EP0014605B1 - Umgekehrte Cassegrain-Antenne für Mehrzweckradar - Google Patents

Umgekehrte Cassegrain-Antenne für Mehrzweckradar Download PDF

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Publication number
EP0014605B1
EP0014605B1 EP80400037A EP80400037A EP0014605B1 EP 0014605 B1 EP0014605 B1 EP 0014605B1 EP 80400037 A EP80400037 A EP 80400037A EP 80400037 A EP80400037 A EP 80400037A EP 0014605 B1 EP0014605 B1 EP 0014605B1
Authority
EP
European Patent Office
Prior art keywords
reflecting
plane
polarization
mirror
elements
Prior art date
Legal status (The legal status 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 status listed.)
Expired
Application number
EP80400037A
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English (en)
French (fr)
Other versions
EP0014605A1 (de
Inventor
Yves Commault
François Gautier
Robert Pierrot
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Thales SA
Original Assignee
Thomson CSF SA
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Filing date
Publication date
Application filed by Thomson CSF SA filed Critical Thomson CSF SA
Publication of EP0014605A1 publication Critical patent/EP0014605A1/de
Application granted granted Critical
Publication of EP0014605B1 publication Critical patent/EP0014605B1/de
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q3/00—Arrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system
    • H01Q3/01—Arrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system varying the shape of the antenna or antenna system
    • 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
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q25/00—Antennas or antenna systems providing at least two radiating patterns
    • H01Q25/002—Antennas or antenna systems providing at least two radiating patterns providing at least two patterns of different beamwidth; Variable beamwidth antennas

Definitions

  • the subject of the present invention is an inverted “Cassegrain” antenna intended to be used in standby or in pursuit and capable of providing an enlarged beam either in the ground view site plan or in the field plan (anti-collision) while retaining the qualities of 'a fine primary beam.
  • the inverted Cassegrain antenna is known and has for example been described in American patent US Pat. No. 3,771,160 which relates to an inverted Cassegrain antenna with polarization rotation.
  • the antenna described in this patent comprises a planar auxiliary reflector constituted by a plurality of arrays of parallel conductive wires and by a metal plate, the plate and the arrays of wires being parallel and separated by a dielectric. It operates at at least two frequencies but cannot be used in combination with a multi-function radar, standby or tracking.
  • the beam emitted by the antenna has a shape adapted, at a given moment, to the function for which it is used. This has already been done on simple antennas, by switching from primary sources or by modifying the shape of the antenna. However, this means of adapting an antenna to the different functions of a radar does not give good results in the case of an inverted “Cassegrain” antenna. In fact, the performance of the Cassegrain antenna is reduced if the primary sources of this antenna are multiplied or if the parabolic reflector is deformed, which makes it necessary to modify the beam focusing device.
  • An advantageous means for producing an inverted Cassegrain antenna, with multiple functions, is to modify the shape of the polarization rotation mirror with which it is provided.
  • an inverted Cassegrain antenna making it possible to widen the beam in a plane during operation, associated with a multi-function radar and comprising a primary source of HF electromagnetic waves with rectilinear polarization, a curved primary reflector having an axis of revolution and intended to reflect the waves coming directly from the primary source and to selectively transmit the electromagnetic waves having a rectilinear crossed polarization, the primary source being disposed substantially at the focus of this primary reflector and a mirror with polarization rotation ensuring the return to the primary reflector of the reflected radiation having undergone a rotation of its plane of polarization, is characterized in that this mirror with polarization rotation is formed of several reflector-polarizing elements planes, articulated with respect to each other by parallel hinges , orthogonal to the desired beam widening plane of the antenna and in that these elements are associated with means for controlling their relative positioning.
  • a reverse Cassegrain antenna comprises, as shown in FIG. 1, a primary source S intended for emitting high frequency electromagnetic waves, a primary parabolic reflector R i , of axis xx of revolution, reflecting the radiation of the primary source S and selectively transmitting radiation having a rectilinear crossed polarization, and an auxiliary reflector R 2 (or mirror) with polarization rotation, of planar shape, the assembly constituting a focusing system.
  • the primary source S has the role, on emission, of illuminating the focusing system with an electromagnetic wave with rectilinear polarization (horizontal polarization for example), radiating a well-defined amplitude, phase and polarization revolution diagram and stable in the frequency band used, and, on reception, to collect in the best conditions, the energy provided by the echo and concentrated by the focusing system in the vicinity of its focus F, in the form of a diffraction diagram .
  • the primary source S (FIG. 1) disposed at the focal point F of the parabolic reflector R i emits radiation with linear (horizontal) polarization which is totally reflected by the parabolic reflector R i , the angle formed by the incident ray with the reflected ray being equal to the angle of the incident ray with the axis xx of the reflector R i .
  • the reflected rays, parallel to the axis xx, are received by the auxiliary reflector R 2 (or mirror), and reflected, after a rotation of ⁇ / 2 of their plane of polarization (the horizontal polarization of the incident wave is transformed in vertical polarization), towards the parabolic reflector R i allowing the radiation having a plane of vertical polarization, the beam from the antenna then being a substantially parallel beam.
  • an inverted Cassegrain antenna comprises, as shown in FIG. 2, a primary source S, a primary parabolic reflector R, reflecting the primary radiation coming from the source S and being able to selectively transmit the radiation having a rectilinear crossed polarization, this source S being substantially disposed at the focal point F of the primary reflector R, a mirror M l with polarization rotation formed of two elements e 1 , e 2 reflector-polarizers of planar shape, joined by a hinge c 1 allowing their articulation.
  • the hinge C 1 is arranged in a direction perpendicular to the beam widening plane, namely in the case of Figure 2 the plane of symmetry of the antenna, coincident with the plane of the figure.
  • These reflector-polarizing elements e 1 , e 2 can be in known manner (FIG. 7), consisting of a metal plate P and a sheet N of parallel wires inclined at 45 ° relative to the direction of the incident rectilinear polarization , this sheet N being placed at k ⁇ / 4 of the plate P, k being an odd integer and ⁇ the operating wavelength of the antenna.
  • an incident wave O 1 with horizontal rectilinear polarization can be considered as the superposition of two component wave equiphase O ' 1 and O'' 1 whose polarization planes are inclined at 45 ° relative to the polarization plane of the 'incident wave O 1 , the first component O' 1 being parallel to the wires of the sheet N and the second component O '' 1 being perpendicular to these wires.
  • the first component O ' 1 is therefore reflected by the wires while the second component 0 ", crosses the sheet N after having traveled a path equal to 2 K ⁇ / 4, that is to say a path equal to k ⁇ / 2.
  • the second reflected 0 " 2 component is therefore depressed by ⁇ with respect to the first reflected 0 ' 2 component and the combination of the two components then creates an O2 wave with vertical polarization which can pass through the parabolic reflector letting the vertically polarized radiation pass and reflecting horizontally polarized radiation. It is also possible to use systems with parallel metal blades also inclined at 45 ° relative to the direction of incident polarization of the radiation to produce these reflector-polarizer elements without departing from the scope of the present invention.
  • This reflector R can consist, for example, of a layer of horizontal wires when the rectilinear polarization of the incident one from the primary source S is horizontal.
  • the mirror M 1 comprises, as shown in FIGS. 2 and 3, a hinge C 1 situated at one third of the diameter of the mirror and perpendicular to the vertical plane of symmetry of the antenna represented by the plane of FIG. 2.
  • a hinge C 1 situated at one third of the diameter of the mirror and perpendicular to the vertical plane of symmetry of the antenna represented by the plane of FIG. 2.
  • D the diameter perpendicular to the hinges
  • D 'the diameter parallel to the hinges we will designate by D the diameter perpendicular to the hinges and by D 'the diameter parallel to the hinges.
  • the element e 2 which is the smallest element, is inclined at an angle a of approximately 7 ° relative to the element e 1 .
  • Such a mirror M 1 allows coverage on site with a decrease in gain substantially obeying a square cosecant law, such that the level at -17 dB is reached at 20 ° from the axis instead of the 5 ° obtained with a beam.
  • conventional end Figure 8
  • the characteristics of the beam are also preserved for any orientation of the mirror M 1 and are not very selective in frequency.
  • the elements e 1 , e 2 of the mirror M 1 can have relative inclinations in one direction or the other.
  • the movement of these elements e 1 , e 2 around the hinge Ci and their immobilization in a determined position are obtained in the antenna according to the invention, by means of a control device 20 intended to be actuated during operation from the radar.
  • the remote control device 20 is shown only, by way of nonlimiting example, in FIG. 2 so as not to overload the drawings and in order to allow a better understanding of the latter.
  • the control device 20 is, for example, constituted by a motor integral with the mirror M 1 , the axis 201 of which is constituted by an endless screw provided with a slider 202 driven by the endless screw 201 in translation ⁇ in the direction of the mirror M 1 in the plane of FIG. 2.
  • the movable cursor 202 is provided with an index 203 movable in a direction y perpendicular to the direction of translation ⁇ of the cursor and driven in this direction by a gear system.
  • the movable index 203 has one of its ends engaged in a slide disposed on the back of the reflecting surface of the polarizing reflective element e 2 .
  • the slide for reasons of simplification, is not shown in FIG. 2.
  • the motor 20 is controlled by control signals at the level of a control input 200.
  • each angular position of the motor shaft corresponds to a value ⁇ , ⁇ representative of an angle a.
  • Any other equivalent control means for the reflective element e 2 does not depart from the scope of the present invention.
  • This mirror M 1 therefore makes it possible to return to the reflector R (FIG. 2) parabolic rays having different angles of reflection depending on the element e 1 or e 2 towards which they fall.
  • R parabolic rays having different angles of reflection depending on the element e 1 or e 2 towards which they fall.
  • the polarizing mirror is a mirror M 2 FIGS. 5, 6 formed of three plane reflector-polarizing elements e 10 , e 20 , e 30 articulated around two hinges c 1 , c 2 .
  • the hinges c 2 , c 2 are according to FIGS. 5 and 6 respectively arranged according to a diameter D 'perpendicular to the diameter D and to two thirds of the diameter D.
  • the two hinges c 1 , c 2 are perpendicular to the diameter D.
  • Such a mirror M 2 makes it possible to operate the antenna according to the invention with a fine beam and single pulse channels (in this case the elements e lo , e 20 , e 30 are coplanar), or with an asymmetrical beam for viewing the ground ( in this case only the elements e lo , e 20 are coplanar, which corresponds to an articulation situated at the third of the mirror M 2 ) or even with a symmetrical widened beam, the inclination of the reflector-polarizing elements e 10 , e 30 causing a widening of the radiation pattern in the vertical plane of symmetry of the antenna, and possibility of using the monopuls channels (M 2 mirror articulated only in the center, e 20 and e 30 then being coplanar), this widened beam being able to be used for a ve It is close to rapid exploration.
  • a fine beam and single pulse channels in this case the elements e lo , e 20 , e 30 are coplanar
  • the polarizing mirror M 2 is made up of three reflector-polarizing elements e 10 , e 20 , e 30 hinged together by two hinges c 1 , c 2 symmetrical with respect to a diameter D ′ of the mirror, perpendicular to the diameter D.
  • Such a mirror in the same manner as above, makes it possible to obtain operation of the antenna with a fine beam and “monopulse” channels, c ’ ie channels making it possible to obtain a signal of deviation from a target echo with respect to the axis xx of the antenna, or a wide beam and “monopulse” channels when the reflector-polarizer elements e 10 , e 20 , e 30 are respectively coplanar or symmetrically inclined by the same dihedral angle a relative to the plane of the element e 20 , and operation with an asymmetric widened beam, as shown in FIG. 8, when the elements reflector-polarizers are tilted asymmetrically.
  • FIG. 8 represents, along the vertical plane of symmetry of the antenna, a radiation diagram as a function of a direction 0 relative to the axis xx. A relative maximum of radiation is obtained in direction 2a.
  • the characteristics of the beam emitted by the antenna according to the invention are preserved whatever the orientation of the whole of the mirror (M 1 or M 2 ) and are not very selective in frequency.

Landscapes

  • Aerials With Secondary Devices (AREA)
  • Variable-Direction Aerials And Aerial Arrays (AREA)

Claims (4)

1. Umgekehrte Cassegrain-Antenne, die es gestattet, während des Betriebes das Strahlenbündel in einer Ebene zu erweitern, und die mit einem Mehrzweckradar zusammenwirkt und eine primäre elektromagnetische Strahlenquelle (S) mit geradliniger Polarisation, sowie einen gewölbten primären Reflektor (R1) mit einer Drehachse aufweist, der dazu dient, die direkt von der primären Quelle ausgehenden Strahlen zu reflektieren und selektiv die elektromagnetischen Wellen mit gekreuzter geradliniger Polarisation zu übertragen, wobei die primäre Quelle (S) im Brennpunkt dieses primären Reflektors angeordnet ist, und wobei ein Polarisationsdrehspiegel vorgesehen ist, der die reflektierte Strahlung, deren Polarisationsebene gedreht worden ist, zum primären Reflektor (R2) zurückwirft, dadurch gekennzeichnet, dass dieser Polarisationsdrehspiegel (R2) aus mehreren ebenen Reflexions-Polarisations-Elementen (e1, e2) besteht, die vermittels paralleler, in bezug auf die gewünschte Erweiterungsebene des Strahlenbündels der Antenne orthogonale Scharniere (C1) gelenkig miteinander verbunden sind, und dass diese Elemente (e1, e2) mit Steuermitteln (20, 202) zusammenwirken, die die relative Lage der Elemente einstellen.
2. Antenne nach Anspruch 1, dadurch gekennzeichnet, dass die Reflexions-Polarisations-Elemente eine ebene metallische Platte (p) umfassen, vor welcher in einem Abstand k = Z ein aus zur Polarisationsrichtung der einfallenden Strahlung um 45° geneigten metallischen Fäden bestehendes ebenes Vlies (N) angeordnet ist, wobei λ die Betriebswellenlänge dieser Antenne darstellt und k eine ungerade ganze Zahl ist.
3. Antenne nach Anspruch 1, dadurch gekennzeichnet, dass die Reflexions-Polarisations-Elemente aus zur Polarisationsrichtung der einfallenden Strahlung ebenfalls um 45° geneigten metallischen Lamellen bestehen.
4. Antenne nach Anspruch 1, dadurch gekennzeichnet, dass die Steuermittel (20) zum Einstellen der relativen Lage der Reftexions-Potarisations-Elemente (e1, e2) einen mit dem Spiegel M, fest verbundenen Motor aufweisen, dessen Achse aus einer Schnecke besteht, die einen von dieser Schnecke geradlinig angetriebenen beweglichen Läufer (202) besitzt, welcher einen in einer zur Richtung der geradlinigen Bewegung des Läufers (202) senkrechten Richtung beweglichen Zeiger (203) bestitzt, dessen eines Ende in eine an der Rückseite der reflektierenden Fläche des Reflexions-Polarisations-Elementes (e2) angeordnete Gleitführung eingreift.
EP80400037A 1979-02-02 1980-01-11 Umgekehrte Cassegrain-Antenne für Mehrzweckradar Expired EP0014605B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR7902768A FR2448233A1 (fr) 1979-02-02 1979-02-02 Antenne cassegrain inversee pour radar a fonctions multiples
FR7902768 1979-02-02

Publications (2)

Publication Number Publication Date
EP0014605A1 EP0014605A1 (de) 1980-08-20
EP0014605B1 true EP0014605B1 (de) 1983-02-23

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ID=9221553

Family Applications (1)

Application Number Title Priority Date Filing Date
EP80400037A Expired EP0014605B1 (de) 1979-02-02 1980-01-11 Umgekehrte Cassegrain-Antenne für Mehrzweckradar

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US (1) US4253100A (de)
EP (1) EP0014605B1 (de)
DE (1) DE3062089D1 (de)
FR (1) FR2448233A1 (de)

Families Citing this family (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2524720A2 (fr) * 1982-04-02 1983-10-07 Thomson Csf Antenne cassegrain inversee pour radar a fonction multiple
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
US4574287A (en) * 1983-03-04 1986-03-04 The United States Of America As Represented By The Secretary Of The Navy Fixed aperture, rotating feed, beam scanning antenna system
GB2277408B (en) * 1989-05-16 1995-03-08 Plessey Co Plc Radar
US5455589A (en) * 1994-01-07 1995-10-03 Millitech Corporation Compact microwave and millimeter wave radar
US5469181A (en) * 1994-03-18 1995-11-21 Celwave Variable horizontal beamwidth antenna having hingeable side reflectors
SE514305C2 (sv) * 1999-04-22 2001-02-05 Celsiustech Electronics Ab Metod och anordning för bestämning av ett skanningsläge för en skannande reflektor hos en antennanordning
US7564419B1 (en) 2006-04-14 2009-07-21 Lockheed Martin Corporation Wideband composite polarizer and antenna system
CN107271796B (zh) * 2017-05-18 2020-04-07 陕西长岭电子科技有限责任公司 倒卡天线的空域稳定功能测试系统及测试方法

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3771160A (en) * 1970-08-04 1973-11-06 Elliott Bros Radio aerial

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3092834A (en) * 1958-12-23 1963-06-04 Canoga Electronics Corp Split parabolic radar antenna utilizing means to discriminate against crosspolarized energy
US3161879A (en) * 1961-01-05 1964-12-15 Peter W Hannan Twistreflector
US3254342A (en) * 1963-07-09 1966-05-31 Bell Telephone Labor Inc Antenna system wherein beamwidth variation is achieved by changing shape of intermediate reflector
DE1296221B (de) * 1965-09-30 1969-05-29 Siemens Ag Richtantenne, bestehend aus einem ueber einen Fangreflektor ausgeleuchteten Hauptreflektor
US3866233A (en) * 1973-09-10 1975-02-11 Nasa Dish antenna having switchable beamwidth
FR2394186A1 (fr) * 1977-06-06 1979-01-05 Thomson Csf Montage periscopique a lobe principal de largeur variable

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3771160A (en) * 1970-08-04 1973-11-06 Elliott Bros Radio aerial

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
ANTENNA ENGINEERING HANDBOOK pp. 25-11, 25-12- Henry Jasik-McGraw Hill 1961. *

Also Published As

Publication number Publication date
FR2448233B1 (de) 1983-05-13
DE3062089D1 (en) 1983-03-31
EP0014605A1 (de) 1980-08-20
US4253100A (en) 1981-02-24
FR2448233A1 (fr) 1980-08-29

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