EP1568104B1 - Multiple-beam antenna with photonic bandgap material - Google Patents

Multiple-beam antenna with photonic bandgap material Download PDF

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Publication number
EP1568104B1
EP1568104B1 EP03778445A EP03778445A EP1568104B1 EP 1568104 B1 EP1568104 B1 EP 1568104B1 EP 03778445 A EP03778445 A EP 03778445A EP 03778445 A EP03778445 A EP 03778445A EP 1568104 B1 EP1568104 B1 EP 1568104B1
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EP
European Patent Office
Prior art keywords
radiating
excitation
electromagnetic waves
antenna
fpb
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
EP03778445A
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German (de)
French (fr)
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EP1568104A1 (en
Inventor
Marc Thevenot
Régis CHANTALAT
Bernard Jecko
Ludovic Leger
Thierry Monediere
Patrick Dumon
Hervé Legay
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Centre National dEtudes Spatiales CNES
Centre National de la Recherche Scientifique CNRS
Original Assignee
Centre National dEtudes Spatiales CNES
Centre National de la Recherche Scientifique CNRS
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Priority claimed from FR0213326A external-priority patent/FR2854737A1/en
Priority claimed from FR0309472A external-priority patent/FR2854734B1/en
Application filed by Centre National dEtudes Spatiales CNES, Centre National de la Recherche Scientifique CNRS filed Critical Centre National dEtudes Spatiales CNES
Publication of EP1568104A1 publication Critical patent/EP1568104A1/en
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Publication of EP1568104B1 publication Critical patent/EP1568104B1/en
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q25/00—Antennas or antenna systems providing at least two radiating patterns
    • H01Q25/007—Antennas or antenna systems providing at least two radiating patterns using two or more primary active elements in the focal region of a focusing device
    • 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
    • H01Q15/0006—Devices acting selectively as reflecting surface, as diffracting or as refracting device, e.g. frequency filtering or angular spatial filtering devices
    • H01Q15/006—Selective devices having photonic band gap materials or materials of which the material properties are frequency dependent, e.g. perforated substrates, high-impedance surfaces
    • 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
    • H01Q19/12—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 wherein the surfaces are concave
    • H01Q19/17—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 wherein the surfaces are concave the primary radiating source comprising two or more radiating elements
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q5/00—Arrangements for simultaneous operation of antennas on two or more different wavebands, e.g. dual-band or multi-band arrangements
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q5/00—Arrangements for simultaneous operation of antennas on two or more different wavebands, e.g. dual-band or multi-band arrangements
    • H01Q5/20—Arrangements for simultaneous operation of antennas on two or more different wavebands, e.g. dual-band or multi-band arrangements characterised by the operating wavebands
    • H01Q5/28—Arrangements for establishing polarisation or beam width over two or more different wavebands

Definitions

  • Multi-beam antennas are widely used in space applications and especially in geostationary satellites to transmit to the earth's surface and / or receive information from the Earth's surface. They comprise for this purpose several radiating elements each generating a beam of electromagnetic waves spaced from the other beams. These radiating elements are, for example, placed near the focus of a parabola forming reflector of electromagnetic wave beams, the parabola and the multi-beam antenna being housed in a geostationary satellite. The parabola is intended to direct each beam on a corresponding area of the earth's surface. Each area of the Earth's surface illuminated by a beam of the multi-beam antenna is commonly referred to as a coverage area. Thus, each coverage area corresponds to a radiating element.
  • each horn produces a substantially circular radiating spot forming the base of a conical beam radiated emission or reception.
  • These horns are arranged next to each other so as to bring as close as possible the radiant spots of each other.
  • FIG. 1A diagrammatically represents a multi-beam antenna with cornets in front view in which seven squares F1 to F7 indicate the bulk of seven cones arranged contiguously to one another. Seven circles S1 to S7, each inscribed in one of the squares F1 to F7, represent the radiating spots produced by the corresponding horns.
  • the antenna of FIG. 1A is placed at the focus of a parabola of a geostationary satellite intended to transmit information on the French territory.
  • Figure 1B shows areas C1 to C7 of coverage at -3 dB, each corresponding to a radiating spot of the antenna of Figure 1A.
  • the center of each circle corresponds to a point on the earth's surface where the power received is maximum.
  • the perimeter of each circle delimits an area within which the power received on the earth's surface is greater than half the maximum power received at the center of the circle.
  • the radiating spots S1 to S7 are substantially contiguous, they produce cover areas at -3 dB disjoined from each other.
  • the regions between the -3 dB coverage areas are referred to here as receiving holes.
  • Each receiving hole therefore corresponds to a region of the earth's surface where the received power is less than half of the maximum power received. In these receiving holes, the received power may be insufficient for a receiver floor to function properly.
  • FIG. 2A A partial front view of such a multi-beam antenna having a plurality of overlapping radiating spots is illustrated in Figure 2A.
  • the radiating spot SR1 is formed from the SdR1 to SdR7 radiation sources arranged contiguously next to one another.
  • a radiating spot SR2 is produced from SdR1, SdR2, SdR3 and SdR7 radiation sources and from SdR8 to SdR10 radiation sources.
  • the SdR1 to SdR7 radiation sources are suitable for working at a first working frequency for creating a first substantially uniform electromagnetic wave beam at this first frequency.
  • the sources of radiation SdR1 to SdR3 and SdR7 to SdR10 are adapted to work at a second working frequency so as to create a second beam of electromagnetic waves substantially uniform at this second working frequency.
  • the sources of radiation SdR1 to SdR3 and SdR7 are able to work simultaneously at the first and second working frequencies.
  • the first and second working frequencies are different from each other so as to limit interference between the first and second beams produced.
  • radiation sources such as SdR1-3 radiation sources, are used both to create the SR1 radiating spot and the SR2 radiating spot, thereby producing an overlap of these two.
  • An illustration of the arrangement of the -3 dB coverage areas created by a multi-beam antenna with overlapping radiating spots is shown in Figure 2B.
  • Such an antenna can significantly reduce the receiving holes, or even make them disappear.
  • this multi-beam antenna is more complex to order than conventional horn antennas.
  • the aim of the invention is to remedy this drawback by proposing a simpler overlapping multi-beam antenna with radiating spots.
  • each excitation element produces a single radiating spot forming the base or cross-section at the origin of an electromagnetic wave beam.
  • this antenna is comparable with conventional horn antennas where a horn produces a single radiating spot.
  • the control of this antenna is therefore similar to that of a conventional horn antenna.
  • the excitation elements are placed so as to overlap the radiating spots. This antenna thus has the advantages of a multi-beam antenna with overlapping radiating spots without the complexity of the control of the excitation elements has been increased compared to that of multi-beam horn antennas.
  • FIG. 3 represents a multi-beam antenna 4.
  • This antenna 4 is formed of a photonic ban band material or BIP material associated with a metal plane 22 reflecting electromagnetic waves.
  • the BIP materials are known and the design of a BIP material such as the material 20 is, for example, described in the patent application FR 99 14521. Thus, only the specific characteristics of the antenna 4 with respect to this state of the art. the technique will be described here in detail.
  • a BIP material is a material which has the property of absorbing certain frequency ranges, that is to say of prohibiting any transmission in said aforementioned frequency ranges. These frequency ranges form what is called here a non-conducting band.
  • FIG. 4 represents a curve representing the variations of the transmission coefficient expressed in decibels as a function of the frequency of the electromagnetic wave emitted or received. This transmission coefficient is representative of the energy transmitted on one side of the BIP material with respect to the energy received on the other side.
  • the non-conducting band B or absorption band B extends substantially from 7 GHz to 17 GHz.
  • This non-conducting band B depends solely on the properties and characteristics of the BIP material.
  • the BIP material generally consists of a periodic arrangement of dielectric permittivity and / or variable permeability.
  • the material 20 is formed from two blades 30, 32 made of a first magnetic material such as alumina and two blades 34 and 36 formed in a second magnetic material such as air.
  • the blade 34 is interposed between the blades 30 and 32, while the blade 36 is interposed between the blade 32 and the reflector plane 22.
  • the blade 30 is disposed at one end of this stack of blades. It has an outer surface 38 opposite its surface in contact with the blade 34. This surface 38 forms a radiating surface in emission and / or reception.
  • the median frequency f m is substantially equal to 1.2 GHz.
  • the radius R is substantially equal to 2.15 ⁇ .
  • Such a parallelepiped resonant cavity has several families of resonant frequencies. Each family of resonance frequencies is formed by a fundamental frequency and its harmonics or integer multiples of the fundamental frequency. Each resonance frequency of the same family excites the same mode of resonance of the cavity. These resonance modes are known under the terms resonance modes TM 0 , TM 1 ,..., TM i , .... These modes of resonance are described in more detail in the document by F. Cardiol, "Electromagnetism, Electricity, Electronics and Electrical Engineering ", Ed. Dunod, 1987.
  • each resonance mode corresponds to a radiation pattern of the particular antenna and to a radiating spot in emission and / or reception formed on the outer surface 38.
  • the radiating spot is here the area of the outer surface 38 containing the entire points where the radiated power in emission and / or in reception is greater than or equal to half of the maximum power radiated from this external surface by the antenna 4.
  • Each radiating spot has a geometrical center corresponding to the point where the power radiated is substantially equal to the maximum radiated power.
  • this radiating spot is part of a circle whose diameter ⁇ is given by the formula (1).
  • the radiation pattern is here highly directional along a direction perpendicular to the outer surface 38 and passing through the geometric center of the radiating spot.
  • the radiation pattern corresponding to the TM 0 resonance mode is illustrated in FIG. 5.
  • the frequencies f mi are placed inside the narrow bandwidth E.
  • excitation elements 40 to 43 are placed next to one another in the cavity 36 on the reflector plane 22.
  • the geometric centers of these excitation elements are placed at the four corners of a rhombus whose sides are strictly smaller than 2R.
  • Each of these excitation elements is able to emit and / or receive an electromagnetic wave at a working frequency f Ti different from that of the other excitation elements.
  • the frequency f Ti of each excitation element is close to f m0 so as to excite the resonance mode TM 0 of the cavity 36.
  • These excitation elements 40 to 43 are connected to a conventional generator / receiver 45 of FIG. electrical signals to be transformed by each excitation element into an electromagnetic wave and vice versa.
  • excitation elements are, for example, constituted by a radiating dipole, a radiating slot, a plate probe or a radiating patch.
  • the lateral bulk of each radiating element that is to say in a plane parallel to the outer surface 38, is strictly smaller than the surface of the radiating spot to which it gives rise.
  • FIG. 6 illustrates an example of application of the antenna 4.
  • FIG. 6 represents a system 60 for transmitting and / or receiving electromagnetic waves suitable for equipping a geostationary satellite.
  • This system 60 comprises a parabola 62 forming an electromagnetic wave beam reflector and the antenna 4 placed at the focus of this dish 62.
  • the electromagnetic wave beams emitted or received by the outer surface 38 of the antenna 4 are represented on this figure by lines 64.
  • the excitation element 40 In transmission, the excitation element 40, activated by the generator / receiver 45, emits an electromagnetic wave at a working frequency f T0 and excites the resonance mode TM 0 of the cavity 36.
  • the other radiating elements 41 to 43 are, for example, simultaneously activated by the generator / receiver 45 and do the same respectively at the working frequencies f T1 , f T2 and f T3 .
  • the radiating spot and the corresponding radiation pattern are independent of the lateral dimensions of the cavity 36.
  • the TM 0 resonance mode depends only on the thickness and nature of the materials of each of the blades 30 to 36 and is established independently of the lateral dimensions of the cavity 36 when they are several times greater than the radius R defined above.
  • several TM 0 resonance modes can be established simultaneously next to each other and thus simultaneously generate several radiating spots arranged next to each other. This is what happens when the excitation elements 40 to 43 excite, each at different points of space, the same mode of resonance.
  • the excitation by the excitation element 40 of the resonance mode TM 0 results in the appearance of a radiant spot 46 that is substantially circular and whose geometric center is placed vertically above the geometric center of the element 40.
  • excitation by the elements 41 to 43 of the TM 0 resonance mode results in the appearance, at the vertical of the geometric center of each of these elements, respectively of radiating spots 47 to 49.
  • geometric center of the element 40 being at a distance strictly less than 2R of the geometric center of the elements 41 and 43, the radiating spot 46 partially overlaps the radiating spots 47 and 49 respectively corresponding to the radiating elements 41 and 43.
  • the radiating spot 49 partially overlaps the radiating spots 46 and 48
  • the radiating spot 48 partly overlaps the radiating spots 49 and 47
  • the radiating spot 47 overlaps with the radiating spots 49 and 47 n part radiant spots 46 and 48.
  • Each radiating spot corresponds to the base or cross-section at the origin of an electromagnetic wave beam radiated towards the dish 62 and reflected by this parabola 62 towards the terrestrial surface.
  • the coverage areas on the terrestrial surface corresponding to each of the emitted beams are close to each other, or even overlap, so as to eliminate or reduce the holes reception.
  • each radiating spot of the outer surface 38 corresponds to a coverage area on the earth's surface.
  • an electromagnetic wave is emitted from the coverage area corresponding to the radiating spot 46, it is received in the surface corresponding to the stain 46 after being reflected by the dish 62. If the received wave is at a frequency in the narrow bandwidth E, it is not absorbed by the BIP material 20 and is received by the excitation element 40.
  • Each electromagnetic wave received by an excitation element is transmitted in the form of an electrical signal to the generator / receiver 45.
  • FIG. 7 represents an antenna 70 made from a BIP material 72 and a reflector 74 of electromagnetic waves
  • FIG. 8 shows the evolution of the transmission coefficient of this antenna as a function of frequency.
  • the BIP material 72 is, for example, identical to the BIP material 20 and has the same non-conducting band B (FIG. 8).
  • the blades forming this BIP material already described with reference to FIG. 3 bear the same numerical references.
  • the reflector 74 is formed, for example, from the reflective plane 22 deformed so as to divide the cavity 36 into two resonant cavities 76 and 78 of different heights.
  • the constant height H 1 of the cavity 76 is determined so as to place, within the non-conducting band B, a narrow bandwidth E 1 (FIG. 8), for example, around the frequency of 10 GHz.
  • the height H 2 of the resonant cavity 78 is determined so as to place, within the same non-conducting band B, a narrow bandwidth E 2 (FIG. 8), for example centered around 14 GHz.
  • the reflector 74 is composed here of two reflective half-planes 80 and 82 arranged in steps and electrically connected to one another.
  • the reflective half-plane 80 is parallel to the blade 32 and spaced therefrom by the height H 1 .
  • the half-plane 82 is parallel to the blade 32 and spaced therefrom from the constant height H 2 .
  • an excitation element 84 is disposed in the cavity 76 and an excitation element 86 is disposed in the cavity 78.
  • These excitation elements 84, 86 are, for example, identical to the excitation elements 40 to 43. with the exception that the excitation element 84 is able to excite the resonance mode TM 0 of the cavity 76, while the excitation element 86 is able to excite the resonance mode TM 0 of the cavity 78.
  • the horizontal distance that is to say parallel to the blade 32, separating the geometric center of the elements of excitation 84 and 86, is strictly less than the sum of the radii of two radiating spots produced respectively by the elements 84 and 86.
  • this antenna 70 is identical to that of the antenna of FIG. 3.
  • the working frequencies of the excitation elements 84 and 86 are located in narrow bandwidths E 1 , E 2 respective.
  • the working frequencies of each of these excitation elements are separated from each other by a large frequency interval, for example here 4 GHz.
  • the positions of the pass bands E 1 , E 2 are chosen so as to be able to use imposed working frequencies.
  • FIG. 9 represents a multi-beam antenna 100.
  • This antenna 100 is similar to the antenna 4 except that the single-defective BIP material 20 of the radiating device 4 is replaced by a multi-fault BIP material 102.
  • the elements already described with reference to FIG. 4 bear the same numerical references.
  • the antenna 100 is shown in section along a section plane perpendicular to the reflector plane 22 and passing through the excitation elements 41 and 43.
  • the BIP material 102 comprises two successive groups 104 and 106 of blades made of a first dielectric material.
  • the groups 104 and 106 are superimposed in the direction perpendicular to the reflective plane 22.
  • Each group 104, 106 is formed, by way of non-limiting example, respectively by two blades 110, 112 and 114, 116 parallel to the reflector plane 22.
  • Each blade of a group has the same thickness as the other blades of this same grouping.
  • each blade of the BIP 102 material is interposed a blade of a second dielectric material, such as air.
  • the thickness of these blades separating the blades 110, 112, 114 and 116 is equal to ⁇ / 4.
  • the first blade 116 is disposed vis-à-vis the reflector plane 22 and separated from this plane by a blade of second dielectric material thickness ⁇ / 2 so as to form a parallelepiped cavity resonant leak.
  • the thickness e i of the blades of dielectric material, consecutive to each group of blades of dielectric material, is in geometric progression of reason q in the direction of successive groups 104, 106.
  • the number of superimposed groups is equal to 2 so as not to overload the drawing, and the geometric progression reason is also taken equal to 2.
  • This radiating device 100 derives directly from that of the antenna 4.
  • the parabola 62 is replaced by an electromagnetic lens.
  • FIG. 10 shows an antenna 200 equipped with a device 202 able to focus the electromagnetic wave beams on an antenna 204.
  • the device 202 is, for example, a metal reflector in the form of a half-cylinder.
  • the antenna 204 is placed at the focus of this device 202.
  • the antenna 204 is similar to the antenna of FIG. 3, except that the reflector plane, and the blades of the BIP material, each have a convex surface corresponding to the concave surface of the half-cylinder.
  • each excitation element is polarized in a direction different from that used by the neighboring excitation elements.
  • the polarization of each excitation element is orthogonal to that used by neighboring excitation elements.
  • the same excitation element is adapted to operate successively or simultaneously at several different working frequencies.
  • Such an element makes it possible to create a coverage area in which, for example, transmission and reception take place at different wavelengths.
  • Such an excitation element is also able to make frequency switching.

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Abstract

A system includes a device for focusing electromagnetic waves, and a multiple-beam antenna. The antenna includes: a photonic bandgap material ( 20 ) having at least one band gap, at least one periodicity defect ( 36 ) of the photonic bandgap material so as to produce at least one narrow bandwidth within the bandgap material, and excitation elements ( 40 to 43 ) for transmitting and/or receiving electromagnetic waves within the at least one narrow bandwidth, the elements being arranged relative to one another so as to produce overlapping radiating spots.

Description

L'invention concerne une antenne multi-faisceaux comportant :

  • un matériau BIP (Bande d'Interdiction Photonique) apte à filtrer spatialement et fréquentiellement des ondes électromagnétiques, ce matériau BIP présentant au moins une bande non passante et formant une surface extérieure rayonnante en émission et/ou en réception,
  • au moins un défaut de périodicité du matériau BIP de manière à créer au moins une bande passante étroite au sein de ladite au moins une bande non passante de ce matériau BIP, et
  • un dispositif d'excitation apte à émettre et/ou recevoir des ondes électromagnétiques à l'intérieur de ladite au moins une bande passante étroite créée par ledit au moins un défaut.
The invention relates to a multi-beam antenna comprising:
  • a BIP material (Photonic Prohibition Tape) capable of filtering spatially and frequency electromagnetic waves, this BIP material having at least one non-conducting band and forming an outer radiating surface in emission and / or reception,
  • at least one periodicity defect of the BIP material so as to create at least a narrow bandwidth within said at least one non-pass band of this BIP material, and
  • an excitation device adapted to emit and / or receive electromagnetic waves within said at least one narrow bandwidth created by said at least one defect.

Les antennes multi-faisceaux sont très utilisées dans les applications spatiales et notamment dans des satellites géostationnaires pour émettre vers la surface terrestre et/ou recevoir des informations à partir de la surface terrestre. Elles comportent à cet effet plusieurs éléments rayonnants générant chacune un faisceau d'ondes électromagnétiques espacé des autres faisceaux. Ces éléments rayonnants sont, par exemple, placés à proximité du foyer d'une parabole formant réflecteur de faisceaux d'ondes électromagnétiques, la parabole et l'antenne multi-faisceaux étant logées dans un satellite géostationnaire. La parabole est destinée à diriger chaque faisceau sur une zone correspondante de la surface terrestre. Chaque zone de la surface terrestre éclairée par un faisceau de l'antenne multi-faisceaux est communément appelée une zone de couverture. Ainsi, chaque zone de couverture correspond à un élément rayonnant.Multi-beam antennas are widely used in space applications and especially in geostationary satellites to transmit to the earth's surface and / or receive information from the Earth's surface. They comprise for this purpose several radiating elements each generating a beam of electromagnetic waves spaced from the other beams. These radiating elements are, for example, placed near the focus of a parabola forming reflector of electromagnetic wave beams, the parabola and the multi-beam antenna being housed in a geostationary satellite. The parabola is intended to direct each beam on a corresponding area of the earth's surface. Each area of the Earth's surface illuminated by a beam of the multi-beam antenna is commonly referred to as a coverage area. Thus, each coverage area corresponds to a radiating element.

Actuellement, les éléments rayonnants utilisés sont connus sous le terme de "cornets" et l'antenne multi-faisceaux équipée de tels cornets est désignée sous le nom d'antenne à cornets. Chaque cornet produit une tache rayonnante sensiblement circulaire formant l'embase d'un faisceau conique rayonné en émission ou en réception. Ces cornets sont disposés les uns à côté des autres de manière à rapprocher le plus possible les taches rayonnantes les unes des autres.Currently, the radiating elements used are known as "horns" and the multi-beam antenna equipped with such horns is referred to as a horn antenna. Each horn produces a substantially circular radiating spot forming the base of a conical beam radiated emission or reception. These horns are arranged next to each other so as to bring as close as possible the radiant spots of each other.

La figure 1A représente schématiquement une antenne multi-faisceaux à cornets en vue de face dans laquelle sept carrés F1 à F7 indiquent l'encombrement de sept cornets disposés jointivement les uns aux autres. Sept cercles S1 à S7, inscrits chacun dans l'un des carrés F1 à F7, représentent les taches rayonnantes produites par les cornets correspondants. L'antenne de la figure 1A est placée au foyer d'une parabole d'un satellite géostationnaire destinée à émettre des informations sur le territoire français.FIG. 1A diagrammatically represents a multi-beam antenna with cornets in front view in which seven squares F1 to F7 indicate the bulk of seven cones arranged contiguously to one another. Seven circles S1 to S7, each inscribed in one of the squares F1 to F7, represent the radiating spots produced by the corresponding horns. The antenna of FIG. 1A is placed at the focus of a parabola of a geostationary satellite intended to transmit information on the French territory.

La figure 1 B représente des zones C1 à C7 de couverture à -3 dB, correspondant chacune à une tache rayonnante de l'antenne de la figure 1A. Le centre de chaque cercle correspond à un point de la surface terrestre où la puissance reçue est maximale. Le pourtour de chaque cercle délimite une zone à l'intérieur de laquelle la puissance reçue sur la surface terrestre est supérieure à la moitié de la puissance maximale reçue au centre du cercle. Bien que les taches rayonnantes S1 à S7 soient pratiquement jointives, celles-ci produisent des zones de couverture à -3 dB disjointes les unes des autres. Les régions situées entre les zones de couverture à -3 dB sont appelées, ici, des trous de réception. Chaque trou de réception correspond donc à une région de la surface terrestre où la puissance reçue est inférieure à la moitié de la puissance maximale reçue. Dans ces trous de réception, la puissance reçue peut s'avérer insuffisante pour qu'un récepteur au sol puisse fonctionner correctement.Figure 1B shows areas C1 to C7 of coverage at -3 dB, each corresponding to a radiating spot of the antenna of Figure 1A. The center of each circle corresponds to a point on the earth's surface where the power received is maximum. The perimeter of each circle delimits an area within which the power received on the earth's surface is greater than half the maximum power received at the center of the circle. Although the radiating spots S1 to S7 are substantially contiguous, they produce cover areas at -3 dB disjoined from each other. The regions between the -3 dB coverage areas are referred to here as receiving holes. Each receiving hole therefore corresponds to a region of the earth's surface where the received power is less than half of the maximum power received. In these receiving holes, the received power may be insufficient for a receiver floor to function properly.

Pour résoudre ce problème de trou de réception, il a été proposé de chevaucher entre elles les taches rayonnantes de l'antenne multi-faisceaux. Une vue de face partielle d'une telle antenne multi-faisceaux comportant plusieurs taches rayonnantes se chevauchant est illustrée à la figure 2A. Sur cette figure, seules deux taches rayonnantes SR1 et SR2 ont été représentées. Chaque tache rayonnante est produite à partir de sept sources de rayonnement indépendantes et distinctes les unes des autres. La tache rayonnante SR1 est formée à partir des sources de rayonnement SdR1 à SdR7 disposées jointivement les unes à côtés des autres. Une tache rayonnante SR2 est produite à partir des sources de rayonnement SdR1, SdR2, SdR3 et SdR7 et de sources de rayonnement SdR8 à SdR10. Les sources de rayonnement SdR1 à SdR7 sont propres à travailler à une première fréquence de travail pour créer un premier faisceau d'ondes électromagnétiques sensiblement uniforme à cette première fréquence. Les sources de rayonnement SdR1 à SdR3 et SdR7 à SdR10 sont propres à travailler à une seconde fréquence de travail de manière à créer un second faisceau d'ondes électromagnétiques sensiblement uniforme à cette seconde fréquence de travail. Ainsi, les sources de rayonnement SdR1 à SdR3 et SdR7 sont aptes à travailler simultanément à la première et à la seconde fréquences de travail. La première et la seconde fréquences de travail sont différentes l'une de l'autre de manière à limiter les interférences entre le premier et le second faisceaux produits.To solve this reception hole problem, it has been proposed to overlap the radiating spots of the multi-beam antenna with each other. A partial front view of such a multi-beam antenna having a plurality of overlapping radiating spots is illustrated in Figure 2A. In this figure, only two radiating spots SR1 and SR2 have been represented. Each radiant spot is produced from seven independent and distinct radiation sources. The radiating spot SR1 is formed from the SdR1 to SdR7 radiation sources arranged contiguously next to one another. A radiating spot SR2 is produced from SdR1, SdR2, SdR3 and SdR7 radiation sources and from SdR8 to SdR10 radiation sources. The SdR1 to SdR7 radiation sources are suitable for working at a first working frequency for creating a first substantially uniform electromagnetic wave beam at this first frequency. The sources of radiation SdR1 to SdR3 and SdR7 to SdR10 are adapted to work at a second working frequency so as to create a second beam of electromagnetic waves substantially uniform at this second working frequency. Thus, the sources of radiation SdR1 to SdR3 and SdR7 are able to work simultaneously at the first and second working frequencies. The first and second working frequencies are different from each other so as to limit interference between the first and second beams produced.

Ainsi, dans une telle antenne multi-faisceaux, des sources de rayonnement, telles que les sources de rayonnement SdR1 à 3, sont utilisées à la fois pour créer la tache rayonnante SR1 et la tache rayonnante SR2, ce qui produit un chevauchement de ces deux taches rayonnantes SR1 et SR2. Une illustration de la disposition des zones de couverture à -3 dB créées par une antenne multi-faisceaux présentant des taches rayonnantes chevauchées est représentée sur la figure 2B. Une telle antenne permet de réduire considérablement les trous de réception, voire même de les faire disparaître. Toutefois, en partie à cause du fait qu'une tache rayonnante est formée à partir de plusieurs sources de rayonnement indépendantes et distinctes les unes des autres, dont au moins certaines sont également utilisées pour d'autres taches rayonnantes, cette antenne multi-faisceaux est plus complexe à commander que les antennes à cornets classiques.Thus, in such a multi-beam antenna, radiation sources, such as SdR1-3 radiation sources, are used both to create the SR1 radiating spot and the SR2 radiating spot, thereby producing an overlap of these two. radiating spots SR1 and SR2. An illustration of the arrangement of the -3 dB coverage areas created by a multi-beam antenna with overlapping radiating spots is shown in Figure 2B. Such an antenna can significantly reduce the receiving holes, or even make them disappear. However, in part because of the fact that a radiating spot is formed from several independent and distinct radiation sources, at least some of which are also used for other radiating spots, this multi-beam antenna is more complex to order than conventional horn antennas.

L'invention vise à remédier à cet inconvénient en proposant une antenne multi-faisceaux à taches rayonnantes chevauchées plus simple.The aim of the invention is to remedy this drawback by proposing a simpler overlapping multi-beam antenna with radiating spots.

Elle a donc pour objet une antenne telle que définie plus haut, caractérisée :

  • en ce que le dispositif d'excitation est apte à travailler simultanément au moins autour d'une première et d'une seconde fréquences de travail distinctes,
  • en ce que le dispositif d'excitation comporte un premier et un second éléments d'excitation distincts et indépendants l'un de l'autre, aptes chacun à émettre et/ou à recevoir des ondes électromagnétiques, le premier élément d'excitation étant apte à travailler à la première fréquence de travail et le second élément d'excitation étant apte à travailler à la seconde fréquence de travail,
  • en ce que le ou chaque défaut de périodicité du matériau BIP forme une cavité résonante à fuites présentant une hauteur constante dans une direction orthogonale à ladite surface extérieure rayonnante, et des dimensions latérales déterminées parallèles à ladite surface extérieure rayonnante,
  • en ce que la première et la seconde fréquences de travail sont aptes à exciter le même mode de résonance d'une cavité résonante à fuites, ce mode de résonance s'établissant de façon identique quelles que soient les dimensions latérales de la cavité, de manière à créer sur ladite surface extérieure respectivement une première et une seconde taches rayonnantes, chacune de ces taches rayonnantes représentant l'origine d'un faisceau d'ondes électromagnétiques rayonnées en émission et/ou en réception par l'antenne,
  • en ce que chacune des taches rayonnantes présente un centre géométrique dont la position est fonction de la position de l'élément d'excitation qui lui donne naissance et dont la surface est supérieure à celle de l'élément rayonnant lui donnant naissance, et
  • en ce que le premier et le second éléments d'excitation sont placés l'un par rapport à l'autre de manière à ce que la première et la seconde taches rayonnantes soient disposées sur la surface extérieure du matériau BIP l'une à côté de l'autre et se chevauchent partiellement.
It therefore relates to an antenna as defined above, characterized:
  • in that the excitation device is able to work simultaneously at least around a first and a second different working frequency,
  • in that the excitation device comprises a first and a second excitation element that are distinct and independent of one another, each capable of transmitting and / or receiving electromagnetic waves, the first excitation element being capable of to work at the first working frequency and the second excitation element being able to work at the second working frequency,
  • in that the or each frequency defect of the BIP material forms a leak resonant cavity having a constant height in a direction orthogonal to said radiating outer surface, and determined lateral dimensions parallel to said radiating outer surface,
  • in that the first and second working frequencies are able to excite the same resonance mode of a resonant leak cavity, this resonance mode being established identically regardless of the lateral dimensions of the cavity, so as to to create on said outer surface respectively a first and a second radiating spots, each of these radiating spots representing the origin of a beam of electromagnetic waves radiated in emission and / or reception by the antenna,
  • in that each of the radiating spots has a geometric center whose position is a function of the position of the excitation element which gives rise to it and whose surface is greater than that of the radiating element giving rise to it, and
  • in that the first and second excitation elements are placed relative to one another so that the first and second radiating spots are arranged on the outer surface of the BIP material next to each other. the other and overlap partially.

Dans l'antenne multi-faisceaux décrite ci-dessus, chaque élément d'excitation produit une seule tache rayonnante formant l'embase ou section droite à l'origine d'un faisceau d'ondes électromagnétiques. Ainsi, de ce point de vue là, cette antenne est comparable avec les antennes à cornets conventionnelles où un cornet produit une seule tache rayonnante. La commande de cette antenne est donc similaire à celle d'une antenne à cornets conventionnelle. De plus, les éléments d'excitation sont placés de manière à chevaucher les taches rayonnantes. Cette antenne présente donc les avantages d'une antenne multi-faisceaux à taches rayonnantes chevauchées sans que la complexité de la commande des éléments d'excitation ait été accrue par rapport à celle des antennes multi-faisceaux à cornets.In the multi-beam antenna described above, each excitation element produces a single radiating spot forming the base or cross-section at the origin of an electromagnetic wave beam. Thus, from this point of view, this antenna is comparable with conventional horn antennas where a horn produces a single radiating spot. The control of this antenna is therefore similar to that of a conventional horn antenna. In addition, the excitation elements are placed so as to overlap the radiating spots. This antenna thus has the advantages of a multi-beam antenna with overlapping radiating spots without the complexity of the control of the excitation elements has been increased compared to that of multi-beam horn antennas.

Suivant d'autres caractéristiques d'une antenne multi-faisceaux conforme à l'invention :

  • chaque tache rayonnante est sensiblement circulaire, le centre géométrique correspondant à un maximum de puissance émise et/ou reçue et la périphérie correspondant à une puissance émise et/ou reçue égale à une fraction de la puissance maximale émise et/ou reçue en son centre, et la distance, dans un plan parallèle à la surface extérieure, séparant les centres géométriques des deux éléments d'excitation, est strictement inférieure au rayon de la tache rayonnante produite par le premier élément d'excitation ajouté au rayon de la tache rayonnante produite par le second élément d'excitation,
  • le centre géométrique de chaque tache rayonnante est placé sur la ligne orthogonale à ladite surface extérieure rayonnante et passant par le centre géométrique de l'élément d'excitation lui donnant naissance,
  • le premier et le second éléments d'excitation sont placés à l'intérieur d'une même cavité,
  • la première et la seconde fréquences de travail sont situées à l'intérieur de la même bande passante étroite créée par cette même cavité,
  • le premier et le second éléments d'excitation sont placés chacun à l'intérieur de cavités résonantes distinctes, et la première et la seconde fréquences de travail sont aptes à exciter chacune un mode de résonance indépendant des dimensions latérales de leur cavité respective,
  • un plan réflecteur de rayonnement électromagnétique associé au matériau BIP, ce plan réflecteur étant déformé de manière à former lesdites cavités distinctes,
  • la ou chaque cavité est de forme parallélépipédique,
  • le dispositif apte à focaliser les ondes électromagnétiques comporte un réflecteur en forme de demi-cylindre, et le matériau BIP de l'antenne présente une surface convexe correspondant à la surface en forme de demi-cylindre du réflecteur.
According to other characteristics of a multi-beam antenna according to the invention:
  • each radiating spot is substantially circular, the geometric center corresponding to a maximum of transmitted and / or received power and the periphery corresponding to an emitted and / or received power equal to a fraction of the maximum power emitted and / or received at its center, and the distance, in a plane parallel to the outer surface, separating the geometric centers from the two excitation elements, is strictly less than the radius of the radiating spot produced by the first excitation element added to the radius of the radiating spot produced by the second excitation element,
  • the geometric center of each radiating spot is placed on the line orthogonal to said radiating outer surface and passing through the geometric center of the excitation element giving rise to it,
  • the first and the second excitation elements are placed inside the same cavity,
  • the first and second working frequencies are located within the same narrow bandwidth created by the same cavity,
  • the first and second excitation elements are each placed inside distinct resonant cavities, and the first and second working frequencies are each able to excite a resonance mode independent of the lateral dimensions of their respective cavity,
  • a reflective plane of electromagnetic radiation associated with the BIP material, this reflective plane being deformed so as to form said distinct cavities,
  • the or each cavity is of parallelepipedal shape,
  • the device for focusing the electromagnetic waves comprises a half-cylinder shaped reflector, and the BIP material of the antenna has a convex surface corresponding to the half-cylinder-shaped surface of the reflector.

L'invention concerne également un système d'émission et/ou de réception d'ondes électromagnétiques comportant :

  • un dispositif apte à focaliser les ondes électromagnétiques émises et/ou reçues par le système sur un point focal, et
  • un émetteur et/ou récepteur d'ondes électromagnétiques placé sensiblement au point focal de manière à émettre et/ou recevoir lesdites ondes électromagnétiques, caractérisé en ce qu'il comporte une antenne selon l'invention, dont la surface extérieure rayonnante est sensiblement placée sur le point focal de manière à former ledit émetteur et/ou récepteur d'ondes électromagnétiques.
The invention also relates to a system for transmitting and / or receiving electromagnetic waves comprising:
  • a device capable of focusing the electromagnetic waves emitted and / or received by the system on a focal point, and
  • an emitter and / or receiver of electromagnetic waves placed substantially at the focal point so as to emit and / or receive said electromagnetic waves, characterized in that it comprises an antenna according to the invention, whose radiating outer surface is substantially placed on the focal point so as to form said transmitter and / or receiver of electromagnetic waves.

Suivant d'autres caractéristiques du système conforme à l'invention :

  • le dispositif apte à focaliser les ondes électromagnétiques est un réflecteur parabolique,
  • le dispositif apte à focaliser les ondes électromagnétiques est une lentille électromagnétique.
According to other features of the system according to the invention:
  • the device capable of focusing the electromagnetic waves is a parabolic reflector,
  • the device capable of focusing the electromagnetic waves is an electromagnetic lens.

L'invention sera mieux comprise à la lecture de la description qui va suivre, donnée uniquement à titre d'exemple, et faite en se référant aux dessins, sur lesquels :

  • les figures 1A, 1B, 2A et 2B représentent des antennes multi-faisceaux connues ainsi que les zones de couverture résultantes ;
  • la figure 3 est une vue en perspective d'une antenne multi-faisceaux conforme à l'invention ;
  • la figure 4 est un graphique représentant le coefficient de transmission de l'antenne de la figure 3 ;
  • la figure 5 est un graphique représentant le diagramme de rayonnement de l'antenne de la figure 3 ;
  • la figure 6 est une illustration schématique et en coupe d'un système d'émission/réception d'ondes électromagnétiques équipé de l'antenne de la figure 3 ;
  • la figure 7 représente un deuxième mode de réalisation d'une antenne multi-faisceaux conforme à l'invention ;
  • la figure 8 représente le coefficient de transmission de l'antenne de la figure 7 ;
  • la figure 9 représente un troisième mode de réalisation d'une antenne multi-faisceaux conforme à l'invention ; et
  • la figure 10 est une illustration d'une antenne semi-cylindrique conforme à l'invention.
The invention will be better understood on reading the description which follows, given solely by way of example, and with reference to the drawings, in which:
  • FIGS. 1A, 1B, 2A and 2B show known multi-beam antennas as well as the resulting coverage areas;
  • Figure 3 is a perspective view of a multi-beam antenna according to the invention;
  • Fig. 4 is a graph showing the transmission coefficient of the antenna of Fig. 3;
  • Fig. 5 is a graph showing the radiation pattern of the antenna of Fig. 3;
  • Figure 6 is a schematic and sectional illustration of an electromagnetic wave transmission / reception system equipped with the antenna of Figure 3;
  • FIG. 7 represents a second embodiment of a multi-beam antenna according to the invention;
  • FIG. 8 represents the transmission coefficient of the antenna of FIG. 7;
  • FIG. 9 represents a third embodiment of a multi-beam antenna according to the invention; and
  • Figure 10 is an illustration of a semicylindrical antenna according to the invention.

La figure 3 représente une antenne multi-faisceaux 4. Cette antenne 4 est formée d'un matériau 20 à bande d'interdiction photonique ou matériau BIP associé à un plan métallique 22 réflecteur d'ondes électromagnétiques.FIG. 3 represents a multi-beam antenna 4. This antenna 4 is formed of a photonic ban band material or BIP material associated with a metal plane 22 reflecting electromagnetic waves.

Les matériaux BIP sont connus et la conception d'un matériau BIP tel que le matériau 20 est, par exemple, décrite dans la demande de brevet FR 99 14521. Ainsi, seules les caractéristiques spécifiques de l'antenne 4 par rapport à cet état de la technique seront décrites ici en détail.The BIP materials are known and the design of a BIP material such as the material 20 is, for example, described in the patent application FR 99 14521. Thus, only the specific characteristics of the antenna 4 with respect to this state of the art. the technique will be described here in detail.

Il est rappelé qu'un matériau BIP est un matériau qui possède la propriété d'absorber certaines gammes de fréquences, c'est-à-dire d'interdire toute transmission dans lesdites gammes de fréquences précitées. Ces gammes de fréquences forment ce qu'il est appelé ici une bande non passante.It is recalled that a BIP material is a material which has the property of absorbing certain frequency ranges, that is to say of prohibiting any transmission in said aforementioned frequency ranges. These frequency ranges form what is called here a non-conducting band.

Une bande non passante B du matériau 20 est illustrée à la figure 4. Cette figure 4 représente une courbe représentant les variations du coefficient de transmission exprimé en décibels en fonction de la fréquence de l'onde électromagnétique émise ou reçue. Ce coefficient de transmission est représentatif de l'énergie transmise d'un côté du matériau BIP par rapport à l'énergie reçue de l'autre côté. Dans le cas du matériau 20, la bande non passante B ou bande d'absorption B s'étend sensiblement de 7 GHz à 17 GHz.A non-conducting band B of the material 20 is illustrated in FIG. 4. This FIG. 4 represents a curve representing the variations of the transmission coefficient expressed in decibels as a function of the frequency of the electromagnetic wave emitted or received. This transmission coefficient is representative of the energy transmitted on one side of the BIP material with respect to the energy received on the other side. In the case of the material 20, the non-conducting band B or absorption band B extends substantially from 7 GHz to 17 GHz.

La position et la largeur de cette bande non passante B est uniquement fonction des propriétés et des caractéristiques du matériau BIP.The position and width of this non-conducting band B depends solely on the properties and characteristics of the BIP material.

Le matériau BIP est généralement constitué d'un arrangement périodique de diélectrique de permittivité et/ou de perméabilité variable. Ici, le matériau 20 est formé à partir de deux lames 30, 32 réalisées dans un premier matériau magnétique tel que de l'alumine et de deux lames 34 et 36 formées dans un second matériau magnétique tel que de l'air. La lame 34 est interposée entre les lames 30 et 32, tandis que la lame 36 est interposée entre la lame 32 et le plan réflecteur 22. La lame 30 est disposée à une extrémité de cet empilement de lames. Elle présente une surface extérieure 38 à l'opposé de sa surface en contact avec la lame 34. Cette surface 38 forme une surface rayonnante en émission et/ou en réception.The BIP material generally consists of a periodic arrangement of dielectric permittivity and / or variable permeability. Here, the material 20 is formed from two blades 30, 32 made of a first magnetic material such as alumina and two blades 34 and 36 formed in a second magnetic material such as air. The blade 34 is interposed between the blades 30 and 32, while the blade 36 is interposed between the blade 32 and the reflector plane 22. The blade 30 is disposed at one end of this stack of blades. It has an outer surface 38 opposite its surface in contact with the blade 34. This surface 38 forms a radiating surface in emission and / or reception.

De façon connue, l'introduction d'une rupture dans cette périodicité géométrique et/ou radioélectrique, rupture encore appelée défaut, permet d'engendrer un défaut d'absorption et donc la création d'une bande passante étroite au sein de la bande non passante du matériau BIP. Le matériau est, dans ces conditions, désigné par matériau BIP à défauts.In a known manner, the introduction of a break in this geometric and / or radio frequency periodicity, a break that is also called a defect, allows to generate a lack of absorption and thus the creation of a narrow bandwidth within the non-pass band of the BIP material. Under these conditions, the material is referred to as defective BIP material.

Ici, une rupture de périodicité géométrique est créée en choisissant la hauteur ou épaisseur H de la lame 36 supérieure à celle de la lame 34. De façon connue, et de manière à créer une bande passante étroite E (figure 4) sensiblement au milieu de la bande passante B, cette hauteur H est définie par la relation suivante : H = 0 , 5 × λ / ε r × μ r

Figure imgb0001

où :

  • λ est la longueur d'onde correspondant à la fréquence médiane fm de la bande passante E,
  • εr est la permittivité relative de l'air, et
  • µr est la perméabilité relative de l'air.
Here, a break in geometric periodicity is created by choosing the height or thickness H of the blade 36 greater than that of the blade 34. In known manner, and so as to create a narrow band E (Figure 4) substantially in the middle of the bandwidth B, this height H is defined by the following relation: H = 0 , 5 × λ / ε r × μ r
Figure imgb0001
or :
  • λ is the wavelength corresponding to the median frequency f m of the bandwidth E,
  • ε r is the relative permittivity of the air, and
  • μ r is the relative permeability of the air.

Ici, la fréquence médiane fm est sensiblement égale à 1.2 GHz.Here, the median frequency f m is substantially equal to 1.2 GHz.

La lame 36 forme une cavité résonante parallélépipédique à fuites dont la hauteur H est constante et dont les dimensions latérales sont définies par les dimensions latérales du matériau BIP 20 et du réflecteur 22. Ces lames 30 et 32, ainsi que le plan réflecteur 22, sont rectangulaires et de dimensions latérales identiques. Ici, ces dimensions latérales sont choisies de manière à être plusieurs fois plus grandes que le rayon R défini par la formule empirique suivante : G dB ≥ 20 log π Φ λ − 2 , 5.

Figure imgb0002

où:

  • GdB est le gain en décibels souhaité pour l'antenne,
  • Φ=2 R,
  • λ est la longueur d'onde correspondant à la fréquence médiane fm
The blade 36 forms a parallelepipedal resonant cavity with leaks whose height H is constant and whose lateral dimensions are defined by the lateral dimensions of the BIP material 20 and the reflector 22. These blades 30 and 32, as well as the reflective plane 22, are rectangular and of identical lateral dimensions. Here, these lateral dimensions are chosen to be several times larger than the radius R defined by the following empirical formula: BOY WUT dB ≥ 20 log π Φ λ - two , 5.
Figure imgb0002
or:
  • G dB is the gain in decibels desired for the antenna,
  • Φ = 2 R,
  • λ is the wavelength corresponding to the median frequency f m

A titre d'exemple, pour un gain de 20 dB, le rayon R est sensiblement égal à 2.15 λ.For example, for a gain of 20 dB, the radius R is substantially equal to 2.15 λ.

De façon connue, une telle cavité résonante parallélépipédique présente plusieurs familles de fréquences de résonance. Chaque famille de fréquences de résonance est formée par une fréquence fondamentale et ses harmoniques ou multiples entiers de la fréquence fondamentale. Chaque fréquence de résonance d'une même famille excite le même mode de résonance de la cavité. Ces mode de résonance sont connus sous les termes de modes de résonance TM0, TM1, ..., TMi, .... Ces modes de résonance sont décrits plus en détail dans le document de F. Cardiol, "Electromagnétisme, traité d'Electricité, d'Electronique et d'Electrotechnique", Ed. Dunod, 1987.In known manner, such a parallelepiped resonant cavity has several families of resonant frequencies. Each family of resonance frequencies is formed by a fundamental frequency and its harmonics or integer multiples of the fundamental frequency. Each resonance frequency of the same family excites the same mode of resonance of the cavity. These resonance modes are known under the terms resonance modes TM 0 , TM 1 ,..., TM i , .... These modes of resonance are described in more detail in the document by F. Cardiol, "Electromagnetism, Electricity, Electronics and Electrical Engineering ", Ed. Dunod, 1987.

Il est rappelé ici que le mode de résonance TM0 est susceptible d'être excité par une gamme de fréquences d'excitation voisine d'une fréquence fondamentale fm0. De façon similaire, chaque mode TMi est susceptible d'être excité par une gamme de fréquences d'excitation voisine d'une fréquence fondamentale fmi. Chaque mode de résonance correspond à un diagramme de rayonnement de l'antenne particulier et à une tache rayonnante en émission et/ou en réception formée sur la surface extérieure 38. La tache rayonnante est ici la zone de la surface extérieure 38 contenant l'ensemble des points où la puissance rayonnée en émission et/ou en réception est supérieure ou égale à la moitié de la puissance maximale rayonnée à partir de cette surface extérieure par l'antenne 4. Chaque tache rayonnante admet un centre géométrique correspondant au point où la puissance rayonnée est sensiblement égale à la puissance rayonnée maximale.It is recalled here that the resonance mode TM 0 is likely to be excited by a range of excitation frequencies close to a fundamental frequency f m0 . Similarly, each TM i mode is likely to be excited by a range of excitation frequencies close to a fundamental frequency f mi . Each resonance mode corresponds to a radiation pattern of the particular antenna and to a radiating spot in emission and / or reception formed on the outer surface 38. The radiating spot is here the area of the outer surface 38 containing the entire points where the radiated power in emission and / or in reception is greater than or equal to half of the maximum power radiated from this external surface by the antenna 4. Each radiating spot has a geometrical center corresponding to the point where the power radiated is substantially equal to the maximum radiated power.

Dans le cas du mode de résonance TM0, cette tache rayonnante s'inscrit dans un cercle dont le diamètre φ est donné par la formule (1). Pour le mode de résonance TM0, le diagramme de rayonnement est ici fortement directif le long d'une direction perpendiculaire à la surface extérieure 38 et passant par le centre géométrique de la tache rayonnante. Le diagramme de rayonnement correspondant au mode de résonance TM0 est illustré sur la figure 5.In the case of the TM 0 resonance mode, this radiating spot is part of a circle whose diameter φ is given by the formula (1). For the resonance mode TM 0 , the radiation pattern is here highly directional along a direction perpendicular to the outer surface 38 and passing through the geometric center of the radiating spot. The radiation pattern corresponding to the TM 0 resonance mode is illustrated in FIG. 5.

Les fréquences fmi sont placées à l'intérieur de la bande passante étroite E.The frequencies f mi are placed inside the narrow bandwidth E.

Finalement, quatre éléments d'excitation 40 à 43 sont placés les uns à côté des autres dans la cavité 36 sur le plan réflecteur 22. Dans l'exemple décrit ici, les centres géométriques de ces éléments d'excitation sont placés aux quatre angles d'un losange dont les dimensions des côtés sont strictement inférieures à 2R.Finally, four excitation elements 40 to 43 are placed next to one another in the cavity 36 on the reflector plane 22. In the example described here, the geometric centers of these excitation elements are placed at the four corners of a rhombus whose sides are strictly smaller than 2R.

Chacun de ces éléments d'excitation est apte à émettre et/ou recevoir une onde électromagnétique à une fréquence de travail fTi différente de celle des autres éléments d'excitation. Ici, la fréquence fTi de chaque élément d'excitation est voisine de fm0 de manière à exciter le mode de résonance TM0 de la cavité 36. Ces éléments d'excitation 40 à 43 sont raccordés à un générateur/récepteur 45 classique de signaux électriques destinés à être transformés par chaque élément d'excitation en une onde électromagnétique et vice-versa.Each of these excitation elements is able to emit and / or receive an electromagnetic wave at a working frequency f Ti different from that of the other excitation elements. Here, the frequency f Ti of each excitation element is close to f m0 so as to excite the resonance mode TM 0 of the cavity 36. These excitation elements 40 to 43 are connected to a conventional generator / receiver 45 of FIG. electrical signals to be transformed by each excitation element into an electromagnetic wave and vice versa.

Ces éléments d'excitation sont, par exemple, constitués par un dipôle rayonnant, une fente rayonnant, une sonde plaque ou un patch rayonnants. L'encombrement latéral de chaque élément rayonnant, c'est-à-dire dans un plan parallèle à la surface extérieure 38, est strictement inférieur à la surface de la tache rayonnante à laquelle il donne naissance.These excitation elements are, for example, constituted by a radiating dipole, a radiating slot, a plate probe or a radiating patch. The lateral bulk of each radiating element, that is to say in a plane parallel to the outer surface 38, is strictly smaller than the surface of the radiating spot to which it gives rise.

La figure 6 illustre un exemple d'application de l'antenne 4. La figure 6 représente un système 60 d'émission et/ou de réception d'ondes électromagnétiques propre à équiper un satellite géostationnaire. Ce système 60 comporte une parabole 62 formant réflecteur de faisceaux d'ondes électromagnétiques et l'antenne 4 placée au foyer de cette parabole 62. Les faisceaux d'ondes électromagnétiques émis ou reçus par la surface extérieure 38 de l'antenne 4 sont représentés sur cette figure par des traits 64.FIG. 6 illustrates an example of application of the antenna 4. FIG. 6 represents a system 60 for transmitting and / or receiving electromagnetic waves suitable for equipping a geostationary satellite. This system 60 comprises a parabola 62 forming an electromagnetic wave beam reflector and the antenna 4 placed at the focus of this dish 62. The electromagnetic wave beams emitted or received by the outer surface 38 of the antenna 4 are represented on this figure by lines 64.

Le fonctionnement de l'antenne de la figure 3 va maintenant être décrit dans le cas particulier du système de la figure 6.The operation of the antenna of FIG. 3 will now be described in the particular case of the system of FIG. 6.

En émission, l'élément d'excitation 40, activé par le générateur/récepteur 45, émet une onde électromagnétique à une fréquence de travail fT0 et excite le mode de résonance TM0 de la cavité 36. Les autres éléments rayonnants 41 à 43 sont, par exemple, simultanément activés par le générateur/récepteur 45 et font de même respectivement aux fréquences de travail fT1, fT2 et fT3.In transmission, the excitation element 40, activated by the generator / receiver 45, emits an electromagnetic wave at a working frequency f T0 and excites the resonance mode TM 0 of the cavity 36. The other radiating elements 41 to 43 are, for example, simultaneously activated by the generator / receiver 45 and do the same respectively at the working frequencies f T1 , f T2 and f T3 .

Il a été découvert que, pour le mode de résonance TM0, la tache rayonnante et le diagramme de rayonnement correspondant sont indépendants des dimensions latérales de la cavité 36. En effet, le mode de résonance TM0 n'est fonction que de l'épaisseur et de la nature des matériaux de chacune des lames 30 à 36 et s'établit indépendamment des dimensions latérales de la cavité 36 lorsque celles-ci sont plusieurs fois supérieures au rayon R défini précédemment. Ainsi, plusieurs modes de résonance TM0 peuvent s'établir simultanément l'un à côté de l'autre et donc générer simultanément plusieurs taches rayonnantes disposées les unes à côté des autres. C'est ce qui se produit lorsque les éléments d'excitation 40 à 43 excitent, chacun en des points différents de l'espace, le même mode de résonance. Par conséquent, l'excitation par l'élément d'excitation 40 du mode de résonance TM0 se traduit par l'apparition d'une tache rayonnante 46 sensiblement circulaire et dont le centre géométrique est placé à la verticale du centre géométrique de l'élément 40. De façon similaire, l'excitation par les éléments 41 à 43 du mode de résonance TM0 se traduit par l'apparition, à la verticale du centre géométrique de chacun de ces éléments, respectivement de taches rayonnantes 47 à 49. Le centre géométrique de l'élément 40 étant à une distance strictement inférieure à 2R du centre géométrique des éléments 41 et 43, la tache rayonnante 46 chevauche en partie les taches rayonnantes 47 et 49 correspondant respectivement aux éléments rayonnants 41 et 43. Pour les mêmes raisons, la tache rayonnante 49 chevauche en partie les taches rayonnantes 46 et 48, la tache rayonnante 48 chevauche en partie les taches rayonnantes 49 et 47 et la tache rayonnante 47 chevauche en partie les taches rayonnantes 46 et 48.It has been found that for the TM 0 resonance mode, the radiating spot and the corresponding radiation pattern are independent of the lateral dimensions of the cavity 36. Indeed, the TM 0 resonance mode depends only on the thickness and nature of the materials of each of the blades 30 to 36 and is established independently of the lateral dimensions of the cavity 36 when they are several times greater than the radius R defined above. Thus, several TM 0 resonance modes can be established simultaneously next to each other and thus simultaneously generate several radiating spots arranged next to each other. This is what happens when the excitation elements 40 to 43 excite, each at different points of space, the same mode of resonance. Consequently, the excitation by the excitation element 40 of the resonance mode TM 0 results in the appearance of a radiant spot 46 that is substantially circular and whose geometric center is placed vertically above the geometric center of the element 40. Similarly, excitation by the elements 41 to 43 of the TM 0 resonance mode results in the appearance, at the vertical of the geometric center of each of these elements, respectively of radiating spots 47 to 49. geometric center of the element 40 being at a distance strictly less than 2R of the geometric center of the elements 41 and 43, the radiating spot 46 partially overlaps the radiating spots 47 and 49 respectively corresponding to the radiating elements 41 and 43. For the same reasons , the radiating spot 49 partially overlaps the radiating spots 46 and 48, the radiating spot 48 partly overlaps the radiating spots 49 and 47 and the radiating spot 47 overlaps with the radiating spots 49 and 47 n part radiant spots 46 and 48.

Chaque tache rayonnante correspond à l'embase ou section droite à l'origine d'un faisceau d'ondes électromagnétiques rayonné vers la parabole 62 et réfléchi par cette parabole 62 vers la surface terrestre. Ainsi, de façon similaire aux antennes multi-faisceaux à taches rayonnantes chevauchées connues, les zones de couverture sur la surface terrestre correspondant à chacun des faisceaux émis sont proches les unes des autres, voire se chevauchent, de manière à supprimer ou à réduire les trous de réception.Each radiating spot corresponds to the base or cross-section at the origin of an electromagnetic wave beam radiated towards the dish 62 and reflected by this parabola 62 towards the terrestrial surface. Thus, similar to the known overlapping multi-beam multi-beam antennas, the coverage areas on the terrestrial surface corresponding to each of the emitted beams are close to each other, or even overlap, so as to eliminate or reduce the holes reception.

En réception, de façon similaire à ce qui a été décrit en émission, chaque tache rayonnante de la surface extérieure 38 correspond à une zone de couverture sur la surface terrestre. Ainsi, par exemple, si une onde électromagnétique est émise à partir de la zone de couverture correspondant à la tache rayonnante 46, celle-ci est reçue dans la surface correspondant à la tache 46 après avoir été réfléchie par la parabole 62. Si l'onde reçue est à une fréquence comprise dans la bande passante étroite E, elle n'est pas absorbée par le matériau BIP 20 et elle est reçue par l'élément d'excitation 40. Chaque onde électromagnétique reçue par un élément d'excitation est transmise sous forme d'un signal électrique au générateur/récepteur 45.In reception, similar to what has been described in emission, each radiating spot of the outer surface 38 corresponds to a coverage area on the earth's surface. Thus, for example, if an electromagnetic wave is emitted from the coverage area corresponding to the radiating spot 46, it is received in the surface corresponding to the stain 46 after being reflected by the dish 62. If the received wave is at a frequency in the narrow bandwidth E, it is not absorbed by the BIP material 20 and is received by the excitation element 40. Each electromagnetic wave received by an excitation element is transmitted in the form of an electrical signal to the generator / receiver 45.

La figure 7 représente une antenne 70 réalisée à partir d'un matériau BIP 72 et d'un réflecteur 74 d'ondes électromagnétiques et la figure 8 l'évolution du coefficient de transmission de cette antenne en fonction de la fréquence.FIG. 7 represents an antenna 70 made from a BIP material 72 and a reflector 74 of electromagnetic waves, and FIG. 8 shows the evolution of the transmission coefficient of this antenna as a function of frequency.

Le matériau BIP 72 est, par exemple, identique au matériau BIP 20 et présente la même bande non passante B (figure 8). Les lames formant ce matériau BIP déjà décrites en regard de la figure 3 portent les mêmes références numériques.The BIP material 72 is, for example, identical to the BIP material 20 and has the same non-conducting band B (FIG. 8). The blades forming this BIP material already described with reference to FIG. 3 bear the same numerical references.

Le réflecteur 74 est formé, par exemple, à partir du plan réflecteur 22 déformé de manière à diviser la cavité 36 en deux cavités résonantes 76 et 78 de hauteurs différentes. La hauteur constante H1 de la cavité 76 est déterminée de manière à placer, au sein de la bande non passante B, une bande passante étroite E1 (figure 8), par exemple, autour de la fréquence de 10 GHz. De façon similaire, la hauteur H2 de la cavité résonante 78 est déterminée pour placer, au sein de la même bande non passante B, une bande passante étroite E2 (figure 8), par exemple centrée autour de 14 GHz. Le réflecteur 74 se compose ici de deux demi-plans réflecteurs 80 et 82 disposés en gradins et reliés électriquement l'un à l'autre. Le demi-plan réflecteur 80 est parallèle à la lame 32 et espacé de celle-ci de la hauteur H1. Le demi-plan 82 est parallèle à la lame 32 et espacé de celle-ci de la hauteur constante H2.The reflector 74 is formed, for example, from the reflective plane 22 deformed so as to divide the cavity 36 into two resonant cavities 76 and 78 of different heights. The constant height H 1 of the cavity 76 is determined so as to place, within the non-conducting band B, a narrow bandwidth E 1 (FIG. 8), for example, around the frequency of 10 GHz. Similarly, the height H 2 of the resonant cavity 78 is determined so as to place, within the same non-conducting band B, a narrow bandwidth E 2 (FIG. 8), for example centered around 14 GHz. The reflector 74 is composed here of two reflective half-planes 80 and 82 arranged in steps and electrically connected to one another. The reflective half-plane 80 is parallel to the blade 32 and spaced therefrom by the height H 1 . The half-plane 82 is parallel to the blade 32 and spaced therefrom from the constant height H 2 .

Finalement, un élément d'excitation 84 est disposé dans la cavité 76 et un élément d'excitation 86 est disposé dans la cavité 78. Ces éléments d'excitation 84, 86 sont, par exemple, identiques aux éléments d'excitation 40 à 43 à l'exception du fait que l'élément d'excitation 84 est propre à exciter le mode de résonance TM0 de la cavité 76, tandis que l'élément d'excitation 86 est propre à exciter le mode de résonance TM0 de la cavité 78.Finally, an excitation element 84 is disposed in the cavity 76 and an excitation element 86 is disposed in the cavity 78. These excitation elements 84, 86 are, for example, identical to the excitation elements 40 to 43. with the exception that the excitation element 84 is able to excite the resonance mode TM 0 of the cavity 76, while the excitation element 86 is able to excite the resonance mode TM 0 of the cavity 78.

Dans ce mode de réalisation, la distance horizontale, c'est-à-dire parallèle à la lame 32, séparant le centre géométrique des éléments d'excitation 84 et 86, est strictement inférieure à la somme des rayons de deux taches rayonnantes produites respectivement par les éléments 84 et 86.In this embodiment, the horizontal distance, that is to say parallel to the blade 32, separating the geometric center of the elements of excitation 84 and 86, is strictly less than the sum of the radii of two radiating spots produced respectively by the elements 84 and 86.

Le fonctionnement de cette antenne 70 est identique à celui de l'antenne de la figure 3. Toutefois, dans ce mode de réalisation, les fréquences de travail des éléments d'excitation 84 et 86 sont situées dans des bandes passantes étroites E1, E2 respectives. Ainsi, contrairement à l'antenne 4 de la figure 3, les fréquences de travail de chacun de ces éléments d'excitation sont séparées l'une de l'autre par un grand intervalle de fréquence, par exemple, ici, 4 GHz. Dans ce mode de réalisation, les positions des bandes passentes E1, E2 sont choisies de manière à pouvoir utiliser des fréquences de travail imposées.The operation of this antenna 70 is identical to that of the antenna of FIG. 3. However, in this embodiment, the working frequencies of the excitation elements 84 and 86 are located in narrow bandwidths E 1 , E 2 respective. Thus, unlike the antenna 4 of FIG. 3, the working frequencies of each of these excitation elements are separated from each other by a large frequency interval, for example here 4 GHz. In this embodiment, the positions of the pass bands E 1 , E 2 are chosen so as to be able to use imposed working frequencies.

La figure 9 représente une antenne multi-faisceaux 100. Cette antenne 100 est similaire à l'antenne 4 à l'exception du fait que le matériau BIP mono-défaut 20 du dispositif rayonnant 4 est remplacé par un matériau BIP 102 à plusieurs défauts. Sur la figure 7, les éléments déjà décrits en regard de la figure 4 portent les mêmes références numériques.FIG. 9 represents a multi-beam antenna 100. This antenna 100 is similar to the antenna 4 except that the single-defective BIP material 20 of the radiating device 4 is replaced by a multi-fault BIP material 102. In FIG. 7, the elements already described with reference to FIG. 4 bear the same numerical references.

L'antenne 100 est représentée en coupe suivant un plan de coupe perpendiculaire au plan réflecteur 22 et passant par les éléments d'excitation 41 et 43.The antenna 100 is shown in section along a section plane perpendicular to the reflector plane 22 and passing through the excitation elements 41 and 43.

Le matériau BIP 102 comporte deux groupements successifs 104 et 106 de lames réalisées dans un premier matériau diélectrique. Les groupements 104 et 106 sont superposés dans la direction perpendiculaire au plan réflecteur 22. Chaque groupement 104, 106 est formé, à titre d'exemple non limitatif, respectivement par deux lames 110, 112 et 114, 116 parallèles au plan réflecteur 22. Chaque lame d'un groupement a la même épaisseur que les autres lames de ce même groupement. Dans le cas du groupement 106, chaque lame a une épaisseur e2 = λ/2 où λ désigne la longueur d'onde de la fréquence médiane de la bande étroite créée par les défauts du matériau BIP.The BIP material 102 comprises two successive groups 104 and 106 of blades made of a first dielectric material. The groups 104 and 106 are superimposed in the direction perpendicular to the reflective plane 22. Each group 104, 106 is formed, by way of non-limiting example, respectively by two blades 110, 112 and 114, 116 parallel to the reflector plane 22. Each blade of a group has the same thickness as the other blades of this same grouping. In the case of the group 106, each plate has a thickness e 2 = λ / 2 where λ denotes the wavelength of the median frequency of the narrow band created by the defects of the BIP material.

Chaque lame du groupement 104 a une épaisseur e1 = λ/4.Each blade of the group 104 has a thickness e 1 = λ / 4.

Le calcul de ces épaisseurs e1 et e2 découle de l'enseignement divulgué dans le brevet français 99 14521 (2 801 428).The calculation of these thicknesses e 1 and e 2 follows from the teaching disclosed in the French patent 99 14521 (2 801 428).

Entre chaque lame du matériau BIP 102 à défaut est interposée une lame en un second matériau diélectrique, tel que de l'air. L'épaisseur de ces lames séparant les lames 110, 112, 114 et 116 est égale à λ/4.Between each blade of the BIP 102 material is interposed a blade of a second dielectric material, such as air. The thickness of these blades separating the blades 110, 112, 114 and 116 is equal to λ / 4.

La première lame 116 est disposée en vis-à-vis du plan réflecteur 22 et séparée de ce plan par une lame en second matériau diélectrique d'épaisseur λ/2 de manière à former une cavité parallélépipédique résonante à fuites. De préférence, l'épaisseur ei des lames de matériau diélectrique, consécutive de chaque groupe de lames de matériau diélectrique, est en progression géométrique de raison q dans la direction des groupements 104, 106 successifs.The first blade 116 is disposed vis-à-vis the reflector plane 22 and separated from this plane by a blade of second dielectric material thickness λ / 2 so as to form a parallelepiped cavity resonant leak. Preferably, the thickness e i of the blades of dielectric material, consecutive to each group of blades of dielectric material, is in geometric progression of reason q in the direction of successive groups 104, 106.

De plus, dans le mode de réalisation décrit ici, à titre d'exemple non limitatif, le nombre de groupements superposés est égal à 2 afin de ne pas surcharger le dessin, et la raison de progression géométrique est également prise égale à 2. Ces valeurs ne sont pas limitatives.In addition, in the embodiment described here, by way of non-limiting example, the number of superimposed groups is equal to 2 so as not to overload the drawing, and the geometric progression reason is also taken equal to 2. These values are not limiting.

Cette superposition de groupements de matériau BIP ayant des caractéristiques de perméabilité magnétique, de permittivité diélectrique et d'épaisseur ei différentes accroît la largeur de la bande passante étroite créée au sein de la même bande non passante du matériau BIP. Ainsi, les fréquences de travail des éléments rayonnants 40 à 43 sont choisies plus espacées les unes des autres que dans le mode de réalisation de la figure 3.This superposition of groups of BIP material having characteristics of magnetic permeability, dielectric permittivity and thickness e i different increases the width of the narrow bandwidth created within the same non-pass band of the BIP material. Thus, the working frequencies of the radiating elements 40 to 43 are chosen more spaced apart from one another than in the embodiment of FIG. 3.

Le fonctionnement de ce dispositif rayonnant 100 découle directement de celui de l'antenne 4.The operation of this radiating device 100 derives directly from that of the antenna 4.

En variante, la parabole 62 est remplacée par une lentille électromagnétique.Alternatively, the parabola 62 is replaced by an electromagnetic lens.

Les dispositifs rayonnants décrits jusqu'à présents sont réalisés à partir de structures planes. Toutefois, en variante, la surface de ces différents éléments est adaptée à la forme de la parabole ou du dispositif apte à focaliser les faisceaux d'ondes électromagnétiques. Par exemple, la figure 10 représente une antenne 200 équipée d'un dispositif 202 apte à focaliser les faisceaux d'ondes électromagnétiques sur une antenne 204. Le dispositif 202 est, par exemple, un réflecteur métallique en forme de demi-cylindre. L'antenne 204 est placée au foyer de ce dispositif 202. L'antenne 204 est similaire à l'antenne de la figure 3, à l'exception du fait que le plan réflecteur, et les lames du matériau BIP à défaut, présentent chacun une surface convexe correspondant à la surface concave du demi-cylindre.The radiating devices described until now are made from flat structures. However, alternatively, the surface of these different elements is adapted to the shape of the parabola or the device capable of focusing the electromagnetic wave beams. For example, FIG. 10 shows an antenna 200 equipped with a device 202 able to focus the electromagnetic wave beams on an antenna 204. The device 202 is, for example, a metal reflector in the form of a half-cylinder. The antenna 204 is placed at the focus of this device 202. The antenna 204 is similar to the antenna of FIG. 3, except that the reflector plane, and the blades of the BIP material, each have a convex surface corresponding to the concave surface of the half-cylinder.

En variante, le rayonnement émis ou reçu par chaque élément d'excitation est polarisé dans une direction différente de celle utilisée par les éléments d'excitation voisins. Avantageusement, la polarisation de chaque élément d'excitation est orthogonale à celle utilisée par les éléments d'excitation voisins. Ainsi, les interférences et les couplages entre éléments d'excitation voisins sont limités.In a variant, the radiation emitted or received by each excitation element is polarized in a direction different from that used by the neighboring excitation elements. Advantageously, the polarization of each excitation element is orthogonal to that used by neighboring excitation elements. Thus, interference and coupling between neighboring excitation elements are limited.

En variante, un même élément d'excitation est adapté pour fonctionner successivement ou simultanément à plusieurs fréquences de travail différentes. Un tel élément permet de créer une zone de couverture dans laquelle, par exemple, l'émission et la réception se font à des longueurs d'ondes différentes. Un tel élément d'excitation est également apte à faire de la commutation de fréquence.Alternatively, the same excitation element is adapted to operate successively or simultaneously at several different working frequencies. Such an element makes it possible to create a coverage area in which, for example, transmission and reception take place at different wavelengths. Such an excitation element is also able to make frequency switching.

Claims (11)

  1. System for transmitting and/or receiving electromagnetic waves comprising:
    • a device (62) capable of focussing the electromagnetic waves transmitted and/or received by the system to a focal point, and
    • an electromagnetic wave transmitter and/or receiver positioned essentially at the focal point in order to transmit and/or receive said electromagnetic waves,
    characterised in that:
    it comprises a multi-beam antenna (4), the outer radiating surface of which is essentially positioned at the focal point in order to form said electromagnetic wave transmitter and/or receiver;
    in that the antenna comprises:
    • an FPB (forbidden photonic band) material (20, 42, 172) capable of spatial and frequency filtering of the electromagnetic waves, this FPB material having at least one stop band and forming an outer radiating surface (38, 158) in transmission and/or reception,
    • at least one periodicity defect (36, 76, 78, 156, 180) of the FPB material in order to create at least one narrow pass-band within said at least one stop band of this FPB material, and
    • an excitation device (40 to 43, 84, 86, 160, 162, 190) capable of transmitting and/or receiving electromagnetic waves inside said at least one narrow pass-band created by said at least one defect, this excitation device being capable of working simultaneously at least around a first and a second separate operating frequency;
    in that the excitation device comprises a first and a second excitation element (40 to 43, 84, 86) separate and independent from one another, each capable of transmitting and/or receiving electromagnetic waves, the first excitation element being capable of working at the first operating frequency and the second excitation element being capable of working at the second operating frequency;
    in that the or each periodicity defect (36, 76, 78) of the FPB material forms a resonant cavity (36, 76, 78) with slots having a constant height in a direction orthogonal to said outer radiating surface (38) and determined lateral dimensions parallel to said outer radiating surface;
    in that the first and second operating frequencies are capable of exciting the same resonance mode of a resonant cavity (36, 76, 78) with slots, this resonance mode developing identically irrespective of the lateral dimensions of the cavity in order to respectively create a first and a second radiating patch (46 to 49) on said outer surface, each of these radiating patches representing the origin of a beam of electromagnetic waves radiated in transmission and/or reception by the antenna;
    in that each of the radiating patches (46 to 49) has a geometric centre, the position of which is a function of the position of the excitation element, which creates it and the surface area of which is greater than that of the radiating element which creates it, and
    in that the first and second excitation elements (40 to 43, 84, 86) are positioned relative to one another such that the first and second radiating patches (46 to 49) are disposed on the outer surface (38) of the FPB material beside each other and partially overlapping.
  2. System according to Claim 1, characterised in that the device capable of focussing the electromagnetic waves is a parabolic reflector (62).
  3. System according to Claim 1, characterised in that the device capable of focussing the electromagnetic waves is an electromagnetic lens.
  4. System according to any one of the preceding claims, characterised in that:
    • each radiating patch (46 to 49) is essentially circular, the geometric centre corresponding to a maximum value of transmitted and/or received power and the periphery corresponding to a maximum value of transmitted and/or received power equal to a fraction of the maximum power transmitted and/or received at its centre, and
    • the distance in a plane parallel to the outer surface separating the geometric centres of the two excitation elements (40 to 43, 84, 86) is strictly less than the radius of the radiating patch produced by the first excitation element added to the radius of the radiating patch produced by the second excitation element.
  5. System according to any one of the preceding claims, characterised in that the geometric centre of each radiating patch (46 to 49) is positioned on the line orthogonal to said outer radiating surface (38) and passing through the geometric centre of the excitation element (40 to 43) creating it.
  6. System according to any one of the preceding claims, characterised in that the first and second excitation elements (40 to 43) are positioned inside the same cavity (36).
  7. System according to Claim 6, characterised in that the first and second operating frequencies are located inside the same narrow pass-band created by this same cavity (36).
  8. System according to any one of Claims 1 to 5, characterised in that the first and second excitation elements (84, 86) are each positioned inside separate resonant cavities (76, 78), and in that the first and second operating frequencies are each capable of exciting a resonance mode irrespective of the lateral dimensions of their respective cavity.
  9. Antenna according to Claim 8, characterised in that it comprises a reflector plane (74) of electromagnetic radiation associated with the FPB material (72), this reflector plane being deformed in order to form said separate cavities.
  10. System according to any one of the preceding claims, characterised in that the or each cavity is parallelepipedal in shape.
  11. System according to any one of Claims 1 to 9, characterised in that the device capable of focussing the electromagnetic waves comprises a semi-cylindrical reflector (202), and in that the FPB material of the antenna (204) has a convex surface corresponding to the semi-cylindrical surface of the reflector (202).
EP03778445A 2002-10-24 2003-10-23 Multiple-beam antenna with photonic bandgap material Expired - Lifetime EP1568104B1 (en)

Applications Claiming Priority (5)

Application Number Priority Date Filing Date Title
FR0213326 2002-10-24
FR0213326A FR2854737A1 (en) 2002-10-24 2002-10-24 Earth communications geostationary satellite multiple beam antenna having focal point radiation pattern and photonic band gap material outer surface with periodicity default providing narrow pass band
FR0309472A FR2854734B1 (en) 2003-07-31 2003-07-31 ELECTROMAGNETIC WAVE EMISSION AND RECEPTION SYSTEM EQUIPPED WITH A BEAM MATERIAL MULTI-BEAM ANTENNA
FR0309472 2003-07-31
PCT/FR2003/003145 WO2004040694A1 (en) 2002-10-24 2003-10-23 Multiple-beam antenna with photonic bandgap material

Publications (2)

Publication Number Publication Date
EP1568104A1 EP1568104A1 (en) 2005-08-31
EP1568104B1 true EP1568104B1 (en) 2006-09-13

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EP03778445A Expired - Lifetime EP1568104B1 (en) 2002-10-24 2003-10-23 Multiple-beam antenna with photonic bandgap material

Country Status (7)

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US (1) US7233299B2 (en)
EP (1) EP1568104B1 (en)
JP (1) JP4181172B2 (en)
AT (1) ATE339782T1 (en)
AU (1) AU2003285444A1 (en)
DE (1) DE60308409T2 (en)
WO (1) WO2004040694A1 (en)

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DE60305056T2 (en) * 2002-10-24 2006-12-07 Centre National De La Recherche Scientifique (C.N.R.S.) MULTI-STREAM LENS WITH PHOTONIC BELT MATERIAL
FR2870642B1 (en) * 2004-05-19 2008-11-14 Centre Nat Rech Scient Cnrse BIP MATERIAL ANTENNA (PHOTONIC PROHIBITED BAND) WITH A SIDE WALL SURROUNDING A AXIS
US7760140B2 (en) * 2006-06-09 2010-07-20 Intel Corporation Multiband antenna array using electromagnetic bandgap structures
FR2906410B1 (en) * 2006-09-25 2008-12-05 Cnes Epic BIP MATERIAL ANTENNA (BAND PHOTONIC PROHIBITED), SYSTEM AND METHOD USING THE ANTENNA
US7586444B2 (en) * 2006-12-05 2009-09-08 Delphi Technologies, Inc. High-frequency electromagnetic bandgap device and method for making same
FR2914506B1 (en) * 2007-03-29 2010-09-17 Centre Nat Rech Scient RESONATOR ANTENNA EQUIPPED WITH A FILTER COATING AND SYSTEM INCORPORATING THIS ANTENNA.
US7642978B2 (en) * 2007-03-30 2010-01-05 Itt Manufacturing Enterprises, Inc. Method and apparatus for steering and stabilizing radio frequency beams utilizing photonic crystal structures
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Also Published As

Publication number Publication date
US20060125713A1 (en) 2006-06-15
AU2003285444A1 (en) 2004-05-25
US7233299B2 (en) 2007-06-19
EP1568104A1 (en) 2005-08-31
AU2003285444A8 (en) 2004-05-25
DE60308409T2 (en) 2007-09-20
JP2006504373A (en) 2006-02-02
DE60308409D1 (en) 2006-10-26
ATE339782T1 (en) 2006-10-15
JP4181172B2 (en) 2008-11-12
WO2004040694A1 (en) 2004-05-13

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