EP0805512B1 - Compact printed antenna with little radiation in elevation - Google Patents

Compact printed antenna with little radiation in elevation Download PDF

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Publication number
EP0805512B1
EP0805512B1 EP97460016A EP97460016A EP0805512B1 EP 0805512 B1 EP0805512 B1 EP 0805512B1 EP 97460016 A EP97460016 A EP 97460016A EP 97460016 A EP97460016 A EP 97460016A EP 0805512 B1 EP0805512 B1 EP 0805512B1
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EP
European Patent Office
Prior art keywords
antenna
mode
radiating element
slots
antenna according
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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
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EP97460016A
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German (de)
French (fr)
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EP0805512A1 (en
Inventor
Patrice Brachat
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Orange SA
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France Telecom SA
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q9/00—Electrically-short antennas having dimensions not more than twice the operating wavelength and consisting of conductive active radiating elements
    • H01Q9/04—Resonant antennas
    • H01Q9/0407—Substantially flat resonant element parallel to ground plane, e.g. patch antenna

Definitions

  • the field of the invention is that of printed planar emission antennas and / or receiving microwave signals.
  • the invention relates to a planar antenna producing a maximum radiation for low elevations.
  • the antenna of the invention has many applications. It can for example be used in a network placed on the roof of a private vehicle, in order to ensure satellite telecommunications. Indeed, some mobiles, and in particular those in connection with geostationary satellites in countries with medium or high latitude (Europe of North for example), require flat antennas producing maximum radiation for low elevations.
  • a printed antenna includes a substrate plate dielectric, a ground plane (consisting of a first conductive deposit deposited on a first face of the dielectric substrate plate), a radiating element (constituted by a second conductive deposit deposited on a second face of the substrate plate dielectric) and antenna feed means.
  • these printed antennas In their current operation, that is to say when they operate in their fundamental mode, these printed antennas generate a radiation diagram having a maximum in the direction perpendicular to the plane containing the antenna.
  • the length of the radiating element is very close to half the length wave taking into account the permittivity of the dielectric substrate used.
  • the printed antennas To be able to generate a radiation having a maximum for weak elevations, i.e. in directions away from the axis perpendicular to the plane containing the antenna, the printed antennas must operate in a higher mode whose current distribution makes it possible to create this type of radiation.
  • the major problem resides in the fact that the higher modes presenting the interest appears for relatively high frequencies compared to those of fundamental mode. This means that to be able to use this type of mode (higher) for the desired frequency band (close to that corresponding to the fundamental mode), the antenna must be very oversized.
  • the invention particularly aims to overcome this major drawback of the state of technique.
  • one of the objectives of the present invention is to provide a printed antenna to obtain radiation for low elevations while with a reduced bulk.
  • the invention also aims to provide such an antenna which retains all the advantages of printed antennas, and in particular a low manufacturing cost.
  • the superior mode chosen is the one in which we want to see operate the antenna, so that the maximum radiation is generated for low elevations.
  • the general principle of the invention consists, for a given higher mode, reduce the resonant frequency only by making notches on the element radiant, that is to say without modifying the overall size of the antenna.
  • the printed antenna of the invention has a smaller footprint than a conventional printed antenna.
  • the notch (s) are arranged substantially perpendicular to the current lines of said selected upper mode.
  • the dimensions (length, width) of the notch (s) are determined from a calculation technique based on an element method finished.
  • said radiating element is in the form of a disc.
  • said upper mode chosen is mode TM21, the streamlines of which form a pattern which is repeated in each quarter of said disc, said radiating element has four radial notches, spaced two by two angularly about 90 °, each of said notches being substantially perpendicular to the current lines in one of said quarters of the disc.
  • said upper mode chosen is mode TM01, the currents of which are arranged radially, said radiating element having at least one circular notch, the one or more notches extending over at least part of the circumference of a circle contained in said disc and having the same center as the latter.
  • each notch cooperates with means of annihilation of its effect, said antenna comprising means for activating / deactivating said means of annihilation.
  • said means for annihilating the effect of a notch comprise a diode connecting the two edges of said notch.
  • This multimode operation makes it possible to cover a solid wide angle with a maximum radiation.
  • said radiating element has a plurality of notches, said activation / deactivation means acting on a time-varying number of annihilation means associated with said plurality of notches, so as to allow multifrequency operation such that each distinct number of annihilation means activated at a given time corresponds to a particular resonant frequency of said selected upper mode.
  • the invention also relates to a dual-band antenna, characterized in that it includes two superimposed antennas, called lower and upper antennas, of the type those presented above, the radiating element of said lower antenna constituting the ground plane of said upper antenna.
  • the invention therefore relates to a planar printed antenna for transmission and / or reception of microwave signals.
  • the antenna presents a fundamental mode, in which it generates a diagram of radiation having a maximum in the direction perpendicular to the plane containing the radiating element, and at least one higher mode, in which it generates a radiation diagram at low elevation.
  • FIG. 2 presents a variation curve, as a function of the frequency, of the Standing wave ratio (ROS) of the conventional antenna in Figure 1. This curve clearly shows the resonant frequencies F1 and F2.
  • ROS Standing wave ratio
  • FIG 3 shows a top view of the first antenna according to the invention.
  • the radiating element 30 has four radial notches 31 to 34, spaced two by two angularly around 90 °.
  • the TM21 mode current lines form a pattern which is repeat according to the quarter of the disc (the currents being represented in dotted lines).
  • the notches 31 to 34 are placed in order to obtain maximum interception of the currents on the element radiating 30. In other words, each notch is substantially perpendicular to the streamlines in one quarter of the disc 30.
  • these values are preferably obtained using a calculation technique (implemented by software) based on an element method finished.
  • the purpose of the first antenna is to decrease the mode's resonant frequency higher TM21.
  • the invention therefore makes it possible to considerably reduce the size of the structure by compared to a conventional antenna. Indeed, to obtain a TM21 mode working on frequency of 1.662 GHz, a solid disk with an approximate diameter is required 119 mm instead of the 73.5 mm diameter of the first antenna of the invention. So, in this specific example, the invention allows a reduction in the size of the antenna about 40%.
  • FIGS. 6 and 9 each show the complete radiation diagram, for the Etheta and Ephi components respectively, of the first antenna of the invention.
  • the radiation patterns were measured at the resonant frequency of the TM21 mode.
  • the directivity is 5.56 dB.
  • Figure 12 shows a top view of the second antenna according to the invention.
  • the radiating element 40 has four circular notches 41 to 44, placed in parallel at the circumference of the disc 40.
  • the current lines of the TM01 mode are circular (the currents, shown in dotted lines, being arranged radially).
  • the notches 41 to 44 are placed in order to obtain maximum interception of the currents on the radiating element 40. In in other words, each notch is substantially perpendicular to the current lines in one of the quarters of disc 40.
  • these values are preferably obtained using the abovementioned calculation technique based on a finite element method.
  • the second antenna aims to decrease the mode resonant frequency upper TM01.
  • the invention therefore makes it possible to considerably reduce the size of the structure by compared to a conventional antenna. Indeed, to obtain a TM01 mode working on the frequency of 2.104 GHz, a solid disc with an approximate diameter is required 117 mm instead of the 73.5 mm diameter of the second antenna of the invention. So, in this specific example, the invention again allows a reduction in the size of the antenna by around 40%.
  • Figures 15 and 18 each present the complete radiation diagram, for the Etheta and Ephi components respectively, of the second antenna of the invention.
  • the radiation patterns were measured at the resonant frequency of the TM01 mode.
  • the radiation patterns are presented in the same way as those Figures 6 and 9.
  • the directivity obtained for this antenna is 6.31 dB.
  • FIG 23 shows a top view of a particular embodiment of a antenna according to the invention, in which each notch cooperates with means 61 annihilation of its effect.
  • the antenna also includes activation means / deactivation of these means 61 of annihilation.
  • These means (not shown) of activation / deactivation are for example an electronic control device.
  • the means for annihilating the effect of a notch comprise a diode varactor 61 connecting the two edges of this notch.
  • the means activation / deactivation act on a variable number in time of diodes, of so that each distinct number of diodes activated at a given time corresponds to a particular resonant frequency of the selected higher mode.
  • Figures 24 and 25 each show a view, respectively from the side and from above, of a particular embodiment of a dual-band antenna according to the invention.
  • This dual band antenna includes two antennas (lower 70 and upper 71) superimposed.
  • the radiating element (for example a disc) 72 of the lower antenna 71 constitutes the ground plane of the upper antenna 71.
  • the lower antenna 70 comprises a ground plane 73, a substrate plate (not shown), a radiating element 72 and a first coaxial supply 74.
  • the upper antenna 71 comprises a ground plane (constituted by the radiating element 72 of the lower antenna 70), a substrate plate (not shown), an element radiating 75 and a second coaxial supply 76.
  • Each antenna 70, 71 operates independently.
  • the two discs 72, 75 are offset so that the attack of the upper disc 75 crosses the lower disc 72 in the middle, so as to minimize the disturbance thus brought.

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  • Waveguide Aerials (AREA)

Description

Le domaine de l'invention est celui des antennes imprimées planes d'émission et/ou de réception de signaux hyperfréquences.The field of the invention is that of printed planar emission antennas and / or receiving microwave signals.

Plus précisément, l'invention concerne une antenne plane produisant un rayonnement maximum pour de faibles élévations.More specifically, the invention relates to a planar antenna producing a maximum radiation for low elevations.

L'antenne de l'invention a de nombreuses applications. Elle peut par exemple être utilisée dans un réseau placé sur le toit d'un véhicule particulier, afin d'assurer des télécommunications par satellite. En effet, certains mobiles, et notamment ceux en liaison avec des satellites géostationnaires dans les pays à latitude moyenne ou élevée (Europe du Nord par exemple), nécessitent des antennes planes produisant un rayonnement maximal pour de faibles élévations.The antenna of the invention has many applications. It can for example be used in a network placed on the roof of a private vehicle, in order to ensure satellite telecommunications. Indeed, some mobiles, and in particular those in connection with geostationary satellites in countries with medium or high latitude (Europe of North for example), require flat antennas producing maximum radiation for low elevations.

Actuellement, pour des raisons d'encombrement et de coût, on utilise dans les mobiles des antennes imprimées de type "patch". En effet, celles-ci ont notamment l'avantage d'être planes et peu coûteuses.Currently, for reasons of space and cost, we use in mobile "printed" patch type antennas. Indeed, these have notably the advantage of being flat and inexpensive.

D'une façon générale, une antenne imprimée comprend une plaque de substrat diélectrique, un plan de masse (constitué par un premier dépôt conducteur déposé sur une première face de la plaque de substrat diélectrique), un élément rayonnant (constitué par un second dépôt conducteur déposé sur une seconde face de la plaque de substrat diélectrique) et des moyens d'alimentation de l'antenne.Generally, a printed antenna includes a substrate plate dielectric, a ground plane (consisting of a first conductive deposit deposited on a first face of the dielectric substrate plate), a radiating element (constituted by a second conductive deposit deposited on a second face of the substrate plate dielectric) and antenna feed means.

Dans leur fonctionnement courant, c'est-à-dire lorsqu'elles fonctionnent dans leur mode fondamental, ces antennes imprimées génèrent un diagramme de rayonnement ayant un maximum dans la direction perpendiculaire au plan contenant l'antenne. Pour ce type de fonctionnement courant, la longueur de l'élément rayonnant est très proche de la demi-longueur d'onde prenant en compte la permittivité du substrat diélectrique utilisé.In their current operation, that is to say when they operate in their fundamental mode, these printed antennas generate a radiation diagram having a maximum in the direction perpendicular to the plane containing the antenna. For this type in current operation, the length of the radiating element is very close to half the length wave taking into account the permittivity of the dielectric substrate used.

Pour pouvoir engendrer un rayonnement possédant un maximum pour de faibles élévations, c'est-à-dire dans des directions éloignées de l'axe perpendiculaire au plan contenant l'antenne, les antennes imprimées doivent fonctionner dans un mode supérieur dont la distribution de courant permet de créer ce type de rayonnement.To be able to generate a radiation having a maximum for weak elevations, i.e. in directions away from the axis perpendicular to the plane containing the antenna, the printed antennas must operate in a higher mode whose current distribution makes it possible to create this type of radiation.

Le problème majeur réside dans le fait que les modes supérieurs présentant de l'intérêt apparaissent pour des fréquences relativement élevées par rapport à celles du mode fondamental. Ceci signifie que pour pouvoir utiliser ce type de mode (supérieur) pour la bande de fréquence désirée (proche de celle correspondant au mode fondamental), l'antenne doit être surdimensionnée de manière très importante.The major problem resides in the fact that the higher modes presenting the interest appears for relatively high frequencies compared to those of fundamental mode. This means that to be able to use this type of mode (higher) for the desired frequency band (close to that corresponding to the fundamental mode), the antenna must be very oversized.

Ce surdimensionnement rend quasiment impossible l'intégration en réseau de tels éléments rayonnants afin d'obtenir des antennes à gain élevé. Ce problème d'encombrement est d'autant plus crucial que, pour un réseau devant générer un rayonnement à faible élévation, les éléments rayonnants doivent être placés très proches les uns des autres afin d'éviter d'importants lobes de réseau qui détériorent fortement le gain de l'antenne.This oversizing makes it almost impossible to integrate such into a network. radiating elements to obtain high gain antennas. This problem congestion is all the more crucial since, for a network having to generate a radiation at low elevation, the radiating elements must be placed very close each other in order to avoid large network lobes which greatly deteriorate the antenna gain.

Le document EP 0 708 492 (ASULAB S.A.) décrit (cf. figures 1-4 et page 4, lignes 36-35) une antenne comprenant un disque conducteur et des paires de fentes s'étendant à partir de la périphérie vers le centre du disque, qui permettent de contrôler la fréquence de résonance. En ce qui concerne la disposition des fentes (5 et 6) de l'antenne selon ce document, elles s'étendent à partir de la périphérie vers le centre du disque conducteur (voir figures 3 et 4). Même si les fentes sont perpendiculaires aux lignes de courant du mode TM21, ce document ne suggère en aucune façon l'utilisation de ces fentes pour contrôler la fréquence de résonance de ce mode supérieur.Document EP 0 708 492 (ASULAB S.A.) describes (cf. Figures 1-4 and page 4, lines 36-35) an antenna comprising a conductive disc and pairs of slots extending from the periphery to the center of the disc, which control the resonant frequency. With regard to the arrangement of slots (5 and 6) of the antenna according to this document, they extend from the periphery towards the center of the conductive disc (see Figures 3 and 4). Even if the slits are perpendicular to the current lines of the TM21 mode, this document in no way suggests the use of these slots to control the resonant frequency of this higher mode.

L'invention a notamment pour objectif de pallier cet inconvénient majeur de l'état de la technique.The invention particularly aims to overcome this major drawback of the state of technique.

Plus précisément, l'un des objectifs de la présente invention est de fournir une antenne imprimée permettant d'obtenir un rayonnement pour de faibles élévations tout en présentant un encombrement réduit.More specifically, one of the objectives of the present invention is to provide a printed antenna to obtain radiation for low elevations while with a reduced bulk.

L'invention a également pour objectif de fournir une telle antenne qui conserve tous les avantages des antennes imprimées, et notamment un faible coût de fabrication.The invention also aims to provide such an antenna which retains all the advantages of printed antennas, and in particular a low manufacturing cost.

Ces différents objectifs, ainsi que d'autres qui apparaítront par la suite, sont atteints selon l'invention à l'aide d'une antenne imprimée plane d'émission et/ou de réception de signaux hyperfréquences, du type comprenant notamment

  • une plaque de substrat diélectrique,
  • un plan de masse constitué par un premier dépôt conducteur déposé sur une première face de ladite plaque de substrat diélectrique,
  • un élément rayonnant constitué par un second dépôt conducteur déposé sur une seconde face de ladite plaque de substrat diélectrique,
  • des moyens d'alimentation de ladite antenne,
   ladite antenne présentant un mode fondamental, dans lequel elle génère un diagramme de rayonnement ayant un maximum dans la direction perpendiculaire au plan contenant l'élément rayonnant, et au moins un mode supérieur, dans lequel elle génère un diagramme de rayonnement à faible élévation,
   ladite antenne étant caractérisée en ce que ledit élément rayonnant présente au moins une encoche agencée pour contrôler la fréquence de résonance d'un mode supérieur choisi.These various objectives, as well as others which will appear subsequently, are achieved according to the invention using a planar printed antenna for transmitting and / or receiving microwave signals, of the type comprising in particular
  • a dielectric substrate plate,
  • a ground plane constituted by a first conductive deposit deposited on a first face of said dielectric substrate plate,
  • a radiating element constituted by a second conductive deposit deposited on a second face of said dielectric substrate plate,
  • means for supplying said antenna,
said antenna having a fundamental mode, in which it generates a radiation diagram having a maximum in the direction perpendicular to the plane containing the radiating element, and at least one higher mode, in which it generates a radiation diagram at low elevation,
said antenna being characterized in that said radiating element has at least one notch arranged to control the resonant frequency of a chosen higher mode.

Le mode supérieur choisi est celui dans lequel on désire voir fonctionner l'antenne, de façon que le rayonnement maximal soit généré pour de faibles élévations.The superior mode chosen is the one in which we want to see operate the antenna, so that the maximum radiation is generated for low elevations.

Ainsi, le principe général de l'invention consiste, pour un mode supérieur donné, à réduire la fréquence de résonance uniquement en réalisant des encoches sur l'élément rayonnant, c'est-à-dire sans modifier l'encombrement global de l'antenne. En d'autres termes, pour un fonctionnement dans un même mode supérieur, l'antenne imprimée de l'invention présente un encombrement plus réduit qu'une antenne imprimée classique.Thus, the general principle of the invention consists, for a given higher mode, reduce the resonant frequency only by making notches on the element radiant, that is to say without modifying the overall size of the antenna. In others terms, for operation in the same higher mode, the printed antenna of the invention has a smaller footprint than a conventional printed antenna.

Avantageusement, la ou les encoches sont disposées sensiblement perpendiculairement aux lignes de courant dudit mode supérieur choisi.Advantageously, the notch (s) are arranged substantially perpendicular to the current lines of said selected upper mode.

De cette façon, on augmente la longueur électrique de ces lignes de courant, et on diminue donc la fréquence de résonance du mode supérieur choisi.In this way, we increase the electrical length of these current lines, and we therefore decreases the resonance frequency of the selected higher mode.

De façon avantageuse, les dimensions (longueur, largeur) de la ou des encoches sont déterminées à partir d'une technique de calcul basée sur une méthode d'éléments finis.Advantageously, the dimensions (length, width) of the notch (s) are determined from a calculation technique based on an element method finished.

Préférentiellement, lesdits-moyens d'alimentation mettent en oeuvre une technique d'alimentation appartenant au groupe comprenant

  • l'alimentation par sonde coaxiale ;
  • l'alimentation par couplage par fente ;
  • l'alimentation par couplage de proximité ;
  • l'alimentation par ligne d'alimentation dans le plan de l'élément rayonnant.
Preferably, said feeding means implement a feeding technique belonging to the group comprising
  • feeding by coaxial probe;
  • slot feed;
  • power supply by proximity coupling;
  • supply by supply line in the plane of the radiating element.

Préférentiellement, ledit élément rayonnant est en forme de disque.Preferably, said radiating element is in the form of a disc.

Dans un premier mode de réalisation préférentiel de l'invention, ledit mode supérieur choisi est le mode TM21, dont les lignes de courant forment un motif qui se répète dans chaque quart dudit disque,
   ledit élément rayonnant présentan quatre encoches radiales, espacées deux à deux angulairement d'environ 90°, chacune desdites encoches étant sensiblement perpendiculaires aux lignes de courant dans un desdits quarts du disque.In a first preferred embodiment of the invention, said upper mode chosen is mode TM21, the streamlines of which form a pattern which is repeated in each quarter of said disc,
said radiating element has four radial notches, spaced two by two angularly about 90 °, each of said notches being substantially perpendicular to the current lines in one of said quarters of the disc.

Dans un second mode de réalisation préférentiel de l'invention, ledit mode supérieur choisi est le mode TM01, dont les courants sont disposés radialement,
   ledit élément rayonnant présentant au moins une encoche circulaire, la ou les encoches s'étendant sur au moins une partie de la circonférence d'un cercle contenu dans ledit disque et de même centre que celui-ci.In a second preferred embodiment of the invention, said upper mode chosen is mode TM01, the currents of which are arranged radially,
said radiating element having at least one circular notch, the one or more notches extending over at least part of the circumference of a circle contained in said disc and having the same center as the latter.

De façon avantageuse, chaque encoche coopère avec des moyens d'annihilation de son effet, ladite antenne comprenant des moyens d'activation / désactivation desdits moyens d'annihilation.Advantageously, each notch cooperates with means of annihilation of its effect, said antenna comprising means for activating / deactivating said means of annihilation.

Préférentiellement, lesdits moyens d'annihilation de l'effet d'une encoche comprennent une diode reliant les deux bords de ladite encoche.Preferably, said means for annihilating the effect of a notch comprise a diode connecting the two edges of said notch.

Dans un premier mode de réalisation particulier de l'invention, ledit élément rayonnant présente une pluralité d'encoches,
   lesdits moyens d'activation / désactivation agissant simultanément sur tous les moyens d'annihilation associés à ladite pluralité d'encoches, de façon à permettre un fonctionnement multimode tel que :

  • lorsque tous les moyens d'annihilation sont activés, l'antenne fonctionne dans ledit mode fondamental,
  • lorsque tous les moyens d'annihilation sont désactivés, l'antenne fonctionne dans ledit mode supérieur choisi.
In a first particular embodiment of the invention, said radiating element has a plurality of notches,
said activation / deactivation means acting simultaneously on all the annihilation means associated with said plurality of notches, so as to allow multimode operation such as:
  • when all the annihilation means are activated, the antenna operates in said fundamental mode,
  • when all the annihilation means are deactivated, the antenna operates in said selected upper mode.

Ce fonctionnement multimode permet de couvrir un grand angle solide avec un maximum de rayonnement. En effet, dans le mode fondamental, on a un maximum de rayonnement dans la direction perpendiculaire au plan contenant l'antenne, et dans le mode supérieur choisi, on a un maximum de rayonnement pour une faible élévation.This multimode operation makes it possible to cover a solid wide angle with a maximum radiation. In fact, in the fundamental mode, we have a maximum of radiation in the direction perpendicular to the plane containing the antenna, and in the higher mode chosen, there is a maximum of radiation for a low elevation.

Dans un second mode de réalisation particulier de l'invention, ledit élément rayonnant présente une pluralité d'encoches,
   lesdits moyens d'activation / désactivation agissant sur un nombre variable dans le temps de moyens d'annihilation associés à ladite pluralité d'encoches, de façon à permettre un fonctionnement multifréquence tel que chaque nombre distinct de moyens d'annihilation activés à un instant donné correspond à une fréquence de résonance particulière dudit mode supérieur choisi.In a second particular embodiment of the invention, said radiating element has a plurality of notches,
said activation / deactivation means acting on a time-varying number of annihilation means associated with said plurality of notches, so as to allow multifrequency operation such that each distinct number of annihilation means activated at a given time corresponds to a particular resonant frequency of said selected upper mode.

Ceci permet un fonctionnement multifréquence pour un même type de mode supérieur.This allows multi-frequency operation for the same type of mode superior.

L'invention concerne également une antenne bibande, caractérisée en ce qu'elle comprend deux antennes superposées, dites antennes inférieure et supérieure, du type de celles présentées ci-dessus, l'élément rayonnant de ladite antenne inférieure constituant le plan de masse de ladite antenne supérieure.The invention also relates to a dual-band antenna, characterized in that it includes two superimposed antennas, called lower and upper antennas, of the type those presented above, the radiating element of said lower antenna constituting the ground plane of said upper antenna.

D'autres caractéristiques et avantages de l'invention apparaítront à la lecture de la description suivante de plusieurs modes de réalisation préférentiel de l'invention, donnés à titre d'exemples indicatifs et non limitatifs, et des dessins annexés, dans lesquels :

  • la figure 1 présente une vue de côté d'une antenne classique alimentée par sonde coaxiale ;
  • la figure 2 présente une courbe de variation, en fonction de la fréquence, du rapport d'onde stationnaire (ROS) de l'antenne classique de la figure 1;
  • la figure 3 présente une vue de dessus d'un mode de réalisation d'une première antenne selon l'invention ;
  • la figure 4 présente de façon schématique les lignes de courant du mode TM21 pour la première antenne de la figure 3 ;
  • la figure 5 présente une courbe de variation, en fonction de la fréquence, du ROS de la première antenne de la figure 3 ;
  • la figure 6 présente le diagramme de rayonnement complet, pour la composante Etheta, de la première antenne de la figure 3 ;
  • les figures 7 et 8 présentent chacune une vue en coupe, pour phi = 0° et 90° respectivement, du diagramme de rayonnement de la figure 6 ;
  • la figure 9 présente le diagramme de rayonnement complet, pour la composante Ephi, de la première antenne de la figure 3 ;
  • les figures 10 et 11 présentent chacune une vue en coupe, pour phi = 45° et 135° respectivement, du diagramme de rayonnement de la figure 9 ;
  • la figure 12 présente une vue de dessus d'un mode de réalisation d'une seconde antenne selon l'invention ;
  • la figure 13 présente de façon schématique les lignes de courant du mode TM01 pour la seconde antenne de la figure 12 ;
  • la figure 14 présente une courbe de variation, en fonction de la fréquence, du ROS de la seconde antenne de la figure 12 ;
  • la figure 15 présente le diagramme de rayonnement complet, pour la composante Etheta, de la seconde antenne de la figure 12 ;
  • les figures 16 et 17 présentent chacune une vue en coupe, pour phi = 0° et 90° respectivement, du diagramme de rayonnement de la figure 15 ;
  • la figure 18 présente le diagramme de rayonnement complet, pour la composante Ephi, de la seconde antenne de la figure 12 ;
  • les figures 19 et 20 présentent chacune une vue en coupe, pour phi = 0° et 90° respectivement, du diagramme de rayonnement de la figure 18 ;
  • les figures 21 et 22 présentent chacune une vue, respectivement de côté et de dessus, d'une antenne selon l'invention alimentée par fente ;
  • la figure 23 présente une vue de dessus d'un mode de réalisation particulier d'une antenne selon l'invention comprenant des moyens d'annihilation de l'effet de chaque encoche ; et
  • les figures 24 et 25 présentent chacune une vue, respectivement de côté et de dessus, d'un mode de réalisation particulier d'une antenne bibande selon l'invention.
Other characteristics and advantages of the invention will appear on reading the following description of several preferred embodiments of the invention, given by way of indicative and nonlimiting examples, and of the appended drawings, in which:
  • Figure 1 shows a side view of a conventional antenna supplied by coaxial probe;
  • FIG. 2 shows a variation curve, as a function of frequency, of the standing wave ratio (ROS) of the conventional antenna of FIG. 1;
  • Figure 3 shows a top view of an embodiment of a first antenna according to the invention;
  • Figure 4 schematically shows the current lines of TM21 mode for the first antenna of Figure 3;
  • FIG. 5 shows a variation curve, as a function of the frequency, of the ROS of the first antenna of FIG. 3;
  • FIG. 6 shows the complete radiation diagram, for the Etheta component, of the first antenna in FIG. 3;
  • Figures 7 and 8 each show a sectional view, for phi = 0 ° and 90 ° respectively, of the radiation diagram of Figure 6;
  • FIG. 9 shows the complete radiation diagram, for the Ephi component, of the first antenna in FIG. 3;
  • Figures 10 and 11 each show a sectional view, for phi = 45 ° and 135 ° respectively, of the radiation diagram of Figure 9;
  • Figure 12 shows a top view of an embodiment of a second antenna according to the invention;
  • Figure 13 schematically shows the current lines of TM01 mode for the second antenna of Figure 12;
  • FIG. 14 shows a variation curve, as a function of the frequency, of the ROS of the second antenna of FIG. 12;
  • FIG. 15 shows the complete radiation diagram, for the Etheta component, of the second antenna of FIG. 12;
  • Figures 16 and 17 each show a sectional view, for phi = 0 ° and 90 ° respectively, of the radiation diagram of Figure 15;
  • FIG. 18 shows the complete radiation diagram, for the Ephi component, of the second antenna of FIG. 12;
  • Figures 19 and 20 each show a sectional view, for phi = 0 ° and 90 ° respectively, of the radiation diagram of Figure 18;
  • Figures 21 and 22 each show a view, respectively from the side and from above, of an antenna according to the invention fed by slot;
  • FIG. 23 shows a top view of a particular embodiment of an antenna according to the invention comprising means for annihilating the effect of each notch; and
  • Figures 24 and 25 each show a view, respectively from the side and from above, of a particular embodiment of a dual-band antenna according to the invention.

L'invention concerne donc une antenne imprimée plane d'émission et/ou de réception de signaux hyperfréquences.The invention therefore relates to a planar printed antenna for transmission and / or reception of microwave signals.

La figure 1 présente une vue de côté d'une antenne classique alimentée par sonde coaxiale. L'antenne comprend :

  • une plaque de substrat diélectrique 1, d'épaisseur H = 2,28 mm et de permittivité relative εr = 2,2 par exemple ;
  • un plan de masse 2 constitué par un premier dépôt conducteur, par exemple de cuivre, déposé sur une première face de la plaque de substrat diélectrique 1 ;
  • un élément rayonnant 3 constitué par un second dépôt conducteur, par exemple un disque de cuivre de 73,5 mm de diamètre, déposé sur une seconde face de la plaque de substrat diélectrique 1 ; et
  • une sonde coaxiale 4 permettant d'alimenter l'antenne et comprenant un conducteur externe 5 soudé au plan de masse 2 et un conducteur interne 6 soudé à l'élément rayonnant 3. Le positionnement de cette sonde coaxiale 4 permet d'obtenir l'adaptation de l'antenne.
Figure 1 shows a side view of a conventional antenna powered by a coaxial probe. The antenna includes:
  • a dielectric substrate plate 1, of thickness H = 2.28 mm and of relative permittivity ε r = 2.2 for example;
  • a ground plane 2 consisting of a first conductive deposit, for example of copper, deposited on a first face of the dielectric substrate plate 1;
  • a radiating element 3 constituted by a second conductive deposit, for example a copper disc 73.5 mm in diameter, deposited on a second face of the dielectric substrate plate 1; and
  • a coaxial probe 4 for supplying the antenna and comprising an external conductor 5 welded to the ground plane 2 and an internal conductor 6 welded to the radiating element 3. The positioning of this coaxial probe 4 makes it possible to obtain the adaptation of the antenna.

L'antenne présente un mode fondamental, dans lequel elle génère un diagramme de rayonnement ayant un maximum dans la direction perpendiculaire au plan contenant l'élément rayonnant, et au moins un mode supérieur, dans lequel elle génère un diagramme de rayonnement à faible élévation.The antenna presents a fundamental mode, in which it generates a diagram of radiation having a maximum in the direction perpendicular to the plane containing the radiating element, and at least one higher mode, in which it generates a radiation diagram at low elevation.

Avec les dimensions indiquées précédemment pour les différents éléments 1, 2, 3 de l'antenne, on obtient :

  • une fréquence de résonance F1 = 1,57 GHz pour le mode fondamental TM11;
  • une fréquence de résonance F2 = 2,63 GHz pour le mode supérieur TM21;
  • une fréquence de résonance F3 = 3,26 GHz pour le mode supérieur TM01.
With the dimensions indicated above for the different elements 1, 2, 3 of the antenna, we obtain:
  • a resonance frequency F1 = 1.57 GHz for the fundamental mode TM11;
  • a resonance frequency F2 = 2.63 GHz for the higher mode TM21;
  • a resonant frequency F3 = 3.26 GHz for the higher mode TM01.

La figure 2 présente une courbe de variation, en fonction de la fréquence, du rapport d'onde stationnaire (ROS) de l'antenne classique de la figure 1. Cette courbe montre clairement les fréquences de résonance F1 et F2.FIG. 2 presents a variation curve, as a function of the frequency, of the Standing wave ratio (ROS) of the conventional antenna in Figure 1. This curve clearly shows the resonant frequencies F1 and F2.

Selon l'invention, l'élément rayonnant 3 (c'est-à-dire le disque de cuivre dans cet exemple) n'est pas plein mais présente une ou plusieurs encoches permettant de contrôler la fréquence de résonance d'un mode supérieur choisi. Dans la suite de la description, on présente notamment :

  • en relation avec les figures 3 à 11, une première antenne selon l'invention, pour laquelle le mode supérieur choisi est le mode TM21 ;
  • en relation avec les figures 12 à 20, une seconde antenne selon l'invention, pour laquelle le mode supérieur choisi est le mode TM01.
According to the invention, the radiating element 3 (that is to say the copper disc in this example) is not solid but has one or more notches making it possible to control the resonance frequency of a chosen higher mode . In the following description, we present in particular:
  • in relation to FIGS. 3 to 11, a first antenna according to the invention, for which the upper mode chosen is the TM21 mode;
  • in relation to FIGS. 12 to 20, a second antenna according to the invention, for which the upper mode chosen is the TM01 mode.

La figure 3 présente une vue de dessus de la première antenne selon l'invention. L'élément rayonnant 30 présente quatre encoches radiales 31 à 34, espacées deux à deux angulairement d'environ 90°. Comme cela apparaít sur la figure 4, pour la première antenne de l'invention, les lignes de courant du mode TM21 forment un motif qui se répète selon le quart du disque (les courants étant représentés en pointillés). Les encoches 31 à 34 sont placées afin d'obtenir une interception maximale des courants sur l'élément rayonnant 30. En d'autres termes, chaque encoche est sensiblement perpendiculaire aux lignes de courant dans un des quarts du disque 30.Figure 3 shows a top view of the first antenna according to the invention. The radiating element 30 has four radial notches 31 to 34, spaced two by two angularly around 90 °. As shown in Figure 4, for the first antenna of the invention, the TM21 mode current lines form a pattern which is repeat according to the quarter of the disc (the currents being represented in dotted lines). The notches 31 to 34 are placed in order to obtain maximum interception of the currents on the element radiating 30. In other words, each notch is substantially perpendicular to the streamlines in one quarter of the disc 30.

Dans cet exemple, la longueur des encoches est Lo = 18,375 mm et la largeur La = 7,35 mm. Dans un but d'optimisation, ces valeurs sont de préférence obtenues à l'aide d'une technique de calcul (mise en oeuvre par logiciel) basée sur une méthode d'éléments finis.In this example, the length of the notches is Lo = 18.375 mm and the width La = 7.35 mm. For the purpose of optimization, these values are preferably obtained using a calculation technique (implemented by software) based on an element method finished.

La première antenne a pour but de diminuer la fréquence de résonance du mode supérieur TM21. La figure 5 présente une courbe de variation, en fonction de la fréquence, du ROS de la première antenne de l'invention. Cette figure 5 montre clairement qu'à l'aide des encoches 31 à 34, la fréquence de résonance du mode supérieur TM21 est ramenée de F2 = 2,63 GHz à F2' = 1,662 GHz. On remarque par ailleurs que la fréquence du mode fondamental se situe maintenant à F1' = 1,325 GHz (au lieu de 1,57 GHz sans les encoches).The purpose of the first antenna is to decrease the mode's resonant frequency higher TM21. Figure 5 shows a variation curve, depending on the frequency, of the ROS of the first antenna of the invention. This figure 5 shows clearly that using the notches 31 to 34, the resonance frequency of the higher mode TM21 is reduced from F2 = 2.63 GHz to F2 '= 1.662 GHz. We also note that the fundamental mode frequency is now at F1 '= 1.325 GHz (instead of 1.57 GHz without the notches).

L'invention permet donc de réduire considérablement la taille de la structure par rapport à une antenne classique. En effet, pour obtenir un mode TM21 travaillant à la fréquence de 1,662 GHz, il faudrait un disque plein ayant approximativement un diamètre de 119 mm au lieu du diamètre de 73,5 mm de la première antenne de l'invention. Ainsi, dans cet exemple précis, l'invention permet une réduction de la taille de l'antenne d'environ 40 %.The invention therefore makes it possible to considerably reduce the size of the structure by compared to a conventional antenna. Indeed, to obtain a TM21 mode working on frequency of 1.662 GHz, a solid disk with an approximate diameter is required 119 mm instead of the 73.5 mm diameter of the first antenna of the invention. So, in this specific example, the invention allows a reduction in the size of the antenna about 40%.

Les figures 6 et 9 présentent chacune le diagramme de rayonnement complet, pour les composantes Etheta et Ephi respectivement, de la première antenne de l'invention. Les figures 7 et 8 présentent chacune une vue en coupe, pour phi = 0° et 90° respectivement, du diagramme de rayonnement de la composante Etheta (figure 6). Les figures 10 et 11 présentent chacune une vue en coupe, pour phi = 45° et 135° respectivement, du diagramme de rayonnement de la composante Ephi (figure 9).Figures 6 and 9 each show the complete radiation diagram, for the Etheta and Ephi components respectively, of the first antenna of the invention. The FIGS. 7 and 8 each show a sectional view, for phi = 0 ° and 90 ° respectively, of the radiation pattern of the Etheta component (Figure 6). Figures 10 and 11 each have a sectional view, for phi = 45 ° and 135 ° respectively, of the radiation pattern of the Ephi component (Figure 9).

Les diagrammes de rayonnement ont été mesurés à la fréquence de résonance du mode TM21. Afin d'être très parlants, les résultats sont présentés pour les deux composantes Etheta et Ephi (avec phi = 0 correspondant à l'axe X de l'antenne (cf fig.3), l'axe Z correspondant à la normale au plan de l'antenne.The radiation patterns were measured at the resonant frequency of the TM21 mode. In order to be very meaningful, the results are presented for the two Etheta and Ephi components (with phi = 0 corresponding to the X axis of the antenna (see fig. 3), the Z axis corresponding to the normal to the plane of the antenna.

Les diagrammes de rayonnement se présentent sous forme de "pétales" ayant un maximum situé aux alentours de theta = 45°, avec une rotation spatiale phi = 45° entre les deux diagrammes de rayonnement associés aux deux composantes. La directivité est de 5,56 dB. Ces diagrammes de rayonnement correspondent parfaitement à ceux d'un mode TM21.The radiation patterns are in the form of "petals" having a maximum located around theta = 45 °, with a spatial rotation phi = 45 ° between two radiation patterns associated with the two components. The directivity is 5.56 dB. These radiation patterns correspond perfectly to those of a mode TM21.

La figure 12 présente une vue de dessus de la seconde antenne selon l'invention. L'élément rayonnant 40 présente quatre encoches circulaires 41 à 44, placés parallèlement à la circonférence du disque 40. Comme cela apparaít sur la figure 13, pour la seconde antenne de l'invention, les lignes de courant du mode TM01 sont circulaires (les courants, représentés en pointillés, étant disposés radialement). Les encoches 41 à 44 sont placées afin d'obtenir une interception maximale des courants sur l'élément rayonnant 40. En d'autres termes, chaque encoche est sensiblement perpendiculaire aux lignes de courant dans un des quarts du disque 40.Figure 12 shows a top view of the second antenna according to the invention. The radiating element 40 has four circular notches 41 to 44, placed in parallel at the circumference of the disc 40. As it appears in Figure 13, for the second antenna of the invention, the current lines of the TM01 mode are circular (the currents, shown in dotted lines, being arranged radially). The notches 41 to 44 are placed in order to obtain maximum interception of the currents on the radiating element 40. In in other words, each notch is substantially perpendicular to the current lines in one of the quarters of disc 40.

Dans cet exemple, le rayon interne des encoches est Ri = 23,52 mm, le rayon externe Re = 25,72 mm et le débattement angulaire Da = 70°. Dans un but d'optimisation, ces valeurs sont de préférence obtenues à l'aide de la technique de calcul précitée basée sur une méthode d'éléments finis.In this example, the internal radius of the notches is Ri = 23.52 mm, the radius external Re = 25.72 mm and the angular movement Da = 70 °. In order to optimize, these values are preferably obtained using the abovementioned calculation technique based on a finite element method.

La seconde antenne a pour but de diminuer la fréquence de résonance du mode supérieur TM01. La figure 14 présente une courbe de variation, en fonction de la fréquence, du ROS de la seconde antenne de l'invention. Cette figure 14 montre clairement qu'à l'aide des encoches 41 à 44, la fréquence de résonance du mode supérieur TM01 est ramenée de F3 = 3,26 GHz à F3' = 2,104 GHz.The second antenna aims to decrease the mode resonant frequency upper TM01. Figure 14 shows a variation curve, depending on the frequency, of the ROS of the second antenna of the invention. This figure 14 shows clearly that using the notches 41 to 44, the resonance frequency of the higher mode TM01 is reduced from F3 = 3.26 GHz to F3 '= 2.104 GHz.

L'invention permet donc de réduire considérablement la taille de la structure par rapport à une antenne classique. En effet, pour obtenir un mode TM01 travaillant à la fréquence de 2,104 GHz, il faudrait un disque plein ayant approximativement un diamètre de 117 mm au lieu du diamètre de 73,5 mm de la seconde antenne de l'invention. Ainsi, dans cet exemple précis, l'invention permet de nouveau une réduction de la taille de l'antenne d'environ 40 %. The invention therefore makes it possible to considerably reduce the size of the structure by compared to a conventional antenna. Indeed, to obtain a TM01 mode working on the frequency of 2.104 GHz, a solid disc with an approximate diameter is required 117 mm instead of the 73.5 mm diameter of the second antenna of the invention. So, in this specific example, the invention again allows a reduction in the size of the antenna by around 40%.

Les figures 15 et 18 présentent chacune le diagramme de rayonnement complet, pour les composantes Etheta et Ephi respectivement, de la seconde antenne de l'invention. Les figures 16 et 17 présentent chacune une vue en coupe, pour phi = 0° et 90° respectivement, du diagramme de rayonnement de la composante Etheta (figure 15). Les figures 19 et 20 présentent chacune une vue en coupe, pour phi = 0° et 90° respectivement, du diagramme de rayonnement de la composante Ephi (figure 18).Figures 15 and 18 each present the complete radiation diagram, for the Etheta and Ephi components respectively, of the second antenna of the invention. Figures 16 and 17 each show a sectional view, for phi = 0 ° and 90 ° respectively, of the radiation pattern of the Etheta component (Figure 15). The Figures 19 and 20 each show a sectional view, for phi = 0 ° and 90 ° respectively, from the radiation pattern of the Ephi component (Figure 18).

Les diagrammes de rayonnement ont été mesurés à la fréquence de résonance du mode TM01. Les diagrammes de rayonnement sont présentés de la même façon que ceux des figures 6 et 9.The radiation patterns were measured at the resonant frequency of the TM01 mode. The radiation patterns are presented in the same way as those Figures 6 and 9.

On constate que la composante Etheta se présente sous la forme d'un tore ayant un maximum situé aux environs de théta = 45°. La directivité obtenue pour cette antenne est de 6,31 dB. Ces diagrammes de rayonnement correspondent parfaitement à ceux d'un mode TM01.We note that the Etheta component is in the form of a torus with a maximum located around theta = 45 °. The directivity obtained for this antenna is 6.31 dB. These radiation patterns correspond perfectly to those of a TM01 mode.

Les figures 21 et 22 présentent chacune une vue, respectivement de côté et de dessus, d'une antenne selon l'invention alimentée par fente. Cette antenne comprend les éléments suivants superposés :

  • un élément rayonnant 50 du type de celui présenté sur la figure 3 (avec quatre encoches radiales) et de diamètre W ;
  • une première couche de substrat 51, de hauteur H1 et de permittivité relative εr1 ;
  • un premier plan de masse 52 comportant une fente de couplage 53 ;
  • une seconde couche de substrat 54, de hauteur H2 et de permittivité relative εr2 ;
  • une ligne d'alimentation 55, dont l'extrémité qui s'étend au-delà de la fente 53 constitue un stub d'adaptation de longueur Lstub ;
  • une troisième couche de substrat 56, de hauteur H3 et de permittivité relative εr3 ;
  • un second plan de masse 57.
Figures 21 and 22 each show a view, respectively from the side and from above, of an antenna according to the invention fed by slot. This antenna includes the following superimposed elements:
  • a radiating element 50 of the type presented in FIG. 3 (with four radial notches) and of diameter W;
  • a first layer of substrate 51, of height H1 and of relative permittivity ε r1 ;
  • a first ground plane 52 comprising a coupling slot 53;
  • a second layer of substrate 54, of height H2 and of relative permittivity ε r2 ;
  • a supply line 55, the end of which extends beyond the slot 53 constitutes an adaptation stub of length Lstub;
  • a third substrate layer 56, of height H3 and of relative permittivity ε r3 ;
  • a second ground plane 57.

On a présenté ci-dessus deux types d'alimentation, à savoir par sonde coaxiale et par couplage par fente. Il est clair cependant que l'invention n'est pas limitée à ces deux types d'alimentation mais peut être utilisée par tout type d'alimentation classique (couplage de proximité, ligne d'alimentation dans le plan de l'élément rayonnant, etc).Two types of feeding have been presented above, namely by coaxial probe and by slot coupling. It is clear however that the invention is not limited to these two feed types but can be used by any conventional feed type (proximity coupling, supply line in the plane of the radiating element, etc.).

La figure 23 présente une vue de dessus d'un mode de réalisation particulier d'une antenne selon l'invention, dans lequel chaque encoche coopère avec des moyens 61 d'annihilation de son effet. L'antenne comprend également des moyens d'activation / désactivation de ces moyens 61 d'annihilation. Ces moyens (non représentés) d'activation / désactivation sont par exemple un dispositif de commande électronique. Dans l'exemple présenté, les moyens d'annihilation de l'effet d'une encoche comprennent une diode varactor 61reliant les deux bords de cette encoche.Figure 23 shows a top view of a particular embodiment of a antenna according to the invention, in which each notch cooperates with means 61 annihilation of its effect. The antenna also includes activation means / deactivation of these means 61 of annihilation. These means (not shown) of activation / deactivation are for example an electronic control device. In the example presented, the means for annihilating the effect of a notch comprise a diode varactor 61 connecting the two edges of this notch.

Ainsi, avec ces moyens supplémentaires, on peut envisager d'autres types de fonctionnement de l'antenne de l'invention, et notamment un fonctionnement multimode et un fonctionnement multifréquence.So, with these additional means, we can envisage other types of operation of the antenna of the invention, and in particular multimode operation and multi-frequency operation.

En fonctionnement multimode, les moyens d'activation / désactivation agissent simultanément sur toutes les diodes, de façon que :

  • lorsque toutes les diodes sont activées, l'antenne fonctionne dans le mode fondamental (ayant un maximum de rayonnement perpendiculaire à l'antenne),
  • lorsque toutes les diodes sont désactivées, l'antenne fonctionne dans un mode supérieur choisi (ayant un maximum de rayonnement pour une faible élévation).
In multimode operation, the activation / deactivation means act simultaneously on all the diodes, so that:
  • when all the diodes are activated, the antenna operates in the fundamental mode (having a maximum of radiation perpendicular to the antenna),
  • when all the diodes are deactivated, the antenna operates in a selected higher mode (having a maximum of radiation for a low elevation).

En fonctionnement multifréquence pour un mode supérieur choisi, les moyens d'activation / désactivation agissent sur un nombre variable dans le temps de diodes, de façon que chaque nombre distinct de diodes activées à un instant donné corresponde à une fréquence de résonance particulière du mode supérieur choisi.In multifrequency operation for a selected higher mode, the means activation / deactivation act on a variable number in time of diodes, of so that each distinct number of diodes activated at a given time corresponds to a particular resonant frequency of the selected higher mode.

Les figures 24 et 25 présentent chacune une vue, respectivement de côté et de dessus, d'un mode de réalisation particulier d'une antenne bibande selon l'invention.Figures 24 and 25 each show a view, respectively from the side and from above, of a particular embodiment of a dual-band antenna according to the invention.

Cette antenne bibande comprend deux antennes (inférieure 70 et supérieure 71) superposées. L'élément rayonnant (par exemple un disque) 72 de l'antenne inférieure 71 constitue le plan de masse de l'antenne supérieure 71.This dual band antenna includes two antennas (lower 70 and upper 71) superimposed. The radiating element (for example a disc) 72 of the lower antenna 71 constitutes the ground plane of the upper antenna 71.

L'antenne inférieure 70 comprend un plan de masse 73, une plaque de substrat (non représentée), un élément rayonnant 72 et une première alimentation coaxiale 74. L'antenne supérieure 71 comprend un plan de masse (constitué par l'élément rayonnant 72 de l'antenne inférieure 70), une plaque de substrat (non représentée), un élément rayonnant 75 et une seconde alimentation coaxiale 76.The lower antenna 70 comprises a ground plane 73, a substrate plate (not shown), a radiating element 72 and a first coaxial supply 74. The upper antenna 71 comprises a ground plane (constituted by the radiating element 72 of the lower antenna 70), a substrate plate (not shown), an element radiating 75 and a second coaxial supply 76.

Chaque antenne 70, 71 fonctionne de façon indépendante. Les deux disques 72, 75 sont décalés de sorte que l'attaque du disque supérieur 75 traverse le disque inférieur 72 en son milieu, de manière à minimiser la perturbation ainsi apportée.Each antenna 70, 71 operates independently. The two discs 72, 75 are offset so that the attack of the upper disc 75 crosses the lower disc 72 in the middle, so as to minimize the disturbance thus brought.

Claims (12)

  1. Flat printed antenna for transmission and/or reception of microwave signals, the antenna comprising:
    a plate of dielectric substrate (1),
    an earth plane (2) formed by a first conductor layer deposited on a first face of said plate of dielectric substrate,
    a radiating element (30; 40; 50) formed by a second conductor layer deposited on a second face of said plate of dielectric substrate,
    means (4) for feeding said antenna,
    said antenna having a fundamental mode (TM11), in which it generates a radiation pattern having a maximum in the direction perpendicular to the plane containing the radiating element, and at least one higher mode (TM21, TM01), in which it generates a radiation pattern at low elevation,
    characterised in that said radiating element has at least one slot (31 to 34; 41 to 44) arranged to control the resonant frequency of a chosen higher mode.
  2. Antenna according to Claim 1, characterised in that the slot or slots (31 to 34; 41 to 44) are arranged approximately perpendicularly to the current lines of said chosen higher mode.
  3. Antenna according to any one of Claims 1 and 2,
    characterised in that the dimensions of the slot or slots (31 to 34; 41 to 44) are determined from a calculation technique based on a finite elements method.
  4. Antenna according to any one of Claims 1 to 3,
    characterised in that said feeding means use a feed technique selected from the group consisting of:
    feed by a coaxial probe (4) ;
    feed by coupling through slits (53);
    feed by proximity coupling;
    feed by a feed line in the plane of the radiating element.
  5. Antenna according to any one of Claims 1 to 4,
    characterised in that said radiating element (30; 40; 50) is in the form of a disc.
  6. Antenna according to Claim 5, characterised in that said chosen higher mode is the TM21 mode, whose current lines form a pattern which is repeated in each quarter of said disc,
    and in that said radiating element (30) has four radial slots (31 to 34), spaced two by two at angles of about 90 degrees, each of said slots being approximately perpendicular to the current lines in one of said quarters of the disc.
  7. Antenna according to Claim 5, characterised in that said chosen higher mode is the TM01 mode, whose current lines are arranged radially,
    and in that said radiating element (40) has at least one circular slot (41 to 44), the slot or slots extending over at least one part of the circumference of a circle contained within said disc and disposed concentrically thereto.
  8. Antenna according to any one of Claims 1 to 7,
    characterised in that each slot works with means (61) for disabling its effect,
    and in that it includes means for activating/deactivating said disabling means.
  9. Antenna according to Claim 8, characterised in that said means for disabling the effect of a slot include a diode (61) connected to two edges of said slot.
  10. Antenna according to any one of Claims 8 and 9,
    characterised in that said radiating element has a plurality of slots,
    and in that said activating/deactivating means act simultaneously on all the disabling means (61) associated with said plurality of slots, in a way that allows multimode operation such that:
    when all the disabling means are activated, the antenna operates in said fundamental mode,
    when all the disabling means are deactivated, the antenna operates in said-chosen higher mode.
  11. Antenna according to any one of Claims 8 and 9,
    characterised in that said radiating element has a plurality of slots,
    and in that said activating/deactivating means act on a number that is variable in time, of disabling means (61) associated with said plurality of slots, in a way that permits multifrequency operation such that each distinct number of disabling means activated at a given instant corresponds to a particular resonant frequency of said chosen higher mode.
  12. Dual-band antenna, characterised in that it includes two superimposed antennas, called lower (70) and upper (71) antennas, according to any one of Claims 1 to 11, the radiating element (72) of said lower antenna forming the earth plane of said upper antenna.
EP97460016A 1996-04-24 1997-04-17 Compact printed antenna with little radiation in elevation Expired - Lifetime EP0805512B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR9605383A FR2748162B1 (en) 1996-04-24 1996-04-24 COMPACT PRINTED ANTENNA FOR LOW ELEVATION RADIATION
FR9605383 1996-04-24

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Publication Number Publication Date
EP0805512A1 EP0805512A1 (en) 1997-11-05
EP0805512B1 true EP0805512B1 (en) 2002-11-06

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EP (1) EP0805512B1 (en)
CA (1) CA2203359A1 (en)
DE (1) DE69716807T2 (en)
FR (1) FR2748162B1 (en)

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DE69716807D1 (en) 2002-12-12
US5966096A (en) 1999-10-12
FR2748162A1 (en) 1997-10-31
FR2748162B1 (en) 1998-07-24
CA2203359A1 (en) 1997-10-24
EP0805512A1 (en) 1997-11-05

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