WO1993010571A1 - Antenne en reseau en phase a balayage ferroelectrique - Google Patents

Antenne en reseau en phase a balayage ferroelectrique Download PDF

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Publication number
WO1993010571A1
WO1993010571A1 PCT/US1992/009939 US9209939W WO9310571A1 WO 1993010571 A1 WO1993010571 A1 WO 1993010571A1 US 9209939 W US9209939 W US 9209939W WO 9310571 A1 WO9310571 A1 WO 9310571A1
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WO
WIPO (PCT)
Prior art keywords
arrangement
radiation
scanner
blocks
electric field
Prior art date
Application number
PCT/US1992/009939
Other languages
English (en)
Inventor
Donald C. Collier
Kevin J. Krug
Brittan Kustom
Original Assignee
United Technologies Corporation
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 United Technologies Corporation filed Critical United Technologies Corporation
Publication of WO1993010571A1 publication Critical patent/WO1993010571A1/fr

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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

Definitions

  • This invention relates to phased array antennas, and more particularly to a ferroelectric-scanned phased array antenna.
  • ferroelectric materials in scanning devices such as antennas for radar applications has been the subject of recent interest. This is because certain dielectric properties of such materials change under the influence of an electric field. In particular, an electrooptic effect can be produced by the application of a bias electric field to some ferroelectric materials. By electrooptically varying the refractive indices of such material, a phase shift will occur in electromagnetic radiation passing therethrough.
  • Regions of ferroelectric materials have a non-zero electric dipole moment in the absence of an applied electric field. For this reason,
  • ferroelectric materials are regarded as spontaneously polarized.
  • a suitably oriented polarized ferroelectric medium changes the propagation conditions of passing electromagnetic radiation.
  • a bias electric field of sufficient magnitude in the appropriate direction may change the refractive index of the medium, thereby further altering the propagation conditions.
  • a first component exhibits polarization of the electric field perpendicular to the optic axis, and refracts in the medium according to Snell's
  • a second component exhibits polarization orthogonal to that of the first, with some constituent of the electric field parallel to the optic axis (the extraordinary ray).
  • the refractive indices of the ferroelectric material for the two wave components, no and n e respectively, determine the different velocities of propagation of the components' phase fronts.
  • the applied bias electric field typically changes the refractive indices, which causes phase shifts in the propagating radiation.
  • Each patent describes and illustrates a monolithic piece of ferroelectric material disposed in front of a source of electromagnetic radio frequency ("RF") radiation.
  • the material has a row of electrically conductive wires disposed on each side of the material and spanning the material from top to bottom.
  • a DC voltage applied to the wires in a pattern produces a voltage gradient across the antenna aperture from one end to the other. Such a voltage gradient
  • ferroelectric material in Kubick patent 4,706,094 (the “electrooptic scanner patent") has an initial domain orientation parallel to the direction of propagation ("c-poled"), such c-poling being perpendicular to the surface of the
  • Objects of the present invention include
  • a arrangement of adjacent blocks of ferroelectric material is disposed in the path of electromagnetic radiation.
  • a plurality of conductive electrodes are provided, each pair of adjacent blocks having a corresponding electrode disposed therebetween.
  • the electrodes are provided with voltage levels in a selected pattern.
  • An electric field results across each block such that the electric field is in a direction both normal to the propagation direction of the radiation and parallel to the polarization direction of the radiation.
  • a change in the electric field varies the extraordinary wave propagation constant (i.e., the refractive index, n e ) of the ferroelectric blocks. Such change produces a phase shift in the radiation which is varied across the face of the aperture, resulting in a controllable alteration of the radiation direction.
  • Fig. 1 is a perspective view of an arrangement of a radar scanner comprised of ferroelectric
  • Fig. 2 is a perspective view of a radar scanner comprised of an arrangement of ferroelectric material according to the present invention
  • Fig. 3 is a perspective view of the arrangement of ferroelectric material of Fig. 3;
  • Fig. 4 is a perspective view of a portion of the arrangement of the ferroelectric material of Fig. 3. Best Mode For Carrying Out The Invention
  • Fig. 1 a perspective view of a prior art radar scanner (13) comprised of a
  • the scanner scans a beam (22) of millimeter wavelength radiation.
  • the scanner illustrated is that described and claimed in the aforecited Kubick patents. (The parenthetical reference numerals are those
  • the scanner includes parallel input and output sides with impedance matching layers (44).
  • Adjacent and opposite parallel wire grid electrodes (31) are excited with voltage levels across the face of the material (17). Such excitation modifies the
  • the wave polarization must be parallel to the optic axis, and, thus, to the bias electric field.
  • the present invention implements this configuration in a manner that provides for very uniform application of bias field, as well as a simplified voltage divider network.
  • Fig. 2 there illustrated is a perspective view of a radar scanner 50 according to the present invention.
  • the scanner is similar in some respects to that of Fig. 1 of the Kubick
  • the scanner 50 comprises an arrangement or stack 51 of blocks 52-70 of ferroelectric material arranged adjacent to one another in a vertical orientation.
  • the material may comprise barium strontium titanate, or any other material, either ferroelectric or non-ferroelectric, having refractive index (e.g., extraordinary wave refractive index, n e ) properties which vary in the presence of an applied electric field.
  • the scanner redirects a wave 72 of electromagnetic radiation emanating from a source of RF energy, such as a flared horn 74.
  • the RF wave illustrated is one having its electric field polarization in a horizontal orientation with respect to the scanner 50 and the blocks 52-70.
  • polarization is orthogonal to the direction of propagation of the RF wave 72.
  • the ferroelectric blocks 52-70 are distributed over the aperture of the horn 74 in the form of a planar layer of substantially uniform thickness "d".
  • the thickness is selected to establish at least a single wavelength (i.e., 2 ⁇ r radian) phase delay under a selected electric field excitation level.
  • each block has an electrode comprising a corresponding thin layer of conductive material, e.g., silver, deposited in a known fashion on an inner surface.
  • the electrode surface contacts, or is closely disposed next to, a similar surface on an adjacent block.
  • Each block also has a uniform width "w”. As described in detail hereinafter, each block acts as an RF wave phase shifting unit.
  • the conductive-coated surfaces can better be seen in Fig. 4.
  • Block 60 has, on two surfaces 80,82, the conductive coating deposited thereon.
  • block 62 has, on two surfaces 84,86, the conductive coating
  • Surfaces 82,84 may be in
  • Corresponding electrical conductive wires 88-108 are provided in electrical contact with the
  • Each layer Adjacent to the front and back sides of the stack 51 of ferroelectric blocks 52-70 are disposed impedance matching layers 110,112. Each layer
  • 110,112 comprises material, e.g., magnesium calcium titanate having a dielectric constant in the range of 15-140.
  • the refractive index is the square root of the dielectric constant, or relative permittivity.
  • the layers are required because of the impedance mismatch between free space and the high dielectric constant (e.g., >500) of the ferroelectric material. Without these layers, the RF wave impinging upon the ferroelectric blocks would be reflected off the face of the blocks.
  • the resulting stack 51 comprising the blocks 52-70 together with the layers 110,112 has parallel front and back sides which are perpendicular to the propagation direction of the RF wave.
  • the magnesium calcium titanate is chosen to have a dielectric constant which equals the square root of the dielectric constant of the corresponding
  • the impedance matching layers are preferably prefabricated into thin sheets or layers having a selected thickness. The layers are attached to each side of the stack 51 using adhesive or other known bonding techniques.
  • the permittivity of each layer is 25 (i.e., the square root of 625).
  • Low-loss microwave ceramics comprised of varying compositions of magnesium and calcium titanates are commercially available with dielectric constants in the range of 10 to 140, measured at the X frequency band (8.2 GHz to 12.4 GHz). As these materials show no dispersion in the X band, it is expected that their dielectric properties will remain constant as the frequencies increase into the Ku frequency band (12.4 GHz to 18.6 GHz). To achieve optimal radiation coupling, the impedance matching layers must be a quarter
  • the layer thickness is 0.159 cm (about 59 mils) for operation at 10 GHz.
  • thickness, d, of the ferroelectric blocks can be freely varied, limited only by structural
  • the conductive wires 88-108 individually connect to a voltage source 116 through a known electronic circuitry switch/addressing ("S/A") function 118.
  • S/A electronic circuitry switch/addressing
  • the S/A function 118 controls the application of a sustained voltage to the individual wires 88-108.
  • the S/A function may comprise, e.g., a number of parallel switches each independently controllable and in series with variable resistances (not shown), thereby applying variable voltage levels to the wires.
  • the voltage on each wire creates an electrical field across each block in an orthogonal orientation with regard to the direction of the RF wave 72 radiating from the horn 74.
  • the magnitude of the voltage on each wire is chosen so that a pattern of ascending voltage differences results across the blocks in one direction.
  • wire 88 may provide an outer surface 120 of block 52 with zero volts DC (0VDC, ground), while wire 90 may have 1VDC applied thereto.
  • the voltage across block 52 equals +1VDC.
  • wire 92 may have -1VDC applied thereto, for a voltage drop across block 54 of 2VDC.
  • Wire 94 may have +2VDC applied thereto, for a voltage drop across the block of 3VDC.
  • Such pattern of voltage application is repeated until an ascending pattern of voltage drops results across all blocks 52-70 in one direction.
  • This method of bias field application provides for a much simplified voltage divider network.
  • the magnitude of applied voltages described above is purely exemplary; the only constraint imposed on the voltage magnitude is that it be sufficient to cause changes in the extraordinary refractive index of the ferroelectric material comprising each block.
  • the RF wave radiating from the horn divides into components upon incidence with the ferroelectric blocks.
  • the phase shift of the RF wave is modified spatially by electrooptically varying the refractive index of the ferroelectric blocks from one side of the antenna to the other. This is accomplished by applying the sustained bias electric field of sufficient magnitude in an appropriate direction. Accordingly, the RF wave component 72 polarized orthogonally to the blocks generally travels through a block of
  • n e (O) an extraordinary refractive index
  • E bias electric field excitation
  • n(O) is the
  • ⁇ 2 2 ⁇ *(d/L)*n(E 2 ) (Eq. 3) where n(E 2 ) is the refractive index of the
  • n(E) is less than n(O), and thus ⁇ 2 is less than ⁇ 1 .
  • ⁇ n 12 n(E 2 ) - n(E 1 ) (Eq. 5)
  • the scan angle is proportional to the scanner (block) thickness, d, the measure of
  • ferroelectric electrooptic activity, F the voltage gradient between the blocks, ⁇ V, and inversely proportional to the square of the block width, w.
  • the conductive surfaces apply a bias electric field perpendicular to their faces
  • ⁇ tot There are two methods to achieve the total phase shift, ⁇ tot, required for the scanner.
  • the first is to choose the block thickness, d, such that any individual layer's maximum phase shift, ⁇ max , is large enough to achieve the total shift necessary, ⁇ tot . This may be many multiples of 2 ⁇ .
  • d/L By making d/L a large number, large variations in ⁇ can be achieved. However, a large value for d will also increase whatever material losses exist.
  • the second method requires a complex controller, programmed to change ⁇ V when a 2 ⁇ phase shift is exceeded.
  • the second method above does have the advantages of a thinner block structure, reducing losses in the material, and the option of increasing the active layer thickness somewhat (so that ⁇ max ⁇
  • first rightmost block 70 becomes the base voltage to which is added the voltage difference required for the second block.
  • succeeding layers are biased anti-parallel to each other, as described hereinbefore. Since the
  • the two aforementioned Kubick patents claimed operation in the millimeter wavelength band. This corresponds to a frequency range of 40-100 GHz.
  • the present invention is not limited as such; it has been observed that the electrooptic activity involved in the present invention occurred at frequencies in the X and Ku bands ( ⁇ 8-18 GHz). Further, the present invention is not limited to even such a frequency range; the invention may be used at any frequency where the aforedescribed electrooptic effect is observed. This may be anywhere in the microwave or millimeter range, or approximately in a frequency range of 1-100 GHz.

Landscapes

  • Optical Modulation, Optical Deflection, Nonlinear Optics, Optical Demodulation, Optical Logic Elements (AREA)

Abstract

Un agencement de blocs adjacents (52-70) en matériau ferroélectrique est disposé dans le chemin (72) d'un rayonnement électromagnétique. Plusieurs électrodes conductrices (88-108) sont utilisées, chaque paire de blocs adjacents ayant une électrode correspondante disposée entre deux blocs. Les électrodes ont des niveaux de tension sélectionnés suivant une configuration. Un champ électrique de polarisation se produit sur chaque bloc de sorte que le champ électrique est crée dans une direction à la fois normale à la propagation et parallèle au sens de polarisation du rayonnement. Une modification du champ électrique de polarisation peut produire une modification de la constante de propagation d'onde extraordinaire (c'est-à-dire l'indice de réfraction ne) des blocs ferroélectriques. Une telle modification produit un déphasage du rayonnement qui varie au niveau de la face de l'ouverture, ce qui a pour résultat une modification contrôlable du sens du rayonnement d'émanation.
PCT/US1992/009939 1991-11-14 1992-11-12 Antenne en reseau en phase a balayage ferroelectrique WO1993010571A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US79184291A 1991-11-14 1991-11-14
US791,842 1991-11-14

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WO1993010571A1 true WO1993010571A1 (fr) 1993-05-27

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Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2000033416A1 (fr) * 1998-12-03 2000-06-08 Telefonaktiebolaget Lm Ericsson Antenne a balayage a ouverture continue
WO2000033417A1 (fr) * 1998-12-03 2000-06-08 Telefonaktiebolaget Lm Ericsson Antenne lentille a balayage
WO2001039324A1 (fr) * 1999-11-23 2001-05-31 Telefonaktiebolaget Lm Ericsson (Publ) Dispositif d'antenne lentille a balayage continu
WO2001039323A1 (fr) * 1999-11-23 2001-05-31 Telefonaktiebolaget Lm Ericsson (Publ) Reflecteur d'antenne a balayage a ouverture continue
US6393392B1 (en) 1998-09-30 2002-05-21 Telefonaktiebolaget Lm Ericsson (Publ) Multi-channel signal encoding and decoding
US6421541B1 (en) 1999-01-22 2002-07-16 Telefonaktiebolaget Lm Ericsson Adaptable bandwidth
WO2006062446A1 (fr) * 2004-12-08 2006-06-15 Telefonaktiebolaget Lm Ericsson (Publ) Lentille ferroelectrique

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2918572A (en) * 1956-05-08 1959-12-22 Decca Record Co Ltd Variable impedance microwave apparatus
WO1986001613A1 (fr) * 1984-08-27 1986-03-13 Eastman Kodak Company Dispositif electro-optique de balayage et de modulation
US4706094A (en) * 1985-05-03 1987-11-10 United Technologies Corporation Electro-optic beam scanner
US5032805A (en) * 1989-10-23 1991-07-16 The United States Of America As Represented By The Secretary Of The Army RF phase shifter
US5061048A (en) * 1990-02-06 1991-10-29 Unisys Corporation Apparatus for optical beam steering using non-linear optical polymers

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2918572A (en) * 1956-05-08 1959-12-22 Decca Record Co Ltd Variable impedance microwave apparatus
WO1986001613A1 (fr) * 1984-08-27 1986-03-13 Eastman Kodak Company Dispositif electro-optique de balayage et de modulation
US4706094A (en) * 1985-05-03 1987-11-10 United Technologies Corporation Electro-optic beam scanner
US5032805A (en) * 1989-10-23 1991-07-16 The United States Of America As Represented By The Secretary Of The Army RF phase shifter
US5061048A (en) * 1990-02-06 1991-10-29 Unisys Corporation Apparatus for optical beam steering using non-linear optical polymers

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6393392B1 (en) 1998-09-30 2002-05-21 Telefonaktiebolaget Lm Ericsson (Publ) Multi-channel signal encoding and decoding
WO2000033416A1 (fr) * 1998-12-03 2000-06-08 Telefonaktiebolaget Lm Ericsson Antenne a balayage a ouverture continue
WO2000033417A1 (fr) * 1998-12-03 2000-06-08 Telefonaktiebolaget Lm Ericsson Antenne lentille a balayage
US6195059B1 (en) 1998-12-03 2001-02-27 Telefonaktiebolaget L M Ericsson Scanning lens antenna
US6313804B1 (en) 1998-12-03 2001-11-06 Telefonaktiebolaget Lm Ericsson (Publ) Continuous aperture scanning antenna
US6421541B1 (en) 1999-01-22 2002-07-16 Telefonaktiebolaget Lm Ericsson Adaptable bandwidth
WO2001039324A1 (fr) * 1999-11-23 2001-05-31 Telefonaktiebolaget Lm Ericsson (Publ) Dispositif d'antenne lentille a balayage continu
WO2001039323A1 (fr) * 1999-11-23 2001-05-31 Telefonaktiebolaget Lm Ericsson (Publ) Reflecteur d'antenne a balayage a ouverture continue
US6400328B1 (en) 1999-11-23 2002-06-04 Telefonaktiebolaget Lm Ericsson (Publ) Scanning continuous lens antenna device
WO2006062446A1 (fr) * 2004-12-08 2006-06-15 Telefonaktiebolaget Lm Ericsson (Publ) Lentille ferroelectrique
US7777683B2 (en) 2004-12-08 2010-08-17 Telefonaktiebolaget L M Ericsson (Publ) Ferroelectric lens
KR101105960B1 (ko) 2004-12-08 2012-01-18 텔레폰악티에볼라겟엘엠에릭슨(펍) 강유전성 렌즈

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