EP0524878A1 - Halbleitender Mikrowellenabsorber mit optischer Steuerung - Google Patents

Halbleitender Mikrowellenabsorber mit optischer Steuerung Download PDF

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Publication number
EP0524878A1
EP0524878A1 EP92402113A EP92402113A EP0524878A1 EP 0524878 A1 EP0524878 A1 EP 0524878A1 EP 92402113 A EP92402113 A EP 92402113A EP 92402113 A EP92402113 A EP 92402113A EP 0524878 A1 EP0524878 A1 EP 0524878A1
Authority
EP
European Patent Office
Prior art keywords
optical
layer
semiconductor material
screen
absorber according
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.)
Ceased
Application number
EP92402113A
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English (en)
French (fr)
Inventor
Olivier Acher
Alain Mathiot
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.)
Commissariat a lEnergie Atomique et aux Energies Alternatives CEA
Original Assignee
Commissariat a lEnergie Atomique CEA
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 Commissariat a lEnergie Atomique CEA filed Critical Commissariat a lEnergie Atomique CEA
Publication of EP0524878A1 publication Critical patent/EP0524878A1/de
Ceased legal-status Critical Current

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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
    • H01Q3/26—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 relative phase or relative amplitude of energisation between two or more active radiating elements; varying the distribution of energy across a radiating aperture
    • H01Q3/2676—Optically controlled phased array
    • 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
    • H01Q3/46—Active lenses or reflecting arrays

Definitions

  • the present invention relates to a microwave absorber with semiconductor and optical control.
  • the device of the invention can have various shapes (planes, curves, pyramids, etc.), most often it has the shape of a flat screen. We will therefore speak, hereinafter, and for simplicity, of microwave screens.
  • Microwave screens comprising, as illustrated in the appended FIG. 1, a conductive plate 10, with, placed opposite this plate and at a distance from a thin layer 12 of surface resistivity close to 377 Ohms per square.
  • SALISBURY screen Such a screen is often called "SALISBURY screen”.
  • An OEM electromagnetic wave, of wavelength ⁇ 4d, directed perpendicular to the screen, is completely absorbed by it. It is therefore an anti-reflective screen.
  • anti-reflective screens which use conductive and / or magnetic materials dispersed in an insulating matrix (rubber loaded with carbon black, iron particles, etc.).
  • the invention uses the property which certain semiconductors have of seeing their conductivity (or, which amounts to the same thing, their resistivity) change under optical excitation.
  • a semiconductor whose forbidden band has a width Eg and which is excited by an optical radiation of energy higher than Eg, is generally the seat of a photonic absorption generating pairs of electrons-holes. The photocreated electrons (as well as the holes, but to a lesser extent because their mobility is much lower) participate in the conductivity of the semiconductor.
  • the increase in conductivity which results from optical excitation is proportional to the optical power of the excitation, the mobility of the electrons and the lifetime of the photocreated pairs.
  • the conductivity of the semiconductor depends on the nature and the concentration of the impurities it contains (doping).
  • a sufficiently low doping level should be chosen so that the semiconductor has a very low conductivity (in other words, a very high resistivity).
  • its conductivity increases (its resistivity decreases).
  • the prohibited bandwidth is 1.1 eV.
  • the excitation radiation can be obtained by means of a gallium arsenide laser (AsGa), which emits photons of 1.4eV energy, therefore greater than the forbidden band of silicon.
  • AsGa gallium arsenide laser
  • a sufficiently pure silicon wafer (resistivity greater than 2500 ⁇ .cm), 20 ⁇ m thick has a surface conductivity less than 1 / 106 S.
  • the mobility of the electrons in the silicon is 1500cm2 / V / s and the lifetime of the pairs can reach 2.5 ms.
  • the penetration depth of the radiation delivered by the AsGa laser is 10 ⁇ m.
  • FIG. 2 shows a SALISBURY type screen comprising a conductive plate 20 and, opposite this plate and at a distance from a layer 22 of semiconductor material.
  • This layer can be optically excited by means which, in the illustrated variant, comprise optical fibers 24 and 26 supplied by a laser 30 through an optic 32. The laser is controlled by a supply circuit 34.
  • the semiconductor 22 When the supply circuit 34 is out of service, the semiconductor 22 has almost zero conductivity and, therefore, is transparent to microwave frequencies. The assembly then behaves like a simple reflective metallic screen, due to the plate 20, the layer 22 and the fibers 24, 26 playing no role.
  • the laser 30 When the supply circuit 34 is put into service, the laser 30 emits light radiation which is directed by the optics 32 into the fibers 24 and 26. The end of these fibers diffuses the light (as will be better understood in connection with FIG. 4) in the layer 22 (on the two faces of the latter in the illustrated variant, but only one face could suffice).
  • the semiconductor then presents a higher conductivity, which can be close to 1/377 S.
  • a screen of the SALISBURY type that is to say a screen absorbing microwave electromagnetic waves having a normal incidence and whose wavelength is equal at four times the distance d. The difference with the prior art is that, according to the invention, this absorber screen is switchable.
  • optical fibers 22, 24, which surround the semiconductor layer 22, do not in any way disturb the OEM microwave wave, because, being generally made of glass or silica, they behave towards this wave like dielectric.
  • the gap between the conductive plate 20 and the plate 22 of semiconductor material can be filled with a dielectric material of index n, playing the role of spacer.
  • the wavelength for which the screen is reflective is then equal to 4 nd.
  • FIG. 3 shows a SALISBURY type screen with three semiconductor layers 22/1, 22/2, 22/3 placed respectively at distances d1, d2, d3 from the conductive plate 20.
  • Lasers 30/1, 30/2, 30/3 allow each of these layers to be excited separately.
  • a common supply circuit 34 is connected to the lasers by a switching means 35 which makes it possible to supply one or the other of the lasers.
  • That of the semiconductor layers which is excited defines the wavelength ( ⁇ 1, ⁇ 2, ⁇ 3) for which there will be absorption. This wavelength will be equal to four times the distance (d1, d2 or d3) separating the excited semiconductor layer from the conductive plate 20.
  • an absorbing screen which is not only switchable but which has a variable wavelength.
  • the number of semiconductor layers can be arbitrary and is not limited to 3.
  • Figure 4 shows a detail of an optical fiber end that can be used in the invention.
  • the fiber comprises a core 40 and a sheath 42. This sheath can be partially removed at the end of the fiber, to provide an opening directed towards the side of the semiconductor layer to be lit.
  • the arrangement of the fibers which has just been described is not the only possible one.
  • the fibers can also be arranged as illustrated in FIG. 5, where the laser still bears the reference 30 and the fibers the reference 25.
  • the fibers 25 of FIG. 5 work transversely.
  • the optical excitation is obtained at the end of the fiber, the end of the latter being perpendicular to the plane of the semiconductor layer. We can consider placing a small lens system in front of each fiber end.
  • the fiber system is not the only means capable of optically exciting a semiconductor layer.
  • a laser 30 which directly illuminates the semiconductor layer 22.
  • Figure 7 shows a device of another type. It is a composite material absorber 40. This material can be deposited on a support 42. To this composite material is added a semiconductor material. Optical fibers 44 are distributed throughout and are fed by a laser 46.
  • such a device is only anti-reflective for a very particular polarization of the incident radiation and only for a well-defined incidence at a well-defined frequency.
  • the device of the invention and thanks to the semiconductor dispersed in the material, it is possible, by variation of the optical excitation, to modify the angle of incidence or else the frequency for which the absorption is maximum.
  • the materials that can be used are rubber mixed with carbon black or rubber with magnetic particles (iron or ferrite for example).
  • the light source used in the invention is not necessarily a semiconductor laser. This could be a gas laser, for example, or an inconsistent source.
EP92402113A 1991-07-25 1992-07-22 Halbleitender Mikrowellenabsorber mit optischer Steuerung Ceased EP0524878A1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR9109425A FR2679703B1 (fr) 1991-07-25 1991-07-25 Dispositif hyperfrequence a semiconducteur et a commande optique.
FR9109425 1991-07-25

Publications (1)

Publication Number Publication Date
EP0524878A1 true EP0524878A1 (de) 1993-01-27

Family

ID=9415527

Family Applications (1)

Application Number Title Priority Date Filing Date
EP92402113A Ceased EP0524878A1 (de) 1991-07-25 1992-07-22 Halbleitender Mikrowellenabsorber mit optischer Steuerung

Country Status (2)

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EP (1) EP0524878A1 (de)
FR (1) FR2679703B1 (de)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0680111A1 (de) * 1994-04-29 1995-11-02 Hollandse Signaalapparaten B.V. Mikrowellenantenne mit einstellbarer Strahlungscharakteristik
NL9400863A (nl) * 1994-05-26 1996-01-02 Hollandse Signaalapparaten Bv Instelbare microgolfantenne.
GB2406718A (en) * 2003-10-03 2005-04-06 Roke Manor Research Antenna beam steering using a Fresnel zone plate with controllable conductivity
WO2007138583A1 (en) * 2006-05-30 2007-12-06 Kilolambda Technologies Ltd. Optically driven antenna
EP2320521A1 (de) * 2009-11-10 2011-05-11 Nederlandse Organisatie voor toegepast -natuurwetenschappelijk onderzoek TNO Verfahren zum gesteuerten Reflektieren von Radarsignalen mittels Reflektionselementen

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3309704A (en) * 1965-09-07 1967-03-14 North American Aviation Inc Tunable absorber
DE1259965B (de) * 1963-09-26 1968-02-01 Siemens Ag Einrichtung zur Erzielung einer veraenderbaren Daempfung
DE2160936A1 (de) * 1971-12-08 1973-06-14 Siemens Ag Holografische antenne
US4751513A (en) * 1986-05-02 1988-06-14 Rca Corporation Light controlled antennas
US5014069A (en) * 1989-09-15 1991-05-07 The United States Of America As Represented By The Secretary Of The Air Force Photoconductive antenna modulator

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5842303A (ja) * 1981-09-05 1983-03-11 Morio Onoe 反射率可変レ−ダリフレクタ
JP2508707B2 (ja) * 1987-04-28 1996-06-19 三菱電機株式会社 光制御アンテナ装置

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1259965B (de) * 1963-09-26 1968-02-01 Siemens Ag Einrichtung zur Erzielung einer veraenderbaren Daempfung
US3309704A (en) * 1965-09-07 1967-03-14 North American Aviation Inc Tunable absorber
DE2160936A1 (de) * 1971-12-08 1973-06-14 Siemens Ag Holografische antenne
US4751513A (en) * 1986-05-02 1988-06-14 Rca Corporation Light controlled antennas
US5014069A (en) * 1989-09-15 1991-05-07 The United States Of America As Represented By The Secretary Of The Air Force Photoconductive antenna modulator

Non-Patent Citations (3)

* Cited by examiner, † Cited by third party
Title
ELECTRO. 11 Avril 1989, LOS ANGELES US A.ROSEN ET AL. 'Laser activated PIN diode switch from DC to mm-wave' pages 13/4/1-6 *
PATENT ABSTRACTS OF JAPAN vol. 13, no. 97 (E-723)(3445) 7 Mars 1989 & JP-A-63 269 807 ( MITSUBISHI ELECTRIC CORP ) 8 Novembre 1988 *
PATENT ABSTRACTS OF JAPAN vol. 7, no. 123 (E-178)(1268) 27 Mai 1983 & JP-A-58 042 303 ( MORIO ONOUE ) 11 Mars 1983 *

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0680111A1 (de) * 1994-04-29 1995-11-02 Hollandse Signaalapparaten B.V. Mikrowellenantenne mit einstellbarer Strahlungscharakteristik
US5585812A (en) * 1994-04-29 1996-12-17 Hollandse Signaalapparaten B.V. Adjustable microwave antenna
NL9400863A (nl) * 1994-05-26 1996-01-02 Hollandse Signaalapparaten Bv Instelbare microgolfantenne.
GB2406718A (en) * 2003-10-03 2005-04-06 Roke Manor Research Antenna beam steering using a Fresnel zone plate with controllable conductivity
WO2007138583A1 (en) * 2006-05-30 2007-12-06 Kilolambda Technologies Ltd. Optically driven antenna
US7911395B2 (en) 2006-05-30 2011-03-22 Kilolambda Technologies, Ltd. Optically driven antenna
EP2320521A1 (de) * 2009-11-10 2011-05-11 Nederlandse Organisatie voor toegepast -natuurwetenschappelijk onderzoek TNO Verfahren zum gesteuerten Reflektieren von Radarsignalen mittels Reflektionselementen
WO2011059317A1 (en) 2009-11-10 2011-05-19 Nederlandse Organisatie Voor Toegepast-Natuurwetenschappelijk Onderzoek Tno System and method for detecting information from an object coding module using radar signals

Also Published As

Publication number Publication date
FR2679703A1 (fr) 1993-01-29
FR2679703B1 (fr) 1993-12-03

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