated from an antenna, e.g. quasi-optical devices
    • H01Q15/14—Reflecting surfaces; Equivalent structures
    • H01Q15/22—Reflecting surfaces; Equivalent structures functioning also as polarisation filter
    • 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

  • the wire network discriminates between waves polarized in two mutually orthogonal planes, passing one type of wave and reflecting the other.
  • Each curved reflector is provided with means for rotating the plane of polarization of an incident wave through upon reflection.
  • the reflectors form a focusing system with a focal plane containing one or more transducers for emitting or receiving radiation of a polarization passing the discriminator before striking the first reflector whence they are directed, via the reflecting discriminator, to the second reflector; upon leaving the latter reflector, they have a direction of polarization enabling them to clear the discriminator once more.
  • the present invention relates to a microwave antenna structure and refers more particularly to the production of a multi-beam aplanatic antenna.
  • the focusing system use should satisfy conditions of aplanatism, i. e. that a slight displacement of the primary source or sources from the focus of the system does not bring about a deterioration in the parallelism of the rays transmitted by the system. Such a deterioration would result in an enlargement of the main lobe and the appearance of aberration secondary or side lobes.
  • a multi-beam, aplanatic antenna the so-called Schwarzschild antenna
  • Schwarzschild antenna which is derived from the so-called Cassegrain antenna and is formed by two surface revolution reflectors, namely a main reflector and an auxiliary reflector or subreflector having the same axis and meridians precisely determined so that the assembly is aplanatic.
  • the Schwarzschild antenna is unsuitable for the purpose of the present invention.
  • this antenna has a masking or aperture blocking effect due to the fact that the sources are generally situated near the main reflector and also to the presence of the subreflector in front of the main reflector. This masking effect tends to increase the level of the side lobes.
  • the object of the invention is to overcome the drawbacks which have been pointed out and to provide a twin-reflector antenna of the multi-beam type which is aplanatic and causes no aperture blocking.
  • a microwave antenna embodying our invention comprises two conjugate reflectors whose meridians are such that they fulfill the condition of aplanatism and whose axes of symmetry intersect; between the sources and the focusing system formed by the two reflectors there is interposed a member which discriminates between differently polarized electromagnetic waves, passing waves polarized in one plane and reflecting those polarized in another plane.
  • FIG. 1 shows a so-called Schwarzschild antenna according to the prior art
  • FIG. 2 shows an antenna according to the invention
  • FIG. 3 is view of the system of FIG. 2, showing the construction of the beams traversing the focusing system
  • FIG. 4 is a radiation diagram obtained with the antenna according to the invention.
  • the so-called Schwarzschild multi-beam, aplanatic antenna is a twin-reflector antenna belonging to the class of twin-reflector antennas of which the best known is the Cassegrain antenna.
  • Such a Cassegrain or Schwarzschild antenna is shown in FIG. 1. It comprises a main reflector l and an auxiliary reflector 2 or subreflector whose axis coincides with the axis of the main reflector.
  • a source 3 is situated at the apex S of the main reflector, this apex generally coinciding with a focus of the subreflector which, in the case of the Cassegrain antenna, is a hyperbolic segment whereas the main reflector is a parabolic segment.
  • These reflectors are so mounted with respect to one another that a beam of parallel rays directed onto the main reflector 1 by an object situated on the axis at infinity is reflected toward the focus F of the main reflector and intercepted by the subreflector 2 which causes it to converge onto the source 3.
  • a beam emitted by primary source 3 toward the subreflector 2 is reflected toward the main reflector l which in turn reflects it in the form of a beam of rays parallel to the axis of the focusing system.
  • the Schwarzschild antenna overcomes this defect of the Cassegrain antenna by utilizing a main reflector and a subreflector whose shape in slightly different from that of the reflectors of the conventional Cassegrain antenna, the meridians of these reflectors being calculated in a manner designed to satisfy the conditions of aplanatism.
  • the Schwarzschild antenna is aplanatic but still has secondary lobes of too high a level for the application envisaged for the present invention.
  • FIG. 2 shows a way of producing an aplanatic antenna, which has a multi-beam pattern with low-level secondary lobes, according to our invention.
  • This antenna comprises two conjugate reflectors, i.e. a main reflector 1 and an auxiliary or subreflector 2 which make up the focusing system of the antenna.
  • the two reflectors have a shape comparable to that of the reflectors in the Schwarzschild antenna.
  • the focusing system is aplanatic.
  • the axes of these reflectors intersect at a point A Figure are mutually perpendicular.
  • a planar member 4 traverses this point and in the Figure lies at 45 with respect to the axes of the reflectors.
  • This member is formed by a network of parallel metal wires. 41 perpendicular to the plane of the two axes. It thus discriminates between differently polarized incident electromagnetic waves, passing those polarized in a plane transverse to its wires and reflecting those polarized in a plane parallel thereto.
  • the feeder 3 comprises three wave transducers 30, 31, 32 located opposite the subreflector in a focal plane of the system 1, 2 so that the waves which they emit or which they receive from an object situated at infinity pass through the polarization discriminator 4.
  • the main and subsidiary reflectors are provided on their active surfaces with respective twist reflectors 11 and 21.
  • Such a twist reflector formed by a network of parallel wires inclined at 45 with respect to the direction of polarization, is placed at a quarter wavelength from the reflecting surface, and is equivalent to a quarterwave plate rotating the plane of polarization of the incident waves by 90.
  • FIG. 2 shows that the aperture blocking due to the sources and the subreflector, which generates side lobes, no longer exists.
  • the antenna system according to the invention is thus indeed aplanatic and its radiation diagram has low-level side lobes.
  • FIG. 4 shows such a diagram for two antennas according to the invention.
  • a beam of rays B-C is emitted by the source with a polarization P parallel to the plane of the Figure.
  • the parallel wires forming the conductor array 4 which allow such a beam to pass are perpendicular to the plane of polarization P.
  • This beam is reflected by the convex side of subreflector 2 at its point of impingement C in the direction C-E.
  • the polarization of the reflected beam is rotated by 90 thus becoming perpendicular to the plane of FIG. 3, as indicated at P and therefore parallel to the direction of the wires 41 of the planar network 4.
  • Beam F-G is of telecentric character, i.e. it consists of parallel rays converging at infinity.
  • Another beam HIJKL emitted from source 32 follows a similar path and is reflected at K in direction K-L.
  • An antenna structure comprising:
  • first and second reflectors conjugate first and second reflectors with intersecting axes defining a focal plane for a beam of microwave frequency passing between a remote point and said first reflector, the point of intersection of said axes lying between said focal plane and said second reflector;
  • transducer means for microwave energy at said focal plane
  • each of said reflectors being provided with polarization-changing means for directing a beam with a polarization passed by said discriminating means, incident upon one of said reflectors, back to said discriminating means for reflection onto the other of said reflectors whence the beam is redirected to said discriminating means with a polarization enabling its passage therethrough.
  • transducer means comprises an emitter of microwaves with a plane of polarization perpendicular to said conductors.
  • An antenna structure comprising:
  • transducer means for emitting and receiving beams of microwave energy with a predetermined plane of polarization
  • a first and a second reflector for microwave energy having mutually orthogonal axes intersecting at an intermediate point of said array, the latter including an angle of 45 with each of said axes, said second reflector lying in line with said path on the side of said array remote from said transducer means;

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  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Aerials With Secondary Devices (AREA)
US00286407A 1971-09-22 1972-09-05 Microwave antenna structure with aperture blocking elimination Expired - Lifetime US3797020A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
FR7134067A FR2153164B1 (de) 1971-09-22 1971-09-22

Publications (1)

Publication Number Publication Date
US3797020A true US3797020A (en) 1974-03-12

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US00286407A Expired - Lifetime US3797020A (en) 1971-09-22 1972-09-05 Microwave antenna structure with aperture blocking elimination

Country Status (5)

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US (1) US3797020A (de)
DE (1) DE2246650C2 (de)
FR (1) FR2153164B1 (de)
GB (1) GB1385737A (de)
IT (1) IT965409B (de)

Cited By (19)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3914768A (en) * 1974-01-31 1975-10-21 Bell Telephone Labor Inc Multiple-beam Cassegrainian antenna
US3953858A (en) * 1975-05-30 1976-04-27 Bell Telephone Laboratories, Incorporated Multiple beam microwave apparatus
US4259674A (en) * 1979-10-24 1981-03-31 Bell Laboratories Phased array antenna arrangement with filtering to reduce grating lobes
US4335387A (en) * 1979-06-13 1982-06-15 Thomson-Csf Radar antenna with rotating linear polarization designed to reduce jamming
US4504835A (en) * 1982-06-15 1985-03-12 The United States Of America As Represented By The Secretary Of The Navy Low sidelobe, high efficiency mirror antenna with twist reflector
US5049893A (en) * 1989-07-07 1991-09-17 Thomson-Csf Microwave energy distributor capable of radiating directly
US5172128A (en) * 1989-11-24 1992-12-15 Thomson-Csf Antenna with circular polarization, notably for antenna array
US5424748A (en) * 1992-11-06 1995-06-13 Thomson-Csf Radar antenna suitable for designation and trajectography radar
WO1995018980A1 (en) * 1994-01-07 1995-07-13 Millitech Corporation Compact microwave and millimeter wave radar
EP0676825A2 (de) * 1994-04-08 1995-10-11 Siemens Aktiengesellschaft Radarantenne mit zumindest einem Primärstrahler und einem parabolförmigen Reflektor für ein Verkehrs-Radargerät zur Verkehrserfassung
US5650786A (en) * 1994-01-21 1997-07-22 Thomson-Csf Compensation device for aiming errors caused by the malfunctioning of electronic scanning antenna phase-shifters or by the malfunctioning of coefficients of antennas with beam-shaping by computation
US5767805A (en) * 1995-08-29 1998-06-16 Thomson-Csf Method for the broadening of a volume antenna beam
US5774090A (en) * 1994-09-23 1998-06-30 Thomson-Csf Method and device to broaden the radiation pattern of an active antenna
US6014108A (en) * 1998-04-09 2000-01-11 Hughes Electronics Corporation Transverse-folded scanning antennas
US6147643A (en) * 1998-02-24 2000-11-14 Thomson-Csf Method to determine the error of orientational adjustment of the radiating face of an electronic scanning array antenna
US6225964B1 (en) * 1999-06-09 2001-05-01 Hughes Electronics Corporation Dual gridded reflector antenna system
EP2854221A4 (de) * 2012-03-26 2016-01-13 Telefrontier Co Ltd Antenne mit zwei kompakten asymmetrischen reflektionsplatten
US20200067196A1 (en) * 2015-07-02 2020-02-27 Sea Tel, Inc. (Dba Cobham Satcom) Multiple-Feed Antenna System Having Multi-Position Subreflector Assembly
US20230282987A1 (en) * 2020-08-10 2023-09-07 Lockeed Martin Corporation Multisegment reflector antenna directing beams

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0170726A1 (de) * 1984-07-13 1986-02-12 Siemens Aktiengesellschaft Zweireflektor-Richtantenne

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR1396404A (fr) * 1964-03-09 1965-04-23 Csf Nouveau système de changement de fréquence pour récepteur à voies multiples
FR1508062A (fr) * 1965-04-12 1968-01-05 Csf Antennes aplanétiques

Cited By (25)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3914768A (en) * 1974-01-31 1975-10-21 Bell Telephone Labor Inc Multiple-beam Cassegrainian antenna
US3953858A (en) * 1975-05-30 1976-04-27 Bell Telephone Laboratories, Incorporated Multiple beam microwave apparatus
US4335387A (en) * 1979-06-13 1982-06-15 Thomson-Csf Radar antenna with rotating linear polarization designed to reduce jamming
US4259674A (en) * 1979-10-24 1981-03-31 Bell Laboratories Phased array antenna arrangement with filtering to reduce grating lobes
US4504835A (en) * 1982-06-15 1985-03-12 The United States Of America As Represented By The Secretary Of The Navy Low sidelobe, high efficiency mirror antenna with twist reflector
US5049893A (en) * 1989-07-07 1991-09-17 Thomson-Csf Microwave energy distributor capable of radiating directly
US5172128A (en) * 1989-11-24 1992-12-15 Thomson-Csf Antenna with circular polarization, notably for antenna array
US5424748A (en) * 1992-11-06 1995-06-13 Thomson-Csf Radar antenna suitable for designation and trajectography radar
WO1995018980A1 (en) * 1994-01-07 1995-07-13 Millitech Corporation Compact microwave and millimeter wave radar
US5455589A (en) * 1994-01-07 1995-10-03 Millitech Corporation Compact microwave and millimeter wave radar
US5680139A (en) * 1994-01-07 1997-10-21 Millitech Corporation Compact microwave and millimeter wave radar
US5650786A (en) * 1994-01-21 1997-07-22 Thomson-Csf Compensation device for aiming errors caused by the malfunctioning of electronic scanning antenna phase-shifters or by the malfunctioning of coefficients of antennas with beam-shaping by computation
EP0676825A3 (de) * 1994-04-08 1996-11-27 Siemens Ag Radarantenne mit zumindest einem Primärstrahler und einem parabolförmigen Reflektor für ein Verkehrs-Radargerät zur Verkehrserfassung.
EP0676825A2 (de) * 1994-04-08 1995-10-11 Siemens Aktiengesellschaft Radarantenne mit zumindest einem Primärstrahler und einem parabolförmigen Reflektor für ein Verkehrs-Radargerät zur Verkehrserfassung
US5774090A (en) * 1994-09-23 1998-06-30 Thomson-Csf Method and device to broaden the radiation pattern of an active antenna
US5767805A (en) * 1995-08-29 1998-06-16 Thomson-Csf Method for the broadening of a volume antenna beam
US6147643A (en) * 1998-02-24 2000-11-14 Thomson-Csf Method to determine the error of orientational adjustment of the radiating face of an electronic scanning array antenna
US6014108A (en) * 1998-04-09 2000-01-11 Hughes Electronics Corporation Transverse-folded scanning antennas
US6225964B1 (en) * 1999-06-09 2001-05-01 Hughes Electronics Corporation Dual gridded reflector antenna system
EP2854221A4 (de) * 2012-03-26 2016-01-13 Telefrontier Co Ltd Antenne mit zwei kompakten asymmetrischen reflektionsplatten
US20200067196A1 (en) * 2015-07-02 2020-02-27 Sea Tel, Inc. (Dba Cobham Satcom) Multiple-Feed Antenna System Having Multi-Position Subreflector Assembly
US10998637B2 (en) * 2015-07-02 2021-05-04 Sea Tel, Inc. Multiple-feed antenna system having multi-position subreflector assembly
US11699859B2 (en) * 2015-07-02 2023-07-11 Sea Tel, Inc. Multiple-feed antenna system having multi-position subreflector assembly
US20230282987A1 (en) * 2020-08-10 2023-09-07 Lockeed Martin Corporation Multisegment reflector antenna directing beams
US12015202B2 (en) * 2020-08-10 2024-06-18 Lockheed Martin Corporation Multisegment reflector antenna directing beams

Also Published As

Publication number Publication date
IT965409B (it) 1974-01-31
FR2153164A1 (de) 1973-05-04
GB1385737A (en) 1975-02-26
FR2153164B1 (de) 1976-10-29
DE2246650C2 (de) 1982-08-12
DE2246650A1 (de) 1973-03-29

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