EP3671955B1 - Monopole wire-plate antenna for differential connection - Google Patents

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 on the figure 1 , a monopolar wire-plate antenna 100, of the type in this article by Ch. Delaveaud et al., comprises a ground plane 101, a planar electrically conductive element 102, called roof, one or more electrically conductive elements 103a, 103b, called ground wire(s), connecting the roof 102 to the ground plane 101 and optionally 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 ensuring 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 an electromagnetic wave, with high efficiency for frequencies located below the TM _nm cavity resonance modes (for “Transverse Magnetic” of indices n and m) classic 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 fed asymmetrically from a suitable radio frequency 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 from microelectronics, particularly within a mobile device. A disadvantage linked to this type of antenna is that its technological integration in a small volume may imply that the radio frequency transmitter connected to the antenna has a differential connection instead of being asymmetrical. The differential connection transmitter makes it possible to generate 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 classic to associate the transmitter with differential connection to a balun, also called balun, to achieve the transition between a symmetrical waveguide structure connected to the radiofrequency transmitter and an asymmetrical topology which is the probe coaxial 105. In other words, the balun makes it possible to adapt the differential connection of the radio frequency transmitter so that it is compatible with the coaxial power 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 not balanced, in French). A disadvantage 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 integrable on a chip, this results in radio frequency losses. In this sense, there is a need to develop a solution making it possible to power an antenna with a roof, in particular capacitive, 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 transmitter with differential connection.

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 feed probe, whose central core is connected to the capacitive roof. However, if the power source for the coaxial power probe is a differentially connected radio frequency transmitter, 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 remote from the roof and parallel to the roof. The spiral is connected to a coaxial feed probe. The spiral associated with the coaxial feed probe makes it possible to excite the antenna. However, if the radio frequency 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.

The documents WO2006/135956 A1 And " Broadband Patch Antennas Fed by Novel Tuned Loop", JING-YA DENG ET AL, published in IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION, IEEE SERVICE CENTER, PISCATAWAY, NJ, US, vol. 61, no. 4, January 3, 2013, pages 2290 -2293 , disclose patch antennas having a feed loop located between the patch and a ground plane,

Object of the invention

The aim of the invention is to enable power supply of a monopolar wire-plate antenna without requiring the presence of a balun.

For this purpose, the invention relates to a monopolar wire-plate antenna, operating at a wavelength denoted λg, and comprising a ground plane, a roof arranged at a distance from the ground plane, and having strictly smaller dimensions at λg/4, at least one electrically conductive element electrically connecting the ground plane to the roof, this antenna comprising a feed loop arranged substantially orthogonal to the ground plane, said feed loop being open in such a way that it comprises two opposite longitudinal ends arranged so as to be connected to a differential connection.

Thus, with such a power 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 loop allows, during operation of the monopolar wire-plate antenna powered by the transmitter with differential connection when transmitting a signal or by an electromagnetic wave propagating in the environment of the antenna when of reception of a signal, to impose a distribution of the electromagnetic field in an appropriate manner between the ground plane and the roof to allow the monopolar wire-plate antenna to present a desired impedance and, where appropriate, to emit a satisfactory electromagnetic wave. Furthermore, the power supply/excitation of the antenna by the power loop makes it possible to obtain a symmetrical system which results in the reduction of the propagation of electric currents on the ground plane of the antenna, thus limiting the influence of the close context of the antenna, such as for example the influence of a person's hand 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/3,7 et λ_g/3,5 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 feed loop and the second electrical conductor being connected to the other of the longitudinal ends of the power loop;
• the power loop comprises a first distal part of the ground plane, a second proximal part of 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 of 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 presents, during operation of the antenna, two excitation regions of the antenna in which the currents are in phase and flow substantially orthogonal to the ground plane;
• said antenna is a wide bandwidth 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 of 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 /3.7 and λ _g /3.5 with λ _g the wavelength of operation of the antenna.

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

Preferably, the differential connection of the radio frequency 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, to one of the longitudinal ends of the power loop and, on the other hand, to the first connection terminal, and the second electrical conductor is connected, on the one hand, to the other of the longitudinal ends of the power loop and, on the other hand, to the second connection terminal.

Summary 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 non-limiting example and made with reference to the appended drawings listed below.

• There figure 1 represents, in section, a monopolar wire-plate antenna according to the prior art.
• There figure 2 illustrates a perspective view of a narrow-band monopolar wire-plate antenna according to one embodiment of the invention.
• There Figure 3 is a side view of the antenna of the figure 2 .
• There figure 4 illustrates a perspective view of a broadband monopolar wire-plate antenna according to one embodiment of the invention.
• There Figure 5 is a side view of the antenna of the figure 4 .
• There Figure 6 illustrates a side view of a radio frequency device comprising a monopolar wire-plate antenna of the type figure 2 .
• There Figure 7 illustrates a side view of a particular embodiment of a monopolar wire-plate antenna of the type figure 2 .
• There figure 8 illustrates a side view of a particular embodiment of a monopolar wire-plate antenna of the type figure 2 .
• There Figure 9 illustrates a side view of a particular embodiment of a monopolar wire-plate antenna of the type figure 2 .
• There Figure 10 illustrates a side view of a particular embodiment of a monopolar wire-plate antenna of the type figure 2 .
• There Figure 11 illustrates a side view of a broadband monopolar wire plate antenna having a multi-layer supporting substrate.
• There Figure 12 illustrates a perspective view of the Figure 11 for which the multilayer support substrate has been removed.
• There figure 13 illustrates the evolution of the reflection coefficient in dB of the antenna of the Figure 12 depending on the antenna frequency in GHz.
• There Figure 14 shows a C2 curve of the evolution of the maximum Gain obtained from the antenna of the Figure 12 in dBi depending on the frequency of the antenna in GHz, and a curve C1 of the evolution of the radiation efficiency in % of the antenna of the Figure 12 depending on 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 on a uniform scale to make the figures more readable.

detailed description

It is defined for the following a reference of orthogonal axes XYZ represented in figures 2 to 12 . In particular, the terms “under”, and “inferior” 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 frame of reference of a monopolar wire-plate antenna as described below. A dimension given along an axis of this reference is a dimension measured parallel to this axis.

Subsequently, the operating frequency of the monopolar wire-plate antenna corresponds to the frequency at which the monopolar wire-plate antenna emits, or receives, an electromagnetic wave, in particular a radio wave, also called where appropriate a transmitted signal. or signal received/captured. More generally, to talk about this electromagnetic wave, reference is made to the electromagnetic wave to be processed (whether in reception or transmission) 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 operating wavelength of the antenna, denoted λ ₀ at the operating frequency of the antenna, 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 a vacuum or in air. The propagation medium of the monopolar wire-plate antenna corresponds to an emission and/or reception medium of the electromagnetic wave to be treated. Thus, the propagation medium is, where applicable, the medium from which the antenna picks up the electromagnetic wave to be processed or to which the antenna transmits the electromagnetic wave to be processed. More generally, we say that the wave electromagnetic to be treated propagates in a propagation medium 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 (i.e. the wavelength associated with the propagation of the electromagnetic wave to be processed at the operating frequency of the antenna) is then denoted λ _g : we also speak of guided wavelength. Subsequently, when the monopolar wire-plate antenna is said to be powered/excited, it is at the operating wavelength of the antenna.

The monopolar wire-plate antenna is said to be impedance matched 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 a monopolar wire-plate antenna 100, 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 minus one electrically conductive element 103a, 103b electrically connecting the ground plane 101 to the roof 102. figures 2 to 5 , two electrically conductive elements 103a, 103b are shown as an example: the number of these electrically conductive elements 103a, 103b can 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 forms in particular a radiating part of the antenna 100. The roof 102 is electrically conductive, and is also called a 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 can each be, in a non-limiting manner, made of copper, aluminum or steel. Furthermore, this antenna 100 includes a feed loop 107, in particular called “antenna 100 feed loop”.

The power 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 in particular that of a radio frequency transmitter 200 ( Figure 6 ). The power supply loop 107 is arranged substantially orthogonal to the ground plane 101. Thanks to this power loop 107, there is no longer any need to use a balun or other circuit carrying out an asymmetric line transformation in symmetrical line (or vice versa) between the radio frequency transmitter and the antenna 100.

By “two opposite longitudinal ends 108, 109 of the power supply loop 107 and arranged so as to be connected to a differential connection”, we mean preferentially that the power 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 subsequently.

When the antenna 100 is used to transmit a signal, the electromagnetic wave generated by the radio frequency transmitter can power the antenna 100 via this power 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) from free space, this signal feeding the feed loop 107 of the antenna 100 in a manner adapted to transmit this signal to the radio frequency transmitter.

The feed 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 power 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 power loop 107 is particularly arranged so that, when the antenna 100 is powered by the radio frequency transmitter 200 or by the signal picked up by the antenna 100:

• currents are established in the supply loop 107 substantially orthogonal 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 orthogonal to the ground plane 101.

In the present description, the term “substantially orthogonal” is understood in particular to be orthogonal or orthogonal to plus or minus ten degrees. Preferably, “substantially orthogonal” can be replaced by “orthogonal”.

In the present description, by substantially parallel, it is understood in particular parallel or parallel to plus or minus ten degrees. Preferably, “substantially parallel” can be replaced by “parallel”.

By "power supply loop 107 arranged substantially orthogonally relative to the ground plane 101", it is understood in particular that the power loop 107 extends along a profile included, or capable of being projected orthogonally, in a plane substantially orthogonal to the ground plane 101. According to another formulation, the profile of the power supply loop 107 can travel, according to the length of the power 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 radio frequency device 1000, in particular as illustrated by way of example in Figure 6 , comprising the antenna 100 as described and the radio frequency transmitter 200 with differential connection connected to the power loop 107, in particular to the power loop 107 of the antenna of the type figures 2 And 3 (as shown in Figure 6 ) or the antenna of the type illustrated in figures 4 and 5 . The radio frequency transmitter 200 is an electronic transmission-reception component whose coupling to the antenna 100 (that is to say the connection to the power loop 107) makes it possible to transmit or receive the electromagnetic wave corresponding, or signal, by the antenna 100. The radio frequency transmitter can in particular power the antenna through a discrete port, for example 50 ohms over its entire operating band. By “differential connection” of the radio frequency transmitter 200, we mean that the radio frequency transmitter 200, and more particularly this differential connection, comprises two terminals 201, 202 from which the electromagnetic wave, making it possible to supply the antenna 100 in intended to transmit the signal is transmitted in a balanced mode. To generate this electromagnetic wave feeding the antenna 100 whose mode is balanced, the radio frequency transmitter 200 can send to its two terminals 201, 202 respectively two signals of equal amplitude and in phase opposition. It is in particular in this sense that the radio frequency 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 “-”. We very frequently find antennas powered from a source in differential mode in mobile terminals such as smart phones (“smartphone” in English). The use of a differential power supply whose source is the radio frequency 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 power supply loop 107 when it is powered 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 that a hand of a person holding the smartphone comprising this antenna 100.

In order to properly power the monopolar wire-plate antenna 100, it is necessary to form an electromagnetic field 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 made possible by the fact that the power supply loop 107 is orthogonal to the ground plane 101. In fact, the power loop 107 has parts substantially orthogonal to the ground plane 101 in which currents can propagate.

Furthermore, still with the aim of allowing the currents to be properly established in the supply loop 107 to operate the monopolar wire-plate antenna 100, the supply loop 107 preferably comprises two regions Z1, Z2 (represented dotted 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 say oriented in the same direction, in particular substantially parallel to the Z axis, and these currents are of close amplitudes, when the antenna 100 is powered by the radio frequency transmitter 200 or by the signal that it picks up. Thus, the supply loop 107 is notably configured so that it presents, 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 flow substantially orthogonal to the ground plane 101.

By “longitudinal ends 108, 109 of the supply loop 107” ( figures 2 to 6 ), we understand that, depending on the length of the supply loop 107, this supply loop 107 has two opposite ends. These opposite longitudinal ends 108, 109 of the power loop 107 are located at a distance from each other, in particular at an appropriate distance to allow the connection of the power loop 107 to the transmitter 200 either directly or by the via 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 paragraph describes an example of a narrow-band monopolar wire-plate antenna as illustrated in figure 2 And 3 . By “narrow band” we mean an operating band of the order of a few percent relative to the central frequency. This antenna 100 includes the roof 102 having a profile, taken in a plane parallel to the XY plane, square with 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 power 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 power loop 107 is 15.2 mm notwithstanding the separation distance between the two longitudinal ends 108, 109 considered negligible,
• the width of the supply loop 107, measured along the Y axis, can be 1.2 mm,
• the thickness of the power loop 107 has no influence as long as it remains within classic 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 presents, when it is differentially powered by a discrete 50 Ohm port, 3% bandwidth at -10 dB (decibels) around 5.5 GHz. The adaptation of such an antenna 100 to 50 Ohms shows similar performances compared to an antenna fed 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 monopolar type radiation, and the gain maximum realized is approximately 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.This paragraph describes an example of a broadband monopolar wire-plate antenna 100, for example as illustrated in figures 4 and 5 . By “wideband” is meant an operating band strictly greater than one 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 infinite. Here, the power loop 107 is in the form of a ribbon and the profile of this power loop 107 taken in a plane parallel to the plane XZ adopts the general shape of a rectangle: the power loop 107 therefore has four successive parts delimiting its outline. For example, the power 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 power loop 107 is 18.5 mm, notwithstanding the separation distance between the two longitudinal ends 108, 109 considered negligible,
• the width of the feed loop 107, or width of the ribbon, can be 1.2 mm,
• the thickness of the power loop 107 has no influence as long as it remains in classic technological values ranging from ten to a few hundred micrometers.

Furthermore, two electrically conductive elements 103a, 103b, formed by tabs 3 mm wide (measured along the Y axis), electrically connect the roof 102 to the ground plane 101. The thickness of these tabs does not have of influence as long as it remains within classic 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 mass 101. Such an antenna 100 has an adaptation, standardized to 100 Ohms broadband, such that, when it is supplied with differential, particularly whether in transmission or reception, its bandwidth is 36% at -10dB ( decibel) around 7.7GHz. At the operating frequency, here 7.7 GHz, and depending on the differential power supply, the broadband antenna 100 has radiation efficiencies strictly greater than 90%, its gain diagram denotes monopolar type radiation, and the gain maximum achieved is close to 5dBi, this being equivalent to the results obtained for a monopolar wire-plate antenna fed asymmetrically by coaxial feed probe.

It was mentioned above that for proper operation of the antenna 100, the currents which flow in the feed loop 107, and in particular in parts of the feed loop 107 extending substantially orthogonal to each other. to the ground plane 101 are in phase and preferably of close amplitudes when this antenna 100 transmits or picks up a signal. For this purpose, the power supply loop 107 advantageously comprises two parts substantially orthogonal to the ground plane 101: this allowing the power 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 power supply loop 107 comprises (see in particular the figures 2 to 5 ) a first part 1071 distal to 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 power supply loop 107 is particularly suitable for obtaining the vertical currents in phase sought 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 orthogonal to the ground plane 101.

In particular, the power 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 circulate 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 opposite longitudinal ends 108, 109 of the supply loop 107 opposite its third part 1073 makes it possible to promote, during the operation of the antenna 100, the obtaining of currents circulating in phase along the Z axis, that is to say in the third and fourth parts 1073, 1074 substantially orthogonal to the ground plane 101 .

The placement of the longitudinal ends 108, 109 of the feed loop 107 at any location opposite the third part 1073 of the feed loop 107 ( figures 2 to 5 And 7 to 8 ) makes it possible to obtain the desired phase currents and substantially orthogonal to the ground plane 101. According to a first case, the power supply loop 107 can be such that it comprises the fourth part 1074 comprising a first portion 1074a extending from the first part 1071 of the power loop 107 in particular towards the second part 1072 of the power loop 107. According to this first case, the first portion 1074a comprises one of the longitudinal ends 108 of the supply loop 107. According to 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 ). According to the first case, the first and second portions 1074a, 1074b can have identical dimensions so that the excitation of the power 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 is done in the middle of the fourth part 1074, the power supply loop 107 has horizontal symmetry favoring the balance of the currents over the entire perimeter of the power loop 107 and therefore in the third and fourth parts 1073, 1074 substantially orthogonal to the ground plane 101, this being advantageous for proper operation 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 loop 107. According to 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 comprises 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 in relation 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 radio frequency device, the radio frequency transmitter 200 can be connected directly to the power loop 107, or can be connected to the power loop via a balanced waveguide 110, also called differential waveguide. This balanced waveguide 110 belongs to the antenna 100. Figure 6 , the waveguide 110 is shown 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 power loop 107 and the second electrical conductor 112 is connected to the other of the longitudinal ends 109 of the power loop 107. The guide waves is called "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 feed loop 107 or the propagation of the electromagnetic wave captured (that is to say the signal picked up) by the antenna 100 from the feed loop 107 to the radio frequency transmitter 200. This has the advantage to be able to adapt the distance between the antenna 100 and the radio frequency transmitter 200. These first and second electrical conductors 111, 112 make it possible to respectively propagate two signals of equal amplitude and in phase opposition from which, where appropriate, results the propagation of the electromagnetic wave feeding the antenna 100 from the radio frequency transmitter 200 or the electromagnetic wave captured by the antenna 100. In the context of the radio frequency device 1000, the first electrical conductor 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 the proper propagation of the electromagnetic supply wave. The balanced waveguide 110 can take the form of coplanar microstrip lines, twin lines, or a bifilar line.

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

Applicable to all the embodiments described, part of the supply loop 107 can be formed by a portion of the roof 102, this is particularly illustrated in 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 bulk of the antenna 100 along the Z axis. , for example by reducing the separation distance between the roof 102 and the ground plane 101. An additional advantage of the power 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 level of metallization 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 narrow band antenna ( figure 2 And 3 ) whose impedance matching is standardized at 50 Ohms, it is proposed to fix the dimensions of the power supply loop 107 along the X axis (that is to say the length of the first part 1071 and the length of the second part 1072) to 5 mm for different study cases for which the length of the supply loop 107, also called perimeter denoted P of the supply loop 107, is respectively fixed at 14 mm, at 14 .5 mm and 15 mm: this results in the height of the supply loop 107 along the Z axis being 2 mm, 2.25 mm and 2.5 mm respectively for these different study cases. Setting the dimensions of the power supply loop 107 along the X axis to 5 mm makes it possible to separate the excitation zones Z1 and Z2 by the same distance for the different study cases. According to the different cases of study 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 study cases, it is possible to deduce that the increase in the perimeter P of the power loop 107 causes a shift of the resonance towards 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 cases of study 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 feed loop 107. Thus, in the present case, the adaptation of the The antenna 100 operates when the perimeter of the loop is of optimal dimension close to λ ₀ /3.6, where λ ₀ is the operating wavelength of the antenna 100. With the lengthening 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 balance of the excitation regions Z1, Z2 in amplitude and 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 perimeter of the feed loop 107. Thus, to obtain good impedance matching 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 /3.7 and λ _g /3.5 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 matching is standardized at 100 Ohms, it is proposed to set the dimensions, in particular the length, of the first and second parts 1071, 1072 of the power supply loop 107 along the axis X each to 5, 5mm. Setting the dimensions of the power loop 107 along the X axis to 5.5 mm makes it possible to separate the excitation zones Z1 and Z2 by the same distance for the different study cases. Then, the different study cases 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, i.e. five study cases with P respectively equal at 16.5mm, 17mm, 17.5mm, 18mm and 18.5mm. It results that the height of the power loop 107 along the Z axis for these different study cases 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 antenna 100 in Ohms as a function of the frequency of antenna 100) of antenna 100 for these five study cases , it is possible to deduce that the increase in the perimeter of the power supply loop 107 causes a shift in the resonance towards low frequencies. Consequently, the frequency presenting the best impedance matching of the antenna 100, normalized at 100 Ω, decreases with the increase in the perimeter of the feed loop 107. Thus, the matching of the antenna 100 becomes 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 propagation medium of the antenna is the air. Furthermore, the balance 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 small compared to 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 out of phase. On the other hand, at this same frequency and in the presence of a power supply loop 107 of 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 of 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 of perimeter P equal to 18.5 mm, the balance in the excitation regions Z1, Z2 of the antenna 100 is lost in amplitude and in phase on current density with increasing frequency. Thus, to obtain good impedance matching of the antenna 100, when said antenna 100 is a wide bandwidth antenna, the feed 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, particularly 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 according to the desired characteristics of the antenna 100.

For example, for the narrow band antenna 100 described, by setting 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 increasing the width of the feed loop 107 results in 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 setting the length of the feed loop 107 to 18.5 mm while varying its width between 0.5 mm and 2 mm in a step of 0.5 mm , it was noted that increasing the width of the power supply loop 107 leads to a decrease in the real part of the input impedance associated with an increase in the imaginary part of the input impedance around 8GHz. Thus, for the specific dimensions of the broadband monopolar wire-plate antenna 100, a width of the feed loop 107 of approximately 0.5 mm is optimal for 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 power 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 (shown in dotted lines in Figure 12 ) of the power loop 107. According to this particular example, the substrate 113 comprises a stack of first to fourth layers 1131, 1132, 1133, 1134 of dielectric material. There 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 face of this second layer 1132 oriented opposite the first layer 1131, the second part 1072 of the power supply loop 107 and the first and second pads 1103 are formed. , 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 pad 1103. 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 balanced waveguide 110 adopting the shape 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 first 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 power supply 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 towards 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 such that the first portion 1074a of the fourth part 1074 links 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 power supply 107 such 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 stacking 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 power loop 107 , the first and second portions 1073a, 1073b of the third part 1073 of the power loop 107, and the third, fourth, seventh and eighth portions 1105, 1106, 1109, 11010 of the 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 11mm. The roof 102 is printed on a dielectric substrate with relative permittivity ε _r = 2.2 and 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 arranged 4.8 mm from the infinite ground plane 101. The feed loop 107 supplying the antenna 100 has the following characteristics:

• the geometric perimeter of the power loop 107 is set at 21.4 mm for a rectangular power 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 power loop 107 is placed, the effectively guided wavelength is reduced to 31 mm, for which it would also be necessary to take into account the effect of changing the section of the roof 102 of the antenna 100, we (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 power 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 differentially via the power loop 107 for integration above a chip package (for example QFN for Quad-Flat No-leads). There Figure 13 presents for this particular example the variation of the reflection coefficient of the antenna 100 in dB as a function of the frequency of the antenna in GHz normalized to 100 Ohms, this Figure 13 shows a satisfactory impedance adaptation (S ₁₁ strictly less than -10dB with S ₁₁ the reflection coefficient of the antenna 100) between 7.5 GHz and 9.2 GHz. There Figure 14 represents on the abscissa the frequency of the antenna in GHz, the left ordinate axis gives, for curve C2, the maximum gain achieved in dBi as a function of the frequency of the antenna 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 allows you to plot the reflection coefficient as a function of frequency to identify where the reflection coefficient is low, synonymous with impedance matching of the antenna 100 and identification of the operating frequency. We see from this Figure 14 that in the targeted 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 powered directly by a differential waveguide, that is to say (without balun) with satisfactory performance. Furthermore, by removing the balun, we avoid losses linked to this balun. Furthermore, the monopolar wire-plate antenna with feed loop 107 as described has performances similar to that of a monopolar wire-plate antenna fed 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 radio frequency device as described above. The radio frequency device described can be integrated into any type of object communicating. For example, the radio frequency device can be integrated into a smartphone worn on a person's belt to transmit via the antenna 100 a video stream to interactive glasses using an ultra-wideband link between 7 GHz and 9 GHz.

Claims (10)

1. Monopolar wire-plate antenna (100), operating at a wavelength denoted λ_g, and comprising:

   - a ground plane (101),

   - a roof (102), arranged at a distance from the ground plane (101), and having dimensions strictly less than λ_g/4,

   - at least one electrically conductive element (103a, 103b) electrically linking the ground plane (101) to the roof (102),

   the antenna comprising a power supply loop (107) arranged substantially orthogonally with respect to the ground plane (101), said power supply loop (107) being open such that it comprises two opposite longitudinal ends (108, 109) arranged so as to be linked to a differential connection (201, 202).
2. Antenna (100) according to Claim 1, characterised 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 power supply loop (107) and the second electrical conductor (112) being connected to the other of the longitudinal ends (109) of the power supply loop (107).
3. Antenna (100) according to either one of the preceding claims, characterised in that the power supply loop (107) comprises:

   • a distal first part (1071) of the ground plane (101),

   • a proximal second part (1072) of the ground plane (101),

   • a third part (1073) linking the first and second parts (1071, 1072),

   • the longitudinal ends (108, 109) being arranged opposite the third part (1073).
4. Antenna (100) according to the preceding claim, characterised in that the power supply loop (107) comprises:

   • a fourth part (1074) comprising:

   • a first portion (1074a) extending from the first part (1071) of the power supply loop (107), this first portion (1074a) comprising one of the longitudinal ends (108) of the power supply loop (107), and

   • a second portion (1074b) extending from the second part (1072) of the power supply loop (107), this second portion (1074b) comprising the other of the longitudinal ends (109) of the power supply loop (107), or

   • a fourth part (1074) extending from the first part (1071) and comprising one of the longitudinal ends (108) of the power supply loop (107), the second part (1072) comprising the other of the longitudinal ends (109) of the power supply loop (107), or

   • a fourth part (1074) extending from the second part (1072) and comprising one of the longitudinal ends (109) of the power supply loop (107), the first part (1071) comprising the other of the longitudinal ends (108) of the power supply loop (107).
5. Antenna (100) according to any one of the preceding claims, characterised in that a part of the power supply loop (107) is formed by a portion of the roof (102), or in that the power supply loop (107) is situated at a distance from the roof (102), or in that the power supply loop (107) is in contact with the roof (102).
6. Antenna (100) according to any one of the preceding claims, characterised in that said power supply loop (107) has, when the antenna (100) is operating, 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).
7. Antenna (100) according to any one of the preceding claims, characterised in that said antenna (100) is a wide bandwidth antenna for which the power supply loop (107) has a length, between its two opposite longitudinal ends (108, 109), of between λ_g/3 and λ_g/1.6.
8. Antenna (100) according to any one of Claims 1 to 6, characterised in that said antenna (100) is a narrowband antenna for which the power supply loop (107) has a length, between its two opposite longitudinal ends (108, 109), of between λ_g/3.7 and λ_g/3.5.
9. Radiofrequency device (1000), characterised in that it comprises a monopolar wire-plate antenna (100) according to any one of the preceding claims, and a radio frequency transmitter (200) with differential connection linked to the power supply loop (107).
10. Radiofrequency device (1000) according to the preceding claim, characterised in that:

    • the differential connection of the radio frequency 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 power 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 power supply loop (107) and, on the other hand, to the second connection terminal (202).

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