EP0091343B1 - Antenne Cassegrain inversée pour radar à fonction multiple - Google Patents

Antenne Cassegrain inversée pour radar à fonction multiple Download PDF

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Publication number
EP0091343B1
EP0091343B1 EP83400605A EP83400605A EP0091343B1 EP 0091343 B1 EP0091343 B1 EP 0091343B1 EP 83400605 A EP83400605 A EP 83400605A EP 83400605 A EP83400605 A EP 83400605A EP 0091343 B1 EP0091343 B1 EP 0091343B1
Authority
EP
European Patent Office
Prior art keywords
layer
reflector
elements
plane
cassegrain antenna
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
EP83400605A
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German (de)
English (en)
French (fr)
Other versions
EP0091343A1 (fr
Inventor
Jean-Michel Brucker
Bernard Estang
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Thales SA
Original Assignee
Thomson CSF SA
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Thomson CSF SA filed Critical Thomson CSF SA
Publication of EP0091343A1 publication Critical patent/EP0091343A1/fr
Application granted granted Critical
Publication of EP0091343B1 publication Critical patent/EP0091343B1/fr
Expired legal-status Critical Current

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    • 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
    • H01Q15/16—Reflecting surfaces; Equivalent structures curved in two dimensions, e.g. paraboloidal
    • H01Q15/161—Collapsible reflectors
    • H01Q15/162—Collapsible reflectors composed of a plurality of rigid panels
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q1/00—Details of, or arrangements associated with, antennas
    • H01Q1/08—Means for collapsing antennas or parts thereof

Definitions

  • the present invention relates to an inverted Cassegrain antenna intended to be used in standby or tracking and capable of providing an enlarged beam either in the ground visualization site plan or in the bearing plane (anti-collision) while retaining the qualities of a primary beam end.
  • 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 inverse Cassegrain antenna with multiple function is to modify the shape of the polarization rotation mirror with which it is provided, in order to widen the beam in a determined direction.
  • EP-A-0014 605 discloses an inverted multiple-function Cassegrain antenna, comprising a polarization rotation mirror consisting of two or more polarizing-reflective elements articulated two by two around a hinge orthogonal to the direction of desired widening for the beam.
  • the articulation between the two polarizing reflector elements can be produced in the form of a simple hinge glued to the rear part of the polarization rotation mirror.
  • this type of articulation causes radioelectric discontinuities both at the level of the front face of the polarizer and at the level of the reflector on the rear face and radioelectric mismatching at the level of the articulation. These discontinuities deteriorate the characteristics of the antenna when the elements of the mirror are made coplanar.
  • the object of the present addition makes it possible to remedy the above-mentioned drawbacks and to maintain mechanical and radioelectric continuity at the level of the hinge articulating two elements of the reflective polarizer according to patent EP-A-0014605, throughout the travel and whatever whatever the angle of inclination of the movable element.
  • the present addition also aims to restore the phase shift of 180 ° at the level of the cut existing between two elements and to keep the flatness of the polarizer-reflector.
  • the inverted Cassegrain antenna provided with a polarization rotation mirror for multiple-function radar the planar reflector-polarizer elements each of which comprises a reflective layer kept parallel, by means of a layer of dielectric material , to a sheet of parallel metal wires, inclined at 45 ° with respect to the direction of polarization of the incident radiation, is characterized in that the hinge, around a slot of which two planar polarizing reflector elements are articulated, is formed at the front by said sheet of metal wires which continuously covers all of the plane polarizing reflecting elements and adheres to said intermediate layer in dielectric and at the rear by a metal tab which is parallel to the surface of said sheet, which is secured to the reflective layer of the first reflector-polarizing element by fixing means and which is in electrical contact by conductive means with the back of the reflective layer of the second reflector-polarizing element, movable relative to the first element.
  • a reverse Cassegrain antenna of known type comprises, as shown in FIG. 1, a primary source S intended to emit high frequency electromagnetic waves, a parabolic primary reflector R 1 , of axis xx 'of revolution, reflecting the radiation of the source. primary S and selectively transmitting the 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 , 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.
  • an electromagnetic wave with rectilinear polarization horizontal polarization for example
  • the primary source S (FIG. 1) disposed at the focal point F of the parabolic reflector R, emits radiation with linear (horizontal) polarization which is totally reflected by the parabolic reflector R, the angle formed by the incident ray and the radius reflected being equal to the angle of the incident ray and the axis xx 'of the reflector R l .
  • auxiliary reflector R 2 or mirror
  • n / 2 of their plane' of polarization the horizontal polarization of the incident wave is transformed into vertical polarization
  • the inverted Cassegrain antenna comprises a primary source S, a parabolic primary 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 polarization rotation mirror formed of at least two reflector-polarizing elements of planar shape, joined two by two by a hinge allowing their articulation.
  • the hinges are arranged in a direction perpendicular to the desired beam widening plane ( Figure 2).
  • This reflector R can for example consist of a layer of horizontal wires when the rectilinear polarization of the incident wave coming from the primary source S is horizontal.
  • the reflector-polarizing elements composing the polarization rotation mirror may have variable relative inclinations.
  • the movement of the elements around their hinge and their immobilization in a determined position are obtained, in the antenna according to the invention, by means of a control device intended to be actuated during the operation of 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 polarization rotation mirror designated by the reference M is made up of two polarizing reflecting elements e 1 , e 2 making an angle between them and joined by the hinge C, perpendicular to the plane of beam widening, which here is the plane of symmetry of the antenna coincident with the plane of the figure.
  • the control device 20 is for example constituted by a motor integral with the mirror M 1 whose axis 201 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 Figure 2.
  • the movable cursor 202 is provided with an index 203 movable in a direction y perpendicular to the direction of translation 8 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 A 8, representative of an angle a.
  • the diameters of the polarization rotation mirror (when the elements which compose it are coplanar) which are respectively perpendicular and parallel to the hinges are designated by D and D 'respectively.
  • This mirror M 1 therefore makes it possible to return to the parabolic reflector R rays having different angles of reflection depending on the element e 1 or e 2 to which they fall. We can therefore consider that there are two radiating pupils with slightly different complex amplitude distributions which cooperate to form the desired beam in space.
  • the hinge C 1 articulating the two elements e 1 and e 2 constituting the polarizing mirror of FIG. 2 is located at one third of the diameter D and is perpendicular to the vertical plane of symmetry of the antenna, represented by the plane of Figure 3 and containing the diameter D.
  • the element e 2 which is the smallest element, is inclined at an angle a by 7 ° for example with respect to the element e l .
  • Such a mirror M 1 allows site coverage with a decrease in gain substantially obeying a square cosecant law, such as the level at 17 dB: be reached 20 ° from the axis instead of the 5 ° obtained with a beam conventional end ( Figure 5).
  • the characteristics of the beam are also not very selective in frequency.
  • the polarizing mirror M 2 consists of three reflector-polarizing elements e 1 , e 2 , e 3 hinged together by two hinges C 1 , C 2 symmetrical with respect to a diameter of the antenna perpendicular to the diameter D.
  • Such a mirror in the same manner as previously, makes it possible to obtain an operation of the antenna with a fine beam and “monopulse” channels ", that is to say channels making it possible to obtain a signal of deviation from a target echo relative to the axis xx 'of the antenna, or a wide beam and a" monopulse "channel when the reflector-polarizing elements e 1 , e 2 , e 3 are respectively coplanar or symmetrically inclined at a dihedral angle a relative to the plane of the element e 2 , and operation with an asymmetrical widened beam, as shown in FIG. 5 when the reflector-polarizing elements are asymmetrically inclined.
  • FIG. 5 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 2 a.
  • the characteristics of the beam emitted by the antenna of FIG. 2 are not very selective in frequency.
  • the reflector-polarizing elements (e 1 , e 2 in FIGS. 2 to 4 for example) can be, in a known manner represented by FIG. 8, consisting of a metal plate P and a sheet N of parallel wires inclined at 45 ° relative to the direction of the incident retilinear polarization, this sheet N being arranged at k ⁇ / 4 of the plate P, k being an odd whole number 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 waves equiphase O 1 and O 1 whose polarization planes are inclined at 45 ° relative to the plane of polarization of the incident wave O 1 , the first component 0 1 being parallel to the wires of the sheet N and the second component 0 ", being perpendicular to these wires.
  • the first component 0 is therefore reflected by the wires while the second component 0 " 1 passes through the tablecloth N after having traveled a path equal to 2k ⁇ / 4, ie a path equal to k ⁇ / 2.
  • the second reflected component 0 " 2 is therefore phase shifted by ⁇ with respect to the first component 0 ' 2 reflected and the combination of the two components then creates a wave 0 2 with vertical polarization which can pass through the parabolic reflector letting pass the radiations with vertical polarization and reflecting the radiations with horizontal polarization. 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-polarizing elements without departing from the scope of patent EP-A-0014 605.
  • the polarization rotation mirror according to the invention comprises a sheet N sufficiently rigid to allow good guidance without being brittle at the level of the joint.
  • This sheet N is composed of a network of wires 100 and of various prepregs of resin and glue 101 and covers the entire surface of the mirror formed in the case of FIG. 8 with two reflector-polarizing elements e 1 considered to be fixed and e 2 movable relative to e 1 around the joint Ci.
  • the slot existing between the two elements e 1 and e 2 is covered by the ply N and is designated by the reference 111.
  • the element e 2 , respectively e 1 is successively formed from the front face covered by the ply N towards the rear face of a layer 102, respectively 103, of foam or honeycomb for example, whose adhesion to the sheet N is facilitated by the composition of said sheet.
  • the element e 2 , or e 1 then comprises a thin layer 104, or 105, serving as a reflector and a layer 106, or 107, as a dielectric.
  • the thin reflective layer 104, or 105 may for example be a metallic film or a network of wires or else a material carbon fiber composite.
  • the thickness of layer 106 or 107 of dielectric is calculated to compensate for the difference between the dielectric constant of layer 102, or 103, of foam or honeycomb and that of air.
  • a metal strip 108 completely covers the slot 111. It is bonded to the dielectric layer 107 of the fixed element e 1 and in electrical contact with the reflective layer 105 by pillars 110. It follows the movement of the mobile element e 2 by maintaining electrical contact with the reflective layer 104 by means 109.
  • This structure provides electrical continuity at the front side since the wire network covers the entire surface of the mirror and therefore both the elements e 1 and e 2 without interruption. On the other hand, it ensures good guidance of the movable element.
  • the metal tongue 108 is movable while ensuring electrical continuity over the entire reflecting surface during the movement of the element e 2 . It is located at a distance from the sheet N, such that the phase shift is 180 ° in the slot.

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  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Aerials With Secondary Devices (AREA)
EP83400605A 1982-04-02 1983-03-23 Antenne Cassegrain inversée pour radar à fonction multiple Expired EP0091343B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8205787 1982-04-02
FR8205787A FR2524720A2 (fr) 1982-04-02 1982-04-02 Antenne cassegrain inversee pour radar a fonction multiple

Publications (2)

Publication Number Publication Date
EP0091343A1 EP0091343A1 (fr) 1983-10-12
EP0091343B1 true EP0091343B1 (fr) 1987-07-22

Family

ID=9272710

Family Applications (1)

Application Number Title Priority Date Filing Date
EP83400605A Expired EP0091343B1 (fr) 1982-04-02 1983-03-23 Antenne Cassegrain inversée pour radar à fonction multiple

Country Status (6)

Country Link
US (1) US4612550A (enrdf_load_stackoverflow)
EP (1) EP0091343B1 (enrdf_load_stackoverflow)
DE (1) DE3372686D1 (enrdf_load_stackoverflow)
FR (1) FR2524720A2 (enrdf_load_stackoverflow)
GR (1) GR78792B (enrdf_load_stackoverflow)
IL (1) IL68272A0 (enrdf_load_stackoverflow)

Families Citing this family (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4845511A (en) * 1987-01-27 1989-07-04 Harris Corp. Space deployable domed solar concentrator with foldable panels and hinge therefor
SE455745B (sv) * 1987-06-30 1988-08-01 Syd Sparbanken Reflektor for en parabolantenn
NL8800538A (nl) * 1988-03-03 1988-08-01 Hollandse Signaalapparaten Bv Antennesysteem met variabele bundelbreedte en bundelorientatie.
GB2277408B (en) * 1989-05-16 1995-03-08 Plessey Co Plc Radar
FR2685081B1 (fr) * 1991-12-11 1994-02-04 Thomson Csf Structure a controle d'endommagement intrinseque, procede de fabrication et methode d'utilisation.
US5469181A (en) * 1994-03-18 1995-11-21 Celwave Variable horizontal beamwidth antenna having hingeable side reflectors
IT1284301B1 (it) * 1996-03-13 1998-05-18 Space Engineering Spa Antenna a singolo o a doppio riflettore, a fasci sagomati, a polarizzazione lineare.
SE517845C2 (sv) * 2000-12-05 2002-07-23 Ericsson Telefon Ab L M Ett antennarrangemang och en kommunikationsanordning som innefattar ett sådant arrangemang
US6980170B2 (en) * 2001-09-14 2005-12-27 Andrew Corporation Co-located antenna design
WO2012112616A2 (en) * 2011-02-15 2012-08-23 Kla-Tencor Corporation Composite polarizer with adjustable polarization angles

Citations (2)

* 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
EP0014605A1 (fr) * 1979-02-02 1980-08-20 Thomson-Csf Antenne Cassegrain inversée pour radar à fonctions multiples

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR964836A (enrdf_load_stackoverflow) * 1945-02-14 1950-08-25
US3161879A (en) * 1961-01-05 1964-12-15 Peter W Hannan Twistreflector
US3176303A (en) * 1962-02-21 1965-03-30 Whittaker Corp Collapsible antenna with plurality of flexible reflector petals releasably retained
US3576566A (en) * 1966-10-31 1971-04-27 Hughes Aircraft Co Closed loop antenna reflector supporting structure
US3717879A (en) * 1968-12-03 1973-02-20 Neotec Corp Collapsible reflector

Patent Citations (2)

* 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
EP0014605A1 (fr) * 1979-02-02 1980-08-20 Thomson-Csf Antenne Cassegrain inversée pour radar à fonctions multiples

Also Published As

Publication number Publication date
US4612550A (en) 1986-09-16
FR2524720B2 (enrdf_load_stackoverflow) 1984-05-18
FR2524720A2 (fr) 1983-10-07
IL68272A0 (en) 1983-06-15
DE3372686D1 (en) 1987-08-27
GR78792B (enrdf_load_stackoverflow) 1984-10-02
EP0091343A1 (fr) 1983-10-12

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