EP1131856A1 - Etalement de faisceaux electromagnetiques - Google Patents

Etalement de faisceaux electromagnetiques

Info

Publication number
EP1131856A1
EP1131856A1 EP99954242A EP99954242A EP1131856A1 EP 1131856 A1 EP1131856 A1 EP 1131856A1 EP 99954242 A EP99954242 A EP 99954242A EP 99954242 A EP99954242 A EP 99954242A EP 1131856 A1 EP1131856 A1 EP 1131856A1
Authority
EP
European Patent Office
Prior art keywords
axis
radiation
aperture
reflected
magnetisation
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.)
Withdrawn
Application number
EP99954242A
Other languages
German (de)
English (en)
Inventor
Balbir Kumar
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.)
MBDA UK Ltd
Original Assignee
BAE Systems Electronics Ltd
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
Priority claimed from GBGB9824800.8A external-priority patent/GB9824800D0/en
Application filed by BAE Systems Electronics Ltd filed Critical BAE Systems Electronics Ltd
Publication of EP1131856A1 publication Critical patent/EP1131856A1/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • 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
    • H01Q3/44—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 electric or magnetic characteristics of reflecting, refracting, or diffracting devices associated with the radiating element
    • 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
    • H01Q15/24—Polarising devices; Polarisation filters 
    • H01Q15/242—Polarisation converters
    • 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
    • H01Q19/06—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 refracting or diffracting devices, e.g. lens
    • H01Q19/08—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 refracting or diffracting devices, e.g. lens for modifying the radiation pattern of a radiating horn in which it is located
    • 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

Definitions

  • This invention relates to a device which is adapted to be positioned in the path of a beam
  • the invention is particularly, but not
  • microwave is generally understood to refer to the part of the electromagnetic
  • millimetre wave which is stated to have a frequency in the range 30 to 300GHz.
  • channels are transmitted in a particular direction in the form of a modulated
  • communication channel or channels can be directed towards a particular location.
  • units which are spatially separated need to communicate with each
  • the directional communication channel could come from any direction in an azimuthal plane. It then becomes important to establish
  • a single omnidirectional antenna is preferred.
  • a known device for electronically steering a microwave beam comprises a body of
  • ferrite material having an aperture through which the beam passes.
  • the device can steer the beam
  • the device is provided with a plurality of magnetic coils, typically
  • the device can steer the beam in
  • azimuthal plane In this context an azimuthal plane is perpendicular to the original
  • Such a device typically has a
  • the invention provides a device for controlling the direction of a beam of
  • the beam follows a steered direction so that on
  • the beam may be offset relative to the axis and steered about
  • the device has a body of magnetic material which comprises the aperture.
  • the beam of radiation may pass through the body.
  • the axis is parallel to and coincident with the direction of the beam before it was offset in the
  • the steering means is magnetic means.
  • the magnetic means applies a gradient in magnetisation across the aperture.
  • this gradient in magnetisation occupies a plane which is not perpendicular to
  • the axis Although the term plane is used, this describes the gradient of magnetisation in an ideal case.
  • the gradient might be non-planar due to non-ideal conditions in its
  • the gradient of magnetisation rotates about the axis.
  • the steering means conically steer a beam of radiation produced by it.
  • the steering means conically steer a beam of radiation produced by it.
  • the axis passes through the centre of the aperture.
  • the offset between the beam and the axis may be angular. Preferably it is spatial. If
  • the angle ⁇ may be small. It may be zero.
  • the steering means may comprise a ferrite material arranged
  • polarisers may be arranged adjacent either end face of the ferrite material so as to reflect
  • an isolator may be arranged to prevent a
  • An absorbing material may be arranged to absorb that portion of the
  • the beam is reflected by a reflective surface placed adjacent to the face of the aperture or array from which the beam emerges. This face is an emergent face.
  • the reflective surface is in the shape of a cone having its apex facing the emergent face and its central axis coincident with the axis of the device. It will be understood that the cone may be a section of a cone.
  • the device sweeps the beam through 360° of a plane which is perpendicular
  • the beam of radiation is microwave radiation. Most preferably it is millimetric radiation. In one embodiment it is at Ka band, typically between 26.5 to 40GHz, and in another it is at W-band, typical between 75 to 1 lOGHz. Alternatively the radiation is in other parts of the electromagnetic spectrum, for example at higher frequencies towards, and including, optical and visible frequencies.
  • Figure 1 illustrates a unit to deflect a beam of radiation
  • Figure 2 illustrates a perspective view of the unit of Figure 1
  • Figure 3 illustrates the unit of Figures 1 and 2 in plan view
  • Figure 4 illustrates the unit of Figures 1 and 2 incorporated into a beam scanning device
  • Figure 5 illustrates alternative embodiment of the invention
  • Figure 6 illustrates the construction of a ferrite device
  • Figure 7 illustrates an alternative construction of a ferrite device
  • Figure 8 illustrates a cross sectional view of the ferrite device in Figure 7 and the flux
  • Figures 9a and 9b illustrate sectors into which a ferrite device can be divided in order to
  • Figure 10a and 10b illustrate embedded coils for providing a directional response for the
  • FIGS 11 to 13 illustrate various alternative embodiments to that shown in Figure 5.
  • Figure 1 shows a unit 10 which is used to deflect a beam of radiation 12 transmitted from
  • the unit 10 comprises a body 14 of
  • ferrite material having a quarter wave plate 16 located adjacent an entry face 18 of the
  • phase correcting dielectric 20 located adjacent an exit face 22 of the body
  • the radiation is in the form of an energy distribution.
  • the body 14 provides a magnetisable medium through which the beam 12 passes.
  • the body 14 has a
  • Pairs of biassing coils 26 and 28 and 30 and 32 are located about sides 34,
  • the magnetic field aligns internal magnetisation in the body 14 to
  • the unit 10 is also shown in Figure 2 in perspective view, where the configuration of the
  • coils 26, 28, 30 and 32 can be more clearly seen wound respectively about arms 42, 44, 46 and 48 which extend from the sides of the body 14. Since the coils 26, 28, 30 and 32
  • the coils of each pair can conveniently be wound from a continuous piece of
  • the arms 42, 44, 46 and 48 can either be integral with the body 14 comprising the same
  • arms 42, 44, 46 and 48 and the body 14 is provided so as to provide a medium through
  • the magnetic field produced by one of the coils, for example 26 or 30, is in an opposite
  • pair of coils 26, 28, 30 and 32 induces a gradient in magnetisation across the body 14,
  • the path 50 described by the beam 12 on the exit face 22 is shown in Figure 3.
  • the path 50 does not have to be circular but may be any shape suitable for operation of the unit 10.
  • the shape of the path is governed by the phase relationship of the oscillating signals applied to the pairs of the coils 26, 28, 30 and 32. Therefore, in certain circumstances, the phase relationship will be other than in quadrature.
  • FIG. 4 shows the unit 10 incorporated into a beam scanning device 60.
  • the same references have been used to label similar integers to those illustrated in Figure 1.
  • the unit 10 is located between a microwave horn 62 and a cone shaped reflector 64. Since
  • the reflector 64 is arranged so that its apex faces the exit face 22 and its central axis is coincidental with the central axis 24, it will be appreciated that as the beam 12 emerges from locations about the circular path 50, it will be reflected from a part of the reflective surface of the reflector 64 located as a circular path about the central axis 24.
  • a potential problem with a cone reflector is that it naturally causes the beam to diverge significantly.
  • One way to reduce this is to increase the size of elements in the device 60, such as the reflector 64, relative to the size of the beam 12 footprint. Finite limits exist as to reasonable sizes for such elements, given particular applications.
  • the reflector 64 can be modified to have particular focussing properties. For example if the reflector 64 does not have a constant taper angle but has a taper angle which increases as the apex is approached, so that in elevational view it appears to have concave sides, then
  • the beam 12 can be focussed in a particular plane, ideally an azimuthal plane which is
  • the reflector 64 may be replaced by a
  • a reflector In one embodiment, a reflector
  • optimise the reflective regions so that 360° scanning is possible with optimised reflection
  • a further refinement of the reflector 64 is to provide it with a non-reflecting end. If the
  • the radiation will be transmitted isotropically in azimuth. If there is a slight offset,
  • a non-reflecting end can be any non-reflecting end.
  • a non-reflecting end can be provided by
  • the reflector 64 has a correctly chosen cone angle, the beam 12 will be scanned 360° through a plane which is perpendicular to the central axis 24.
  • the quarter wave plate 16 located adjacent the entry face 18 is provided to convert linearly polarised radiation transmitted by the horn 62 into circularly polarised radiation. However, if a horn 62 is used which transmits circularly polarised radiation, the quarter wave plate 16 will not be necessary. It is preferred to use a beam 12 of circularly polarised radiation because it is deviated as a single beam 12 as is discussed above. However, if a beam 12 of linearly polarised radiation is used, which is consequently split into two circularly polarised beams, they would be reflected by the reflector 64 at an angular separations of
  • the phase correcting dielectric 20 is provided to optimise the direction taken by the beam 12 as it emerges from the exit face 22 of the body 14 and is reflected off the reflector 64. As can be seen in Figures 1 and 4 the passage of the beam 12 through the body 14 is schematically illustrated as a curved path 66. As a result the beam 12 will tend to emerge from the body 14 in a direction not parallel to the central axis 24.
  • the phase correcting dielectric 20 changes the direction of the beam 12 so that it travels towards the reflector 64 in a direction parallel to the central axis 24. Such a direction is preferred so as to minimise the size of the device 60 and reduce divergence in the reflected beam 12.
  • the phase correcting dielectric 20 is in the form of a shallow cone having a large taper angle.
  • the taper angle is chosen to provide azimuthal scanning. It will be understood that the phase correcting dielectric 20 is not essential to the invention as an arrangement is envisaged having a reflector 64 situated to reflect the beam 12 as it emerges from the body 14 along its curved path 66.
  • the unit 10 and the beam scanning device 60 have been described transmitting radiation, in certain embodiments they are to be used to receive as well as to transmit. For example, in a communication system, if a station receives a signal to which it is convenient or it is necessary to respond, such as an interrogation signal, it is desirable to determine the direction from which the signal originates. In this way a response signal can be transmitted in that direction only rather than omnidirectionally.
  • a typical interrogation sequence might proceed as follows.
  • the station to be interrogated is identified and an interrogating station transmits an interrogation signal.
  • the interrogation signal typically has a first portion simply comprising a pulse of electromagnetic radiation which can be detected by the station being interrogated to know that an interrogation sequence has begun. It is not necessary for the pulse to contain any data and it may be about lOO ⁇ s in duration.
  • a second portion containing data is transmitted, for example in a burst 300 to 400 ⁇ s in duration. Therefore, the station being interrogated has 400 to 500 ⁇ s to determine the direction from which the interrogation signal is originating in order that it can send its response signal in the correct direction.
  • the device 60 can scan to receive.
  • the unit 10 is electrically biassed by a small amount such that radiation is being preferentially received from one sector and less preferentially received from other sectors.
  • the coils 26, 28, 30 and 32 of the unit 10 are electrically biassed such that the composite gradient
  • processing means associated with the device 60 will determine that the station being
  • the processing means can identify the electrical biassing at
  • the unit 10 of the responding station can be electrically biassed so
  • the unit 10 is omitted and replaced with a phase
  • the beam could not only be steered but also focussed so that a relative
  • the array could be configured so that it can receive
  • phase array could scan for received signals in a manner
  • phase array could comprise a plurality of sub-arrays which are
  • sub-array corresponds to a specific direction in azimuth thereby providing directionality
  • phase of the array or elements of the sub-array can be varied to
  • Such systems may be tracking systems.
  • a linearly polarised beam 70 is arranged
  • a ferrite device 71 can typically be constructed by placing a ferrite material in a solenoid.
  • a coil 72 of a solenoid is
  • Figure 5 illustrates a quasi-optical type polarisation switch or rotator wherein the ferrite device 71 is positioned between a pair of first and second polarisers, 75 and 76 respectively.
  • the polarisers 75, 76 are typically formed from wire grids which are arranged to reflect or allow some or all of the beam 70 to pass
  • a horn 77 is arranged to transmit the beam 70 along an axis 78 which passes through the ferrite device 71.
  • the first polariser 75 is inclined to the axis 78 and is arranged to allow the beam 70 to pass therethrough and to remove any cross polarisation in the beam 70 generated by the horn 77. This is achieved by reflecting cross polarised radiation generated by the horn 77 onto a suitably arranged absorbing material 79.
  • a cone shape reflector 81 allows the beam 70 to be reflected into free space through 360° in a plane substantially perpendicular to axis 78, that is in this case the azimuth plane, and hence, in the right conditions to pass through the second polariser 76.
  • the second polariser 76 is shaped to surround the reflector 81 and the beam 70 is allowed to pass, into free space, as a pair of beams 70a and 70b separated by 180° in a scanning type arrangement, when the beams 70a and 70b are correctly polarised, otherwise the beams 70a and 70b will not pass through the second polariser 76.
  • the apparatus should firstly be considered without the presences of the second polariser 76.
  • the beam 70 will be reflected as a notional reflected beam from the cone shaped reflector 81 into free space through 360 degrees in a plane substantially perpendicular to the axis 78, that is in the azimuth plane.
  • the polarisation vector, in the far field of the reflected beam, will undergo
  • device 71 is in a unenergised state, that is coil 72 or coils 72a and 72b are not energised,
  • the direction of the field in the beam 70 will be in the same direction as when it emerged
  • reflector 81 is to allow energy to emerge only in certain directions. The direction of the
  • the polariser 76 is designed to transmit vertical polarisation then, when the ferrite
  • device 71 is in an unenergised state, that is coil 72 or coils 72a and 72b are not energised
  • the beam 70 will pass through the ferrite
  • the ferrite device 71 is energised longitudinally by the coil 72 or coils 72a and 72b the polarisation state of the beam 70 emerging from the ferrite device 71 will alter, that is the direction of the field in the beam 70 in this case it will rotate about the axis 78. Since the vertical polarisation direction of the reflected beam in the azimuth plane coincides with the direction of the field in the beam 70, the azimuth direction of the emergent beam from the reflector 76 will be changed accordingly.
  • Figures 9a and 9b illustrate that a directional response can be made by dividing the ferrite device
  • the directional response can be improved by increasing the number of sectors and attaching pole pieces to the machine faces 83 of the ferrite device 71 shown in figure 9b.
  • the ferrite material 73 shown in Figures 5 to 8 can also be divided up into a number of sectors using biasing coils 72 imbedded within the ferrite material 73 which are arranged to energise one or more sectors of the ferrite material to be magnetised.
  • a second layer of biasing coils, not shown, could be either arranged in a Helmholtzian paired arrangement with the
  • biasing coils 72 to increase the magnetisation of the ferrite material 73 or arranged
  • first and second polarisers 75 and 76 are perpendicular to the axis 78.
  • reflections from the polarisers 75 and 76 may be picked
  • an isolator not shown, such as a fixed Faraday rotation
  • the device can be positioned between the first polariser 75 and the horn 77 or a waveguide
  • isolator can be positioned behind the horn 77 to mitigate the effect of reflections from
  • a focusing lens 84 is used to focus the beam 70 emitted by the horn
  • a quarter wave plate 85 can be
  • received beam can be received in direction orthogonal to the axis 78. That is a receiving
  • horn 87 is arranged in a position orthogonal to axis 78 and the received beam 70 is
  • a suitably arranged absorbing material 80 is used to absorb the beam 70 when
  • This arrangement also lends itself to the inclusion of a briefringence phase plate 86 in front of the receiving horn 87 so that the direction of the incoming received beam 70 can
  • the ferrite device 71 can be suitable energised to make a directional response

Landscapes

  • Variable-Direction Aerials And Aerial Arrays (AREA)

Abstract

La présente invention concerne un dispositif magnétique (10) d'étalement d'un faisceau (12) de rayonnement micro-onde. Le dispositif (10) comprend un corps magnétisable (14) présentant une ouverture et un axe (24) perpendiculaire à l'ouverture. Une pluralité d'enroulements (30,32) situés sur les côtés du corps (14) produisent un gradient dans la magnétisation du corps (14) mis en rotation autour de l'axe (24) à l'aide de variations du courant parcourant les enroulements. Une interaction entre le faisceau (12) et le matériau magnétisé du corps (14) provoque une décalage du faisceau en le plaçant en révolution autour de l'axe (24). Un miroir conique placé au dessus du corps face à la sortie du faisceau place le faisceau en position de balayage sur 360°.
EP99954242A 1998-11-12 1999-11-12 Etalement de faisceaux electromagnetiques Withdrawn EP1131856A1 (fr)

Applications Claiming Priority (5)

Application Number Priority Date Filing Date Title
GBGB9824800.8A GB9824800D0 (en) 1998-11-12 1998-11-12 Scanning of electromagnetic beams
GB9824800 1998-11-12
GB9915359 1999-07-02
GB9915359A GB2343789B (en) 1998-11-12 1999-07-02 Scanning of electromagnetic beams
PCT/GB1999/003782 WO2000030212A1 (fr) 1998-11-12 1999-11-12 Etalement de faisceaux electromagnetiques

Publications (1)

Publication Number Publication Date
EP1131856A1 true EP1131856A1 (fr) 2001-09-12

Family

ID=26314665

Family Applications (1)

Application Number Title Priority Date Filing Date
EP99954242A Withdrawn EP1131856A1 (fr) 1998-11-12 1999-11-12 Etalement de faisceaux electromagnetiques

Country Status (3)

Country Link
EP (1) EP1131856A1 (fr)
AU (1) AU1065400A (fr)
WO (1) WO2000030212A1 (fr)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
MA41179A (fr) 2014-12-19 2017-10-24 Cancer Research Tech Ltd Composés inhibiteurs de parg

Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2973516A (en) * 1957-10-17 1961-02-28 Gen Dynamics Corp Scanning antenna using magneticallycontrolled internal ferrite wave refraction
FR2445040A1 (fr) * 1978-12-22 1980-07-18 Thomson Csf Antenne a balayage conique pour radar, notamment radar de poursuite
FR2548836B1 (fr) * 1983-07-08 1986-02-21 Thomson Csf Antenne a couverture quasi torique a deux reflecteurs
GB2253947A (en) * 1991-03-22 1992-09-23 Marconi Gec Ltd Microwave beam-steering devices.
JP3277590B2 (ja) * 1993-02-18 2002-04-22 株式会社村田製作所 誘電体ロッドアンテナ
US5486838A (en) * 1993-08-23 1996-01-23 Andrew Corporation Broadband omnidirectional microwave antenna for minimizing radiation toward the upper hemisphere
GB9602395D0 (en) * 1996-02-06 1996-04-03 Secr Defence Omnidirectional antenna

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO0030212A1 *

Also Published As

Publication number Publication date
WO2000030212A1 (fr) 2000-05-25
AU1065400A (en) 2000-06-05

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