EP0604338A1 - Space-saving broadband antenna with corresponding transceiver - Google Patents

Space-saving broadband antenna with corresponding transceiver Download PDF

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Publication number
EP0604338A1
EP0604338A1 EP93460039A EP93460039A EP0604338A1 EP 0604338 A1 EP0604338 A1 EP 0604338A1 EP 93460039 A EP93460039 A EP 93460039A EP 93460039 A EP93460039 A EP 93460039A EP 0604338 A1 EP0604338 A1 EP 0604338A1
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EP
European Patent Office
Prior art keywords
antenna
strands
antenna according
horizontal element
horizontal
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.)
Granted
Application number
EP93460039A
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German (de)
French (fr)
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EP0604338B1 (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
    • H01Q9/0421—Substantially flat resonant element parallel to ground plane, e.g. patch antenna with a shorting wall or a shorting pin at one end of the element
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q1/00—Details of, or arrangements associated with, antennas
    • H01Q1/12—Supports; Mounting means
    • H01Q1/22—Supports; Mounting means by structural association with other equipment or articles
    • H01Q1/24—Supports; Mounting means by structural association with other equipment or articles with receiving set
    • H01Q1/241—Supports; Mounting means by structural association with other equipment or articles with receiving set used in mobile communications, e.g. GSM
    • H01Q1/242—Supports; Mounting means by structural association with other equipment or articles with receiving set used in mobile communications, e.g. GSM specially adapted for hand-held use
    • H01Q1/243—Supports; Mounting means by structural association with other equipment or articles with receiving set used in mobile communications, e.g. GSM specially adapted for hand-held use with built-in antennas

Definitions

  • the field of the invention is that of radio transmissions. More specifically, the invention relates to transmit and / or receive antennas, in particular for equipment of reduced size, such as portable devices.
  • the invention thus applies, in particular, to telecommunications systems with mobiles.
  • the extension of radiocommunication networks with land mobiles requires the development of portable autonomous stations having the dual functionality of transmitting and receiving microwave signals. These stations must therefore include an integrated antenna.
  • These antennas are generally in the form of a radiating element located outside of a metal case, for example of rectangular shape, constituting the shielding of one or more electronic cards ensuring in particular the modulation and demodulation functions.
  • microwave signals in transmission and reception respectively.
  • Such an antenna in inverted F is shown in section in Figure 1 and in perspective in Figure 2. It consists of a horizontal rectangular conductive element 11 and a vertical conductive element 12. The vertical element 12 performs a function short-circuit on the horizontal element 11, by connecting one of its ends 13 to a ground plane 14.
  • the other end 15 of the horizontal element 11 is open.
  • the microwave signal is conveyed by an excitation coaxial 16, which is connected to the horizontal element 11 at a location 17.
  • the choice of this location 17 between the short-circuited end 13 and the open end 15 of the horizontal element 11 determines the impedance of the antenna thus obtained.
  • the antenna obtained is therefore very compact. Furthermore, the radiation pattern of this antenna is substantially omnidirectional, which is essential for portable devices (this characteristic is generally verified by all antennas with a small footprint).
  • this antenna has very frequency dispersive characteristics, and therefore, consequently, a very low bandwidth, and for example of the order of 2 to 3%. This is due to the fact that this antenna structure behaves substantially like a ⁇ / 4 resonator.
  • the bandwidth of an antenna is defined here as the frequency band over which the Standing Wave Ratio (ROS) is less than 2. This last parameter represents the ability of the antenna to transmit the active power which is which is most critical for small antennas.
  • ROS Standing Wave Ratio
  • This quantity is directly linked to the input impedance of the antenna, which must be adapted to the impedance of the transmission line carrying the microwave signal to be transmitted and / or received.
  • this impedance remains substantially constant (that is to say that the R.O.S remains less than 2) over a large frequency band.
  • a bandwidth of 2 to 3% as obtained using an inverted F antenna is generally insufficient.
  • the invention particularly aims to overcome this drawback of the prior art.
  • an objective of the invention is to provide a compact antenna having a large pass.
  • the invention has in particular the objective of providing such an antenna, the bandwidth of which is at least of the order of 8 to 10%.
  • Another objective of the invention is to provide such an antenna, which is of reduced cost price.
  • the invention aims to provide such an antenna which is easy to produce, and which does not use expensive material.
  • the invention also aims to provide such an antenna, which can operate over a wide range of input impedances, and in particular for input impedances between 10 and 200 Ohms.
  • the invention also aims to provide such an antenna, the tuning frequency of which can be adjusted precisely.
  • an object of the invention is to provide such an antenna, the tuning frequency of which can be modified continuously and quickly, for example to allow alternating operation.
  • the useful volume of the antenna is increased, compared to the known antenna in inverted F. This results in an increase in bandwidth.
  • the overall size of the antenna is not changed.
  • Such an antenna has an omnidirectional type radiation diagram, which is essential, since it is in particular intended to equip portable devices, which can therefore take all positions.
  • the terms “horizontal” and “vertical” are therefore used only to simplify the understanding of the invention, and should not be interpreted strictly. In practice, the concepts of horizontality and verticality will often be defined in relation to a ground plane on which the antenna will be fixed.
  • the device of the invention forms a single antenna (a single vertical short-circuit element and a single intermediate element), and not a combination of two separate antenna elements.
  • At least a first of the strands is a radiating element, and at least a second constitutes an adaptation strand, brought in parallel with the radiation impedance of the first strand.
  • the second strand therefore behaves like an incorporated adaptation circuit.
  • Such an antenna may include two parallel strands.
  • the principle of the invention can also be generalized to more than two strands.
  • said strands of the antenna are of substantially rectangular shape, and have a substantially identical width but different lengths. Other geometrical characteristics can also be retained, depending on the characteristics desired for the antenna.
  • each of said strands is open at its end furthest from said first end of said horizontal element.
  • each of said strands is a resonant element.
  • the end furthest from said first end of said horizontal element of at least one of said strands is connected to the electrical ground of said processing unit, via a short element - additional circuit.
  • the strand short-circuited at its two ends plays the role of adaptation circuit.
  • the combination of the antenna strands provides a resonance loop, which leads to a bandwidth of the order of 10% for example.
  • the strand shorted at its two ends can be, depending on the needs and the desired characteristics, the longest strand or the shortest strand.
  • the two strands can be the same length.
  • the antenna comprises more than two strands, it is possible to combine the advantages of the first and of the second embodiments. One or more strands can then be short-circuited at their two ends.
  • the end furthest from said first end of said horizontal element of at least one of said strands is connected to the electrical ground of said processing unit, by means of a capacity.
  • This operating mode corresponds to an intermediate position between the first embodiment (open circuit) and the second embodiment (short circuit).
  • all the strands of the antenna are connected to the electrical ground of said processing unit, via a capacitor. The tuning of the antenna is thus facilitated.
  • At least one of these capacities is an adjustable capacity (or varactor).
  • the same physical antenna can operate alternately in a transmission band and in a reception band, for example to operate in half-duplex. This saves the cost of installing a second antenna.
  • This technique can of course be generalized to more than two frequency bands.
  • the coaxial cable carrying the microwave signals has an impedance substantially between 10 Ohms to 200 Ohms.
  • the antenna input impedance can be chosen between 10 and 200 Ohms.
  • this impedance can be equal to 50 Ohms.
  • this wavelength ⁇ of said microwave signals is between 100 and 200 mm.
  • the dimensions of the antenna are very small, of the order of a few centimeters.
  • the antenna is located on a box containing said processing unit, said electrical ground corresponding to the electromagnetic shielding of said box.
  • said vertical element and said horizontal element are formed in the same strip of a conductive material.
  • the manufacture of the assembly is particularly simple.
  • the invention therefore relates to a small antenna with large bandwidth.
  • This antenna is in particular intended to equip portable devices, and for example transmitters / receivers of radio communication networks with land mobiles.
  • the antenna of the invention comprises a horizontal element (relative to a ground plane), connected at one of its ends to ground by a vertical short circuit.
  • the main characteristic of the invention is to produce, for example by cutting, at least two substantially parallel antenna strands in the horizontal element. The geometric and connection characteristics of these strands are chosen so as to obtain for the antenna desired characteristics, such as a large bandwidth.
  • the antenna according to the invention can comprise more than two strands, by simple generalization of the examples described.
  • FIG. 3 therefore illustrates a first embodiment of the invention.
  • the antenna 31 (hatched) is located on a housing 32, capable of containing electronic cards (in particular for demodulation and / or modulation of the microwave signals received and / or transmitted by the antenna).
  • the dimensions and shape of this case 32 are of course purely indicative.
  • the base b of the housing is 60 mm, and its height h1 is 150 mm.
  • This box 32 is shielded, and constitutes the ground to which the antenna 31 is connected.
  • the antenna 31 comprises a horizontal element 33, one of the ends 34 of which is connected to ground (shielding of the housing 32) by a vertical short-circuit element 35.
  • the first end of a strand will be used to designate the end connected to the base 36, and the second end of a strand will be the opposite end, that is to say in other words, the end furthest from the first end 34 of the horizontal element 33.
  • the base 36 can be eliminated, the strands 37 and 38 then being directly connected to the vertical element 35.
  • the horizontal element 33 is obtained by cutting a space 39 between the two strands 37 and 38 into a rectangular surface, up to the base 36.
  • a second cutting of a surface 310 is then carried out on the shortest strand 38, to adapt its length.
  • the vertical element 35 and the horizontal element 33 can be formed from the same material, the angle of the end 34 being produced for example by folding.
  • the vertical part 35 can extend along the housing 32, and be fixed to this housing by any suitable fixing means (not shown).
  • the microwave signals are conveyed by an excitation coaxial 311, which connects the electronic card contained in the housing 32 and the horizontal element 33.
  • the location of the connection 312 between the vertical element 35 and the second ends 313 and 314 of the two strands 37 and 38 defines the impedance of the antenna.
  • This connection 312 can be on the base 36 or on one of the strands 37 or 38.
  • the impedance can for example vary between 10 and 200 Ohms.
  • the strands may have different widths, ends of various shapes, etc.
  • the two strands 37 and 38 have their second ends 313 and 314 open.
  • the strand 37 of length ⁇ / 4 resonates at the working frequency f r (corresponding to the wavelength ⁇ ).
  • the second strand 38 is also a resonant element, but at a frequency f ' r , different but close to f r . It behaves like a real incorporated adaptation circuit, placed in parallel with the base and the open circuit. In other words, it is brought back in parallel with the radiation impedance of the other strand, which constitutes the main radiating element.
  • This first embodiment therefore relies on the introduction of multiple resonant frequencies into the antenna.
  • more than two strands can be used.
  • Figure 4 shows the Smith diagram with the impedance curve 41 strand 37 (resonating at f r ).
  • the bandwidth corresponding to this strand 37 alone is defined by the frequencies f1 and f2 corresponding to the intersections of the impedance curve 41 with the hatched disc 42 defining the area where the ROS is less than 2.
  • This bandwidth is written (f2 - f1) / f r , and is typically between 2 and 4%. As already mentioned, such a bandwidth is insufficient in many applications.
  • the element 38 behaves similarly, but at the frequency f ' r . Its impedance curve 51 is illustrated in FIG. 5. The corresponding bandwidth (f4 - f3) / f ' r is also worth approximately 2 to 4%. However, the frequency band [f3, f4] is significantly offset from the frequency band [f1, f2].
  • the coupling of the two radiating strands makes it possible to obtain a resonance loop, if the frequencies f r and f ' r are well chosen, as is illustrated in FIG. 6.
  • the impedance curve 61 corresponding to the combination of the strands 37 and 38 has a resonance loop 62, centered on f0. This loop 62 remains in the disk 63 defining the zone in which the ROS is less than 2.
  • FIG. 7 shows a second embodiment of the invention, in which one of the antenna strands is short-circuited at its two ends.
  • the general structure of this antenna is similar to that of FIG. 3, as regards the shape of the horizontal 33 and vertical 35 elements. It is therefore not described again.
  • the fundamental difference with the first embodiment is that the strand 72 is no longer open at its second end 313, but short-circuited by a vertical short-circuit element 71 connecting this end 313 to the shielding of the housing 32.
  • This strand 72 therefore no longer plays the role of resonant element, but the role of a short-circuit "stub" (or section), which plays the role of adaptation circuit, making it possible to widen the band on which the the overall input impedance of the antenna remains close to the impedance of the excitation coaxial.
  • stub short-circuit
  • several stubs can be made.
  • the antenna comprises at least three strands, the embodiments of FIGS. 3 and 7 can be combined.
  • FIG. 8 presents the Smith diagram carrying the impedance curve 81 corresponding to the resonant strand 38.
  • the corresponding passband (f2-f1) / f0 is always in the range of 2 to 4%.
  • the Smith diagram of FIG. 9 presents the impedance 91 of the short-circuit "stub" 72. This curve 91 is substantially symmetrical to the curve 81 of FIG. 8.
  • This curve 101 has a resonance loop 102 which remains in the disc 103 of ROS less than 2. Consequently, the bandwidth resulting (f4 - f3) / f0 is again widened, and for example of the order of 10%.
  • Figure 11 shows a third embodiment of the invention. This is in fact a generalization of the antenna of FIGS. 3 and 7, in which the second ends of the strands are neither open nor short-circuited, but connected to ground using capacitors.
  • the antenna 111 comprises a first strand 112, connected to the ground 113 by a capacitor 114, and a second strand 115 connected to the ground by a capacitor 116.
  • These capacitors 114 and 116 make it possible to vary the equivalent length of the strands (which is therefore no longer frozen at ⁇ / 4). This allows fine tuning of the tuning frequency.
  • the antenna strands can have the same physical length, the equivalent length being modified by the capacities. It should be noted, moreover, that it is not compulsory for all the strands to be associated with a capacity. Some of them can be opened or short-circuited.
  • the capacities 114 and 116 are adjustable (these are for example varactors, or several capacities in parallel capable of being selected independently), and controlled (118) by an electronic control circuit 117 placed in the housing 32 It is thus possible to vary at all times and almost instantaneously the passband of the antenna 111. This makes it possible to operate the same physical antenna in several frequency bands, selectively.
  • this antenna 111 allows alternating operation in a transmission band (corresponding to a transmission frequency) and in a reception band (corresponding to a reception frequency).
  • the device equipped with this antenna can therefore operate in "half duplex".
  • FIG. 12 shows, in top view, the horizontal element of an antenna as illustrated in FIG. 7.
  • the aim of this embodiment is to operate in the nominal frequency band 2.4 GHz - 2.5 GHz.
  • This impedance can be modified between 10 and 200 Ohms, by modifying this distance d.
  • the longest strand 122 is open at its second end 125, and the shortest strand 123 is short-circuited at its second end 126.
  • FIG. 13 shows the curve 131 for adapting this antenna, that is to say the curve of the R.O.S (on the ordinate) as a function of the frequency (on the abscissa).
  • the R.O.S is less than 2 between 2.37 GHz and 2.55 GHz. This corresponds to a bandwidth of the order of 8%, which is much higher than the bandwidths obtained with the antennas of the prior art.
  • the R.O.S is less than 1.6.
  • the Smith diagram in FIG. 14 shows the impedance curve 141 of the antenna in FIG. 12, between 2 GHz and 3 GHz. Markers 142 and 143 delimit the antenna work area (2.4 - 2.5 GHz).
  • This curve shows that this antenna is not yet fully optimized, and that better centering of the curve 141 relative to the abacus would lead to better performance.
  • the invention also relates to any device for transmitting and / or receiving microwave signals equipped with an antenna according to the invention, as illustrated for example by the housing 32 of Figures 3, 7 and 11.
  • such device can comprise several antennas, and in particular a transmitting antenna and a receiving antenna.

Abstract

The invention relates to a space-saving broadband antenna, especially for independent portable stations used in networks for radio communication with land-based mobiles, comprising a substantially flat element (33), called horizontal element, and a short-circuit element (35) substantially perpendicular to the said horizontal element (33), called vertical element (35), the said vertical element connecting a first extremity (34) of the said horizontal element (33) to the electrical earth of a processing unit, and the said UHF signals being transported between the said processing unit and the said horizontal element (33) by a coaxial cable (311) connected to the said horizontal element (33), the said horizontal element (33) comprising: - a substantially rectangular intermediate surface (36), a first extremity of which corresponds to the said first extremity (34) of the said horizontal element (33); and - at least two strands (37, 38), substantially parallel to each other and substantially perpendicular to the said vertical element, the second extremity of the said intermediate surface (36) corresponding to a first extremity (313, 314) of each of the said strands (37, 38). <IMAGE>

Description

Le domaine de l'invention est celui des transmissions hertziennes. Plus précisément, l'invention concerne les antennes d'émission et/ou de réception, notamment pour les équipements de taille réduite, tels que les appareils portables.The field of the invention is that of radio transmissions. More specifically, the invention relates to transmit and / or receive antennas, in particular for equipment of reduced size, such as portable devices.

L'invention s'applique ainsi, en particulier, aux systèmes de télécommunication avec des mobiles. En effet, l'extension des réseaux de radiocommunication avec des mobiles terrestres impose la mise au point de stations autonomes portables possédant la double fonctionnalité d'émission et de réception de signaux hyperfréquences. Ces stations doivent donc comprendre une antenne intégrée.The invention thus applies, in particular, to telecommunications systems with mobiles. In fact, the extension of radiocommunication networks with land mobiles requires the development of portable autonomous stations having the dual functionality of transmitting and receiving microwave signals. These stations must therefore include an integrated antenna.

Les fréquences actuellement mises en oeuvre pour ces applications (de l'ordre de 2 GHz), ainsi que différentes contraintes liées à l'ergonomie et à l'esthétisme des combinés (intégration de l'antenne dans le dessins de l'appareil, facilité de stockage et d'utilisation, fragilité des antennes de grande taille,...) conduisent à l'utilisation d'antennes de dimensions très réduites. On connaît ainsi plusieurs types d'antennes, dont les dimensions sont inférieures à la longueur d'onde du signal hyperfréquence.The frequencies currently used for these applications (of the order of 2 GHz), as well as various constraints linked to the ergonomics and aesthetics of the handsets (integration of the antenna in the drawings of the device, ease storage and use, fragility of large antennas, ...) lead to the use of antennas of very small dimensions. Several types of antenna are thus known, the dimensions of which are less than the wavelength of the microwave signal.

Ces antennes se présentent en général sous la forme d'un élément rayonnant implanté à l'extérieur d'un boîtier métallique, par exemple de forme parallélépipédique, constituant le blindage d'une ou plusieurs cartes électroniques assurant notamment les fonctions de modulation et de démodulation des signaux hyperfréquences, en émission et en réception respectivement.These antennas are generally in the form of a radiating element located outside of a metal case, for example of rectangular shape, constituting the shielding of one or more electronic cards ensuring in particular the modulation and demodulation functions. microwave signals, in transmission and reception respectively.

L'ouvrage "Small Antennas" (Petites Antennes), par K. Fujimoto, A. Henderson, K. Hirasawa et J.R. James (édité par Research Studies Press Ltd et John Wiley & Sons Inc.) présente ainsi différents types de petites antennes, parmi lesquelles l'antenne dite en F inversé semble la plus efficace.The book "Small Antennas", by K. Fujimoto, A. Henderson, K. Hirasawa and JR James (edited by Research Studies Press Ltd and John Wiley & Sons Inc.) thus presents different types of small antennas, among which the so-called inverted F antenna seems the most effective.

Une telle antenne en F inversé est représentée en coupe sur la figure 1 et en perspective sur la figure 2. Elle est constituée d'un élément conducteur rectangulaire horizontal 11 et d'un élément conducteur vertical 12. L'élément vertical 12 assure une fonction de court-circuit sur l'élément horizontal 11, en reliant l'une de ses extrémités 13 à un plan de masse 14.Such an antenna in inverted F is shown in section in Figure 1 and in perspective in Figure 2. It consists of a horizontal rectangular conductive element 11 and a vertical conductive element 12. The vertical element 12 performs a function short-circuit on the horizontal element 11, by connecting one of its ends 13 to a ground plane 14.

L'autre extrémité 15 de l'élément horizontal 11 est ouverte.The other end 15 of the horizontal element 11 is open.

Le signal hyperfréquence est véhiculé par un coaxial d'excitation 16, qui est connecté à l'élément horizontal 11 en un emplacement 17. Le choix de cet emplacement 17 entre l'extrémité court-circuitée 13 et l'extrémité ouverte 15 de l'élément horizontal 11 détermine l'impédance de l'antenne ainsi obtenue.The microwave signal is conveyed by an excitation coaxial 16, which is connected to the horizontal element 11 at a location 17. The choice of this location 17 between the short-circuited end 13 and the open end 15 of the horizontal element 11 determines the impedance of the antenna thus obtained.

Si λ est la longueur d'onde du signal hyperfréquence transmis, l'encombrement de ce type d'antenne est en général :

  • L = λ/4 ;
  • l = λ/8 ;
  • h = λ/25.
If λ is the wavelength of the transmitted microwave signal, the size of this type of antenna is generally:
  • L = λ / 4;
  • l = λ / 8;
  • h = λ / 25.

Ainsi, pour des fréquences de l'ordre de 2 GHz, ces dimensions sont de l'ordre de quelques centimètres. L'antenne obtenue est donc d'encombrement très réduit. Par ailleurs, le diagramme de rayonnement de cette antenne est sensiblement omnidirectionnel, ce qui est essentiel pour des dispositifs portables (cette caractéristique est en général vérifiée par toutes les antennes de faible encombrement).Thus, for frequencies of the order of 2 GHz, these dimensions are of the order of a few centimeters. The antenna obtained is therefore very compact. Furthermore, the radiation pattern of this antenna is substantially omnidirectional, which is essential for portable devices (this characteristic is generally verified by all antennas with a small footprint).

En revanche, cette antenne présente des caractéristiques très dispersives en fréquence, et donc, en conséquence, une bande passante très faible, et par exemple de l'ordre de 2 à 3 %. Cela est dû au fait que cette structure d'antenne se comporte sensiblement comme un résonateur λ/4.On the other hand, this antenna has very frequency dispersive characteristics, and therefore, consequently, a very low bandwidth, and for example of the order of 2 to 3%. This is due to the fact that this antenna structure behaves substantially like a λ / 4 resonator.

La bande passante d'une antenne est ici définie comme la bande de fréquence sur laquelle le Rapport d'Onde Stationnaire (R.O.S) est inférieur à 2. Ce dernier paramètre représente l'aptitude de l'antenne à transmettre la puissance active qui lui est fournie, ce qui est le plus critique pour les antennes de taille réduite.The bandwidth of an antenna is defined here as the frequency band over which the Standing Wave Ratio (ROS) is less than 2. This last parameter represents the ability of the antenna to transmit the active power which is which is most critical for small antennas.

Cette grandeur est directement liée à l'impédance d'entrée de l'antenne, qui doit être adaptée à l'impédance de la ligne de transmission véhiculant le signal hyperfréquence à émettre et/ou à recevoir. Pour un fonctionnement optimal de l'antenne, il est nécessaire que cette impédance reste sensiblement constante (c'est-à-dire que le R.O.S reste inférieur à 2) sur un grande bande de fréquence. Une bande passante de 2 à 3 % telle qu'obtenue à l'aide d'une antenne en F inversée est généralement insuffisante.This quantity is directly linked to the input impedance of the antenna, which must be adapted to the impedance of the transmission line carrying the microwave signal to be transmitted and / or received. For optimal functioning of the antenna, it is necessary that this impedance remains substantially constant (that is to say that the R.O.S remains less than 2) over a large frequency band. A bandwidth of 2 to 3% as obtained using an inverted F antenna is generally insufficient.

L'invention a notamment pour objectif de pallier cet inconvénient de la technique antérieure.The invention particularly aims to overcome this drawback of the prior art.

Plus précisément, un objectif de l'invention est de fournir une antenne d'encombrement réduit présentant une large passante. Ainsi, l'invention a notamment pour objectif de fournir une telle antenne, dont la bande passante est au moins de l'ordre de 8 à 10 %.More specifically, an objective of the invention is to provide a compact antenna having a large pass. Thus, the invention has in particular the objective of providing such an antenna, the bandwidth of which is at least of the order of 8 to 10%.

Un autre objectif de l'invention est de fournir une telle antenne, qui soit d'un coût de revient réduit. En d'autres termes, l'invention a pour objectif de fournir une telle antenne qui soit aisée à réaliser, et qui n'utilise pas de matériau coûteux.Another objective of the invention is to provide such an antenna, which is of reduced cost price. In other words, the invention aims to provide such an antenna which is easy to produce, and which does not use expensive material.

L'invention a encore pour objectif de fournir une telle antenne, qui puisse fonctionner sur une grande plage d'impédances d'entrée, et en particulier pour des impédances d'entrée comprises entre 10 et 200 Ohms.The invention also aims to provide such an antenna, which can operate over a wide range of input impedances, and in particular for input impedances between 10 and 200 Ohms.

L'invention a également pour objectif de fournir une telle antenne, dont la fréquence d'accord peut être réglée de façon précise. En particulier, un objectif de l'invention est de fournir une telle antenne, dont la fréquence d'accord peut être modifiée en permanence et rapidement, par exemple pour permettre un fonctionnement en alternat.The invention also aims to provide such an antenna, the tuning frequency of which can be adjusted precisely. In particular, an object of the invention is to provide such an antenna, the tuning frequency of which can be modified continuously and quickly, for example to allow alternating operation.

Ces objectifs, ainsi que d'autres qui apparaîtront par la suite, sont atteints selon l'invention à l'aide d'une antenne d'émission et/ou de réception de signaux hyperfréquences, comprenant un élément sensiblement plan, dit élément horizontal, et un élément de court-circuit sensiblement perpendiculaire audit élément horizontal, dit élément vertical, ledit élément vertical connectant une première extrémité dudit élément horizontal à la masse électrique d'une unité de traitement,
lesdits signaux hyperfréquences étant véhiculés entre ladite unité de traitement et ledit élément horizontal par un câble coaxial connecté audit élément horizontal,
ledit élément horizontal comprenant :

  • une surface intermédiaire sensiblement rectangulaire, dont une première extrémité correspond à ladite première extrémité dudit élément horizontal ; et
  • au moins deux brins sensiblement parallèles entre eux et sensiblement perpendiculaires audit élément vertical, la seconde extrémité de ladite surface intermédiaire correspondant à une première extrémité de chacun desdits brins.
These objectives, as well as others which will appear subsequently, are achieved according to the invention using an antenna for transmitting and / or receiving microwave signals, comprising a substantially planar element, called a horizontal element, and a short-circuit element substantially perpendicular to said horizontal element, said vertical element, said vertical element connecting a first end of said horizontal element to the electrical ground of a processing unit,
said microwave signals being conveyed between said processing unit and said horizontal element by a coaxial cable connected to said horizontal element,
said horizontal element comprising:
  • a substantially rectangular intermediate surface, a first end of which corresponds to said first end of said horizontal element; and
  • at least two strands substantially parallel to each other and substantially perpendicular to said vertical element, the second end of said intermediate surface corresponding to a first end of each of said strands.

De cette façon, le volume utile de l'antenne est augmenté, par rapport à l'antenne connue en F inversée. Il en résulte une augmentation de la bande passante. En revanche, l'encombrement global de l'antenne n'est pas modifié.In this way, the useful volume of the antenna is increased, compared to the known antenna in inverted F. This results in an increase in bandwidth. However, the overall size of the antenna is not changed.

Par ailleurs, une telle antenne présente un diagramme de rayonnement du type omnidirectionnel, ce qui est essentiel, du fait qu'elle est notamment destinée à équiper des appareils portables, pouvant donc prendre toutes les positions. Les termes "horizontal" et "vertical" sont donc utilisés uniquement pour simplifier la compréhension de l'invention, et ne doivent pas être interprétés strictement. Dans la pratique, les notions d'horizontalité et de verticalité seront souvent définies par rapport à un plan de masse sur lequel l'antenne sera fixée.Furthermore, such an antenna has an omnidirectional type radiation diagram, which is essential, since it is in particular intended to equip portable devices, which can therefore take all positions. The terms "horizontal" and "vertical" are therefore used only to simplify the understanding of the invention, and should not be interpreted strictly. In practice, the concepts of horizontality and verticality will often be defined in relation to a ground plane on which the antenna will be fixed.

La présence d'une surface intermédiaire, ou base, entre l'élément vertical et les brins présente de nombreux avantages. En particulier, elle permet de réaliser des antennes adaptables à plusieurs fréquences, et d'optimiser l'adaptation globale de l'antenne. Il est à noter que le dispositif de l'invention forme une antenne unique (un seul élément vertical de court-circuit et un seul élément intermédiaire), et non une combinaison de deux éléments d'antenne distincts.The presence of an intermediate surface, or base, between the vertical element and the strands has many advantages. In particular, it makes it possible to produce antennas adaptable to several frequencies, and to optimize the overall adaptation of the antenna. It should be noted that the device of the invention forms a single antenna (a single vertical short-circuit element and a single intermediate element), and not a combination of two separate antenna elements.

Dans cette antenne, au moins un premier des brins est un élément rayonnant, et au moins un deuxième constitue un brin d'adaptation, ramené en parallèle avec l'impédance de de rayonnement du premier brin. Le deuxième brin se comporte donc comme un circuit d'adaptation incorporé.In this antenna, at least a first of the strands is a radiating element, and at least a second constitutes an adaptation strand, brought in parallel with the radiation impedance of the first strand. The second strand therefore behaves like an incorporated adaptation circuit.

Une telle antenne peut comprendre deux brins parallèles. Le principe de l'invention peut également être généralisé à plus de deux brins.Such an antenna may include two parallel strands. The principle of the invention can also be generalized to more than two strands.

De façon avantageuse, lesdits brins de l'antenne sont de forme sensiblement rectangulaire, et présentent une largeur sensiblement identique mais des longueurs différentes. D'autres caractéristiques géométriques peuvent également être retenues, en fonction des caractéristiques souhaitées pour l'antenne.Advantageously, said strands of the antenna are of substantially rectangular shape, and have a substantially identical width but different lengths. Other geometrical characteristics can also be retained, depending on the characteristics desired for the antenna.

Selon un premier mode de réalisation avantageux de l'invention, chacun desdits brins est ouvert à son extrémité la plus éloignée de ladite première extrémité dudit élément horizontal.According to a first advantageous embodiment of the invention, each of said strands is open at its end furthest from said first end of said horizontal element.

Dans ce cas, chacun desdits brins est un élément résonant.In this case, each of said strands is a resonant element.

Si deux brins présentent des longueurs légèrement différentes, leurs fréquences de résonance sont différentes, mais voisines. Le couplage des deux brins permet alors d'obtenir, pour l'impédance, une boucle de résonance, et donc, en conséquence, une bande passante importante, par exemple de l'ordre de 10 %.If two strands have slightly different lengths, their resonant frequencies are different, but similar. The coupling of the two strands then makes it possible to obtain, for the impedance, a resonance loop, and therefore, consequently, a large bandwidth, for example of the order of 10%.

Selon un second mode de réalisation préférentiel, l'extrémité la plus éloignée de ladite première extrémité dudit élément horizontal d'au moins un desdits brins est connectée à la masse électrique de ladite unité de traitement, par l'intermédiaire d'un élément de court-circuit supplémentaire.According to a second preferred embodiment, the end furthest from said first end of said horizontal element of at least one of said strands is connected to the electrical ground of said processing unit, via a short element - additional circuit.

Le brin court-circuité à ses deux extrémités (ou stub court-circuit) joue le rôle de circuit d'adaptation. A nouveau, la combinaison des brins de l'antenne permet d'obtenir une boucle de résonance, qui conduit à une bande passante de l'ordre de 10 % par exemple.The strand short-circuited at its two ends (or short-circuit stub) plays the role of adaptation circuit. Again, the combination of the antenna strands provides a resonance loop, which leads to a bandwidth of the order of 10% for example.

Si l'antenne comprend deux brins, le brin court-circuité à ses deux extrémités peut être, suivant les besoins et les caractéristiques voulues, le brin le plus long ou le brin le plus court. Eventuellement, les deux brins peuvent être de la même longueur.If the antenna comprises two strands, the strand shorted at its two ends can be, depending on the needs and the desired characteristics, the longest strand or the shortest strand. Optionally, the two strands can be the same length.

Si l'antenne comprend plus de deux brins, il est possible de combiner les avantages du premier et du second modes de réalisation. Un ou plusieurs brins peuvent alors être court-circuités à leurs deux extrémités.If the antenna comprises more than two strands, it is possible to combine the advantages of the first and of the second embodiments. One or more strands can then be short-circuited at their two ends.

Selon un troisième mode de réalisation avantageux de l'invention, l'extrémité la plus éloignée de ladite première extrémité dudit élément horizontal d'au moins un desdits brins est reliée à la masse électrique de ladite unité de traitement, par l'intermédiaire d'une capacité.According to a third advantageous embodiment of the invention, the end furthest from said first end of said horizontal element of at least one of said strands is connected to the electrical ground of said processing unit, by means of a capacity.

Ce mode de fonctionnement correspond à une position intermédiaire entre le premier mode de réalisation (circuit ouvert) et le second mode de réalisation (court-circuit).This operating mode corresponds to an intermediate position between the first embodiment (open circuit) and the second embodiment (short circuit).

De façon préférentielle, tous les brins de l'antenne sont reliés à la masse électrique de ladite unité de traitement, par l'intermédiaire d'une capacité. La mise au point de l'antenne est ainsi facilitée.Preferably, all the strands of the antenna are connected to the electrical ground of said processing unit, via a capacitor. The tuning of the antenna is thus facilitated.

Avantageusement, au moins une de ces capacités est une capacité ajustable (ou varactor).Advantageously, at least one of these capacities is an adjustable capacity (or varactor).

Cela permet notamment, sous le contrôle de l'unité de traitement, de faire varier les capacités entre deux valeurs distinctes, une première valeur correspondant au fonctionnement de l'antenne à une fréquence d'émission de signaux hyperfréquences et une seconde valeur correspondant au fonctionnement de l'antenne à une fréquence de réception de signaux hyperfréquences.This allows in particular, under the control of the processing unit, to vary the capacities between two distinct values, a first value corresponding to the operation of the antenna at a frequency of transmission of microwave signals and a second value corresponding to the operation of the antenna at a frequency for receiving microwave signals.

Ainsi, la même antenne physique peut fonctionner en alternat dans une bande d'émission et dans une bande de réception, par exemple pour fonctionner en half-duplex. On fait de cette façon l'économie de l'implantation d'une seconde antenne. Cette technique peut bien sûr être généralisée à plus de deux bandes de fréquence.Thus, the same physical antenna can operate alternately in a transmission band and in a reception band, for example to operate in half-duplex. This saves the cost of installing a second antenna. This technique can of course be generalized to more than two frequency bands.

Avantageusement, le câble coaxial véhiculant les signaux hyperfréquences présente une impédance sensiblement comprise entre 10 Ohms à 200 Ohms. En d'autres termes, l'impédance d'entrée de l'antenne peut être choisie entre 10 et 200 Ohms. Classiquement, cette impédance peut être égale à 50 Ohms.Advantageously, the coaxial cable carrying the microwave signals has an impedance substantially between 10 Ohms to 200 Ohms. In other words, the antenna input impedance can be chosen between 10 and 200 Ohms. Conventionally, this impedance can be equal to 50 Ohms.

De façon préférentielle, si λ est la longueur d'onde desdits signaux hyperfréquences, les dimensions essentielles de l'antenne de l'invention sont :

  • largeur de ladite première extrémité dudit élément horizontal: de l'ordre de λ/8 ;
  • longueur maximale dudit élément horizontal, correspondant à la distance entre ladite première extrémité dudit élément horizontal et l'extrémité la plus éloignée de ladite première extrémité dudit élément horizontal du brin le plus long : de l'ordre de λ/4 ;
  • hauteur dudit élément vertical, correspondant à la distance entre ladite première extrémité dudit élément horizontal et ladite masse électrique : de l'ordre de λ/25 ;
  • largeur d'au moins un desdits brins : de l'ordre de λ/20.
Preferably, if λ is the wavelength of said microwave signals, the essential dimensions of the antenna of the invention are:
  • width of said first end of said horizontal element: of the order of λ / 8;
  • maximum length of said horizontal element, corresponding to the distance between said first end of said horizontal element and the end furthest from said first end of said horizontal element of the longest strand: of the order of λ / 4;
  • height of said vertical element, corresponding to the distance between said first end of said horizontal element and said electrical mass: of the order of λ / 25;
  • width of at least one of said strands: of the order of λ / 20.

De façon préférentielle, cette longueur d'onde λ desdits signaux hyperfréquences est comprise entre 100 et 200 mm. Dans ce cas, les dimensions de l'antenne sont très réduites, de l'ordre de quelques centimètres.Preferably, this wavelength λ of said microwave signals is between 100 and 200 mm. In this case, the dimensions of the antenna are very small, of the order of a few centimeters.

Dans un mode de réalisation préférentiel de l'invention, l'antenne est implantée sur un boîtier contenant ladite unité de traitement, ladite masse électrique correspondant au blindage électromagnétique dudit boîtier.In a preferred embodiment of the invention, the antenna is located on a box containing said processing unit, said electrical ground corresponding to the electromagnetic shielding of said box.

Avantageusement, ledit élément vertical et ledit élément horizontal sont formés dans une même bande d'un matériau conducteur. Ainsi, la fabrication de l'ensemble est particulièrement simple.Advantageously, said vertical element and said horizontal element are formed in the same strip of a conductive material. Thus, the manufacture of the assembly is particularly simple.

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

  • les figures 1 et 2 représentent une antenne de l'art antérieur à l'invention dite en F inversé, respectivement en coupe et en perspective. Ces figures ont déjà été discutées en préambule de la présente description ;
  • la figure 3 présente un premier mode de réalisation d'une antenne selon l'invention, comprenant deux brins résonants ouverts à l'une de leurs extrémités ;
  • les figures 4 à 6 sont trois diagrammes de Smith présentant respectivement la réponse en fréquence correspondant au premier brin de l'antenne de la figure 3, au second brin et à la combinaison des deux brins ;
  • la figure 7 illustre un second mode de réalisation d'une antenne selon l'invention, comprenant un brin résonant et un brin court-circuité à ses deux extrémités ;
  • les figures 8 et 10 sont trois diagrammes de Smith présentant respectivement les courbes d'impédance correspondant au premier brin de l'antenne de la figure 7, au second brin et à la combinaison des deux brins ;
  • la figure 11 présente un troisième mode de réalisation d'une antenne selon l'invention, dont l'impédance des deux brins est ajustable ;
  • la figure 12 est une vue de dessus à l'échelle d'un mode de réalisation d'une antenne selon l'invention, dans le cas d'une fréquence de fonctionnement de 2,5 GHz ;
  • les figures 13 et 14 présentent respectivement la courbe d'adaptation et la courbe d'impédance correspondant à l'antenne de la figure 12.
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 illustrative and nonlimiting examples, and of the appended drawings, in which:
  • Figures 1 and 2 show an antenna of the prior art to the invention called inverted F, respectively in section and in perspective. These figures have already been discussed in the preamble to the present description;
  • FIG. 3 shows a first embodiment of an antenna according to the invention, comprising two resonant strands open at one of their ends;
  • Figures 4 to 6 are three Smith diagrams respectively presenting the frequency response corresponding to the first strand of the antenna of Figure 3, the second strand and the combination of the two strands;
  • FIG. 7 illustrates a second embodiment of an antenna according to the invention, comprising a resonant strand and a short-circuited strand at its two ends;
  • Figures 8 and 10 are three Smith diagrams respectively presenting the impedance curves corresponding to the first strand of the antenna of Figure 7, the second strand and the combination of the two strands;
  • FIG. 11 shows a third embodiment of an antenna according to the invention, the impedance of the two strands of which is adjustable;
  • Figure 12 is a top view to scale of an embodiment of an antenna according to the invention, in the case of an operating frequency of 2.5 GHz;
  • FIGS. 13 and 14 respectively present the adaptation curve and the impedance curve corresponding to the antenna in FIG. 12.

L'invention concerne donc une antenne de taille réduite à grande bande passante. Cette antenne est notamment destinée à équiper des appareils portables, et par exemple des émetteurs/récepteurs de réseaux de radio-communication avec des mobiles terrestres.The invention therefore relates to a small antenna with large bandwidth. This antenna is in particular intended to equip portable devices, and for example transmitters / receivers of radio communication networks with land mobiles.

D'une façon générale, l'antenne de l'invention comprend un élément horizontal (par rapport à un plan de masse), connecté à l'une de ses extrémités à la masse par un court-circuit vertical. La caractéristique principale de l'invention est de réaliser, par exemple par découpage, au moins deux brins d'antenne sensiblement parallèles dans l'élément horizontal. Les caractéristiques géométriques et de connexion de ces brins sont choisies de façon à obtenir pour l'antenne des caractéristiques souhaitées, telles qu'une bande passante importante.In general, the antenna of the invention comprises a horizontal element (relative to a ground plane), connected at one of its ends to ground by a vertical short circuit. The main characteristic of the invention is to produce, for example by cutting, at least two substantially parallel antenna strands in the horizontal element. The geometric and connection characteristics of these strands are chosen so as to obtain for the antenna desired characteristics, such as a large bandwidth.

Par la suite, on décrit en détail trois modes de réalisation préférentiels de l'invention, comprenant deux brins d'antenne. Il est clair toutefois que l'antenne selon l'invention peut comprendre plus de deux brins, par simple généralisation des exemples décrits.In the following, three preferred embodiments of the invention are described in detail, comprising two antenna strands. It is clear however that the antenna according to the invention can comprise more than two strands, by simple generalization of the examples described.

La figure 3 illustre donc un premier mode de réalisation de l'invention. Sur cette figure, l'antenne 31 (hachurée) est implantée sur un boîtier 32, susceptible de contenir des cartes électroniques (notamment pour la démodulation et/ou la modulation des signaux hyperfréquences reçus et/ou émis par l'antenne). Les dimensions et la forme de ce boîtier 32 sont bien sûr purement indicatives. Dans l'exemple représenté, la base b du boîtier fait 60 mm, et sa hauteur h1 fait 150 mm.FIG. 3 therefore illustrates a first embodiment of the invention. In this figure, the antenna 31 (hatched) is located on a housing 32, capable of containing electronic cards (in particular for demodulation and / or modulation of the microwave signals received and / or transmitted by the antenna). The dimensions and shape of this case 32 are of course purely indicative. In the example shown, the base b of the housing is 60 mm, and its height h1 is 150 mm.

Ce boîtier 32 est blindé, et constitue la masse à laquelle est connectée l'antenne 31.This box 32 is shielded, and constitutes the ground to which the antenna 31 is connected.

L'antenne 31 comprend un élément horizontal 33, dont l'une des extrémités 34 est connectée à la masse (blindage du boîtier 32) par un élément vertical de court-circuit 35.The antenna 31 comprises a horizontal element 33, one of the ends 34 of which is connected to ground (shielding of the housing 32) by a vertical short-circuit element 35.

L'élément horizontal 33 peut se décomposer (fictivement, puisqu'il est en pratique réalisé d'une seule pièce) en trois parties :

  • une partie intermédiaire 36, ou base, qui est connectée à l'élément vertical 35 et qui est sensiblement de la même largeur que cet élément vertical ;
  • un premier brin 37 s'étendant dans le prolongement de la base 36, le bord extérieur de ce brin 37 correspondant à un premier bord de la base 36 ;
  • un second brin 38, parallèle au premier brin 37, dont le bord extérieur correspond au prolongement du second bord de la base 36.
The horizontal element 33 can be broken down (fictitiously, since it is in practice made in one piece) into three parts:
  • an intermediate part 36, or base, which is connected to the vertical element 35 and which is substantially the same width as this vertical element;
  • a first strand 37 extending in the extension of the base 36, the outer edge of this strand 37 corresponding to a first edge of the base 36;
  • a second strand 38, parallel to the first strand 37, the outer edge of which corresponds to the extension of the second edge of the base 36.

Par la suite, on désignera par première extrémité d'un brin l'extrémité connectée à la base 36, et par seconde extrémité d'un brin l'extrémité opposée, c'est-à-dire, en d'autres termes, l'extrémité la plus éloignée de la première extrémité 34 de l'élément horizontal 33. Eventuellement, la base 36 peut être supprimée, les brins 37 et 38 étant alors directement connectés à l'élément vertical 35.Thereafter, the first end of a strand will be used to designate the end connected to the base 36, and the second end of a strand will be the opposite end, that is to say in other words, the end furthest from the first end 34 of the horizontal element 33. Optionally, the base 36 can be eliminated, the strands 37 and 38 then being directly connected to the vertical element 35.

Dans la pratique, l'élément horizontal 33 est obtenu par découpage dans une surface rectangulaire d'un espace 39 entre les deux brins 37 et 38, jusqu'à la base 36.In practice, the horizontal element 33 is obtained by cutting a space 39 between the two strands 37 and 38 into a rectangular surface, up to the base 36.

Un second découpage d'une surface 310 est ensuite effectuée sur le brin le plus court 38, pour adapter sa longueur.A second cutting of a surface 310 is then carried out on the shortest strand 38, to adapt its length.

Par ailleurs, l'élément vertical 35 et l'élément horizontal 33 peuvent être formés dans le même matériau, l'angle de l'extrémité 34 étant réalisé par exemple par pliage.Furthermore, the vertical element 35 and the horizontal element 33 can be formed from the same material, the angle of the end 34 being produced for example by folding.

Avantageusement, la partie verticale 35 peut se prolonger le long du boîtier 32, et être fixée à ce boîtier par tout moyen de fixation adéquat (non représenté).Advantageously, the vertical part 35 can extend along the housing 32, and be fixed to this housing by any suitable fixing means (not shown).

Les signaux hyperfréquences sont véhiculés par un coaxial d'excitation 311, qui relie la carte électronique contenue dans le boîtier 32 et l'élément horizontal 33. L'emplacement de la connexion 312 entre l'élément vertical 35 et les secondes extrémités 313 et 314 des deux brins 37 et 38 définit l'impédance de l'antenne. Cette connexion 312 peut être sur la base 36 ou sur l'un des brins 37 ou 38. Selon sa position, l'impédance peut par exemple varier entre 10 et 200 Ohms.The microwave signals are conveyed by an excitation coaxial 311, which connects the electronic card contained in the housing 32 and the horizontal element 33. The location of the connection 312 between the vertical element 35 and the second ends 313 and 314 of the two strands 37 and 38 defines the impedance of the antenna. This connection 312 can be on the base 36 or on one of the strands 37 or 38. Depending on its position, the impedance can for example vary between 10 and 200 Ohms.

Préférentiellement, pour une longueur d'onde de fonctionnement λ (de l'ordre de quelques cm), les dimensions de l'antenne sont sensiblement :

  • longueur du plus long brin 37 : 11 = λ/4 ;
  • longueur du second brin 38 : 12 légèrement inférieure à λ/4 (par exemple : 9λ/40) ;
  • hauteur de l'élément vertical 35 : h = λ/24 ;
  • largeur de la base 36 et de l'élément vertical 35 :1 = λ/8 ;
  • longueur de la base 36 : s = λ/30 ;
  • distance entre la connexion 312 et l'élément vertical 35 : d = λ/24;
  • largeur des brins 37 et 38 : w1 = w2 = λ/20.
Preferably, for an operating wavelength λ (of the order of a few cm), the dimensions of the antenna are substantially:
  • length of longest strand 37: 11 = λ / 4;
  • length of the second strand 38: 12 slightly less than λ / 4 (for example: 9λ / 40);
  • height of the vertical element 35: h = λ / 24;
  • width of the base 36 and of the vertical element 35: 1 = λ / 8;
  • length of the base 36: s = λ / 30;
  • distance between connection 312 and vertical element 35: d = λ / 24;
  • width of the strands 37 and 38: w1 = w2 = λ / 20.

Dans d'autres modes de réalisation, les brins peuvent avoir des largeurs différentes, des extrémités de formes diverses,...In other embodiments, the strands may have different widths, ends of various shapes, etc.

Dans le mode de réalisation de la figure 3, les deux brins 37 et 38 ont leur deuxièmes extrémités 313 et 314 ouvertes. Dans ce cas, le brin 37 de longueur λ/4, résonne à la fréquence de travail fr (correspondant à la longueur d'onde λ). Le deuxième brin 38 est également un élément résonant, mais à une fréquence f'r, différente mais proche de fr. Il se comporte comme un véritable circuit d'adaptation incorporé, placé en parallèle avec la base et le circuit ouvert. En d'autres termes, il est ramené en parallèle avec l'impédance de rayonnement de l'autre brin, qui constitue l'élément rayonnant principal.In the embodiment of Figure 3, the two strands 37 and 38 have their second ends 313 and 314 open. In this case, the strand 37 of length λ / 4, resonates at the working frequency f r (corresponding to the wavelength λ). The second strand 38 is also a resonant element, but at a frequency f ' r , different but close to f r . It behaves like a real incorporated adaptation circuit, placed in parallel with the base and the open circuit. In other words, it is brought back in parallel with the radiation impedance of the other strand, which constitutes the main radiating element.

Ce premier mode de réalisation repose donc sur l'introduction de fréquences de résonance multiples dans l'antenne. Bien sûr, plus de deux brins peuvent être utilisés.This first embodiment therefore relies on the introduction of multiple resonant frequencies into the antenna. Of course, more than two strands can be used.

La longueur de ces brins (et donc leur fréquence de résonance) est choisie de façon à obtenir, pour l'impédance de l'antenne, une boucle de résonance, et donc d'élargir la largeur de bande correspondante. Ceci est notamment illustré par les figures 4 et 6.The length of these strands (and therefore their resonant frequency) is chosen so as to obtain, for the impedance of the antenna, a resonant loop, and therefore to widen the corresponding bandwidth. This is illustrated in particular in Figures 4 and 6.

La figure 4 présente le diagramme de Smith portant la courbe d'impédance 41 du brin 37 (résonant à fr). La bande passante correspondant à ce brin 37 seul, c'est-à-dire la bande de fréquence sur laquelle le ROS est inférieur à 2, est définie par les fréquences f₁ et f₂ correspondant aux intersections de la courbe d'impédance 41 avec le disque hachuré 42 définissant la zone où le ROS est inférieur à 2.Figure 4 shows the Smith diagram with the impedance curve 41 strand 37 (resonating at f r ). The bandwidth corresponding to this strand 37 alone, that is to say the frequency band on which the ROS is less than 2, is defined by the frequencies f₁ and f₂ corresponding to the intersections of the impedance curve 41 with the hatched disc 42 defining the area where the ROS is less than 2.

Cette largeur de bande s'écrit (f₂ - f₁)/ fr, et vaut classiquement entre 2 et 4 %. Ainsi qu'on l'a déjà mentionné, une telle largeur de bande est insuffisante dans de nombreuses applications.This bandwidth is written (f₂ - f₁) / f r , and is typically between 2 and 4%. As already mentioned, such a bandwidth is insufficient in many applications.

L'élément 38 se comporte de façon analogue, mais à la fréquence f'r. Sa courbe d'impédance 51 est illustrée en figure 5. La bande passante correspondante (f₄ - f₃) / f'r vaut également environ 2 à 4 %. Toutefois, la bande de fréquence [f₃, f₄] est sensiblement décalée par rapport à la bande de fréquence [f₁, f₂].The element 38 behaves similarly, but at the frequency f ' r . Its impedance curve 51 is illustrated in FIG. 5. The corresponding bandwidth (f₄ - f₃) / f ' r is also worth approximately 2 to 4%. However, the frequency band [f₃, f₄] is significantly offset from the frequency band [f₁, f₂].

Le couplage des deux brins rayonnants permet d'obtenir une boucle de résonance, si les fréquences fr et f'r sont bien choisies, ainsi que cela est illustré en figure 6. La courbe d'impédance 61 correspondant à la combinaison des brins 37 et 38 présente une boucle de résonance 62, centré sur f₀. Cette boucle 62 reste dans le disque 63 définissant la zone dans laquelle le ROS est inférieur à 2.The coupling of the two radiating strands makes it possible to obtain a resonance loop, if the frequencies f r and f ' r are well chosen, as is illustrated in FIG. 6. The impedance curve 61 corresponding to the combination of the strands 37 and 38 has a resonance loop 62, centered on f₀. This loop 62 remains in the disk 63 defining the zone in which the ROS is less than 2.

On obtient ainsi une bande passante très élargie (f₁ - f₄) / f₀, valant par exemple 10 %.This gives a very wide bandwidth (f₁ - f₄) / f₀, worth for example 10%.

La figure 7 présente un second mode de réalisation de l'invention, dans lequel l'un des brins d'antenne est court-circuité à ses deux extrémités. La structure générale de cette antenne est similaire à celle de la figure 3, en ce qui concerne la forme des éléments horizontal 33 et vertical 35. Elle n'est donc pas décrite à nouveau.FIG. 7 shows a second embodiment of the invention, in which one of the antenna strands is short-circuited at its two ends. The general structure of this antenna is similar to that of FIG. 3, as regards the shape of the horizontal 33 and vertical 35 elements. It is therefore not described again.

La différence fondamentale avec le premier mode de réalisation est que le brin 72 n'est plus ouvert à sa seconde extrémité 313, mais court-circuité par un élément vertical de court-circuit 71 reliant cette extrémité 313 au blindage du boîtier 32.The fundamental difference with the first embodiment is that the strand 72 is no longer open at its second end 313, but short-circuited by a vertical short-circuit element 71 connecting this end 313 to the shielding of the housing 32.

Ce brin 72 ne joue donc plus le rôle d'élément résonant, mais le rôle d'un "stub" (ou tronçon) court-circuit, qui joue le rôle de circuit d'adaptation, permettant d'élargir la bande sur laquelle l'impédance d'entrée globale de l'antenne reste voisine de l'impédance du coaxial d'excitation. Eventuellement, plusieurs stubs peuvent être réalisés. De même, si l'antenne comprend au moins trois brins, les modes de réalisation des figures 3 et 7 peuvent être combinés.This strand 72 therefore no longer plays the role of resonant element, but the role of a short-circuit "stub" (or section), which plays the role of adaptation circuit, making it possible to widen the band on which the the overall input impedance of the antenna remains close to the impedance of the excitation coaxial. Optionally, several stubs can be made. Similarly, if the antenna comprises at least three strands, the embodiments of FIGS. 3 and 7 can be combined.

La figure 8 présente le diagramme de Smith portant la courbe d'impédance 81 correspondant au brin résonant 38. La bande passante correspondante (f₂-f₁) / f₀ est toujours de l'ordre de 2 à 4 %.FIG. 8 presents the Smith diagram carrying the impedance curve 81 corresponding to the resonant strand 38. The corresponding passband (f₂-f₁) / f₀ is always in the range of 2 to 4%.

Le diagramme de Smith de la figure 9 présente quant à lui l'impédance 91 du "stub" court-circuit 72. Cette courbe 91 est sensiblement symétrique à la courbe 81 de la figure 8.The Smith diagram of FIG. 9 presents the impedance 91 of the short-circuit "stub" 72. This curve 91 is substantially symmetrical to the curve 81 of FIG. 8.

La combinaison des deux brins 37 et 38 permet d'obtenir la courbe d'impédance 101 de la figure 10. Cette courbe 101 présente une boucle de résonance 102 qui reste dans le disque 103 de ROS inférieur à 2. En conséquence, la bande passante résultante (f₄ - f₃) / f₀ est à nouveau élargie, et par exemple de l'ordre de 10 %.The combination of the two strands 37 and 38 makes it possible to obtain the impedance curve 101 of FIG. 10. This curve 101 has a resonance loop 102 which remains in the disc 103 of ROS less than 2. Consequently, the bandwidth resulting (f₄ - f₃) / f₀ is again widened, and for example of the order of 10%.

Il est donc à noter que, du point de vue de la largeur de bande, on obtient des résultats similaires avec les deux premiers modes de réalisation décrits.It should therefore be noted that, from the point of view of the bandwidth, similar results are obtained with the first two embodiments described.

La figure 11 présente un troisième mode de réalisation de l'invention. Il s'agit en fait d'une généralisation de l'antenne des figures 3 et 7, dans lesquelles les secondes extrémités des brins ne sont ni ouvertes, ni court-circuitées, mais reliées à la masse à l'aide de capacités.Figure 11 shows a third embodiment of the invention. This is in fact a generalization of the antenna of FIGS. 3 and 7, in which the second ends of the strands are neither open nor short-circuited, but connected to ground using capacitors.

Ainsi, l'antenne 111 comprend un premier brin 112, relié à la masse 113 par une capacité 114, et un second brin 115 relié à la masse par une capacité 116. Ces capacités 114 et 116 permettent de faire varier la longueur équivalente des brins (qui n'est donc plus figée à λ/4). Cela permet un réglage fin de la fréquence d'accord.Thus, the antenna 111 comprises a first strand 112, connected to the ground 113 by a capacitor 114, and a second strand 115 connected to the ground by a capacitor 116. These capacitors 114 and 116 make it possible to vary the equivalent length of the strands (which is therefore no longer frozen at λ / 4). This allows fine tuning of the tuning frequency.

Dans ce mode de réalisation, les brins d'antenne peuvent avoir la même longueur physique, la longueur équivalente étant modifiée par les capacités. Il est à noter, par ailleurs, qu'il n'est pas obligatoire que tous les brins soient associés à une capacité. Certains d'entre eux peuvent être ouverts ou court-circuités.In this embodiment, the antenna strands can have the same physical length, the equivalent length being modified by the capacities. It should be noted, moreover, that it is not compulsory for all the strands to be associated with a capacity. Some of them can be opened or short-circuited.

Préférentiellement, au moins certaines des capacités 114 et 116 sont ajustables (ce sont par exemple des varactors, ou plusieurs capacités en parallèle susceptibles d'être sélectionnées indépendamment), et contrôlées (118) par un circuit électronique de commande 117 placé dans le boîtier 32. Il est ainsi possible de faire varier à tout instant et quasi instantanément la bande passante de l'antenne 111. Cela permet de faire fonctionner la même antenne physique dans plusieurs bandes de fréquence, sélectivement.Preferably, at least some of the capacities 114 and 116 are adjustable (these are for example varactors, or several capacities in parallel capable of being selected independently), and controlled (118) by an electronic control circuit 117 placed in the housing 32 It is thus possible to vary at all times and almost instantaneously the passband of the antenna 111. This makes it possible to operate the same physical antenna in several frequency bands, selectively.

Par exemple, cette antenne 111 permet un fonctionnement en alternat dans une bande d'émission (correspondant à une fréquence d'émission) et dans une bande de réception (correspondant à une fréquence de réception). Le dispositif équipé de cette antenne peut donc fonctionner en "half duplex".For example, this antenna 111 allows alternating operation in a transmission band (corresponding to a transmission frequency) and in a reception band (corresponding to a reception frequency). The device equipped with this antenna can therefore operate in "half duplex".

A titre d'exemple détaillé, on donne notamment la description géométrique exacte d'une antenne selon l'invention. Ce mode de réalisation correspond au meilleur mode actuellement développé. Toutefois, comme on le verra par la suite, les résultats sont encore perfectibles. La figure 12 présente, en vue de dessus, l'élément horizontal d'une antenne telle qu'illustrée en figure 7.By way of detailed example, the exact geometric description of an antenna according to the invention is given in particular. This embodiment corresponds to the best currently developed mode. However, as we will see later, the results are still room for improvement. FIG. 12 shows, in top view, the horizontal element of an antenna as illustrated in FIG. 7.

Ce mode de réalisation a pour objectif de fonctionner dans la bande nominale de fréquence 2,4 GHz - 2,5 GHz.The aim of this embodiment is to operate in the nominal frequency band 2.4 GHz - 2.5 GHz.

Les dimensions retenues pour l'élément horizontal sont :

  • largeur : l = 15 mm ;
  • longueur du brin le plus long 122 : 11 = 30 mm ;
  • longueur du brin le plus court 123 : 12 = 27 mm ;
  • largeur de la base 124 : s = 4 mm ;
  • largeur des brins 122 et 123 : w1 = w2 = 6 mm.
The dimensions used for the horizontal element are:
  • width: l = 15 mm;
  • length of longest strand 122: 11 = 30 mm;
  • length of the shortest strand 123: 12 = 27 mm;
  • width of the base 124: s = 4 mm;
  • width of the strands 122 and 123: w1 = w2 = 6 mm.

La hauteur de l'élément vertical est : h = 5 mm.The height of the vertical element is: h = 5 mm.

L'emplacement 121 de connexion du câble coaxial est éloigné de d = 5 mm de l'élément vertical, pour obtenir une impédance d'entrée de 50 Ohms.The coaxial cable connection location 121 is spaced d = 5 mm from the vertical element, to obtain an input impedance of 50 Ohms.

Cette impédance peut être modifiée entre 10 et 200 Ohms, en modifiant cette distance d.This impedance can be modified between 10 and 200 Ohms, by modifying this distance d.

Dans ce mode de réalisation, le brin le plus long 122 est ouvert à sa seconde extrémité 125, et le brin le plus court 123 est court-circuité à sa seconde extrémité 126.In this embodiment, the longest strand 122 is open at its second end 125, and the shortest strand 123 is short-circuited at its second end 126.

La figure 13 présente la courbe 131 d'adaptation de cette antenne, c'est-à-dire la courbe du R.O.S (en ordonnée) en fonction de la fréquence (en abscisse).FIG. 13 shows the curve 131 for adapting this antenna, that is to say the curve of the R.O.S (on the ordinate) as a function of the frequency (on the abscissa).

Ainsi que le montre les marqueurs 132 et 133, le R.O.S est inférieur à 2 entre 2,37 GHz et 2,55 GHz. Cela correspond à une bande passante de l'ordre de 8 %, ce qui est très supérieur aux bandes passantes obtenues avec les antennes de l'art antérieur.As shown by markers 132 and 133, the R.O.S is less than 2 between 2.37 GHz and 2.55 GHz. This corresponds to a bandwidth of the order of 8%, which is much higher than the bandwidths obtained with the antennas of the prior art.

Par ailleurs, sur la bande de travail, c'est-à-dire entre 2,4 GHz (marqueur 134) et 2,5 GHz (marqueur 135), le R.O.S est inférieur à 1,6.Furthermore, on the working band, i.e. between 2.4 GHz (marker 134) and 2.5 GHz (marker 135), the R.O.S is less than 1.6.

Le diagramme de Smith de la figure 14 présente la courbe d'impédance 141 de l'antenne de la figure 12, entre 2 GHz et 3 GHz. Les marqueurs 142 et 143 délimitent la zone de travail de l'antenne (2,4 - 2,5 GHz).The Smith diagram in FIG. 14 shows the impedance curve 141 of the antenna in FIG. 12, between 2 GHz and 3 GHz. Markers 142 and 143 delimit the antenna work area (2.4 - 2.5 GHz).

Cette courbe montre que cette antenne n'est pas encore complètement optimisée, et qu'un meilleur centrage de la courbe 141 par rapport à l'abaque amènerait des performances meilleures.This curve shows that this antenna is not yet fully optimized, and that better centering of the curve 141 relative to the abacus would lead to better performance.

L'invention concerne également tout appareil d'émission et/ou de réception de signaux hyperfréquences équipés d'une antenne selon l'invention, tel qu'illustré par exemple par le boîtier 32 des figures 3, 7 et 11. Eventuellement, un tel appareil peut comprendre plusieurs antennes, et en particulier une antenne d'émission et une antenne de réception.The invention also relates to any device for transmitting and / or receiving microwave signals equipped with an antenna according to the invention, as illustrated for example by the housing 32 of Figures 3, 7 and 11. Optionally, such device can comprise several antennas, and in particular a transmitting antenna and a receiving antenna.

Claims (21)

Antenne d'émission et/ou de réception de signaux hyperfréquences, comprenant un élément (33) sensiblement plan, dit élément horizontal, et un élément (35) de court-circuit sensiblement perpendiculaire audit élément horizontal (33), dit élément vertical, ledit élément vertical (35) connectant une première extrémité (34) dudit élément horizontal (33) à la masse électrique d'une unité de traitement,
lesdits signaux hyperfréquences étant véhiculés entre ladite unité de traitement et ledit élément horizontal (33) par un câble coaxial (311) connecté audit élément horizontal (33), caractérisée en ce que ledit élément horizontal (33) comprend : - une surface intermédiaire (36) sensiblement rectangulaire, dont une première extrémité correspond à ladite première extrémité (34) dudit élément horizontal (33) ; et - au moins deux brins (37,38;72;112,115;122,123) sensiblement parallèles entre eux et sensiblement perpendiculaires audit élément vertical, la seconde extrémité de ladite surface intermédiaire (36) correspondant à une première extrémité (313,314) de chacun desdits brins (37, 38). An antenna for transmitting and / or receiving microwave signals, comprising a substantially planar element (33), said horizontal element, and a short-circuit element (35) substantially perpendicular to said horizontal element (33), said vertical element, said vertical element (35) connecting a first end (34) of said horizontal element (33) to the electrical ground of a processing unit,
said microwave signals being conveyed between said processing unit and said horizontal element (33) by a coaxial cable (311) connected to said horizontal element (33), characterized in that said horizontal element (33) comprises: - a substantially rectangular intermediate surface (36), a first end of which corresponds to said first end (34) of said horizontal element (33); and - at least two strands (37,38; 72; 112,115; 122,123) substantially parallel to each other and substantially perpendicular to said vertical element, the second end of said intermediate surface (36) corresponding to a first end (313,314) of each of said strands ( 37, 38). Antenne selon la revendication 1, caractérisée en ce que lesdits brins (37,38) sont de forme sensiblement rectangulaire.Antenna according to claim 1, characterized in that said strands (37,38) are of substantially rectangular shape. Antenne selon l'une quelconque des revendications 1 et 2, caractérisée en ce que lesdits brins (37,38) ont des longueurs différentes.Antenna according to any one of claims 1 and 2, characterized in that said strands (37,38) have different lengths. Antenne selon l'une quelconque des revendications 1 à 3, caractérisée en ce que lesdits brins (37,38) ont des largeurs sensiblement identiques.Antenna according to any one of claims 1 to 3, characterized in that said strands (37,38) have substantially identical widths. Antenne selon l'une quelconque des revendications 1 à 4, caractérisée en ce que chacun desdits brins (37,38) est ouvert à son extrémité (313,314) la plus éloignée de ladite première extrémité (34) dudit élément horizontal (33).Antenna according to any one of claims 1 to 4, characterized in that each of said strands (37,38) is open at its end (313,314) furthest from said first end (34) of said horizontal element (33). Antenne selon l'une quelconque des revendications 1 à 5, caractérisée en ce que l'extrémité (313) la plus éloignée de ladite première extrémité (34) dudit élément horizontal (33) d'au moins un desdits brins (72) est connectée à la masse électrique de ladite unité de traitement, par l'intermédiaire d'un élément (71) de court-circuit supplémentaire.Antenna according to any one of claims 1 to 5, characterized in that the end (313) furthest from said first end (34) of said horizontal element (33) of at least one of said strands (72) is connected to the electrical ground of said processing unit, by means of an additional short-circuit element (71). Antenne selon l'une quelconque des revendications 1 à 6, caractérisée en ce que l'extrémité la plus éloignée de ladite première extrémité dudit élément horizontal d'au moins un desdits brins (112,115) est reliée à la masse électrique de ladite unité de traitement, par l'intermédiaire d'une capacité (114,116).Antenna according to any one of claims 1 to 6, characterized in that the end furthest from said first end of said horizontal element at least at least one of said strands (112,115) is connected to the electrical ground of said processing unit, via a capacitor (114,116). Antenne selon la revendication 7, caractérisée en ce que l'extrémité la plus éloignée de ladite première extrémité dudit élément horizontal de chacun desdits brins (112,115) est reliée à la masse électrique de ladite unité de traitement, par l'intermédiaire d'une capacité (114,116).Antenna according to claim 7, characterized in that the end furthest from said first end of said horizontal element of each of said strands (112,115) is connected to the electrical ground of said processing unit, via a capacitor (114,116). Antenne selon l'une quelconque des revendications 7 et 8, caractérisée en ce que ladite capacité (114,116) est ajustable, et en ce que ladite unité de traitement comprend des moyens (117) de contrôle de la valeur de ladite capacité ajustable.An antenna according to any one of claims 7 and 8, characterized in that said capacity (114,116) is adjustable, and in that said processing unit comprises means (117) for controlling the value of said adjustable capacity. Antenne selon la revendication 11, caractérisée en ce que ladite capacité ajustable (114,116) peut prendre au moins deux valeurs distinctes, une première valeur correspondant au fonctionnement de ladite antenne à une fréquence d'émission de signaux hyperfréquences et une seconde valeur correspondant au fonctionnement de ladite antenne à une fréquence de réception de signaux hyperfréquences.Antenna according to claim 11, characterized in that said adjustable capacity (114,116) can take at least two distinct values, a first value corresponding to the operation of said antenna at a frequency of transmission of microwave signals and a second value corresponding to the operation of said antenna at a frequency for receiving microwave signals. Antenne selon l'une quelconque des revendications 1 à 10, caractérisée en ce que ledit câble coaxial (311) présente une impédance sensiblement comprise entre 10 Ohms à 200 Ohms.An antenna according to any one of claims 1 to 10, characterized in that said coaxial cable (311) has an impedance substantially between 10 Ohms to 200 Ohms. Antenne selon la revendication 11, caractérisée en ce que ladite impédance est sensiblement égale à 50 Ohms.Antenna according to claim 11, characterized in that said impedance is substantially equal to 50 Ohms. Antenne selon l'une quelconque des revendications 1 à 12, caractérisée en ce que la largeur (1) de ladite première extrémité dudit élément horizontal (33) est sensiblement égale à λ/8, λ étant la longueur d'onde desdits signaux hyperfréquences.An antenna according to any one of claims 1 to 12, characterized in that the width (1) of said first end of said horizontal element (33) is substantially equal to λ / 8, λ being the wavelength of said microwave signals. Antenne selon l'une quelconque des revendications 1 à 13, caractérisée en ce que la longueur maximale (11) dudit élément horizontal (33), correspondant à la distance entre ladite première extrémité (34) dudit élément horizontal (33) et l'extrémité (313) la plus éloignée de ladite première extrémité (34) dudit élément horizontal (33) du brin le plus long (37) est sensiblement égale à λ/4, λ étant la longueur d'onde desdits signaux hyperfréquences.Antenna according to any one of claims 1 to 13, characterized in that the maximum length (11) of said horizontal element (33), corresponding to the distance between said first end (34) of said horizontal element (33) and the end (313) the farthest from said first end (34) of said horizontal element (33) of the longest strand (37) is substantially equal to λ / 4, λ being the wavelength of said microwave signals. Antenne selon l'une quelconque des revendications 1 à 14, caractérisée en ce que la hauteur (h) dudit élément vertical (35), correspondant à la distance entre ladite première extrémité (34) dudit élément horizontal (33) et ladite masse électrique est sensiblement égale à λ/25, λ étant la longueur d'onde desdits signaux hyperfréquences.Antenna according to any one of claims 1 to 14, characterized in that the height (h) of said vertical element (35), corresponding to the distance between said first end (34) of said horizontal element (33) and said electrical mass is substantially equal to λ / 25, λ being the wavelength of said microwave signals. Antenne selon l'une quelconque des revendications 1 à 15, caractérisée en ce que la largeur (w1, w2) d'au moins un desdits brins (37,38) est sensiblement égale à λ/20, λ étant la longueur d'onde desdits signaux hyperfréquences.Antenna according to any one of claims 1 to 15, characterized in that that the width (w1, w2) of at least one of said strands (37,38) is substantially equal to λ / 20, λ being the wavelength of said microwave signals. Antenne selon l'une quelconque des revendications 1 à 16, caractérisée en ce que la longueur d'onde λ desdits signaux hyperfréquences est comprise entre 100 et 200 mm.Antenna according to any one of claims 1 to 16, characterized in that the wavelength λ of said microwave signals is between 100 and 200 mm. Antenne selon l'une quelconque des revendications 1 à 17, caractérisée en ce qu'elle comprend deux brins (37,38).Antenna according to any one of claims 1 to 17, characterized in that it comprises two strands (37,38). Antenne selon l'une quelconque des revendications 1 à 18, caractérisé en ce qu'elle est implantée sur un boîtier (32) contenant ladite unité de traitement, ladite masse électrique correspondant au blindage électromagnétique dudit boîtier (32).Antenna according to any one of claims 1 to 18, characterized in that it is located on a box (32) containing said processing unit, said electrical mass corresponding to the electromagnetic shielding of said box (32). Antenne selon la revendication 19, caractérisée en ce qu'au moins une partie dudit élément vertical (35) et ledit élément horizontal (33) sont formés dans une même bande d'un matériau conducteur.Antenna according to claim 19, characterized in that at least a part of said vertical element (35) and said horizontal element (33) are formed in the same strip of a conductive material. Dispositif d'émission et/ou de réception de signaux hyperfréquences, caractérisé en ce qu'il comprend au moins une antenne (31,111) selon l'une quelconque des revendications 1 à 20.Device for transmitting and / or receiving microwave signals, characterized in that it comprises at least one antenna (31,111) according to any one of claims 1 to 20.
EP19930460039 1992-12-23 1993-12-20 Space-saving broadband antenna with corresponding transceiver Expired - Lifetime EP0604338B1 (en)

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FR9215813A FR2699740B1 (en) 1992-12-23 1992-12-23 Broadband antenna with reduced overall dimensions, and corresponding transmitting and / or receiving device.
FR9215813 1992-12-23

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FR2699740A1 (en) 1994-06-24
DE69317235T2 (en) 1998-10-15
FR2699740B1 (en) 1995-03-03
EP0604338B1 (en) 1998-03-04

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