EP0248686A1 - Array of elements scattering electromagnetic energy by optical control - Google Patents

Array of elements scattering electromagnetic energy by optical control Download PDF

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Publication number
EP0248686A1
EP0248686A1 EP87400891A EP87400891A EP0248686A1 EP 0248686 A1 EP0248686 A1 EP 0248686A1 EP 87400891 A EP87400891 A EP 87400891A EP 87400891 A EP87400891 A EP 87400891A EP 0248686 A1 EP0248686 A1 EP 0248686A1
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European Patent Office
Prior art keywords
frequency
radiating element
modulation
network
microwave
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EP87400891A
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German (de)
French (fr)
Inventor
François Gautier
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Thales SA
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Thomson CSF SA
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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
    • H01Q3/44—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

  • the main object of the invention is a network of optically controlled electromagnetic energy diffusing elements.
  • the main object of the invention is a network ensuring the diffusion of microwave energy in the near field. It is known to produce controllable diffusing networks comprising radiating elements charged by variable impedances. For example, electronically controlled diodes are used. In the absence of a control signal, an electromagnetic wave illuminating the network is reflected and / or broadcast without changing the frequency.
  • a modulated state of the network is obtained by modulating the impedance of the charges at a frequency f m of one or more elements of the network.
  • the modulation of certain diffusing elements is a phase modulation.
  • a wave of frequency f0 lighting the network will be diffused with a spectrum of the lines and the frequency will be equal to: f0 + kf m k being a relative integer.
  • the modulation is a pure amplitude modulation.
  • the waves diffused by the network comprise in addition to the spectral line at the frequency f0 the spectral line f0 + f m thus the spectral line corresponding to the frequency f0 - f m .
  • the device of known type included an electrical control of the modulation of the diodes organized in the matrix form. Such a device is described in French patent n ° 81 09855.
  • a diode for example the diode located at the intersection of line I and column J is controlled by simultaneously receiving a signal on line I and the column J. So the device greatly reduces the number of connections required.
  • the matrix control prohibits the individual control of a plurality of diodes.
  • the length of the modulation current supply lines prevents obtaining high frequency modulations for large panels. For example, it is practically impossible to exceed 100 MHz for panels whose surface exceeds 1 m2.
  • each radiating element is associated with a diode, the modulation control of which is provided by a photoreceptor.
  • a diode the modulation control of which is provided by a photoreceptor.
  • the light wave is for example emitted by laser.
  • the control of each radiating element is completely independent.
  • the main object of the invention is a microwave radiating element capable of being modulated at a frequency f m , characterized in that it comprises a photoelectric detector capable of transforming a light signal modulated at the frequency f m into an electrical signal of control of the modulation of the radiating element.
  • the subject of the invention is also a network of microwave radiating elements, characterized in that it comprises microwave radiating elements with beam modulation control luminous.
  • FIGS. 1 to 7 the same references have been used to designate the same elements.
  • a scattering network 1 comprising radiating elements charged by variable impedances.
  • the radiating elements are diodes 2.
  • Each diode 2 is capable of being supplied by a current modulated at the frequency f m .
  • the modulation of the diode 2 is symbolized by two electric wires 4.
  • the reflective network 1 is illuminated by a radio wave 3 the radiating elements 2 modulated at the frequency f m omnidirectionally diffuse waves of frequency f0 + kf m .
  • phase modulation k is a relative integer.
  • FIG 2 we can see a diagram illustrating the device for controlling the modulation of four diodes 2 of a panel 1 of known type.
  • Diodes 2 are at the intersection of lines I and K and columns J and L. If, for example, we want to modulate at a frequency f1 diode 2 located at the intersection of line I and column J we send a signal of frequency f1 in column J to a validation signal in line I. If we wish to modulate at a frequency f2 diode 2 located at the intersection of column L and line K we send a signal of frequency f2 in column L to a validation signal in line K.
  • the radiating element comprises for example a dipole 20 between the branches of which is disposed a diode 2.
  • the diode 2 is supplied by an amplifier 6 controlled by a photoelectric receiver 5.
  • the photoreceptor 5 as well as the diode 2 are connected to ground by a line 9.
  • the amplifier 6 is electrically supplied by a line 8 connected to the + terminal of a generator not shown.
  • a second terminal of the photoreceptor 5 is connected to the amplifier 6.
  • a capacitor 7 connects the supply lines 8 and 9.
  • the capacitor 7 stores the electrical energy necessary for supplying the amplifier 6 and to the polarization of the diode 2.
  • the local storage of the electrical energy makes it possible to instantly deliver the necessary electrical power and thus to reach high frequencies.
  • the photoreceptor 5 is for example a photoresistor, a phototransistor or a photodiode.
  • the sensitivity of the photoreceptor 5 is compatible with the frequency of the carrier of the modulation used.
  • the amplifier 6 is adapted to the modulation frequencies used.
  • FIG. 4 we can see a second embodiment of a diffusing element according to the invention.
  • the diode 2 placed between the two branches of the dipole 20 is supplied by two transistors 10 and 11 controlled by the photodetector 5.
  • a first terminal of the photodetector 5 is brought to ground.
  • a second terminal of the photodetector 5 is connected to the base of the transistor 11.
  • the emitter of the transistor 11 is connected to the base of the transistor 10.
  • the collectors of the transistors 10 and 11 are connected to the power supply (not shown).
  • the emitter of transistor 10 is connected to one of the terminals of diode 2.
  • the generator (not shown) maintains for example a potential difference of three volts between the positive terminal and ground.
  • a capacitor 70 is placed at the terminals of the diode 2 ensuring the decoupling of the microwave field received and / or emitted by the dipole 20 and the diode 2 from the electrical supply.
  • a capacitor 7 is placed at the terminals of the power supply.
  • the terminal of diode 2 opposite to that connected to the emitter of transistor 10 is connected to ground.
  • FIG. 5 we can see an embodiment of the device according to the invention capable of directly emitting modulated radiation, the modulation being transmitted optically.
  • the photodetector 5 is connected to the two branches of the dipole 20.
  • a amplifier 6, for example supplied by a line 8 makes it possible to amplify the signal picked up by the photodetector 5 and sent to the dipole 20.
  • the device of FIG. 5 makes it possible to emit modulated radiation without being lit by a source of microwave radiation.
  • the device illustrated in FIG. 5 applies in particular to the production of autonomous beacons without electrical connection with a microwave signal generator.
  • diodes 2 are used, the variation of the microwave impedance of which is sufficient when it goes from a zero bias voltage to the voltage of one volt.
  • the diode has a capacitance of less than 0.16 pF at 0 volts, ie 100 J ⁇ at 1010 Hz; direct resistance of the order of 1 ⁇ for a voltage substantially equal to 1 volt.
  • the diodes do not have to support power.
  • diodes are chosen which are suitable for high switching frequencies. For example, diodes capable of switching several hundred megahertz are used.
  • the amplifier 6 is composed of a single transistor.
  • the amplifier 6 comprises two transistors 10 and 11 mounted in Darlington.
  • an integrated amplifier is used.
  • the factor 1 ⁇ 2 takes into account the modulation of the signal. So that the capacitor 7 does not discharge by more than 10%, its capacity C must be equal to:
  • Such a capacitor 7 is capable of supplying 2 V necessary for the operation of the amplifier 6 and the 1 V serving for the polarization of the diode 2.
  • the device comprises a microwave energy receiver 30, a network 1 provided with its electrical supply 40, a control circuit 39 ensuring the control, lasers 31 and devices 38 for deflecting the laser beams.
  • the microwave radiation receiver 30 is for example the antenna of a radar whose performance is to be tested.
  • the network 1 comprises devices illustrated in FIGS. 3 or 4 distributed periodically over the surface of the network.
  • the network 1 comprises between 10,000 and 100,000 devices illustrated in FIG. 4.
  • the increase in the number of devices in FIG. 4 allows a reduction in the pitch and therefore an increase in the resolution of the device.
  • the network 1 is produced in the form of a printed circuit by photoengraving the radiating elements and the supply lines, the active components being transferred to said printed circuit.
  • the modulation circuits receive, in parallel, the supply voltage supplied by the generator 41.
  • the supply lines are arranged so as to minimize the disturbances of the electromagnetic field.
  • the supply lines are arranged perpendicular to the electric field of the radiation capable of illuminating the network 1.
  • the laser or lasers 31 comprise a source of radiation whose frequency and power are adapted to the photodetector 5 used, a modulation device as well as a beam orientation device 38.
  • a modulation device for amplitude modulation, use will be made, for example, of a Kerr effect cell making it possible to modulate and interrupt the light emission.
  • the beam orientation device 38 comprises for example movable mirrors and servomechanisms.
  • the device beam orientation includes variable index electronic devices.
  • the lasers 31 and the beam orientation devices 38 are controlled by a control device 39.
  • the control device 39 supplies each laser 31 via a line 36 with the signal modulated at the frequency f m ensuring the modulation of the laser beam at the desired frequency.
  • the orientation of the beam is controlled by lines 37 connecting the control circuit 39 to the beam orientation device 38.
  • FIG. 6 only two lasers 31 have been illustrated. It is understood that the use of a larger number of lasers is not outside the scope of the present invention.
  • a single laser makes it possible to modulate a plurality of diodes 2, the beam orientation device 38 making it possible to illuminate these diodes successively, the modulation cell stopping the beam before pointing is not established.
  • the network 1 is enclosed in an enclosure 40 absorbing light radiation liable to excite the photodetectors 5 and / or the microwave radiation.
  • the antenna 30 whose performance we want to measure illuminates the network 1 according to the invention and measures the field reflected by said networks.
  • the network 1 is illuminated by a source of microwave radiation 33, the antenna 30 analyzing the field transmitted by the network 1.
  • the antenna 33 has a diagram adapted to the geometry of the network 1.
  • the antenna 33 transmits the frequency f0 whose spectrum has the purity necessary for the operation of the receiver connected to the antenna 30.
  • the antenna 33 permanently illuminates the entire reflecting network 1.
  • the antenna 33 alone illuminates the zone or zones of the network 1 where the modulation is applied. Scanning is obtained either by mechanically pointing the antenna 33 or by electronic scanning.
  • FIG 7 we can see a microwave tomography device of the human body.
  • a patient 34 is illuminated by microwave energy at the antenna of an antenna 33.
  • a network 1 according to the invention associated with a laser 31 and devices 38 for deflecting the beam makes it possible to analyze the fields transmitted by the bodies from the patient 34.
  • the field transmitted for example inside an enclosure 40 is picked up by a receiving antenna 32.
  • Advantageously water bags 35 are provided above and below the patient 34 allowing better adaptation microwave energy.
  • a power wave P0 illuminate a surface network S made up of elements whose collection surface is s.
  • the modulation efficiency depends considerably on the modulation frequency and on the characteristics of the charging diode 2. We will take as typical value an efficiency of 1%.
  • the diffracted power is then:
  • the device according to the present invention is mainly applied to the measurement of electromagnetic field, to the simulation of bright spots for radar antenna test, to the production of beacons as well as to the tomography of the human body using microwaves.

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Abstract

Array able to diffract the electromagnetic energy illuminating it, certain elements of the said array being capable of being modulated. The device according to the invention comprises photodetectors (5) permitting optical modulation of the diffracting or scattering emitter/reflector elements. Optical modulation permits individual control of each radiating element right up to very high frequencies. Moreover the device according to the invention permits the complexity of an array (1) to be reduced by eliminating the control wiring. <??>The invention applies mainly to the construction of test devices for radar, for example simulation of bright points, hyperfrequency tomography of the human body, and the construction of beacons. <IMAGE>

Description

L'invention a principalement pour objet un réseau d'éléments diffusants d'énergie électromagnétique à commande optique.The main object of the invention is a network of optically controlled electromagnetic energy diffusing elements.

L'invention a principalement pour objet un réseau assurant la diffusion d'énergie hyperfréquence en champ proche. Il est connu de réaliser des réseaux diffusants commandables comportant des éléments rayonnants chargés par des impédances variables. Par exemple on utilise des diodes commandées électroniquement. En l'absence de signal de commande une onde électromagnétique éclairant le réseau est réfléchie et/ou diffusée sans changement de fréquence.The main object of the invention is a network ensuring the diffusion of microwave energy in the near field. It is known to produce controllable diffusing networks comprising radiating elements charged by variable impedances. For example, electronically controlled diodes are used. In the absence of a control signal, an electromagnetic wave illuminating the network is reflected and / or broadcast without changing the frequency.

On obtient un état modulé du réseau par modulation de l'impédance des charges à une fréquence fm d'un ou plusieurs éléments du réseau.A modulated state of the network is obtained by modulating the impedance of the charges at a frequency f m of one or more elements of the network.

Dans un premier exemple, la modulation de certains éléments diffusants est une modulation de phase. Dans ce cas une onde de fréquence f₀ éclairant le réseau sera diffusée avec un spectre des raies et la fréquence sera égale à:
f₀ + kfm
k étant un entier relatif.In a first example, the modulation of certain diffusing elements is a phase modulation. In this case a wave of frequency f₀ lighting the network will be diffused with a spectrum of the lines and the frequency will be equal to:
f₀ + kf m
k being a relative integer.

Dans un second exemple, la modulation est une pure modu­lation d'amplitude. Dans ce cas, les ondes diffusées par le réseau comportent en plus de la raie spectrale à la fréquence f₀ la raie spectrale f₀ + fm ainsi la raie spectrale correspondant à la fré­quence f₀ - fm.In a second example, the modulation is a pure amplitude modulation. In this case, the waves diffused by the network comprise in addition to the spectral line at the frequency f₀ the spectral line f₀ + f m thus the spectral line corresponding to the frequency f₀ - f m .

Le dispositif de type connu comportait une commande élec­trique de la modulation des diodes organisée sous la forme matri­cielle. Un tel dispositif est décrit dans le brevet français n° 81 09855. Une diode, par exemple la diode se trouvant à l'inter­section de la ligne I et de la colonne J est commandée en recevant simultanément un signal sur la ligne I et la colonne J. Ainsi le dispositif réduit dans une très grande proportion le nombre de connexions nécessaires.The device of known type included an electrical control of the modulation of the diodes organized in the matrix form. Such a device is described in French patent n ° 81 09855. A diode, for example the diode located at the intersection of line I and column J is controlled by simultaneously receiving a signal on line I and the column J. So the device greatly reduces the number of connections required.

Les dispositifs de type connu présentent des inconvénients. D'une part la commande matricielle interdit la commande indivi­duelle d'une pluralité de diodes.Known type devices have drawbacks. On the one hand, the matrix control prohibits the individual control of a plurality of diodes.

D'autre part, la longueur des lignes d'amenée de courant de modulation empêche l'obtention des modulations à fréquence élevée pour des panneaux de grande dimension. Par exemple, il est prati­quement impossible de dépasser 100 MHz pour des panneaux dont la surface dépasse 1 m².On the other hand, the length of the modulation current supply lines prevents obtaining high frequency modulations for large panels. For example, it is practically impossible to exceed 100 MHz for panels whose surface exceeds 1 m².

De plus il est extrémement difficile de réaliser des circuits de modulation. En effet il faut pouvoir alimenter l'une quelconque des colonnes et des lignes. Il est donc nécessaire de réaliser un aiguilleur comportant de nombreuses sorties. Par exemple un réseau de pas 20 mm d'une surface de 2 m sur 2 m comporte 100 colonnes et 100 lignes.In addition, it is extremely difficult to produce modulation circuits. Indeed it must be able to supply any of the columns and rows. It is therefore necessary to make a switch with numerous outputs. For example, a 20 mm pitch network with a surface area of 2 m by 2 m has 100 columns and 100 rows.

Dans le dispositif selon l'invention chaque élément rayonnant est associé à une diode dont la commande de modulation est assurée par un photorécepteur. Pour moduler un élément donné il suffit d'envoyer une onde lumineuse sur le photorécepteur connecté à l'élément rayonnant correspondant. L'onde lumineuse est par exemple émise par laser. Pour alimenter simultanément une plura­lité d'éléments rayonnants il suffit de moduler plusieurs photo­récepteurs avec par exemple une pluralité de lasers. La commande de chaque élément rayonnant est parfaitement indépendante.In the device according to the invention, each radiating element is associated with a diode, the modulation control of which is provided by a photoreceptor. To modulate a given element, it is sufficient to send a light wave to the photoreceptor connected to the corresponding radiating element. The light wave is for example emitted by laser. To simultaneously supply a plurality of radiating elements, it suffices to modulate several photoreceptors with, for example, a plurality of lasers. The control of each radiating element is completely independent.

L'invention a principalement pour objet un élément rayonnant hyperfréquence susceptible d'être modulé à une fréquence fm, caractérisé par le fait qu'il comporte un détecteur photoélectrique susceptible de transformer un signal lumineux modulé à la fréquence fm en un signal électrique de commande de la modulation de l'élément rayonnant.The main object of the invention is a microwave radiating element capable of being modulated at a frequency f m , characterized in that it comprises a photoelectric detector capable of transforming a light signal modulated at the frequency f m into an electrical signal of control of the modulation of the radiating element.

L'invention a aussi pour objet un réseau d'éléments rayonnants hyperfréquence, caractérisé par le fait qu'il comporte des éléments rayonnants hyperfréquence à commande de modulation par rayon­ nement lumineux.The subject of the invention is also a network of microwave radiating elements, characterized in that it comprises microwave radiating elements with beam modulation control luminous.

L'invention sera mieux comprise au moyen de la description ci-­après et des figures données comme des exemples non limitatifs parmi lesquels :

  • - la figure 1 est un schéma illustrant le principe du fonctionnement d'un réseau diffusant ;
  • - la figure 2 est un schéma illustrant les inconvénients du dispositif de type connu ;
  • - la figure 3 est un schéma d'un premier exemple de réalisation d'éléments rayonnants selon l'invention ;
  • - la figure 4 est un schéma d'une seconde variante de réalisation d'un élément rayonnant selon l'invention ;
  • - la figure 5 est un schéma d'un troisième exemple de réalisation d'un élément rayonnant selon l'invention ;
  • - la figure 6 est un schéma d'un premier exemple d'application du dispositif selon l'invention ;
  • - la figure 7 est un schéma d'un second exemple d'application du dispositif selon l'invention.
The invention will be better understood by means of the description below and the figures given as nonlimiting examples among which:
  • - Figure 1 is a diagram illustrating the principle of operation of a broadcasting network;
  • - Figure 2 is a diagram illustrating the drawbacks of the known type of device;
  • - Figure 3 is a diagram of a first embodiment of radiating elements according to the invention;
  • - Figure 4 is a diagram of a second alternative embodiment of a radiating element according to the invention;
  • - Figure 5 is a diagram of a third embodiment of a radiating element according to the invention;
  • - Figure 6 is a diagram of a first example of application of the device according to the invention;
  • - Figure 7 is a diagram of a second example of application of the device according to the invention.

Sur les figures 1 à 7 on a utilisé les mêmes références pour désigner les mêmes éléments.In FIGS. 1 to 7, the same references have been used to designate the same elements.

Sur la figure 1, on peut voir un réseau diffusant 1 comportant des éléments rayonnants chargés par des impédances variables. Dans l'exemple illustré sur la figure 1 les éléments rayonnants sont des diodes 2. Pour la clarté de la figure seules six diodes 2 ont été représentées. Chaque diode 2 est susceptible d'être alimentée par un courant modulé à la fréquence fm. Sur la figure 1 la modulation de la diode 2 est symbolisée par deux fils électriques 4. Quand le réseau réflecteur 1 est illuminé par une onde radioélectrique 3 les éléments rayonnants 2 modulés à la fréquence fm diffusent omnidirection­nellement des ondes de fréquence f₀ + kfm.In Figure 1, we can see a scattering network 1 comprising radiating elements charged by variable impedances. In the example illustrated in Figure 1 the radiating elements are diodes 2. For the clarity of the figure only six diodes 2 have been shown. Each diode 2 is capable of being supplied by a current modulated at the frequency f m . In FIG. 1 the modulation of the diode 2 is symbolized by two electric wires 4. When the reflective network 1 is illuminated by a radio wave 3 the radiating elements 2 modulated at the frequency f m omnidirectionally diffuse waves of frequency f₀ + kf m .

Dans le cas d'une modulation d'amplitude k = ± 1.In the case of amplitude modulation k = ± 1.

Dans le cas d'une modulation de phase k est un entier relatif.In the case of a phase modulation k is a relative integer.

Sur la figure 2, on peut voir un schéma illustrant le dispositif de commande de modulation de quatre diodes 2 d'un panneau 1 de type connu. Les diodes 2 se trouvent à l'intersection des lignes I et K et des colonnes J et L. Si, par exemple, on désire moduler à une fréquence f₁ la diode 2 se trouvant à l'intersection de la ligne I et de la colonne J on envoie un signal de fréquence f₁ dans la colonne J à un signal de validation dans la ligne I. Si on désire moduler à une fréquence f₂ la diode 2 se trouvant à l'intersection de la colonne L et de la ligne K on envoie un signal de fréquence f₂ dans la colonne L à un signal de validation dans la ligne K. Ainsi, si l'on désire obtenir les deux modulations précédentes simultanément avec un réseau de type connu, en plus de la diode 2 se trouvant à l'inter­section de la colonne J et de la ligne I qui sera modulée à la fréquence f₁ et de la diode 2 se trouvant à l'intersection de la colonne L et de la ligne K qui sera modulée à une frquence f₂, les diodes 2 se trouvant à l'intersection de la colonne J et de la ligne K et la diode 2 se trouvant à l'intersection de la colonne L et de la ligne I seront modulées, respectivement, aux fréquences f₁ et f₂. Ainsi, avec les dispositifs de type connu il est impossible de moduler deux diodes ne se trouvant pas sur la même colonne. De plus il est impossible de moduler deux diodes appartenant à une même colonne avec deux fréquences différentes.In Figure 2, we can see a diagram illustrating the device for controlling the modulation of four diodes 2 of a panel 1 of known type. Diodes 2 are at the intersection of lines I and K and columns J and L. If, for example, we want to modulate at a frequency f₁ diode 2 located at the intersection of line I and column J we send a signal of frequency f₁ in column J to a validation signal in line I. If we wish to modulate at a frequency f₂ diode 2 located at the intersection of column L and line K we send a signal of frequency f₂ in column L to a validation signal in line K. Thus, if one wishes to obtain the two preceding modulations simultaneously with a network of known type, in addition to the diode 2 being at the intersection of column J and line I which will be modulated at frequency f₁ and diode 2 located at the intersection of column L and line K which will be modulated at a frequency f₂, diodes 2 being at the intersection of column J and row K and diode 2 located at the intersection of column L and l a line I will be modulated, respectively, at frequencies f₁ and f₂. Thus, with the devices of known type it is impossible to modulate two diodes not being on the same column. In addition, it is impossible to modulate two diodes belonging to the same column with two different frequencies.

Sur la figure 3, on peut voir un exemple de réalisation d'un élément rayonnant selon l'invention. L'élément rayonnant comporte par exemple un dipôle 20 entre les branches duquel est disposée une diode 2. Avantageusement la diode 2 est alimentée par un amplifi­cateur 6 commandé par un récepteur photoélectrique 5. Par exemple, le photorécepteur 5 ainsi que la diode 2 sont reliés à la masse par une ligne 9. L'amplificateur 6 est alimenté électri­quement par une ligne 8 reliée à la borne + d'un générateur non représenté. Une seconde borne du photorécepteur 5 est reliée à l'amplificateur 6. Avantageusement, un condensateur 7 relie les lignes d'alimentation 8 et 9. Ainsi le condensateur 7 stocke l'énergie électrique nécessaire à l'alimentation de l'amplificateur 6 et à la polarisation de la diode 2. Le stockage local de l'énergie électrique permet de délivrer instantanément la puissance électrique néces­saire et ainsi d'atteindre des fréquences élevées.In Figure 3, we can see an embodiment of a radiating element according to the invention. The radiating element comprises for example a dipole 20 between the branches of which is disposed a diode 2. Advantageously the diode 2 is supplied by an amplifier 6 controlled by a photoelectric receiver 5. For example, the photoreceptor 5 as well as the diode 2 are connected to ground by a line 9. The amplifier 6 is electrically supplied by a line 8 connected to the + terminal of a generator not shown. A second terminal of the photoreceptor 5 is connected to the amplifier 6. Advantageously, a capacitor 7 connects the supply lines 8 and 9. Thus the capacitor 7 stores the electrical energy necessary for supplying the amplifier 6 and to the polarization of the diode 2. The local storage of the electrical energy makes it possible to instantly deliver the necessary electrical power and thus to reach high frequencies.

Le photorécepteur 5 est par exemple une photorésistance, un phototransistor ou une photodiode. La sensibilité du photorécepteur 5 est compatible avec la fréquence de la porteuse de la modulation utilisée. L'amplificateur 6 est adapté aux fréquences de modulation utilisée.The photoreceptor 5 is for example a photoresistor, a phototransistor or a photodiode. The sensitivity of the photoreceptor 5 is compatible with the frequency of the carrier of the modulation used. The amplifier 6 is adapted to the modulation frequencies used.

Sur la figure 4, on peut voir un second exemple de réalisation d'un élément diffusant selon l'invention. Dans l'exemple de réali­sation illustré sur la figure 4, la diode 2 placée entre les deux branches du dipôle 20 est alimentée par deux transistors 10 et 11 commandés par le photodétecteur 5. Une première borne du photo­détecteur 5 est portée à la masse. Une seconde borne du photo­détecteur 5 est reliée à la base du transistor 11. L'émetteur du transistor 11 est relié à la base du transistor 10. Les collecteurs des transistors 10 et 11 sont connectés à l'alimentation électrique (non représentée). L'émetteur du transistor 10 est relié à une des bornes de la diode 2. Le générateur (non représenté) maintient par exemple une différence de potentiel de trois volts entre la borne positive et la masse. Avantageusement, un condensateur 70 est placé aux bornes de la diode 2 assurant le découplage du champ hyper­fréquence reçu et/ou émis par le dipôle 20 et la diode 2 de l'alimentation électrique.In Figure 4, we can see a second embodiment of a diffusing element according to the invention. In the embodiment illustrated in FIG. 4, the diode 2 placed between the two branches of the dipole 20 is supplied by two transistors 10 and 11 controlled by the photodetector 5. A first terminal of the photodetector 5 is brought to ground. A second terminal of the photodetector 5 is connected to the base of the transistor 11. The emitter of the transistor 11 is connected to the base of the transistor 10. The collectors of the transistors 10 and 11 are connected to the power supply (not shown). The emitter of transistor 10 is connected to one of the terminals of diode 2. The generator (not shown) maintains for example a potential difference of three volts between the positive terminal and ground. Advantageously, a capacitor 70 is placed at the terminals of the diode 2 ensuring the decoupling of the microwave field received and / or emitted by the dipole 20 and the diode 2 from the electrical supply.

Avantageusement un condensateur 7 est placé aux bornes de l'alimentation. La borne de la diode 2 opposée à celle reliée à l'émetteur du transistor 10 est reliée à la masse.Advantageously, a capacitor 7 is placed at the terminals of the power supply. The terminal of diode 2 opposite to that connected to the emitter of transistor 10 is connected to ground.

Sur la figure 5, on peut voir un exemple de réalisation du dispositif selon l'invention susceptible d'émettre directement des rayonnements modulés, la modulation étant transmise par voie optique. Le photodétecteur 5 est relié aux deux branches du dipôle 20. Avantageusement, pour obtenir une puissance supérieure, un amplificateur 6 par exemple alimenté par une ligne 8 permet d'amplifier le signal capté par le photodétecteur 5 et envoyé au dipôle 20. Le dispositif de la figure 5 permet d'émettre un rayon­nement modulé sans être éclairé par une source de rayonnement hyperfréquence. Ainsi le dispositif illustré sur la figure 5 s'applique notamment à la réalisation des balises autonomes sans liaison électrique avec un générateur de signal hyperfréquence.In Figure 5, we can see an embodiment of the device according to the invention capable of directly emitting modulated radiation, the modulation being transmitted optically. The photodetector 5 is connected to the two branches of the dipole 20. Advantageously, to obtain a higher power, a amplifier 6, for example supplied by a line 8, makes it possible to amplify the signal picked up by the photodetector 5 and sent to the dipole 20. The device of FIG. 5 makes it possible to emit modulated radiation without being lit by a source of microwave radiation. Thus the device illustrated in FIG. 5 applies in particular to the production of autonomous beacons without electrical connection with a microwave signal generator.

Dans un exemple de réalisation du dispositif selon l'invention on utilise des diodes 2 dont la variation de l'impédance en hyper­fréquence est suffisante lorsqu'elle passe d'une tension de polari­sation nulle à la tension d'un volt. La diode présente une capacité inférieure à 0,16 pF à 0 volt soit 100 J Ω à 10¹⁰ Hz ; résistance directe de l'ordre de 1 Ω pour une tension sensiblement égale à 1 volt.In an exemplary embodiment of the device according to the invention, diodes 2 are used, the variation of the microwave impedance of which is sufficient when it goes from a zero bias voltage to the voltage of one volt. The diode has a capacitance of less than 0.16 pF at 0 volts, ie 100 J Ω at 10¹⁰ Hz; direct resistance of the order of 1 Ω for a voltage substantially equal to 1 volt.

Dans le dispositif selon l'invention les diodes n'ont pas à supporter de puissance. Avantageusement on choisit donc des diodes adaptées aux fréquences de commutation élevée. Par exemple on utilise des diodes capables de commuter plusieurs centaines de megahertz.In the device according to the invention the diodes do not have to support power. Advantageously, therefore, diodes are chosen which are suitable for high switching frequencies. For example, diodes capable of switching several hundred megahertz are used.

Dans un premier exemple de réalisation du dispositif selon l'invention, l'amplificateur 6 est composé d'un unique transistor.In a first embodiment of the device according to the invention, the amplifier 6 is composed of a single transistor.

Dans un second exemple de réalisation du dispositif selon l'invention l'amplificateur 6 comporte deux transistors 10 et 11 montés en Darlington.In a second embodiment of the device according to the invention, the amplifier 6 comprises two transistors 10 and 11 mounted in Darlington.

Dans un troisième exemple de réalisation du dispositif selon l'invention on utilise un amplificateur intégré.In a third embodiment of the device according to the invention, an integrated amplifier is used.

Le condensateur 7 permet de fournir instantanément l'énergie nécessaire aux diodes 2. Par exemple pour une durée de fonction­nement de 1 µs avec un débit de 20 mA sous 3 V il est nécessaire de fournir une charge Q = ½ 10⁻⁶ . 20 . 10⁻³ = 10⁻⁸ × CThe capacitor 7 makes it possible to instantly supply the energy necessary for the diodes 2. For example for an operating time of 1 μs with a flow rate of 20 mA at 3 V, it is necessary to supply a charge Q = ½ 10⁻⁶. 20. 10⁻³ = 10⁻⁸ × C

Le facteur ½ tient compte de la modulation du signal. Pour que le condensateur 7 ne se décharge pas de plus de 10% il faut que sa capacité C soit égale à : The factor ½ takes into account the modulation of the signal. So that the capacitor 7 does not discharge by more than 10%, its capacity C must be equal to:

Un tel condensateur 7 est capable de fournir 2 V nécessaires au fonctionnement de l'amplificateur 6 et le 1 V servant à la polarisation de la diode 2.Such a capacitor 7 is capable of supplying 2 V necessary for the operation of the amplifier 6 and the 1 V serving for the polarization of the diode 2.

Sur la figure 6, on peut voir un dispositif de mesure de champ selon l'invention. Le dispositif comporte un récepteur d'énergie hyperfréquence 30, un réseau 1 muni de son alimentation électrique 40, un circuit de commande 39 assurant la commande, des lasers 31 et des dispositifs 38 de déflexion des faisceaux laser.In Figure 6, we can see a field measuring device according to the invention. The device comprises a microwave energy receiver 30, a network 1 provided with its electrical supply 40, a control circuit 39 ensuring the control, lasers 31 and devices 38 for deflecting the laser beams.

Le récepteur 30 de rayonnement hyperfréquence est par exemple l'antenne d'un radar dont on veut tester les performances. Le réseau 1 comporte des dispositifs illustrés sur les figures 3 ou 4 répartis périodiquement sur la surface du réseau. Par exemple le réseau 1 comporte entre 10000 et 100000 dispositifs illustrés sur la figure 4. L'augmentation du nombre de dispositifs de la figure 4 permet une diminution du pas et donc une augmentation de la résolution du dispositif. Avantageusement le réseau 1 est réalisé sous forme d'un circuit imprimé en photogravant les éléments rayonnants et les lignes d'alimentation, les composants actifs étant reportés sur ledit circuit imprimé.The microwave radiation receiver 30 is for example the antenna of a radar whose performance is to be tested. The network 1 comprises devices illustrated in FIGS. 3 or 4 distributed periodically over the surface of the network. For example, the network 1 comprises between 10,000 and 100,000 devices illustrated in FIG. 4. The increase in the number of devices in FIG. 4 allows a reduction in the pitch and therefore an increase in the resolution of the device. Advantageously, the network 1 is produced in the form of a printed circuit by photoengraving the radiating elements and the supply lines, the active components being transferred to said printed circuit.

Avantageusement, les circuits de modulation reçoivent, en parallèle la tension d'alimentation fournie par le générateur 41.Advantageously, the modulation circuits receive, in parallel, the supply voltage supplied by the generator 41.

Avantageusement, les lignes d'alimentation sont disposées de façon à minimiser les perturbations du champ électromagnétique. Par exemple les lignes d'alimentation sont disposées perpendicu­lairement au champ électrique du rayonnement susceptible d'éclairer le réseau 1. Le ou les lasers 31 comportent une source de rayonnement dont la fréquence et la puissance sont adaptées au photodétecteur 5 utilisé, un dispositif de modulation ainsi qu'un dispositif 38 d'orientation du faisceau. Pour une modulation d'ampli­tude on utilisera par exemple une cellule à effet Kerr permettant de moduler et d'interrompre l'émission lumineuse. Le dispositif d'orien­tation du faisceau 38 comporte par exemple des miroirs mobiles et des servomécanismes. Dans une variante de réalisation le dispositif d'orientation du faisceau comporte des dispositifs électroniques à indice variable. Les lasers 31 et les dispositifs d'orientation de faisceau 38 sont commandés par un dispositif de commande 39. Le dispositif de commande 39 fournit à chaque laser 31 par l'intermé­diaire d'une ligne 36 le signal modulé à la fréquence fm assurant la modulation du faisceau laser à la fréquence désirée. L'orientation du faisceau est commandé par des lignes 37 reliant le circuit de commande 39 au dispositif d'orientation du faisceau 38. Sur la figure 6 seuls deux lasers 31 ont été illustrés. Il est bien entendu que l'utilisation d'un nombre plus grand de laser ne sort pas du cadre de la présente invention.Advantageously, the supply lines are arranged so as to minimize the disturbances of the electromagnetic field. For example, the supply lines are arranged perpendicular to the electric field of the radiation capable of illuminating the network 1. The laser or lasers 31 comprise a source of radiation whose frequency and power are adapted to the photodetector 5 used, a modulation device as well as a beam orientation device 38. For amplitude modulation, use will be made, for example, of a Kerr effect cell making it possible to modulate and interrupt the light emission. The beam orientation device 38 comprises for example movable mirrors and servomechanisms. In an alternative embodiment the device beam orientation includes variable index electronic devices. The lasers 31 and the beam orientation devices 38 are controlled by a control device 39. The control device 39 supplies each laser 31 via a line 36 with the signal modulated at the frequency f m ensuring the modulation of the laser beam at the desired frequency. The orientation of the beam is controlled by lines 37 connecting the control circuit 39 to the beam orientation device 38. In FIG. 6 only two lasers 31 have been illustrated. It is understood that the use of a larger number of lasers is not outside the scope of the present invention.

Dans une variante de réalisation du dispositif selon l'invention un laser unique permet de moduler une pluralité des diodes 2, le dispositif d'orientation du faisceau 38 permettant d'éclairer succes­sivement ces diodes, la cellule de modulation arrêtant le faisceau avant que le pointage ne soit établi.In an alternative embodiment of the device according to the invention, a single laser makes it possible to modulate a plurality of diodes 2, the beam orientation device 38 making it possible to illuminate these diodes successively, the modulation cell stopping the beam before pointing is not established.

Avantageusement, le réseau 1 est enfermé dans une enceinte 40 absorbant les rayonnements lumineux suceptibles d'exciter les photodétecteurs 5 et/ou le rayonnement hyperfréquence.Advantageously, the network 1 is enclosed in an enclosure 40 absorbing light radiation liable to excite the photodetectors 5 and / or the microwave radiation.

Dans une première variante de réalisation l'antenne 30 dont on veut mesurer les performances éclaire le réseau 1 selon l'invention et mesure le champ réfléchi par lesdits réseaux.In a first alternative embodiment, the antenna 30 whose performance we want to measure illuminates the network 1 according to the invention and measures the field reflected by said networks.

Dans une autre variante de réalisation du dispositif selon l'invention le réseau 1 est éclairé par une source de rayonnement hyperfréquence 33, l'antenne 30 analysant le champ transmis par le réseau 1. L'antenne 33 a un diagramme adapté à la géométrie du réseau 1. L'antenne 33 émet la fréquence f₀ dont le spectre à la pureté nécessaire au fonctionnement du récepteur connecté à l'an­tenne 30.In another alternative embodiment of the device according to the invention, the network 1 is illuminated by a source of microwave radiation 33, the antenna 30 analyzing the field transmitted by the network 1. The antenna 33 has a diagram adapted to the geometry of the network 1. The antenna 33 transmits the frequency f₀ whose spectrum has the purity necessary for the operation of the receiver connected to the antenna 30.

Dans une première variante du dispositif selon l'invention l'antenne 33 illumine en permanence la totalité du réseau réflecteur 1.In a first variant of the device according to the invention, the antenna 33 permanently illuminates the entire reflecting network 1.

Dans une seconde variante de réalisation du dispositif selon l'invention l'antenne 33 illumine seule la ou les zones du réseau 1 où on applique la modulation. Le balayage est obtenu soit en pointant mécaniquement l'antenne 33 soit par un balayage électronique.In a second alternative embodiment of the device according to the invention, the antenna 33 alone illuminates the zone or zones of the network 1 where the modulation is applied. Scanning is obtained either by mechanically pointing the antenna 33 or by electronic scanning.

Sur la figure 7, on peut voir un dispositif de tomographie hyperfréquence du corps humain. Un patient 34 est illuminé par une énergie hyperfréquence à l'antenne d'une antenne 33. Un réseau 1 selon l'invention associé à un laser 31 et à des dispositifs 38 des déviations du faisceau permet d'analyser les champs transmis par les corps du patient 34. Le champ transmis par exemple à l'intérieur d'une enceinte 40 est capté par une antenne de réception 32. Avantageusement des poches d'eau 35 sont prévues en-dessus et au-­dessous du patient 34 permettant une meilleure adaptation de l'énergie hyperfréquence.In Figure 7, we can see a microwave tomography device of the human body. A patient 34 is illuminated by microwave energy at the antenna of an antenna 33. A network 1 according to the invention associated with a laser 31 and devices 38 for deflecting the beam makes it possible to analyze the fields transmitted by the bodies from the patient 34. The field transmitted for example inside an enclosure 40 is picked up by a receiving antenna 32. Advantageously water bags 35 are provided above and below the patient 34 allowing better adaptation microwave energy.

Nous pouvons évaluer la puissance reçue par l'antenne à tester 30.We can evaluate the power received by the antenna to be tested 30.

Soit une onde de puissance P₀ éclairant un réseau de surface S constituée d'éléments dont la surface de captation est s.Let a power wave P₀ illuminate a surface network S made up of elements whose collection surface is s.

En supposant un rendement de 50% entre l'illuminateur et l'éclairement du réseau, la puissance captée par chaque élément est :

Figure imgb0002
Assuming a 50% efficiency between the illuminator and the network illumination, the power captured by each element is:
Figure imgb0002

Le rendement de modulation dépend considérablement de la fréquence de modulation et des caractéristiques de la diode de charge 2. Nous prendrons comme valeur typique un rendement de 1%.The modulation efficiency depends considerably on the modulation frequency and on the characteristics of the charging diode 2. We will take as typical value an efficiency of 1%.

La puissance diffractée est alors :

Figure imgb0003
The diffracted power is then:
Figure imgb0003

Avec un gain de l'élément égal, en première approximation, à

Figure imgb0004
la puissance reçue par une antenne radar 30 de gain G située à distance D est :
Figure imgb0005
 Soit :
Figure imgb0006
 With an element gain equal, as a first approximation, to
Figure imgb0004
 the power received by a gain G radar antenna 30 located at distance D is:
Figure imgb0005
 Is :
Figure imgb0006

Par exemple pour :
P₀= 10 W
S= 10 m²
s= 10 cm²
D= 10 m
G= 30 dB
On obtient :
Pd= 5 uw
et
Pr = 4 nw soit - 54 dBmFor example for:
P₀ = 10 W
S = 10 m²
s = 10 cm²
D = 10 m
G = 30 dB
We obtain :
P d = 5 uw
and
P r = 4 nw or - 54 dBm

Le dispositif selon la présente invention s'applique principa­lement à la mesure de champ électromagnétique, à la simulation des points brillants pour test d'antenne radar, à la réalisation des balises ainsi qu'à la tomographie du corps humain utilisant des hyper­fréquences.The device according to the present invention is mainly applied to the measurement of electromagnetic field, to the simulation of bright spots for radar antenna test, to the production of beacons as well as to the tomography of the human body using microwaves.

Claims (12)

1. Elément rayonnant hyperfréquence susceptible d'être modulé à une fréquence fm, caractérisé par le fait qu'il comporte un détecteur photoélectrique (5) susceptible de transformer un signal lumineux modulé à la fréquence fm en un signal électrique de commande de la modulation de l'élément rayonnant de fréquence fm.1. Microwave radiating element capable of being modulated at a frequency f m , characterized in that it comprises a photoelectric detector (5) capable of transforming a light signal modulated at the frequency f m into an electrical signal for controlling the modulation of the radiating element of frequency f m . 2. Elément rayonnant selon la revendication 1, caractérisé par le fait qu'il comporte un dipôle (20) susceptible d'émettre et/ou de diffracter de l'énergie hyperfréquence.2. Radiating element according to claim 1, characterized in that it comprises a dipole (20) capable of emitting and / or diffracting microwave energy. 3. Elément rayonnant selon la revendication 1 ou 2, carac­térisé par le fait qu'il comporte une diode (2) à capacité variable et des moyens de commande (5, 6) de la polarisation de la dite diode (2) la modulation de la diode (2) de l'état passant à l'état bloqué à une fréquence fm provoquant quand l'élément rayonnant est illuminé par une onde hyperfréquence de fréquence f₀ un rayonnement de fré­quence f = f₀ + k fm où k est un entier relatif.3. Radiating element according to claim 1 or 2, characterized in that it comprises a diode (2) with variable capacity and control means (5, 6) for the polarization of said diode (2) the modulation of the diode (2) of the state passing to the blocked state at a frequency f m causing when the radiating element is illuminated by a microwave of frequency f₀ a radiation of frequency f = f₀ + kf m where k is an integer relative. 4. Elément rayonnant selon la revendication 3, caractérisé par le fait que la modulation à la fréquence fm est une modulation d'amplitude, k étant égal à ± 1.4. A radiating element according to claim 3, characterized in that the modulation at the frequency f m is an amplitude modulation, k being equal to ± 1. 5. Elément rayonnant selon l'une quelconque des revendi­cations précédentes, caractérisé par le fait qu'il comporte un amplificateur (6) assurant l'amplification du signal capté par le détecteur (5).5. A radiating element according to any one of the preceding claims, characterized in that it comprises an amplifier (6) ensuring the amplification of the signal picked up by the detector (5). 6. Réseau (1) d'éléments rayonnants hyperfréquence, carac­térisé par le fait qu'il comporte des éléments rayonnants hyper­fréquence à commande de modulation par rayonnement lumineux.6. Network (1) of microwave radiating elements, characterized in that it comprises microwave radiating elements with modulation control by light radiation. 7. Dispositif d'analyse de champ ou de simulation de point brillant électromagnétique, caractérisé par le fait qu'il comporte un réseau (1) selon la revendication 6 et au moins un laser (31) susceptible de transmettre un signal lumineux modulé à une fré­quence fm à au moins un élément rayonnant comportant un détecteur photoélectrique (5).7. Device for field analysis or simulation of electromagnetic bright point, characterized in that it comprises a network (1) according to claim 6 and at least one laser (31) capable of transmitting a modulated light signal to a frequency f m at least one radiating element comprising a photoelectric detector (5). 8. Dispositif selon la revendication 7, caractérisé par le fait qu'il comporte des moyens (38) de déflection des faisceaux des lasers (31) permettant d'illuminer successivement une pluralité de détecteurs photoélectriques (5).8. Device according to claim 7, characterized in that it comprises means (38) for deflecting the laser beams (31) making it possible to successively illuminate a plurality of photoelectric detectors (5). 9. Dispositif selon la revendication 8, caractérisé par le fait que les moyens (38) de déflection des faisceaux laser (31) com­portent des miroirs et des servomécanismes.9. Device according to claim 8, characterized in that the means (38) for deflecting the laser beams (31) comprise mirrors and servomechanisms. 10. Dispositif selon la revendication 7, 8 ou 9, caractérisé par le fait qu'il comporte une source (33) de rayonnement hyper­fréquence susceptible d'illuminer le réseau (1).10. Device according to claim 7, 8 or 9, characterized in that it comprises a source (33) of microwave radiation capable of illuminating the network (1). 11. Dispositif selon la revendication 10, caractérisé par le fait que ledit dispositif comporte un récepteur (32) susceptible de recevoir le rayonnement hyperfréquence ayant traversé un corps humain et un réseau selon la revendication 6, ledit dispositif permettant de générer l'image d'au moins une partie du corps.11. Device according to claim 10, characterized in that said device comprises a receiver (32) capable of receiving microwave radiation having passed through a human body and a network according to claim 6, said device making it possible to generate the image of at least part of the body. 12. Balise, caractérisée par le fait qu'elle comporte un ou plusieurs éléments selon l'une quelconque des revendications 1 à 5.12. Beacon, characterized in that it comprises one or more elements according to any one of claims 1 to 5.
EP87400891A 1986-04-22 1987-04-17 Array of elements scattering electromagnetic energy by optical control Withdrawn EP0248686A1 (en)

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EP0595726A1 (en) * 1992-10-30 1994-05-04 Thomson-Csf Phase shifter for electromagnetic waves and application in an antenna with electronic scanning
FR2697679A1 (en) * 1992-10-30 1994-05-06 Thomson Csf Electromagnetic wave shifter and application to a scanning antenna.
USD917500S1 (en) 2017-09-29 2021-04-27 Ethicon Llc Display screen or portion thereof with graphical user interface

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US4896033A (en) 1990-01-23
FR2597621A1 (en) 1987-10-23

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