EP4175068A1 - Antenna cell with transmitter or reflector array - Google Patents

Abstract

The present description relates to a cell (105) of a transmitting network or of a reflecting network, comprising at least two switches made of phase change material.

Description

Technical area

This description relates generally to electronic devices. The present application relates more particularly to the field of radio antennas with a transmitter array ("transmitarray antenna" in English) and radio antennas with a reflectarray ("reflectarray antenna" in English).

Prior technique

Among the different technologies of existing radio communication antennas, radio antennas called “transmitter network” are known in particular. These antennas generally comprise several elementary cells each comprising a first antenna element irradiated by an electromagnetic field emitted by one or more sources, a second antenna element transmitting a modified signal to the outside of the antenna and a coupling element between the first and second antenna elements.

Also known are so-called “reflector array” radio antennas. These antennas generally comprise several elementary cells each comprising an antenna element irradiated by an electromagnetic field emitted by one or more sources, a reflective element, for example a ground plane, reflecting a modified signal towards the outside of the antenna and a coupling element between the antenna element and the reflector element. Unlike the elementary cells of transmitter array antennas, which transmit a radio signal in a direction opposite to the source or sources irradiating their first antenna element, the elementary cells of reflector array antennas reflect a radio signal in the direction of the source(s) irradiating their antenna element.

For applications, for example such as satellite communication ("satellite communication" or "SatCom", in English), it would be desirable to have antennas with a transmitter array and antennas with a reconfigurable reflector array making it possible to modify, in a dynamic, the phase of the radiated wave.

Summary of the invention

There is a need to improve existing transmitter array antennas and reflector array antennas.

One embodiment overcomes all or part of the drawbacks of known transmitter array antennas and reflector array antennas. An object of an embodiment is more particularly to allow electronic phase control in a frequency range comprised for example between 50 and 350 GHz, corresponding to millimeter wavelengths, and to have switches whose polarization causes reduced power consumption.

One embodiment provides a transmitter grating or reflector grating cell, comprising at least two switches made of phase change material.

According to one embodiment, said phase change material is a chalcogenide material.

According to one embodiment, each phase-change material switch comprises a region of said phase-change material located on and in contact with first and second separate conductive regions of a patch antenna.

According to one embodiment, each phase-change material switch further comprises an element electrically insulated heating region of said phase change material.

According to one embodiment, the phase change material switches form part of a first antenna element suitable for switching a radio frequency signal between at least two phase states.

According to one embodiment, the first antenna element comprises exactly two switches made of phase-change material and a conductive plane having an annular-shaped opening, electrically isolating a central region of the conductive plane from a peripheral region of the conductive plane, each phase change material switch connecting the central region to the peripheral region of the conductive plane.

According to one embodiment, the cell further comprises a second antenna element connected to the first antenna element by a central conductive via, a ground plane interposed between the first and second antenna elements and electrically isolated from the conductive via central, the ground plane being connected to the second antenna element by two lateral conductive vias.

One embodiment provides a transmitter network comprising a plurality of cells as described.

According to one embodiment, the first antenna element comprises exactly two switches made of phase-change material and a flat conductive frame inside which are located first and second separate conductive regions, one of the two switches connecting the second conductive region to the planar conductive frame and the other switch connecting the first and second conductive regions together.

According to one embodiment, the first conductive region is connected to the planar conductive frame by a delay line.

According to one embodiment, the cell further comprises a reflector element connected to the first antenna element by a central conductor via.

One embodiment provides a reflective array comprising a plurality of cells as described.

One embodiment provides an antenna comprising a transmitter grating as described or a reflector grating as described and at least one source configured to irradiate one face of the grating.

Brief description of the drawings

• la figure 1 est une vue de côté, schématique et partielle, d'un exemple d'antenne à réseau transmetteur du type auquel s'appliquent, à titre d'exemple, des modes de réalisation décrits ;
• la figure 2 est une vue en perspective, schématique et partielle, d'une cellule élémentaire du réseau transmetteur de l'antenne de la figure 1 selon un mode de réalisation ;
• la figure 3 est une vue de dessus, schématique et partielle, d'un premier élément d'antenne de la cellule élémentaire de la figure 2 ;
• la figure 4 est une vue de dessus, schématique et partielle, d'une partie de la cellule élémentaire de la figure 2 ;
• la figure 5 est une vue de dessus, schématique et partielle, d'un deuxième élément d'antenne de la cellule élémentaire de la figure 2 ;
• la figure 6 est une vue de dessus, schématique et partielle, d'un élément de commutation du deuxième élément d'antenne de la figure 5 ;
• la figure 7 est une vue en coupe, selon le plan AA de la figure 6, du commutateur du deuxième élément d'antenne de la figure 5 ;
• la figure 8 est une vue de dessus, schématique et partielle, d'un réseau d'interconnexion associé au deuxième élément d'antenne de la figure 5 ;
• la figure 9 est une vue de dessus, schématique et partielle, illustrant une variante de réalisation du deuxième élément d'antenne de la figure 5 et du réseau d'interconnexion de la figure 8 ;
• la figure 10 est une vue de côté, schématique et partielle, d'un exemple d'antenne à réseau réflecteur du type auquel s'appliquent, à titre d'exemple, des modes de réalisation décrits ;
• la figure 11 est une vue en perspective, schématique et partielle, d'une cellule élémentaire du réseau réflecteur de l'antenne de la figure 10 selon un mode de réalisation ;
• la figure 12 est une vue de dessus, schématique et partielle, d'un élément d'antenne de la cellule élémentaire de la figure 11 ;
• la figure 13 est une vue de dessus, schématique et partielle, d'une partie de la cellule élémentaire de la figure 11 ;
• la figure 14 est une vue de dessus, schématique et partielle, d'une autre partie de la cellule élémentaire de la figure 11 ;
• la figure 15 est une vue de dessus, schématique et partielle, d'encore une autre partie de la cellule élémentaire de la figure 11 ; et
• la figure 16 est une vue de dessus, schématique et partielle, d'un élément réflecteur de la cellule élémentaire de la figure 11.

These characteristics and advantages, as well as others, will be set out in detail in the following description of particular embodiments given on a non-limiting basis in relation to the attached figures, among which:

• there figure 1 is a side view, schematic and partial, of an example of a transmitter array antenna of the type to which the described embodiments apply, by way of example;
• there picture 2 is a perspective view, schematic and partial, of an elementary cell of the transmitter array of the antenna of the figure 1 according to one embodiment;
• there picture 3 is a top view, schematic and partial, of a first antenna element of the elementary cell of the figure 2 ;
• there figure 4 is a top view, schematic and partial, of part of the elementary cell of the figure 2 ;
• there figure 5 is a top view, schematic and partial, of a second antenna element of the elementary cell of the figure 2 ;
• there figure 6 is a top view, schematic and partial, of a switching element of the second antenna element of the figure 5 ;
• there figure 7 is a sectional view, according to plan AA of the figure 6 , of the switch of the second antenna element of the figure 5 ;
• there figure 8 is a schematic partial top view of an interconnect network associated with the second antenna element of the figure 5 ;
• there figure 9 is a top view, schematic and partial, illustrating a variant embodiment of the second antenna element of the figure 5 and the interconnection network of the figure 8 ;
• there figure 10 is a side view, schematic and partial, of an example of a reflective array antenna of the type to which the described embodiments apply, by way of example;
• there figure 11 is a perspective view, schematic and partial, of an elementary cell of the reflector array of the antenna of the figure 10 according to one embodiment;
• there figure 12 is a top view, schematic and partial, of an antenna element of the elementary cell of the figure 11 ;
• there figure 13 is a top view, schematic and partial, of part of the elementary cell of the figure 11 ;
• there figure 14 is a top view, schematic and partial, of another part of the elementary cell of the figure 11 ;
• there figure 15 is a top view, schematic and partial, of yet another part of the elementary cell of the figure 11 ; And
• there figure 16 is a top view, schematic and partial, of a reflector element of the elementary cell of the figure 11 .

Description of embodiments

The same elements have been designated by the same references in the different figures. In particular, the structural and/or functional elements common to the various embodiments may have the same references and may have identical structural, dimensional and material properties.

For the sake of clarity, only the steps and elements useful for understanding the embodiments described have been represented and are detailed. In particular, embodiments of a cell for an antenna with a transmitter array and embodiments of a cell for an antenna with a reflective array will be described below. The structure and operation of the primary source(s) of the antenna, intended to irradiate the transmitter network or the reflector network, will however not be detailed, the embodiments described being compatible with all or most of the primary sources of irradiation for known transmitter array or reflector array antenna. By way of example, each primary source is adapted to produce a beam of generally conical shape irradiating all or part of the transmitter network or of the reflector network. Each primary source comprises for example a horn antenna. As For example, the central axis of each primary source is substantially orthogonal to the mean plane of the network.

Furthermore, the manufacturing methods of the transmitter gratings and of the reflector gratings described will not be detailed, the production of the structures described being within the reach of those skilled in the art based on the indications of the present description.

Unless otherwise specified, when reference is made to two elements connected together, this means directly connected without intermediate elements other than conductors, and when reference is made to two elements connected (in English "coupled") between them, this means that these two elements can be connected or be linked through one or more other elements.

In the following description, when referring to absolute position qualifiers, such as "front", "rear", "up", "down", "left", "right", etc., or relative, such as the terms "above", "below", "upper", "lower", etc., or to qualifiers of orientation, such as the terms "horizontal", "vertical", etc., it reference is made unless otherwise specified to the orientation of the figures.

Unless specified otherwise, the expressions “about”, “approximately”, “substantially”, and “of the order of” mean to within 10%, preferably within 5%.

There figure 1 is a side view, schematic and partial, of an example of an antenna 100 with a transmitter array of the type to which the described embodiments apply, by way of example.

The antenna 100 typically comprises one or more primary sources 101 (a single source 101, in the example represented) irradiating a transmitter network 103. The source 101 can have any polarization, for example linear or circular. The network 103 comprises a plurality of elementary cells 105, for example arranged in a matrix along rows and columns. Each cell 105 typically comprises a first antenna element 105a, located on the side of a first face of the array 103 arranged facing the primary source 101, and a second antenna element 105b, located on the side of a second face network opposite the first face. The second face of the grating 103 is for example turned towards a transmission medium of the antenna 100.

Each cell 105 is able, in transmission, to receive electromagnetic radiation on its first antenna element 105a and to re-emit this radiation from its second antenna element 105b, for example by introducing a known phase shift φ. In reception, each cell 105 is able to receive electromagnetic radiation on its second antenna element 105b and to re-emit this radiation from its first antenna element 105a, in the direction of the source 101, with the same phase shift φ. The radiation re-emitted by the first antenna element 105a is for example focused on the source 101.

The characteristics of the beam produced by the antenna 100, in particular its shape (or template) and its direction of maximum emission (or pointing direction), depend on the values of the phase shifts respectively introduced by the different cells 105 of the network 103.

Transmitter array antennas have the advantages, among others, of having good energy efficiency and of being relatively simple, inexpensive and compact. This stems in particular from the fact that the transmitting networks can be produced using planar technology, generally on a printed circuit.

We are particularly interested here in the antennas with a reconfigurable transmitter network 103 . The transmitter network 103 is said to be reconfigurable when the elementary cells 105 are individually electronically controllable to modify their phase shift value φ, which makes it possible to dynamically modify the characteristics of the beam generated by the antenna, and in particular to modify its pointing direction. without mechanically moving the antenna or part of the antenna by means of a motorized element.

There figure 2 is a perspective view, schematic and partial, of one of the elementary cells 105 of the transmitter network 103 of the antenna 100 of the figure 1 according to one embodiment.

According to this embodiment, the first antenna element 105a of the elementary cell 105 comprises a patch antenna 110 adapted to pick up the electromagnetic radiation emitted by the source 101 and the second element of antenna 105b comprises another patch antenna 112 adapted to emit, towards the outside of antenna 100, a phase-shifted signal. In the example shown, the elementary cell 105 further comprises a ground plane 114 inserted between the patch antennas 110 and 112.

The antenna 110, the ground plane 114 and the antenna 112 are for example respectively formed in three successive metallization levels, superposed and separated from each other by dielectric layers, for example of quartz. By way of example, the ground plane 114 is separated from each of the antennas 110 and 112 by a thickness of dielectric material of the order of 200 μm.

In the example shown, a central conductor via 116 connects the antenna 110 to the antenna 112. More precisely, in the orientation of the picture 2 , the via 116 has a lower end in contact with an upper face of the antenna 110 and an upper end in contact with a lower face of the antenna 112. The central conductor via 116 is electrically insulated from the ground plane 114. In the example shown, the ground plane 114 has an orifice allowing the via 116 to cross the ground plane 114 without contacting it. By way of example, the central conductor via 116 has a diameter equal to around 80 μm.

Furthermore, in this example, lateral conductive vias 118, located on either side of the central conductive via 116, contact the antenna 110 at the ground plane 114. More precisely, in the orientation of the figure 2 , each via 118 has a lower end in contact with the upper face of the antenna 110 and an upper end in contact with a lower face of the ground plane 114.

There picture 3 is a top view, schematic and partial, of the first antenna element 105a of the elementary cell 105 of the figure 2 . There picture 3 more precisely illustrates the patch antenna 110 of the elementary cell 105.

In the example represented, the patch antenna 110 comprises a conductive plane 120 of substantially square shape inside which is formed a slot 122, or groove, in the shape of a U. The slot 122 is for example substantially centered with respect to to the conductive plane 120. In this example, the central conductive via 116 contacts a zone of the conductive plane 120 located between the two branches of the U formed by the slot 122. The via 116 is for example connected substantially to the center of the conductive plane 120.

Also, in the example shown in picture 3 , the lateral conductive vias 118 are located on either side of the slot 122. More precisely, each via 118 is for example connected to a zone of the conductive plane 120 located outside the U formed by the slot 122 and the along one vertical branches of the U. In other words, in this example, the area of the conductive plane 120 where each lateral via 118 is connected is separated from the area of the conductive plane 120 where the central via 116 is connected by one of the vertical branches of the U formed by slot 122.

By way of example, the square formed by the conductive plane 120 has a side of the order of 0.44 mm, the vertical branches and the horizontal branch of the U formed by the slot 122 each have a length of the order of 0.32 mm, and the slot 122 has a width equal to approximately 50 μm.

There figure 4 is a top view, schematic and partial, of part of the elementary cell 105 of the figure 2 . There figure 4 more precisely illustrates the ground plane 114 located between the first and second antenna elements 105a, 105b.

In the example represented, the ground plane 114 comprises a conductive plane 130 of substantially square shape. In this example, the central conductor via 116 passes through the ground plane 114 approximately at its center. The via 116 is isolated from the conductive plane 130 by an annular or crown-shaped opening 132 formed in the conductive plane 130 around the via 116. By way of example, the square formed by the conductive plane 130 has a side of the order of 1 mm.

In this example, the side of the square formed by the conductive plane 130 substantially defines the external dimensions of the elementary cell 105 of the transmitter network 103.

Ground plane 114 is adapted to form electromagnetic shielding between antenna 110 and antenna 112 of cell 105.

In the example shown in figure 4 , the lateral conductive vias 118 contact the underside of the conductive plane 130 in diametrically opposite zones relative to the central conductive via 116. In this example, the vias 116 and 118 are located on the same straight line parallel to one of the sides of the conductive plane 130. Further, vias 118 are equidistant from via 116.

There figure 5 is a top view, schematic and partial, of the second antenna element 105b of the elementary cell 105 of the figure 2 . There figure 5 more precisely illustrates the patch antenna 112 of the elementary cell 105.

According to one embodiment, the antenna 112 includes a conductive plane 140 with four sides. The conductive plane 140 is for example more precisely of rectangular shape or, as in the example illustrated in figure 5 , substantially square in shape.

According to this embodiment, the conductive plane 140 includes an opening 142 separating a central region 140C of the conductive plane 140 from a peripheral region 140P of the conductive plane 140. In this example, the opening 142 has a substantially annular shape, for example a rectangular or square ring shape.

In the example represented, the central conductive via 116 contacts the central region 140C of the conductive plane 140. More precisely, in this example, the upper end of the via 116 is connected substantially to the center of a lower face of the region 140C. The central region 140C of the conductive plane 140, delimited laterally by the annular opening 142, constitutes for example an input terminal of the antenna 112.

The antenna 112 further comprises a first switching element C1 and a second switching element C2 each connecting the central region 140C to the peripheral region 140P of the conductive plane 140. More precisely, in the example illustrated in figure 5 , the first and second switching elements C1, C2 contact the peripheral region 140P in diametrically opposite zones with respect to the central via conductor 116. In this example, the switching elements C1, C2 and the via conductor 116 are located on the same line parallel to one of the sides of the conductive plane 140. In this example, the switch C1 is located substantially vertically to the horizontal branch of the U formed by the slot 122.

The switching elements C1 and C2 are controlled in opposition, that is to say so that, if one of the switches C1, C2 is on, the other switch C2, C1 is blocked. This allows the second antenna element 105b of the elementary cell 105 to switch between two phase states φ, substantially equal to 0° and 180° in this example. The 0° and 180° phase states correspond respectively to the case where switch C1 is off while switch C2 is on, and to the case where switch C1 is on while switch C2 is off.

By way of example, the square formed by the conductive plane 140 has a side of the order of 0.44 mm, the sides of the square annular opening 142 each have a length of the order of 0.32 mm, and the opening 142 has a width equal to approximately 50 μm.

THE figures 6 and 7 are views respectively from above and in section according to plan AA of the figure 6 , schematic and partial, of the switching element C1 of the second antenna element 105b of the figure 5 .

According to one embodiment, the switching element C1, or switch, is based on phase change material. Phase change materials are materials which can switch, under the effect of heat, between a crystalline phase and an amorphous phase, the amorphous phase having an electrical resistance greater than that of the crystalline phase. One can in particular take advantage of this phenomenon to produce, as in the case of the second antenna element 105b, switches having off (amorphous phase) and on (crystalline phase) states differentiated by a resistance through the change of phase.

In the example shown in figure 7 , a continuous region 160 of a phase change material is located on and in contact with the upper faces of the central 140C and peripheral 140P regions of the conductive plane 140. In this example, the regions 140C and 140P are disjoint and separated from one another. on the other by a distance D1 of approximately 1 μm.

In the example shown, an electrically insulating region 162, for example made of silicon dioxide, laterally separates the central region 140C from the peripheral region 140P of the conductive plane 140. The region 162 for example has a thickness substantially equal to that of the conductive plane. 140, for example equal to approximately 0.6 μm, and extends laterally between regions 140C and 140P. Although not shown in figure 7 , other electrically insulating regions coplanar with region 162 may further extend laterally between regions 140C and 140P as well as outside of region 140P. By way of example, the regions 140C and 140P can in practice be formed in the same electrically conductive layer.

The region 160 of phase change material completely covers the upper face of the electrically insulating region 162 and extends laterally on and in contact with parts of the upper faces of regions 140C and 140P adjoining region 162. Region 160 has, for example, seen from above, a substantially rectangular shape of width D2 ( figure 7 ) equal to approximately 3 µm and of length D3 ( figure 6 ) equal to about 20 µm.

By way of example, region 160 is made of a so-called "chalcogenide" material, that is to say a material or an alloy comprising at least one chalcogen element, for example a material from the family of germanium telluride (GeTe ) or germanium-antimony-tellurium (GeSbTe, also referred to by the acronym "GST").

In the example shown, the upper face and the side faces of the layer 160, as well as parts of the regions 140C and 140P not coated by the layer 160, are coated with an electrically insulating layer 164, for example of silicon nitride . By way of example, layer 164 has a thickness equal to approximately 0.4 μm.

In the example shown, the switch C1 further comprises a heating element 166 ("heater", in English) located on and in contact with the electrically insulating layer 164, above the layer 160 of phase change material. The heating element 166 is thus electrically isolated from the layer 160. The heating element 166 has for example, seen from above, a substantially rectangular shape, of length D4 equal to about 37 μm, centered with respect to the rectangle formed by the region 160 in phase change material. By way of example, the heating element 166 is made of a metal, for example tungsten.

The heating element 166 is for example intended to be traversed by an electric current making it possible to heat, by Joule effect, the phase change material of the region 160. Such a mode of heating is qualified as indirect, as opposed to a direct heating in which a current electricity would circulate inside region 160 in order to cause it to heat up.

In this example, the upper face and the side faces of the heating element 166, as well as parts of the layer 164 not coated by the heating element 166, are coated with an electrically insulating layer 168, for example of nitride of silicon. By way of example, layer 168 has a thickness equal to around 0.2 μm.

The electrically insulating layers 168 and 164 have not been shown in figure 6 so as not to overload the drawing.

In top view, the regions 140C and 140P of the conductive plane 140 jointly form, in the vicinity of the heating element 166 of the switch C1, an H-shaped structure whose horizontal part has a width D5 equal to about 30 μm and whose two vertical branches are separated from each other by a distance D6 equal to approximately 50 μm.

To switch switch C1 from the off state to the on state, the region 160 is heated for example, using the heating element 166, to a temperature T1 and for a duration d1. The temperature T1 and the duration d1 are chosen so as to cause a phase change of the material of the region 160 from the amorphous phase to the crystalline phase. By way of example, the temperature T1 is higher than a crystallization temperature and lower than a melting temperature of the phase change material and the duration d1 is between 10 and 100 ns.

Conversely, to switch the switch C1 from the on state to the off state, the region 160 is heated for example, using the heating element 166, to a temperature T2, higher than the temperature T1, and during a duration d2, less than the duration d1. The temperature T2 and the duration d2 are chosen so as to cause a phase change of the material of the region 160 from the crystalline phase to the amorphous phase. By way of example, the temperature T2 is higher than the melting temperature of the phase change material and the duration d2 is of the order of 10 ns.

Switch C2, for example, has a structure, dimensions and operation similar to what has been described previously in relation to switch C1.

In addition, although an indirect heating switch C1 has been described above in which the heating element 166 is electrically isolated from the region 160 of phase change material, one could provide, as a variant, a indirect heating switch C1 in which the heating element 166 would be in contact with the region 160, or a direct heating switch C1 without a heating element and in which the region 160 would be traversed by an electric current making it possible to cause its heating, or even a switch C1 whose phase changes would be caused by a light source, for example a laser source illuminating region 160 via an optical fiber.

There figure 8 is a top view, schematic and partial, of an interconnection network associated with the second antenna element 105b of the figure 5 .

In the example shown, the heating element 166 of each switch C1, C2 of the second antenna element 105b comprises a first end, or terminal, connected to the central region 140C of the conductive plane 140 and a second end, or terminal, connected to a node N1, N2 for applying a bias potential Vpol1, Vpol2. More precisely, in this example, the first terminal of each element heater 166 is connected, by a conductive via 170, to one end of a conductive track 172, the other end of the conductive track 172 being connected to the region 140C by another conductive via 174. The second terminal of each heating element 166 is connected, by yet another conductive via 176, to one end of another conductive track 178, the other end of the conductive track 178 being connected to the corresponding node N1 or node N2. Provision can be made for the nodes N1 and N2 to be located in the metallization level of the conductive plane 140, the ends of the conductive tracks 178 then being for example connected to the nodes N1 and N2 by conductive vias not shown in figure 8 .

By way of example, the conductive tracks 170 and 178 are formed on and in contact with the upper face of an electrically insulating layer (not shown), for example a layer of silicon dioxide having a thickness approximately equal to 3 μm, covering the upper face of the layer 168.

The polarization potentials Vpol1 and Vpol2 applied to the nodes N1 and N2 make it possible to control the passage of an electric current through the heating elements 166 of the switches C1 and C2. By controlling the intensity and duration of circulation of this current, it is possible for example to adjust the temperatures T1, T2 and the durations d1, d2 making it possible to cause the phase changes of the material of the region 160 as explained above.

There figure 9 is a top view, schematic and partial, illustrating a variant embodiment of the second antenna element 105b of the figure 5 and the interconnection network of the figure 8 . In this variant, the conductive tracks 172 and 178 and the conductive plane 140 are located in the same plane and the vias 174 are omitted. Tracks 172 and 178 and the plane 140 are for example formed in the same level of metallization. The conductive tracks 172 and 178 are for example connected to the ends of the heating elements 166 by conductive vias not shown in figure 9 . In the example represented, the peripheral region 140P of the conductive plane 140 comprises two openings 180 allowing the passage of the conductive tracks 178 connecting the heating elements 166 to the nodes N1, N2 from the inside of the annular opening 142 towards the outside of the peripheral region 140P. In this example, the openings 180 are diametrically opposed with respect to the central conductor via 116.

Although not shown in figures 8 and 9 , the conductive tracks 172 and/or 178 may include radiofrequency filters.

There figure 10 is a side view, schematic and partial, of an example of antenna 200 with a reflective array of the type to which the described embodiments apply, by way of example.

The antenna 200 typically comprises one or more primary sources 201 (a single source 201, in the example shown) irradiating a reflective array 203. The source 201 can have any polarization, for example linear or circular. The network 203 comprises a plurality of elementary cells 205, for example arranged in a matrix along rows and columns. Each cell 205 typically comprises an antenna element 205a, located on the side of a first face of the grating 203 arranged facing the primary source 201, and a reflector element 205b, located on the side of a second face of the grating opposite to the first side. The first face of the grating 203 is for example turned towards an emission medium of the antenna 200. The reflective element 205b is for example, as shown in figure 10 , common to all the elementary cells 205 of the network 203.

Each cell 205 is able, in transmission, to receive electromagnetic radiation emitted by the source 201 on its antenna element 205a and to re-emit this radiation, after reflection by the reflector element 205b, from its antenna element 205a, by example by introducing a known phase shift φ. In reception, each cell 205 is able to receive electromagnetic radiation on its antenna element 205a and to re-emit this radiation, after reflection by the reflector element 205b, from its antenna element 205a, in the direction of the source 201, with the same phase shift φ. The radiation re-emitted by the antenna element 205a is for example focused on the source 201.

The characteristics of the beam produced by the antenna 200, in particular its shape (or template) and its direction of maximum emission (or pointing direction), depend on the values of the phase shifts respectively introduced by the different cells 205 of the network 203.

Reflector array antennas have similar advantages to transmitter array antennas.

We are particularly interested here in antennas with a reconfigurable reflector array 203, that is to say whose elementary cells 205 are individually electronically controllable to modify their phase shift value φ in a manner analogous to what has been previously described. in relation to the antenna 100 to the transmitter network 103.

There figure 11 is a schematic partial perspective view of an elementary cell 205 of the reflector array 203 of the antenna 200 of the figure 10 according to one embodiment.

According to this embodiment, the antenna element 205a of the elementary cell 205 comprises a plate antenna 210, adapted to pick up the electromagnetic radiation emitted by the source 201 and to emit, towards the outside of the antenna 200, a phase-shifted signal, and the reflector element 205b comprises a ground plane 212. In the example shown, the elementary cell 205 further comprises an interconnection structure 214, a filtering or radiofrequency decoupling structure 216, and a line to delay 218.

The antenna 210, the delay line 218, the structure 216, the structure 214 and the ground plane 212 are for example respectively formed in five successive metallization levels, superposed and separated from each other by dielectric layers.

In the example shown, a central conductor via 220 connects the antenna 210 to the ground plane 212. More precisely, in the orientation of the figure 11 , the via 220 has a lower end in contact with an upper face of the antenna 210 and an upper end in contact with a lower face of the ground plane 212. The via 220 is also connected to a central part of the structure 214 of interconnection. As illustrated in figure 11 , conductive vias 222 connect ends of structure 214 to ground plane 212. Further, conductive vias 224 connect ends of radio frequency filter structure 216 to patch antenna 210 and other conductive vias 226 connect from the ends of the delay line 218 to the antenna 210.

Antenna 210, delay line 218, radio frequency filter structure 216, interconnect structure 214 and ground plane 212 are described in more detail below in relation to Figures 12 to 16 respectively.

There figure 12 is a top view, schematic and partial, of the antenna element 205a of the elementary cell 205 of the figure 11 .

In the example shown, the patch antenna 210 of the antenna element 205a comprises a planar conductive frame 230 and separate conductive regions 232 and 234 located inside the frame 230. In this example, the frame 230 and regions 232 and 234 are coplanar.

The conductive region 234 is in contact with the central conductive via 220 and is connected to the conductive frame 230 by a switching element C3, or switch, of which one conduction terminal is for example in contact with the region 234 and of which another conduction is for example in contact with the frame 230. In the example shown, the conductive region 234 is further connected to the conductive region 232 by another switching element C4, one conduction terminal of which is for example in contact with the region 234 and of which another conduction terminal is for example in contact with region 232.

Each switch C3, C4 of the antenna element 205a of the elementary cell 205 of the reflector array 203 has for example a structure, dimensions and operation similar to what has been described above in relation to the switches C1 and C2 of the antenna element 105b of the elementary cell 105 of the transmitter network 103. In particular, the switching elements C3 and C4 are controlled in opposition. This allows antenna element 205a of elementary cell 205 to switch between two phase states φ, for example substantially equal to 0° and 180°. The 0° and 180° phase states correspond respectively to the case where switch C3 is on while switch C4 is off, and to the case where switch C3 is off while switch C4 is on.

There figure 13 is a top view, schematic and partial, of part of the elementary cell 205 of the figure 11 . There figure 13 more particularly illustrates the delay line 218.

In the example shown, the delay line comprises a conductive track 240, one end of which is connected to the conductive region 232, via one of the two conductive vias 226, and the other end of which is connected. to frame 230, through the other conductive via 226. By way of example, track 240 and vias 226 form a conduction path having a total length adjusted so that the phase shift introduced when switch C4 is passing is equal to φ, that is to say approximately 180° in this example.

There figure 14 is a top view, schematic and partial, of another part of the elementary cell 205 of the figure 11 . There figure 14 more particularly illustrates the structure 216 of radio frequency filtering.

In the example shown, the structure 216 comprises a U-shaped conductive track 250, one end of which is connected to one of the two conductive vias 224 and the other end of which is connected to the other via 224. In this example , the structure 216 further comprises radio frequency decoupling elements or sections 252, for example in the form of a disk sector, connected to the conductive track 250. In the example illustrated in figure 14 , the structure 216 comprises more precisely two elements 252, each element being connected to one of the vertical branches of the U formed by the track 250.

There figure 15 is a top view, schematic and partial, of yet another part of the elementary cell 205 of the figure 11 . There figure 15 more particularly illustrates the structure 214 of interconnection.

In the example represented, the structure 214 comprises two conductive tracks 260 each connecting one of the conductive vias 222 to the central conductive via 220. The conductive tracks 260 extend for example laterally, below the ground plane 212 in the direction of the figure 15 , in diametrically opposite directions from the central via 311 to the vias 260. In this example, the tracks 260 are aligned and have identical lengths. Each conductive track 260 forms for example a quarter wave line (λ/4), that is to say a line having a length substantially equal to a quarter of the operating wavelength of the antenna.

There figure 16 is a top view, schematic and partial, of the reflector element 205b of the elementary cell 205 of the figure 11 .

In the example shown, the central conductor via 220 and the conductor vias 222 located at the ends of the quarter-wave lines 260 of the interconnection structure 214 are connected to the ground plane 212 of the reflector element 205b.

Preferably, the cells 105 and 205 of the networks 103 and 203 are produced by a process comprising successive steps of forming, on the same substrate, for example of quartz, the antenna elements 105a and 105b, in the case of the network 103, and of the reflector element 205b and of the antenna element 205a, in the case of the network 203. In particular, the switches C1 and C2 of the cells 105 are for example formed on the substrate at the end of the production of the central 140C and peripheral 140P regions of the conductive plane 140. Similarly, the switches C3 and C4 of the cells 205 are for example formed on the substrate after the production of the flat conductive frame 230 and the conductive regions 232 and 234. In this case the cells 105 and 205 (and networks 103 and 203) have a so-called "monolithic" structure. By way of example, the manufacturing process for cells 105 and 205 in particular dispenses with transfer steps, and cells 105 and 205 have no interconnection elements, such as pads assembled with solder balls , between the first antenna element 105a, 205a and the second antenna element 105b or the reflector element 205b.

An advantage of the switches C1, C2, C3 and C4 made of phase-change material integrated into the elementary cells 105 and 205 is that they are capable of operating at power levels at least as high as the switches generally employed in elementary cells of antennas with a reconfigurable transmitter or reflector array, while exhibiting better linearity. Furthermore, switches C1, C2, C3 and C4 have excellent stability in frequency ranges of the order of terahertz.

An advantage of cells 105 and 205 is that they allow electronic phase control in a frequency range comprised for example between 50 and 350 GHz, corresponding to millimetric wavelengths, and to have reduced electrical consumption.

Various embodiments and variants have been described. Those skilled in the art will understand that certain features of these various embodiments and variations could be combined, and other variations will occur to those skilled in the art. In particular, the shape of the antenna elements 105a and 205a can be adapted according to the polarization of the associated source 101, 201.

Furthermore, although examples of elementary cells 105 and 205 each comprising two phase-change material switches C1, C2 and C3 have been described, C4, the embodiments described can be transposed by the person skilled in the art to any number of switches made of phase change material. By way of example, a number of phase-change material switches greater than two could be provided in a case where it is desired to produce a reconfigurable elementary cell exhibiting more than two different phase states.

We have described above in connection with the figures 1 to 16 embodiments in which the heating element of the phase change material switches is a resistive element intended to heat the phase change material by Joule effect. As a variant, provision may be made for the heating element to be a waveguide electrically isolated from the phase-change material region and comprising a first end facing a face of the region made of phase-change material. phase change and a second end, opposite the first end, intended to be illuminated by a laser source. In this case, the waveguide comprises for example a central region of silicon nitride (SiN) surrounded by a peripheral region of silicon dioxide (SiO ₂ ). The laser source can be of the integrated type, that is to say forming part of the same chip as the switch or switches with which it is associated, or not integrated, that is to say formed on a chip different from that of the switch(es) with which it is associated, the laser source then being for example connected to the waveguide of each switch with which it is associated by an optical link, for example an optical fiber. Furthermore, the optical couplings between the laser source and the waveguide, and between the waveguide and the phase-change material region can each be obtained by coupling of the "adiabatic" type or by so-called coupling "end-to-end"("buttcoupling", in English). In the case of an adiabatic coupling between the waveguide and the region in phase-change material, the output surface of the waveguide has for example a tapered shape narrowing in the vicinity of the phase-change material region, the latter possibly having a tapered shape narrowing near the waveguide.

Finally, the practical implementation of the embodiments and variants described is within the abilities of those skilled in the art based on the functional indications given above. In particular, the practical implementation of the switches C1, C2, C3 and C4 in the elementary cells 105 and 205 described above can be adapted by the person skilled in the art according to the application.

Claims (14)

Cell (105; 205) of the transmitter network (103) or of the reflector network (203), comprising at least two switches (C1, C2; C3, C4) made of phase change material, each switch (C1, C2; C3, C4) in phase change material comprising: - a region (160) of said phase change material located on and in contact with first (140P; 234) and second (140C; 230, 232) disjoint conductive regions of a patch antenna (112; 210); And - a heating element (166) electrically isolated from the region (160) in said phase change material. A cell according to claim 1, wherein said phase change material is a chalcogenide material. Cell according to claim 1 or 2, in which the heating element (166) is a resistive element intended to heat the phase change material by the Joule effect. Cell according to claim 1 or 2, in which the heating element (166) is a waveguide comprising a first end facing a face of the region (160) of said phase change material and a second end, opposite the first end, intended to be illuminated by a laser source. Cell according to any one of Claims 1 to 4, in which the switches (C1, C2; C3, C4) made of phase-change material form part of a first antenna element (105a; 205a) adapted to switch a radio frequency signal between at least two phase states (φ). A cell (105) of a transmitter array (103) according to claim 5, wherein the first antenna element (105a) comprises exactly two switches (C1, C2) made of phase change material and a conductive plane (140) having an opening (142) of annular shape, electrically isolating a central region (140C) of the conductive plane from a region peripheral (140P) of the conductive plane, each switch made of phase change material connecting the central region to the peripheral region of the conductive plane. A transmitter array cell according to claim 6, further comprising a second antenna element (105b) connected to the first antenna element (105a) by a central conductor via (116), a ground plane (114) interposed between the first and second antenna elements and electrically isolated from the central conductor via, the ground plane being connected to the second antenna element by two side conductor vias (118). A cell (205) of a reflective array (203) according to claim 5, wherein the first antenna element (205a) comprises exactly two switches (C3, C4) of phase change material and a planar conductive frame (230) at inside which are located first (232) and second (234) separate conductive regions, one of the two switches (C3) connecting the second conductive region to the planar conductive frame and the other switch (C4) connecting the first and second conductive regions between them. A reflective grating cell according to claim 8, wherein the first conductive region (232) is connected to the planar conductive frame (230) by a delay line (218). A reflective array cell according to claim 8 or 9, further comprising a reflective element (205b) connected to the first antenna element (205a) by a central conductor via (220). A transmit array cell as claimed in claim 6 or 7, or a reflect array cell as claimed in any one of claims 8 to 10, wherein the first antenna element (105a) and the second antenna element (105b), or the reflector element (205b) and the first antenna element (205a) are successively formed on the same substrate so as to obtain a monolithic structure. A transmitter network (103) comprising a plurality of cells (105) according to claim 6, 7 or 11. A reflective array (203) comprising a plurality of cells (205) according to any of claims 8 to 11. Antenna (100; 200) comprising a transmitting grating (103) according to claim 12 or a reflecting grating (203) according to claim 13 and at least one source (101; 201) configured to irradiate a face of the grating.

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