EP3671955A1 - Monopolar wire-plate antenna for differential connection - Google Patents

Abstract

The antenna (100) monopolar wire-plate comprises a ground plane (101), a roof (102) arranged at a distance from the ground plane (101) and at least one electrically conductive element (103a) electrically connecting the ground plane (101) to the roof (102). This antenna (100) comprises a feed loop (107) arranged substantially orthogonal to the ground plane (101), said feed loop (107) being open so that it has two longitudinal ends ( 108, 109) opposite arranged so as to be connected to a differential connection.

Description

Technical field of the invention

The technical field of the invention relates to monopolar wire-plate antennas. More particularly, the invention relates to a monopolar wire-plate antenna comprising a ground plane, a roof arranged at a distance from the ground plane, and at least one electrically conductive element electrically connecting the ground plane to the roof.

State of the art

The article "New kind of microstrip antenna: the monopolar wire-patch antenna" by Ch. Delaveaud et al., Published in ELECTRONICS LETTERS of January 6, 1994 vol. 30, No. 1 pages 1 and 2 , defines an example of a monopolar wire-plate antenna. As illustrated in the figure 1 , a 100-wire monopolar plate antenna, of the type of this article by Ch. Delaveaud et al., comprises a ground plane 101, an electrically conductive planar element 102, called roof, one or more electrically conductive elements 103a, 103b, called (s) ground wire (s), connecting the roof 102 to the ground plane 101 and possibly a dielectric substrate 104 on which the roof 102 can be printed. In addition, ground wires 103a, 103b connecting the roof 102 to the ground plane 101, the antenna 100 comprises a coaxial feed probe 105 having a central core 106a passing through the ground plane 101, without electrical contact with it. ci, and extending to the roof 102 so as to establish an electrical connection therewith. The core 106a is also successively surrounded by a sheath 106b of dielectric material 106b, then a metal tube 106c electrically connected to the ground plane, the sheath 106b of dielectric material providing electrical insulation between the core 106a and the metal tube 106c. Such a coaxial feed probe 105 forms a coaxial waveguide in which a quasi-transverse electric magnetic (TEM) mode is established to guide and propagate the wave in the waveguide. This type of antenna 100 makes it possible to emit an electromagnetic field, also called electromagnetic wave, with a high efficiency for frequencies located below the resonance modes of cavity TM _nm (for “Transverse Magnetic” of indices n and m) classics for this antenna geometry. By resonance of classical cavity, we mean the particular distribution of an electromagnetic field resulting from the resolution of Maxwell's equations with the boundary conditions imposed by the topology of the antenna. Conventionally, this monopolar wire-plate antenna can be supplied asymmetrically from a suitable radiofrequency transmitter having an asymmetrical connection (for example a microstrip line or a coaxial connector).

Such an antenna 100 has the advantage of having a small footprint, it is therefore particularly suitable for being associated with components originating from microelectronics, in particular within a mobile device. A disadvantage linked to this type of antenna is that its technological integration in a small volume can imply that the radiofrequency transmitter connected to the antenna is with differential connection instead of being asymmetrical. The differential connection transmitter generates two signals of equal amplitude and in phase opposition: the transmitter then forms a so-called “balanced” power source for the antenna. However, due to the use of the coaxial feed probe 105, it is necessary to transform the balanced feed into an unbalanced feed to feed the monopolar wire-plate antenna using this coaxial feed probe 105 In this sense, it is conventional to associate the differential connection transmitter with a balun, also called a balun, to make the transition between a symmetrical waveguide structure connected to the radiofrequency transmitter and an asymmetric topology that is the probe. coaxial 105. In other words, the balun makes it possible to adapt the differential connection of the radiofrequency transmitter so that it is compatible with the coaxial supply probe. The balun, well known to those skilled in the art, comes from the English words BALanced (for balanced, or balanced, in French) and UNbalanced (for unbalanced, or unbalanced, in French). A drawback of this adaptation of the differential connection is that it increases the bulk of the radio frequency front ends, implying the addition of additional components to be assembled which are generally not integrated on a chip, this results in radio frequency losses. In this sense, there is a need to develop a solution making it possible to feed an antenna with a roof, in particular a capacitive one, and with a ground plane electrically connected to each other without having to resort to the use of a balun when the antenna is intended to be connected to a differential connection transmitter.

It is known from the patent application FR2709878 a monopolar wire-plate antenna comprising a ground plane, a first radiating element in the form of a capacitive roof, and a second radiating element in the form of a conductive wire connecting the capacitive roof to the ground plane. This antenna also includes a cable, or coaxial supply probe, the central core of which is connected to the capacitive roof. However, if the power source for the coaxial power probe is a radiofrequency transmitter with differential connection, this again requires the use of a balun.

The document "Electromagnetically Coupled Small Broadband Monopole Antenna" by Jong-Ho Jung and Ikmo Park published in IEEE ANTENNAS AND WIRELESS PROPAGATION LETTERS, Vol. 2, 2003, pages 349 to 351 describes a monopolar wire-plate antenna whose roof is coupled to a spiral located in a plane distant from the roof and parallel to the roof. The spiral is connected to a coaxial feeding probe. The spiral associated with the coaxial feeding probe makes it possible to excite the antenna. However, if the radiofrequency transmitter has a differential connection, this again requires the use of a balun.

The document "A WIDEBAND BALUN FROM COAXIAL LINE TO TEM LINE" by PR Foster and Soe Min Tun published in Antennas and Propagation, 4-7 April 1995 Conference Publication No. 407 , © IEE 1955 describes in particular the operation of a balun.

Subject of the invention

The object of the invention is to allow a supply of a monopolar wire-plate antenna not requiring the presence of a balun.

To this end, the invention relates to a monopolar wire-plate antenna comprising a ground plane, a roof arranged at a distance from the ground plane, at least one electrically conductive element electrically connecting the ground plane to the roof, this antenna being characterized in that it comprises a supply loop arranged substantially orthogonal to the ground plane, said supply loop being open so that it has two opposite longitudinal ends arranged so as to be connected to a differential connection.

Thus, with such a feed loop, it is possible to connect the antenna to a transmitter with differential connection without having to carry out an adaptation of the differential connection via a balun between the transmitter and the power loop. The power supply loop allows, during the operation of the monopolar wire-plate antenna supplied by the transmitter with differential connection during the emission of a signal or by an electromagnetic wave propagating in the environment of the antenna during reception of a signal, to impose a distribution of the electromagnetic field in a suitable way between the ground plane and the roof to allow the antenna wire-monopolar plate to present a desired impedance and, if necessary, emit a satisfactory electromagnetic wave. Furthermore, the feed / excitation of the antenna by the feed loop makes it possible to obtain a symmetrical system from which the reduction of the propagation of electric currents on the ground plane of the antenna results, thus limiting the influence of the close context of the antenna, such as for example the influence of a hand of a person holding a device equipped with the antenna.

• l'antenne comporte un guide d'ondes équilibré, le guide d'ondes équilibré comportant un premier conducteur électrique et un deuxième conducteur électrique, le premier conducteur électrique étant connecté à l'une des extrémités longitudinales de la boucle d'alimentation et le deuxième conducteur électrique étant connecté à l'autre des extrémités longitudinales de la boucle d'alimentation ;
• la boucle d'alimentation comporte une première partie distale du plan de masse, une deuxième partie proximale du plan de masse, une troisième partie reliant les première et deuxième parties, les extrémités longitudinales étant agencées à l'opposé de la troisième partie ;
• la boucle d'alimentation comporte une quatrième partie comportant : une première portion s'étendant depuis la première partie de la boucle d'alimentation, cette première portion comportant l'une des extrémités longitudinales de la boucle d'alimentation ; et une deuxième portion s'étendant depuis la deuxième partie de la boucle d'alimentation, cette deuxième portion comportant l'autre des extrémités longitudinales de la boucle d'alimentation ;
• la boucle d'alimentation comporte une quatrième partie s'étendant depuis la première partie et comportant l'une des extrémités longitudinales de la boucle d'alimentation, la deuxième partie comportant l'autre des extrémités longitudinales de la boucle d'alimentation ;
• la boucle d'alimentation comporte une quatrième partie s'étendant depuis la deuxième partie et comportant l'une des extrémités longitudinales de la boucle d'alimentation, la première partie comportant l'autre des extrémités longitudinales de la boucle d'alimentation ;
• une partie de la boucle d'alimentation est formée par une portion du toit, ou la boucle d'alimentation est située à distance du toit, ou la boucle d'alimentation est en contact avec le toit ;
• ladite boucle d'alimentation présente, lors du fonctionnement de l'antenne, deux régions d'excitation de l'antenne dans lesquelles les courants sont en phase et circulent sensiblement orthogonalement par rapport au plan de masse ;
• ladite antenne est une antenne à large bande passante pour laquelle la boucle d'alimentation présente une longueur, entre ses deux extrémités longitudinales opposées, comprise entre λ_g/3 et λ_g/1,6 avec λ_g la longueur d'onde de fonctionnement de l'antenne ;
• ladite antenne est une antenne à bande étroite pour laquelle la boucle d'alimentation présente une longueur, entre ses deux extrémités longitudinales opposées, comprise entre λ_g/3,5 et λ_g/3,7 avec λ_g la longueur d'onde de fonctionnement de l'antenne.

The monopolar wire-plate antenna may have one or more of the following characteristics:

• the antenna comprises a balanced waveguide, the balanced waveguide comprising a first electrical conductor and a second electrical conductor, the first electrical conductor being connected to one of the longitudinal ends of the supply loop and the second electrical conductor being connected to the other of the longitudinal ends of the supply loop;
• the supply loop comprises a first part distal from the ground plane, a second part proximal to the ground plane, a third part connecting the first and second parts, the longitudinal ends being arranged opposite the third part;
• the supply loop comprises a fourth part comprising: a first portion extending from the first part of the supply loop, this first portion comprising one of the longitudinal ends of the supply loop; and a second portion extending from the second part of the supply loop, this second portion comprising the other of the longitudinal ends of the supply loop;
• the supply loop comprises a fourth part extending from the first part and comprising one of the longitudinal ends of the supply loop, the second part comprising the other of the longitudinal ends the power loop;
• the supply loop comprises a fourth part extending from the second part and comprising one of the longitudinal ends of the supply loop, the first part comprising the other of the longitudinal ends of the supply loop;
• a part of the supply loop is formed by a portion of the roof, or the supply loop is located at a distance from the roof, or the supply loop is in contact with the roof;
• said feed loop has, during the operation of the antenna, two excitation regions of the antenna in which the currents are in phase and circulate substantially orthogonally with respect to the ground plane;
• said antenna is a broadband antenna for which the feed loop has a length, between its two opposite longitudinal ends, between λ _g / 3 and λ _g / 1.6 with λ _g the operating wavelength the antenna;
• said antenna is a narrow band antenna for which the feed loop has a length, between its two opposite longitudinal ends, between λ _g / 3.5 and λ _g / 3.7 with λ _g the wavelength of antenna operation.

The invention also relates to a radiofrequency device comprising a monopolar wire-plate antenna as described and a radiofrequency transmitter with differential connection connected to the supply loop.

Preferably, the differential connection of the radiofrequency transmitter comprises first and second connection terminals, the antenna comprises a balanced waveguide, the balanced waveguide comprising first and second electrical conductors, the first electrical conductor is connected, on the one hand, at one of the longitudinal ends of the supply loop and, on the other hand, at the first connection terminal, and the second electrical conductor is connected, on the one hand, to the other of the longitudinal ends of the supply loop and, on the other hand, to the second connection terminal.

Brief description of the drawings

• La figure 1 représente, en coupe, une antenne fil-plaque monopolaire selon l'art antérieur.
• La figure 2 illustre une vue en perspective d'une antenne fil-plaque monopolaire à bande étroite selon un mode de réalisation de l'invention.
• La figure 3 est une vue de côté de l'antenne de la figure 2.
• La figure 4 illustre une vue en perspective d'une antenne fil-plaque monopolaire à large bande selon un mode de réalisation de l'invention.
• La figure 5 est une vue de côté de l'antenne de la figure 4.
• La figure 6 illustre une vue de côté d'un dispositif radiofréquence comprenant une antenne fil-plaque monopolaire du type de la figure 2.
• La figure 7 illustre une vue de côté d'une réalisation particulière d'antenne fil-plaque monopolaire du type de la figure 2.
• La figure 8 illustre une vue de côté d'une réalisation particulière d'antenne fil-plaque monopolaire du type de la figure 2.
• La figure 9 illustre une vue de côté d'une réalisation particulière d'antenne fil-plaque monopolaire du type de la figure 2.
• La figure 10 illustre une vue de côté d'une réalisation particulière d'antenne fil-plaque monopolaire du type de la figure 2.
• La figure 11 illustre une vue de côté d'une antenne fil plaque monopolaire à large bande comportant un substrat de support multicouches.
• La figure 12 illustre une vue en perspective de la figure 11 pour laquelle le substrat de support multicouches a été retiré.
• La figure 13 illustre l'évolution du coefficient de réflexion en dB de l'antenne de la figure 12 en fonction de la fréquence de l'antenne en GHz.
• La figure 14 montre une courbe C2 de l'évolution du Gain maximum obtenu de l'antenne de la figure 12 en dBi en fonction de la fréquence de l'antenne en GHz, et une courbe C1 de l'évolution de l'efficacité de rayonnement en % de l'antenne de la figure 12 en fonction de la fréquence de l'antenne en GHz.

The invention will be better understood on reading the detailed description which follows of particular embodiments, given solely by way of nonlimiting example and made with reference to the attached drawings and listed below.

• The figure 1 shows, in section, a monopolar wire-plate antenna according to the prior art.
• The figure 2 illustrates a perspective view of a narrow-band monopolar wire-plate antenna according to an embodiment of the invention.
• The figure 3 is a side view of the antenna of the figure 2 .
• The figure 4 illustrates a perspective view of a broadband monopolar wire-plate antenna according to an embodiment of the invention.
• The figure 5 is a side view of the antenna of the figure 4 .
• The figure 6 illustrates a side view of a radiofrequency device comprising a monopolar wire-plate antenna of the type of figure 2 .
• The figure 7 illustrates a side view of a particular embodiment of monopolar wire-plate antenna of the type of figure 2 .
• The figure 8 illustrates a side view of a particular embodiment of monopolar wire-plate antenna of the type of figure 2 .
• The figure 9 illustrates a side view of a particular embodiment of monopolar wire-plate antenna of the type of figure 2 .
• The figure 10 illustrates a side view of a particular embodiment of monopolar wire-plate antenna of the type of figure 2 .
• The figure 11 illustrates a side view of a broadband monopolar wire antenna having a multilayer support substrate.
• The figure 12 illustrates a perspective view of the figure 11 for which the multilayer support substrate has been removed.
• The figure 13 illustrates the evolution of the reflection coefficient in dB of the antenna of the figure 12 as a function of the antenna frequency in GHz.
• The figure 14 shows a curve C2 of the evolution of the maximum gain obtained from the antenna of the figure 12 in dBi as a function of the antenna frequency in GHz, and a curve C1 of the evolution of the radiation efficiency in% of the antenna of the figure 12 as a function of the antenna frequency in GHz.

In these figures, the same references are used to designate the same elements.

Furthermore, the elements represented in these figures are not necessarily represented according to a uniform scale to make the figures more legible.

detailed description

It is defined below for a coordinate system of orthogonal axes XYZ represented in figures 2 to 12 . In particular, the terms "under", and "lower" in relation to elements represented on these figures 2 to 12 are interpreted according to the orientation given by the Z axis. This reference is that of the reference frame of a monopolar wire-plate antenna as described below. A dimension given along an axis of this coordinate system is a dimension measured parallel to this axis.

Thereafter, the operating frequency of the monopolar wire-plate antenna corresponds to the frequency at which the monopolar wire-plate antenna transmits, or receives, an electromagnetic wave, in particular a radio wave, also called if necessary signal emitted. or received / received signal. More generally, to speak of this electromagnetic wave, reference is made to the electromagnetic wave to be processed (whether receiving or transmitting) at the operating frequency of the monopolar wire-plate antenna. In other words, the monopolar wire-plate antenna is configured to transmit and / or receive a corresponding electromagnetic wave.

Furthermore, an antenna operating wavelength, denoted λ ₀ at the antenna operating frequency, corresponds to the spatial period of the electromagnetic wave to be processed by the antenna propagating in a vacuum or in the air when the monopolar wire-plate antenna includes such a propagation medium. λ ₀ is associated with the propagation of the electromagnetic wave in vacuum or in air. The propagation medium of the monopolar wire-plate antenna corresponds to a medium for transmitting and / or receiving the electromagnetic wave to be treated. Thus, the propagation medium is, if necessary, the medium from which the antenna picks up the electromagnetic wave to be treated or to which the antenna emits the electromagnetic wave to be treated. More generally, we say that the wave electromagnetic to be propagated propagates in a medium of propagation of the monopolar wire-plate antenna (for example air, vacuum, a dielectric material, etc.) in contact with one or more radiating parts of the antenna, and the operating wavelength of the antenna (that is to say the wavelength associated with the propagation of the electromagnetic wave to be processed at the operating frequency of the antenna) is then noted λ _g : we also speak of guided wavelength. Subsequently, when the monopolar wire-plate antenna is said to be supplied / excited, it is at the operating wavelength of the antenna.

The monopolar wire-plate antenna is said to be adapted in impedance when it has a reflection coefficient strictly lower than a given level (typically -9.54 dB for communication terminals, and -15 dB for example for base stations ).

As illustrated according to different realizations in figures 2 to 5 , the invention relates to an antenna 100 monopolar wire-plate, also simply called antenna 100, comprising a ground plane 101 (in particular planar), a roof 102 (in particular planar) arranged at a distance from the ground plane 101, and at at least one electrically conductive element 103a, 103b electrically connecting the ground plane 101 to the roof 102. In figures 2 to 5 , two electrically conductive elements 103a, 103b are shown by way of example: the number of these electrically conductive elements 103a, 103b may be higher. Each electrically conductive element 103a, 103b electrically connecting the ground plane 101 to the roof 102 is also called a short-circuit element between the roof 102 and the ground plane 101, or ground wire. Each electrically conductive element 103a, 103b in particular forms a radiating part of the antenna 100. The roof 102 is electrically conductive, and is also called planar element, or plate, electrically conductive. The ground plane 101 is electrically conductive and preferably adopts a planar shape. The ground plane 101, the roof 102 and each electrically conductive element 103a, 103b may each be, without limitation, copper, aluminum or steel. Furthermore, this antenna 100 includes a feed loop 107 in particular called “feed loop of the antenna 100”.

The supply loop 107 is open so that it has two opposite longitudinal ends 108, 109 arranged so as to be connected to a differential connection. The differential connection is notably that of a 200 radio frequency transmitter ( figure 6 ). The supply loop 107 is arranged substantially orthogonal to the ground plane 101. Thanks to this supply loop 107, there is no longer any need to use a balun or other circuit performing an asymmetrical line transformation in symmetrical line (or vice versa) between the radiofrequency transmitter and the antenna 100.

By “two opposite longitudinal ends 108, 109 of the supply loop 107 and arranged so as to be connected to a differential connection”, it is preferably meant that the supply loop 107 can be directly connected to terminals 201, 202 of the transmitter 200 ( figure 6 ), or via a differential waveguide 110 as will be described later.

When the antenna 100 is used to emit a signal, the electromagnetic wave generated by the radiofrequency transmitter can feed the antenna 100 via this supply loop 107 arranged under the roof 102 in order to emit this electromagnetic wave as signal.

When the antenna 100 is used to receive a signal, the antenna 100 picks up the signal (the electromagnetic wave) of the free space, this signal supplying the supply loop 107 of the antenna 100 in a manner suitable for transmitting this signal to the radio frequency transmitter.

The supply loop 107 can be arranged between the roof 102 and the ground plane 101, this has the advantage of satisfactory integration, and the advantage of reducing the overall size of the antenna 100 by integrating the loop supply 107 in a separation space between the roof 102 and the ground plane 101.

• des courants s'établissent dans la boucle d'alimentation 107 sensiblement orthogonalement au plan de masse 101 et
• ces courants sont majoritaires et en phase dans deux parties opposées de la boucle d'alimentation 107 s'étendant entre le plan de masse 101 et le toit 102, notamment sensiblement orthogonalement au plan de masse 101.

Such a supply loop 107 is in particular arranged so that, when the antenna 100 is supplied by the radiofrequency transmitter 200 or by the signal picked up by the antenna 100:

• currents are established in the supply loop 107 substantially orthogonally to the ground plane 101 and
• these currents are in the majority and in phase in two opposite parts of the supply loop 107 extending between the ground plane 101 and the roof 102, in particular substantially orthogonally to the ground plane 101.

In the present description by “substantially orthogonal”, it is understood in particular to be orthogonal or orthogonal to more or less ten degrees. Preferably, "substantially orthogonal" can be replaced by "orthogonal".

In the present description, by substantially parallel, it is understood in particular to be parallel or parallel to more or less ten degrees. Preferably, "substantially parallel" can be replaced by "parallel".

By “supply loop 107 arranged substantially orthogonal to the ground plane 101”, it is understood in particular that the supply loop 107 extends along an included profile, or can be projected orthogonally, in a plane substantially orthogonal to the ground plane 101. According to another formulation, the profile of the supply loop 107 can travel, along the length of the supply loop 107, within a plane substantially orthogonal to the ground plane 101. In particular , the profile of the supply loop 107 is rectangular in a plane substantially orthogonal to the ground plane 101 and in particular to the roof 102. According to yet another formulation, the supply loop 107 can be placed in a plane substantially orthogonal to the plane mass 101.

The invention also relates to a radiofrequency device 1000, in particular as illustrated by way of example in figure 6 , comprising the antenna 100 as described and the radiofrequency transmitter 200 with differential connection connected to the supply loop 107, in particular to the supply loop 107 of the antenna of the type of figures 2 and 3 (as illustrated in figure 6 ) or the antenna of the type illustrated in Figures 4 and 5 . The radiofrequency transmitter 200 is an electronic transmission-reception component whose coupling to the antenna 100 (that is to say the connection to the supply loop 107) makes it possible to transmit or receive the electromagnetic wave. corresponding, or signal, by the antenna 100. The radiofrequency transmitter can in particular supply the antenna by a discrete port for example of 50 ohms over its entire operating band. By “differential connection” of the radiofrequency transmitter 200 is meant by this that the radiofrequency transmitter 200, and more particularly this differential connection, has two terminals 201, 202 from which the electromagnetic wave, making it possible to supply the antenna 100 with view of transmitting the signal is transmitted in a balanced mode. To generate this electromagnetic wave supplying the antenna 100 whose mode is balanced, the radiofrequency transmitter 200 can send on its two terminals 201, 202 respectively two signals of equal amplitude and in phase opposition. It is in particular in this sense that the radiofrequency transmitter 200 of the figure 6 , and more particularly the differential connection, comprises a first connection terminal 201 denoted “+”, and a second connection terminal 202 denoted “-”. There are very often antennas powered from a source in differential mode in mobile terminals such as smartphones ("smartphone" in English). The use of a differential supply whose source is the radiofrequency transmitter 200 in association with the present antenna 100 does not require the use of a balun, and can make it possible to make the structure of the antenna symmetrical. Conversely, during reception, the signal picked up by the antenna 100 is transmitted to the differential connection of the transmitter by two signals of equal amplitude and in phase opposition generated within the supply loop 107 when it is supplied by the signal picked up by the antenna 100. Furthermore, such an antenna 100 has the advantage that the currents on its ground plane 101 are limited, thus limiting the influence of the close context of the antenna 100 such than a hand of a person holding the smart phone having this antenna 100.

In order to properly feed the monopolar wire-plate antenna 100, an electromagnetic field should be formed in accordance with the mode which is established under the roof 102. In particular, the electric field, resulting from this electromagnetic field, is oriented according to the Z axis, that is to say substantially orthogonal to the ground plane 101. This is allowed by the fact that the supply loop 107 is orthogonal to the ground plane 101. In fact, the supply loop 107 has parts substantially orthogonal to the ground plane 101 in which currents can propagate.

Furthermore, still with the aim of allowing currents to settle properly in the supply loop 107 to operate the monopolar wire-plate antenna 100, the supply loop 107 preferably comprises two regions Z1, Z2 (shown dotted in figures 3, 5 and 6 ) excitation of the antenna 100 formed by parts of the supply loop 107 substantially orthogonal to the ground plane 101. In these excitation regions Z1, Z2, the currents must be in phase, that is to say -to say oriented in the same direction in particular substantially parallel to the axis Z, and these currents are of close amplitudes, when the antenna 100 is supplied by the radiofrequency transmitter 200 or by the signal which it picks up. Thus, the supply loop 107 is notably configured so that it exhibits, during the operation of the antenna 100 (that is to say when the antenna 100 transmits or receives a signal), two regions Z1, Z2 for excitation of the antenna 100 in which the currents are in phase and circulate substantially orthogonally with respect to the ground plane 101.

By “longitudinal ends 108, 109 of the supply loop 107” ( figures 2 to 6 ), it is understood that, along the length of the supply loop 107, this supply loop 107 has two opposite ends. These opposite longitudinal ends 108, 109 of the supply loop 107 are located at a distance from one another, in particular at a suitable distance to allow connection of the supply loop 107 to the transmitter 200 either directly or by 'through a differential waveguide.

• selon l'axe Z une dimension de 2,5 mm,
• selon l'axe X une dimension de 5,1 mm,
• la longueur, aussi appelée périmètre, de la boucle d'alimentation 107 est de 15,2 mm nonobstant la distance de séparation entre les deux extrémités longitudinales 108, 109 considérée comme négligeable,
• la largeur de la boucle d'alimentation 107, mesurée selon l'axe Y, peut être de 1,2 mm,
• l'épaisseur de la boucle d'alimentation 107 n'a pas d'influence tant qu'elle reste dans des valeurs technologiques classiques allant de la dizaine à quelques centaines de micromètres.

Par ailleurs, deux éléments électriquement conducteurs 103a, 103b sont formés par des fils parallèles, de diamètre de 0,25 mm, reliant électriquement le toit 102 au plan de masse 101. Notamment, les axes longitudinaux des deux éléments électriquement conducteurs 103a, 103b sont séparés l'un de l'autre de 2 mm, et sont disposés de part et d'autre d'un axe sensiblement orthogonal au plan du toit 102 et passant par le centre du toit 102. Une telle antenne 100 présente, lorsqu'elle est alimentée en différentiel par un port discret de 50 Ohms, 3 % de bande passante à -10 dB (décibels) autour de 5,5 GHz. L'adaptation d'une telle antenne 100 à 50 Ohms montre des performances similaires par rapport à une antenne alimentée de façon asymétrique par sonde d'alimentation coaxiale. Par ailleurs, lorsque l'antenne fonctionne à la fréquence pour laquelle elle est adaptée en impédance, le rendement de rayonnement de l'antenne 100 est strictement supérieur à 95 %, son diagramme de gain indique bien un rayonnement de type monopolaire, et le gain réalisé maximal est d'environ 4,5 dBi.This example describes a narrow band monopolar wire-plate antenna as illustrated in figures 2 and 3 . By "narrow band" is meant an operating band of the order of a few percent relative to the center frequency. This antenna 100 comprises the roof 102 having a profile, taken in a plane parallel to the XY plane, square of dimensions 7 mm by 7 mm. This roof 102 is located 3 mm from the ground plane 101 in particular considered to be infinite. Here, the supply loop 107 is in the form of a ribbon, and the profile of this supply loop 107 seen parallel to the plane XZ adopts the general shape of a rectangle: the supply loop 107 therefore comprises four successive parts delimiting its outline. For example, the supply loop 107 has the following dimensions:

• along the Z axis a dimension of 2.5 mm,
• along the X axis a dimension of 5.1 mm,
• the length, also called perimeter, of the supply loop 107 is 15.2 mm notwithstanding the separation distance between the two longitudinal ends 108, 109 considered to be negligible,
• the width of the supply loop 107, measured along the Y axis, can be 1.2 mm,
• the thickness of the supply loop 107 has no influence as long as it remains within conventional technological values ranging from ten to a few hundreds of micrometers.

Furthermore, two electrically conductive elements 103a, 103b are formed by parallel wires, with a diameter of 0.25 mm, electrically connecting the roof 102 to the ground plane 101. In particular, the longitudinal axes of the two electrically conductive elements 103a, 103b are separated from each other by 2 mm, and are arranged on either side of an axis substantially orthogonal to the plane of the roof 102 and passing through the center of the roof 102. Such an antenna 100 has, when is supplied differential by a discrete port of 50 Ohms, 3% bandwidth at -10 dB (decibels) around 5.5 GHz. The adaptation of such an antenna 100 to 50 Ohms shows similar performance compared to an antenna supplied asymmetrically by coaxial feed probe. Furthermore, when the antenna operates at the frequency for which it is adapted in impedance, the radiation efficiency of the antenna 100 is strictly greater than 95%, its gain diagram clearly indicates radiation of the monopolar type, and the gain maximum realized is around 4.5 dBi.

• selon l'axe Z une dimension de 3,75 mm,
• selon l'axe X une dimension de 5,5 mm,
• la longueur, aussi appelée périmètre, de la boucle d'alimentation 107 est de 18,5 mm, nonobstant la distance de séparation entre les deux extrémités longitudinales 108, 109 considérée comme négligeable,
• la largeur de la boucle d'alimentation 107, ou largeur du ruban, peut être de 1,2 mm,
• l'épaisseur de la boucle d'alimentation 107 n'a pas d'influence tant qu'elle reste dans des valeurs technologiques classiques allant de la dizaine à quelques centaines de micromètres.

Par ailleurs, deux éléments électriquement conducteurs 103a, 103b, formés par des languettes de largeur de 3 mm (mesurée selon l'axe Y), relient électriquement le toit 102 au plan de masse 101. L'épaisseur de ces languettes n'a pas d'influence tant qu'elle reste dans des valeurs technologiques classiques allant de la dizaine à quelques centaines de micromètres. Notamment, les deux éléments électriquement conducteurs 103a, 103b sont en contact respectivement avec deux bords périphériques opposés de la face inférieure (c'est-à-dire orienté vers le plan de masse 101) du toit 102, et sont notamment sensiblement orthogonaux au plan de masse 101. Une telle antenne 100 présente une adaptation, normalisée à 100 Ohms large bande, telle que, lorsqu'elle est alimentée en différentiel notamment que cela soit en émission ou en réception, sa bande passante est de 36% à -10dB (décibel) autour de 7,7GHz. A la fréquence de fonctionnement, ici 7,7GHz, et selon l'alimentation différentielle, l'antenne 100 à large bande présente des rendements de rayonnement strictement supérieurs à 90%, son diagramme de gain dénote un rayonnement de type monopolaire, et le gain maximal réalisé est proche de 5dBi, ceci étant équivalent aux résultats obtenus pour une antenne fil-plaque monopolaire alimentée de façon asymétrique par sonde d'alimentation coaxiale.An example of a broadband monopolar wire-plate antenna 100 is described in this paragraph, for example as illustrated in Figures 4 and 5 . By "broadband" is meant an operating band strictly greater than the octave. The roof 102 has a profile, seen along a plane parallel to the XY plane, of square shape with dimensions 9.5 mm by 9.5 mm located 4 mm from the ground plane 101 considered to be infinite. Here, the supply loop 107 is in the form of a ribbon and the profile of this supply loop 107 taken in a plane parallel to the plane XZ adopts the general shape of a rectangle: the supply loop 107 therefore comprises four successive parts delimiting its outline. For example, the supply loop 107 has the following dimensions:

• along the Z axis a dimension of 3.75 mm,
• along the X axis, a dimension of 5.5 mm,
• the length, also called perimeter, of the supply loop 107 is 18.5 mm, notwithstanding the separation distance between the two longitudinal ends 108, 109 considered to be negligible,
• the width of the supply loop 107, or width of the ribbon, can be 1.2 mm,
• the thickness of the supply loop 107 has no influence as long as it remains in conventional technological values ranging from ten to a few hundred micrometers.

Furthermore, two electrically conductive elements 103a, 103b, formed by tongues with a width of 3 mm (measured along the Y axis), electrically connect the roof 102 to the ground plane 101. The thickness of these tongues has no influence as long as it remains within conventional technological values ranging from ten to a few hundred micrometers. In particular, the two electrically conductive elements 103a, 103b are in contact respectively with two opposite peripheral edges of the lower face (that is to say oriented towards the ground plane 101) of the roof 102, and are in particular substantially orthogonal to the plane of mass 101. Such an antenna 100 has an adaptation, standardized to 100 Ohms broadband, such that, when it is supplied with a differential notably whether it is in transmission or in reception, its bandwidth is 36% at -10dB ( decibel) around 7.7 GHz. At the operating frequency, here 7.7 GHz, and according to the differential supply, the broadband antenna 100 has radiation yields strictly greater than 90%, its gain diagram denotes radiation of the monopolar type, and the gain maximum realized is close to 5dBi, this being equivalent to the results obtained for a monopolar wire-plate antenna supplied asymmetrically by coaxial feed probe.

It has been mentioned above that for a good functioning of the antenna 100, the currents which circulate in the supply loop 107, and in particular in parts of the supply loop 107 extending substantially orthogonally with respect to to the ground plane 101 are in phase and preferably of close amplitudes when this antenna 100 transmits or receives a signal. To this end, the supply loop 107 advantageously comprises two parts substantially orthogonal to the ground plane 101: this allowing the supply loop 107 to take advantage of the currents substantially orthogonal to the ground plane 101 and in phase to excite the antenna 100 in a suitable manner during its operation. Preferably, the supply loop 107 comprises (see in particular the figures 2 to 5 ) a first part 1071 distal from the ground plane 101, a second part 1072 proximal to the ground plane 101, a third part 1073 connecting the first and second parts 1071, 1072 (in particular connecting two longitudinal ends of the first and second parts 1071, 1072 ). In particular, the opposite longitudinal ends 108, 109 of the supply loop 107 are then arranged opposite the third part 1073, that is to say on one side of the supply loop 107 opposite the third part 1073. Such a supply loop 107 is very particularly suitable for obtaining the vertical currents in phase desired to properly excite the electromagnetic field under the roof 102 of the antenna 100 and in particular between the roof 102 and the ground plane 101 when the antenna 100 transmits or receives a signal. In particular, the first and second parts 1071, 1072 extend along their length substantially parallel to the ground plane 101, and the third part 1073 extends along its length substantially orthogonally to the ground plane 101.

In particular, the supply loop 107 may include a fourth part 1074 ( figures 2 to 5 ) connected to at least one of the first and second parts 1071, 1072, this fourth part 1074 being located on the side of the supply loop 107 where its longitudinal ends 108, 109 are arranged. The first, third, second and fourth parts 1071, 1073, 1072, 1074 are arranged successively so as to delimit the contour of the supply loop 107. Thus, the currents substantially orthogonal to the ground plane 101 referred to above flow in particular in the third and fourth parts 1073, 1074. In particular, the fourth part 1074 is, in particular along its length, substantially orthogonal to the ground plane 101. The arrangement of the longitudinal ends 108, 109 opposite to the supply loop 107 opposite its third part 1073 allows to favor, during the operation of the antenna 100, obtaining currents flowing in phase along the Z axis, that is to say in the third and fourth parts 1073, 1074 substantially orthogonal a u ground plan 101.

The placement of the longitudinal ends 108, 109 of the supply loop 107 at any location opposite the third part 1073 of the supply loop 107 ( figures 2 to 5 and 7 to 8 ) makes it possible to obtain the currents in phase sought and substantially orthogonal to the ground plane 101. In a first case, the supply loop 107 may be such that it includes the fourth part 1074 comprising a first portion 1074a extending from the first part 1071 of the supply loop 107 in particular towards the second part 1072 of the supply loop 107. In this first case, the first portion 1074a has one of the longitudinal ends 108 of the supply loop 107. In this first case, the fourth part 1074 of the supply loop 107 comprises a second portion 1074b extending from the second part 1072 of the supply loop 107 in particular towards the first part 1071 of the supply loop 107, this second portion 1074b comprising the other of the longitudinal ends 109 of the supply loop 107 ( figures 2 to 5 ). In the first case, the first and second portions 1074a, 1074b can have identical dimensions so that the excitation of the supply loop 107 by the transmitter 200 can be done in the middle of the fourth part 1074, or alternatively dimensions different. When, in the first case, the excitation by the transmitter 200 takes place in the middle of the fourth part 1074, the supply loop 107 has a horizontal symmetry favoring the balance of the currents over the entire perimeter of the supply loop 107 and therefore in the third and fourth parts 1073, 1074 substantially orthogonal to the ground plane 101, this being advantageous for the proper functioning of the antenna 100. According to a second case illustrated in figure 7 , the fourth part 1074 extends from the first part 1071 of the supply loop 107 in particular towards the second part 1072 of the supply loop 107, and the fourth part 1074 comprises one of the longitudinal ends 108 of the loop supply 107. In this second case, the second part 1072 of the supply loop 107 comprises the other of the longitudinal ends 109 of the supply loop 107. According to a third case illustrated in figure 8 , the fourth part 1074 extends from the second part 1072 in particular towards the first part 1071, and the fourth part 1074 comprises one of the longitudinal ends 109 of the supply loop 107. According to this third case, the first part 1071 has the other of the longitudinal ends 108 of the supply loop 107. The second and third cases are functional alternatives to the first case which is preferred. In these different cases, the excitation regions Z1, Z2 of the antenna 100 are two in number and are advantageously formed by the third and fourth parts 1073, 1074.

The roof 102 is in particular a so-called “capacitive” roof considered to be small compared to the operating wavelength of the antenna 100, that is to say that the dimensions of the roof 102 are in particular strictly less than λ _g / 4.

Depending on the degree of integration of the radiofrequency device, the radiofrequency transmitter 200 can be connected directly to the power supply loop 107, or can be connected to the power supply loop via a balanced waveguide 110, also called differential waveguide. This balanced waveguide 110 belongs to the antenna 100. In figure 6 , there is shown the waveguide 110 comprising first and second electrical conductors 111, 112, for example adopting the form of electrically conductive tracks. The first electrical conductor 111 is connected to one of the longitudinal ends 108 of the supply loop 107 and the second electrical conductor 112 is connected to the other of the longitudinal ends 109 of the supply loop 107. The guide waves is said to be “balanced” because it allows, thanks to its electrical conductors 111, 112, where appropriate, the propagation of the electromagnetic wave supplying the supply loop 107 generated by the radiofrequency transmitter 200 up to the supply loop 107 or the propagation of the electromagnetic wave picked up (that is to say the signal picked up) by the antenna 100 from the feed loop 107 to the radiofrequency transmitter 200. This has the advantage to be able to adapt the distance between the antenna 100 and the radiofrequency transmitter 200. These first and second electrical conductors 111, 112 make it possible to propagate respectively two signals of equal amplitude and in phase opposition from which it results, where appropriate, from the propagation of the electromagnetic wave supplying the antenna 100 originating from the radiofrequency transmitter 200 or from the electromagnetic wave picked up by the antenna 100. In the context of the radiofrequency device 1000, the first conductor electrical 111 is also connected to the first connection terminal 201, and the second electrical conductor 112 is also connected to the second connection terminal 202. The balanced waveguide 110 adopts a symmetrical geometry to ensure proper propagation of the wave electromagnetic power supply. The balanced waveguide 110 can take the form of coplanar microstrip lines, twin lines, a two-wire line.

Of course, the waveguide 110 is not necessary if the supply loop 107 can be directly connected to the radiofrequency transmitter 200. In this sense, more generally, the two opposite longitudinal ends 108, 109 of the loop supply 107 can be connected a differential connection of a differential waveguiding device, this differential device can be the balanced waveguide 110 or the connection terminals 201, 202 of the radiofrequency transmitter 200.

In a manner applicable to all of the embodiments described, part of the supply loop 107 may be formed by a portion of the roof 102, this is illustrated in particular figure 9 where the third and fourth parts 1073, 1074 are in direct contact with the roof 102 which delimits the first part of the supply loop 107. Alternatively, the supply loop 107 can be in contact with the roof 102 ( figures 3, 5 , 7 and 8 ) or can be located at a distance from the roof 102 ( figure 10 ). The fact that a part, in particular the first part 1071 described above is formed by a portion of the roof 102, or is in contact with the roof 102, makes it possible to limit the size of the antenna 100 along the axis Z , for example by reducing the separation distance between the roof 102 and the ground plane 101. An additional advantage of the supply loop 107, part of which is delimited by the roof 102, is that this reduces the complexity of the manufacturing process of the antenna 100 since there will be one less metallization level to deposit.

The perimeter, also called length, of the feed loop 107 has an impact on the impedance matching of the antenna 100.

To study the impact of the length of the feed loop 107 in the context of the example of the narrowband antenna ( figures 2 and 3 ) whose impedance matching is normalized to 50 Ohms, it is proposed to fix the dimensions of the supply loop 107 along the X axis (i.e. the length of the first part 1071 and the length of the second part 1072) at 5 mm for different case studies for which the length of the supply loop 107, also called perimeter noted P of the supply loop 107, is respectively fixed at 14 mm, at 14 , 5 mm and 15 mm: it follows that the height of the supply loop 107 along the Z axis is respectively 2 mm, 2.25 mm and 2.5 mm for these different case studies. The fact of fixing the dimensions of the supply loop 107 along the X axis at 5 mm makes it possible to separate the excitation zones Z1 and Z2 by the same distance for the different case studies. According to the different case studies of the narrow band antenna, the opposite longitudinal ends 108, 109 of the feed loop 107 are located equidistant, for example at 0.25 mm, from the middle of the fourth part 1074 mentioned above along the Z axis. By analyzing the input impedance (real and imaginary part) of the antenna 100 for these three case studies, it is possible to deduce therefrom that the increase in the perimeter P of the supply loop 107 causes a resonance shift towards the low frequencies. Consequently, by analyzing the reflection coefficient (in dB) of the antenna 100 as a function of the frequency, normalized to 50 Ω, for these three case studies of the antenna 100, it is possible to note that the frequency of operation of the antenna 100 for which the best impedance adaptation of the antenna 100 is obtained decreases with the increase in the perimeter P of the supply loop 107. Thus, in the present case, the adaptation of the antenna 100 operates as soon as the perimeter of the loop is of optimal dimension close to λ ₀ / 3.6, where λ ₀ is the operating wavelength of antenna 100. With the extension of the loop power supply 107, the phasing of the currents in the excitation regions Z1, Z2 can thus take place at lower frequencies. Furthermore, the equilibrium of the regions Z1, Z2 of excitation in amplitude and in phase on the current density is lost at the frequency of interest when the perimeter P is too small or too large with respect to this dimension. optimal of λ ₀ / 3.6 of the perimeter of the feed loop 107. Thus, to obtain a good impedance adaptation of the antenna 100, when the antenna is a narrow band antenna 100, the feed loop 107 preferably has a length, between its two opposite longitudinal ends 108, 109, between λ _g / 3.5 and λ _g / 3.7 with λ _g the operating wavelength of the antenna 100 in the medium of propagation of the antenna 100. The propagation medium of the antenna 100 is the medium in contact with each radiating element of the antenna 100, for example the medium in contact with each electrically conductive element 103a, 103b. This propagation medium can be air or a dielectric material.

To study the impact of the length of the feed loop 107 on the broadband antenna 100 ( Figures 4 and 5 ) whose impedance adaptation is normalized to 100 Ohms, it is proposed to fix the dimensions, in particular the length, of the first and second parts 1071, 1072 of the supply loop 107 along the X axis each at 5, 5 mm. Fixing the dimensions of the supply loop 107 along the X axis at 5.5 mm makes it possible to separate the excitation zones Z1 and Z2 by the same distance for the different case studies. Then, the different case studies are such that the length of the supply loop 107 varies between 16.5 mm and 18.5 mm in a step of 0.5 mm, or five case studies with P respectively equal at 16.5mm, 17mm, 17.5mm, 18mm and 18.5mm. The result that the height of the supply loop 107 along the Z axis for these different case studies is respectively 2.75 mm, 3 mm, 3.25 mm, 3.5 mm, 3.75 mm. By analyzing the input impedance (real and imaginary part of the input impedance of the antenna 100 in Ohms as a function of the frequency of the antenna 100) of the antenna 100 for these five case studies , it is possible to deduce therefrom that the increase in the perimeter of the supply loop 107 causes a shift of the resonance towards the low frequencies. Consequently, the frequency presenting the best impedance adaptation of the antenna 100, normalized to 100 Ω, decreases with the increase in the perimeter of the power loop 107. Thus, the adaptation of the antenna 100 s' operates as soon as the perimeter of the feed loop 107 is of optimal dimension close to λ _0/2 , where λ ₀ is the operating wavelength of the antenna 100 when the medium of propagation of the antenna is the air. Furthermore, the equilibrium of the excitation of the antenna 100, in the excitation regions Z1, Z2, in amplitude and in phase on the current density is lost when the supply loop 107 has too large a perimeter or too weak vis-à-vis its optimal dimension. Thus, at 6.5 GHz, for the antenna 100 having a loop with a perimeter P equal to 16.5 mm, the currents in the excitation regions Z1, Z2 of the antenna 100 are phase shifted. On the other hand, at this same frequency and in the presence of a supply loop 107 with a larger perimeter (for example with P equal to 18.5 mm), the currents are in phase and of the same amplitude in the regions Z1, Z2 excitation of the antenna 100. For the antenna 100 having a feed loop 107 with a perimeter P equal to 16.5 mm and with the increase in the operating frequency of the antenna 100, it is found that the phasing of the currents improves in the excitation regions Z1, Z2. On the other hand, for the antenna 100 comprising a feed loop 107 with a perimeter P equal to 18.5 mm, the equilibrium in the regions Z1, Z2 of excitation of the antenna 100 is lost in amplitude and in phase on current density with increasing frequency. Thus, to obtain a good impedance matching of the antenna 100, when said antenna 100 is a broadband antenna, the supply loop 107 preferably has a length, between its two opposite longitudinal ends 108, 109, between λ _g / 3 and λ _g / 1.6 with λ _g the operating wavelength of the antenna 100, in particular in the propagation medium of the antenna 100.

The width of the feed loop 107, in particular measured along the Y axis, can also be adapted as a function of the desired characteristics of the antenna 100.

For example, for the antenna 100 with narrow band described, by fixing the length of the feed loop 107 to 15 mm while varying its width between 0.8 mm and 1.4 mm in a step of 0.2 mm, it has been noted that the increase in the width of the feed loop 107 leads to an adaptation of the antenna 100 for lower operating frequencies. This is synonymous with an elongation of the loop equivalent to the supply loop 107 linked to the increase in its width.

For example, for the broadband antenna 100, by fixing the length of the feed loop 107 to 18.5 mm while varying its width between 0.5 mm and 2 mm in a 0.5 mm step , it has been noted that the increase in the width of the supply loop 107 causes a reduction in the real part of the input impedance associated with an increase in the imaginary part of the input impedance around 8 GHz. Thus, for the specific dimensions of the broadband monopolar 100 wire-plate antenna, a width of the supply loop 107 of approximately 0.5 mm is optimal for a good adaptation (strictly less than -10 dB) according to a normalization impedance of 100 ohms for an antenna operating frequency between 6.3 GHz and 9 GHz.

• le périmètre géométrique de la boucle d'alimentation 107 est fixé à 21,4 mm pour une boucle d'alimentation 107 rectangulaire de côtés 7,5 mm selon l'axe X et 3,2 mm selon l'axe Z (compte tenu du diélectrique dans lequel est placé la boucle d'alimentation 107, la longueur d'onde effectivement guidée est réduite 31 mm, pour laquelle il faudrait aussi prendre en compte l'effet de changement de section du toit 102 de l'antenne 100, on s'approche de la longueur d'onde de 37,5 mm à 8 GHz, qui est le milieu de la bande de fonctionnement) ;
• le guide d'ondes 110 est connecté à la boucle d'alimentation 107 au centre de sa quatrième partie 1074 selon l'axe Z ;
• la largeur de la deuxième partie 1072 de la boucle d'alimentation 107 selon l'axe Y est fixée à 2 mm ;
• les trous métallisés évoqués ci-dessus ont un diamètre, selon l'axe Y, égal à 0,2 mm.

Les première et deuxième portions 1101, 1102 du guide d'ondes 110 forment des lignes coplanaires différentielles imprimées par exemple sur une zone de la première couche 1131 non couverte par le plan de masse 101. Par ailleurs, il est envisageable d'utiliser cette antenne 100 alimentée en différentiel via la boucle d'alimentation 107 pour une intégration au-dessus d'un boitier à puce (par exemple QFN pour Quad-Flat No-leads). La figure 13 présente pour cet exemple particulier la variation du coefficient de réflexion de l'antenne 100 en dB en fonction de la fréquence de l'antenne en GHz normalisé sur 100 Ohms, cette figure 13 montre une adaptation d'impédance satisfaisante (S₁₁ strictement inférieur à -10dB avec S₁₁ le coefficient de réflexion de l'antenne 100) entre 7,5 GHz et 9,2 GHz. La figure 14 représente en abscisse la fréquence de l'antenne en GHz, l'axe des ordonnées de gauche donne, pour la courbe C2, le gain maximum réalisé en dBi en fonction de la fréquence de l'antenne 100, et l'axe des ordonnées de gauche donne, pour la courbe C1, l'efficacité de rayonnement de l'antenne 100 en % en fonction de la fréquence de l'antenne 100. La figure 14 permet de tracer le coefficient de réflexion en fonction de la fréquence pour identifier là où le coefficient de réflexion est faible, synonyme d'adaptation en impédance de l'antenne 100 et d'identification de la fréquence de fonctionnement. On constate à partir de cette figure 14 que dans la bande de fréquence visée comprise entre 7,5 GHz et 9,2 GHz, l'efficacité est satisfaisante et que le gain maximal de l'antenne 100 est compris entre 4 dBi et 6 dBi. La présente invention permet donc de construire une antenne fil-plaque monopolaire pouvant être alimentée directement par un guide d'ondes différentiel, c'est-à-dire (sans balun) avec des performances satisfaisantes. Par ailleurs, en retirant le balun, on évite les pertes liées à ce balun. Par ailleurs, l'antenne fil-plaque monopolaire à boucle d'alimentation 107 telle que décrite présente des performances similaires à celle d'antenne fil-plaque monopolaire alimentée de façon asymétrique par sonde coaxiale.A particular example is now described (illustrated in Figures 11 and 12 ) for which the antenna 100 comprises a multilayer dielectric substrate 113, in particular with four layers of dielectric material, within which is formed an electrically conductive structure comprising the ground plane 101, the roof 102, the supply loop 107, the electrically conductive elements 103a, 103b and the balanced waveguide 110. Here, the dielectric material of the layers of the substrate 113 forms the propagation medium of the antenna 100. A portion of the roof 102 forms the first part 1071 (represented by dotted lines in figure 12 ) of the supply loop 107. According to this particular example, the substrate 113 comprises a stack of first to fourth layers 1131, 1132, 1133, 1134 made of dielectric material. The figure 12 represents a perspective of the figure 11 for which the first to fourth layers have been removed to visualize the electrically conductive structure (comprising the elements referenced 101, 102, 103a, 103b, 107, 110). On the first layer 1131 are arranged the ground plane 101 and two tracks 1101, 1102 forming first and second portions of the balanced waveguide 110. The second layer 1132 is stacked on the first layer 1131. On one side of this second layer 1132 oriented opposite the first layer 1131 are formed the second part 1072 of the supply loop 107 and the first and second studs 1103 , 1104 forming corresponding portions of the balanced waveguide 110. This second layer 1132 is crossed by a third portion 1105 of the waveguide 110 in contact, on the one hand, with the first portion 1101 of the waveguide 110 and, on the other hand, with the first stud 1103. By elsewhere, this second layer 1132 is crossed by a fourth portion 1106 of the waveguide 110, this fourth portion 1106 being in contact, on the one hand, with the second portion 1102 of the waveguide 110 and, on the other hand , with the second pad 1104. The third layer 1133 is stacked on the second layer 1132. On this third layer 1133 are formed an electrically conductive terminal 114, as well as fifth and sixth portions 1107, 1108 of the waveguide 110 balanced adopting the form of electrically conductive tracks parallel to the ground plane 101. This third layer 1133 is crossed by seventh and eighth portions 1109, 11010 of the waveguide 110, the seventh portion 1109 electrically connecting the fifth portion 1107 to the prem ier pad 1103, and the eighth portion 11010 connecting the sixth portion 1108 to the second pad 1104. This third layer 1133 is also crossed by a first portion 1073a of the third part 1073 of the supply loop 107, this first portion 1073a connecting the second part 1072 of the supply loop 107 to terminal 114. This third layer 1133 is also crossed by the second portion 1074b of the fourth part 1074 of the supply loop 107, this second portion 1074b connecting the second part 1072 of the supply loop 107 to the sixth portion 1108 of the waveguide 110. The fourth layer 1134 is stacked on the third layer 1133. The roof 102, and therefore the first part 1071 of the supply loop 107, are arranged on a face of this fourth layer 1134 oriented in a direction opposite to the third layer 1133. This fourth layer 1134 is crossed by the first portion 1074a of the fourth part 1074 of the supply loop 107 so that the first portion 1074a of the fourth portion 1074 connects the fifth portion 1107 of the waveguide 110 to the portion of the roof 102 forming the first part 1071 of the supply loop 107. This fourth layer 1134 is also crossed by a second portion 1073b of the third part 1073 of the loop d supply 107 so that the second portion 1073b of the third part 1073 connects the portion of the roof 102 forming the first part 1071 of the supply loop 107 to the terminal 114. The stack of the second, third and fourth layers 1132 , 1133, 1134 has two opposite metallized sides forming the electrically conductive elements 103a, 103b electrically connecting the roof 102 to the ground plane 101. In particular, the first and second portions 1074a, 1074b of the fourth part 1074 of the supply loop 107 , the first and second portions 1073a, 1073b of the third portion 1073 of the supply loop 107, and the third, fourth, seventh and eighth portions 1105, 1106, 1109, 11010 d u waveguide 110 are vias (also called metallized holes) passing through the corresponding layers of the substrate 113. According to this particular example, the roof 102 of the antenna 100 is rectangular and has a first side of dimension L ₁ equal to 8 mm and a second side of dimension L ₂ equal to 11 mm. The roof 102 is printed on a dielectric substrate of relative permittivity ε _r = 2.2 and of parameter tanδ = 0.0009, tanδ characterizing the dielectric losses of the material of the dielectric substrate. Such a multilayer dielectric substrate can be of the Rogers RT / duroid® 5880 type. The roof 102 is disposed at 4.8 mm from the infinite ground plane 101. The supply loop 107 supplying the antenna 100 has the following characteristics:

• the geometric perimeter of the supply loop 107 is fixed at 21.4 mm for a rectangular supply loop 107 with sides 7.5 mm along the X axis and 3.2 mm along the Z axis (taking into account the dielectric in which the supply loop 107 is placed, the effectively guided wavelength is reduced 31 mm, for which the effect of changing the section of the roof 102 of the antenna 100 should also be taken into account. 'approaching the wavelength of 37.5 mm at 8 GHz, which is the middle of the operating band);
• the waveguide 110 is connected to the supply loop 107 at the center of its fourth part 1074 along the Z axis;
• the width of the second part 1072 of the supply loop 107 along the Y axis is fixed at 2 mm;
• the metallized holes mentioned above have a diameter, along the Y axis, equal to 0.2 mm.

The first and second portions 1101, 1102 of the waveguide 110 form differential coplanar lines printed for example on an area of the first layer 1131 not covered by the ground plane 101. Furthermore, it is possible to use this antenna 100 supplied by differential via the power loop 107 for integration above a smart box (for example QFN for Quad-Flat No-leads). The figure 13 presents for this particular example the variation of the reflection coefficient of the antenna 100 in dB as a function of the antenna frequency in GHz normalized to 100 Ohms, this figure 13 shows a satisfactory impedance adaptation (S ₁₁ strictly less than -10dB with S ₁₁ the antenna reflection coefficient 100) between 7.5 GHz and 9.2 GHz. The figure 14 on the abscissa is the frequency of the antenna in GHz, the ordinate axis on the left gives, for curve C2, the maximum gain achieved in dBi as a function of the antenna frequency 100, and the ordinate axis of left gives, for curve C1, the radiation efficiency of antenna 100 in% as a function of the frequency of antenna 100. The figure 14 used to plot the reflection coefficient as a function of the frequency to identify where the reflection coefficient is low, synonymous with adaptation in impedance of the antenna 100 and identification of the operating frequency. We can see from this figure 14 that in the target frequency band between 7.5 GHz and 9.2 GHz, the efficiency is satisfactory and that the maximum gain of the antenna 100 is between 4 dBi and 6 dBi. The present invention therefore makes it possible to construct a monopolar wire-plate antenna which can be supplied directly by a differential waveguide, that is to say (without balun) with satisfactory performance. Furthermore, by removing the balun, losses associated with this balun are avoided. Furthermore, the monopolar wire-plate antenna with feed loop 107 as described has performances similar to that of the monopolar wire-plate antenna supplied asymmetrically by coaxial probe.

Such a monopolar wire-plate antenna has an industrial application in the field of telecommunications where such an antenna can be manufactured and arranged within a radiofrequency device as described above. The radio frequency device described can be integrated into any type of object communicating. For example, the radiofrequency device can be integrated into a smart phone worn on a person's belt to transmit via the antenna 100 a video stream to interactive glasses using an ultra broadband link between 7 GHz and 9 GHz.

Claims (10)

Antenna (100) monopolar wire-plate comprising a ground plane (101), a roof (102) arranged at a distance from the ground plane (101), at least one electrically conductive element (103a, 103b) electrically connecting the ground plane (101) to the roof (102), characterized in that it includes a supply loop (107) arranged substantially orthogonal to the ground plane (101), said supply loop (107) being open from such that it has two opposite longitudinal ends (108, 109) arranged so as to be connected to a differential connection (201, 202). Antenna (100) according to claim 1, characterized in that it comprises a balanced waveguide (110), the balanced waveguide (110) comprising a first electrical conductor (111) and a second electrical conductor (112 ), the first electrical conductor (111) being connected to one of the longitudinal ends (108) of the supply loop (107) and the second electrical conductor (112) being connected to the other of the longitudinal ends (109) of the supply loop (107). Antenna (100) according to any one of the preceding claims, characterized in that the feed loop (107) comprises: A first part (1071) distal from the ground plane (101), A second part (1072) proximal to the ground plane (101), A third part (1073) connecting the first and second parts (1071, 1072), • the longitudinal ends (108, 109) being arranged opposite the third part (1073). Antenna (100) according to the preceding claim, characterized in that the feed loop (107) comprises: • a fourth part (1074) comprising: ◆ a first portion (1074a) extending from the first portion (1071) of the supply loop (107), this first portion (1074a) comprising one of the longitudinal ends (108) of the supply loop (107), and ◆ a second portion (1074b) extending from the second part (1072) of the supply loop (107), this second portion (1074b) comprising the other of the longitudinal ends (109) of the supply loop ( 107), or • a fourth part (1074) extending from the first part (1071) and comprising one of the longitudinal ends (108) of the supply loop (107), the second part (1072) comprising the other of the ends longitudinal (109) of the supply loop (107), or • a fourth part (1074) extending from the second part (1072) and comprising one of the longitudinal ends (109) of the supply loop (107), the first part (1071) comprising the other of the ends longitudinal (108) of the supply loop (107). Antenna (100) according to any one of the preceding claims, characterized in that a part of the supply loop (107) is formed by a portion of the roof (102), or in that the supply loop ( 107) is located at a distance from the roof (102), or in that the supply loop (107) is in contact with the roof (102). Antenna (100) according to any one of the preceding claims, characterized in that said supply loop (107) has, during the operation of the antenna (100), two regions (Z1, Z2) of excitation of the antenna (100) in which the currents are in phase and circulate substantially orthogonally with respect to the ground plane (101). Antenna (100) according to any one of the preceding claims, characterized in that said antenna (100) is a broadband antenna for which the feed loop (107) has a length, between its two opposite longitudinal ends (108, 109), between λ _g / 3 and λ _g / 1.6 with λ _g the operating wavelength of the antenna (100). Antenna (100) according to any one of claims 1 to 6, characterized in that said antenna (100) is a narrow band antenna for which the feed loop (107) has a length, between its two longitudinal ends ( 108, 109) opposite, between λ _g / 3.5 and λ _g / 3.7 with λ _g the operating wavelength of the antenna (100). Radiofrequency device (1000), characterized in that it comprises a monopolar wire antenna (100) according to any one of the preceding claims, and a radiofrequency transmitter (200) with differential connection connected to the supply loop (107 ). Radiofrequency device (1000) according to the preceding claim, characterized in that : The differential connection of the radiofrequency transmitter (200) comprises first and second connection terminals (201, 202), The antenna (100) comprises a balanced waveguide (110), the balanced waveguide (110) comprising first and second electrical conductors (111, 112), • the first electrical conductor (111) is connected, on the one hand, to one of the longitudinal ends (108) of the supply loop (107) and, on the other hand, to the first connection terminal (201 ), and • the second electrical conductor (112) is connected, on the one hand, to the other of the longitudinal ends (109) of the supply loop (107) and, on the other hand, to the second connection terminal (202 ).

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