COMPACT ANTENNA WITH RESONANCE CAVITY

Description

Technical field

[0001] The invention relates to the technical field of transmitting array antennas (“ Transmit array antenna » in English). A transmitting array antenna comprises: a transmitting network (also called an electromagnetic lens), comprising a set of elementary cells which can be arranged in a matrix form (the matrix can be regular or sparse; the regular matrix can, for example, comprise a square or triangular mesh); at least one radiating source (called a primary source), arranged to illuminate the transmitting network.

[0002] Each elementary cell of the transmitter network is capable of introducing a phase shift to the incident wave emitted by the primary source(s) in order to compensate for each difference in the path of the radiation emitted between the primary source(s) and the transmitter network.

[0003] More precisely, each elementary cell of the transmitter network comprises at least: a first planar antenna (called reception antenna), arranged to receive the incident wave emitted by the primary source(s); a second planar antenna (called transmission antenna), arranged to transmit with a phase shift the incident wave received by the first antenna.

[0004] A "planar antenna" means an electrically conductive flat surface (typically metallic) capable of emitting / receiving electromagnetic radiation. An example of a planar antenna is the microstrip patch (" patch » in English).

[0005] Other elementary cell architectures can also be used, such as multilayer structures based on the concept of frequency-selective surfaces, or on the concept of Fabry-Pérot cavities. Radiating elements such as dipoles, slots, etc. can also be used at the elementary cell level.

[0006] It should be noted that an elementary cell of a transmitter network can operate in reception or transmission, that is to say that the first antenna of the elementary cell can also be a transmission antenna, while the second antenna of the elementary cell can also be a reception antenna.

[0007] The invention finds its application in particular in obtaining a reconfigurable antenna. By "reconfigurable", we mean that at least one characteristic of the antenna can be modified during its lifetime, after its manufacture. The characteristic(s) that can generally be modified are the frequency response (in amplitude and phase), the radiation pattern (also called beam), and the polarization. The reconfiguration of the frequency response covers different functionalities such as frequency switching, frequency tuning, bandwidth variation, phase shift, frequency filtering, etc.The reconfiguration of the radiation pattern covers different functionalities such as angular scanning of the beam pointing direction (also called depointing), beam opening typically defined at half power (i.e. the concentration of the radiation in a particular direction), spatial filtering (related to beam opening and beam forming), beam or multi-beam forming (e.g. several narrow beams replacing a wide beam) etc. A reconfigurable antenna with a transmitting array is particularly advantageous from the C band (4-8 GHz) up to the W band (75-110 GHz), or even the D band (110-170 GHz) or up to the 300 GHz band, for the following applications: . automotive radars for assistance and driving assistance, with a view to active safety, very high resolution imaging and surveillance systems, very high speed communication systems, operating in particular in millimeter bands (inter-building or intra-building communications in home automation or building automation environments, and particularly suited to user monitoring), ground-satellite telemetry links in low LEO orbit (for " Low Earth Orbit » in English) in Ka-band, satellite telecommunications with reconfigurable primary source (SOTM ™< for " Satcom-on-the-Move » in English, internet, television etc.), point-to-point and point-to-multipoint connection systems (metropolitan networks, systems " Fronthaul " And " Backhaul » for cellular networks, radio access for fifth generation mobile networks etc.). State of the art

[0008] A transmitting array antenna known from the state of the art, in particular from document WO 2012 / 085067, comprises: an emissive zone, comprising a radiating source arranged to emit electromagnetic waves; an electromagnetic lens (transmitting network), comprising: a set of phase shifting cells, comprising switches configured to introduce a phase shift to the electromagnetic waves, polarization lines, arranged to polarize the switches.

[0009] Such a transmitting array antenna has a thickness, defined by the distance (called "focal length") between the radiating source and the electromagnetic lens. The various electromagnetic and geometric parameters (e.g. the typology of the radiating elements of the phase-shifting cells and the emissive zone, the surface of the electromagnetic lens, the focal length, etc.) condition the gain of the antenna and its frequency evolution. For example, at parity of F / D ratio, where F is the focal length and D the diameter of the electromagnetic lens, the parameter D - and therefore the parameter F - must be doubled to obtain a gain of 6 dBi (isotropic decibel) and maintain the same relative bandwidth at 1 dB or 3 dB. The F / D ratio is typically between 0.3 and 0.7. If one wishes to maintain the F / D ratio, it is then necessary to increase F.

[0010] Such a state-of-the-art antenna is not entirely satisfactory since the search for a high gain for the antenna will therefore lead to increasing the focal length, and therefore the thickness of the antenna. The search for a high gain, while maintaining the same relative frequency behavior, will therefore require good control of the excitation of the phase-shifting cells over a large aperture. However, controlling the excitation of the phase-shifting cells over a large aperture can prove to be a complex task, in particular when the operating frequency of the antenna is of the order of tens / hundreds of GHz or THz, and this due to a need for high precision of the assembly between the emissive zone and the electromagnetic lens.

[0011] In addition, the switch control electronics must be carefully positioned so as to minimally disturb the radiation transmitted by the phase-shifting cells.

[0012] US 2008 / 042917 A1 discloses a compact high gain antenna. Statement of the invention

[0013] The invention is defined in the appended claims and the invention aims to remedy in whole or in part the aforementioned drawbacks. To this end, the invention relates to a reconfigurable antenna, comprising: an emissive zone, comprising at least one radiating source arranged to emit electromagnetic waves; an electromagnetic lens, comprising: a set of phase-shifting cells, comprising switches configured to introduce a phase shift to the electromagnetic waves, polarization lines, arranged to polarize the switches; an electromagnetic coupling zone, arranged between the emissive zone and the electromagnetic lens to generate an electromagnetic coupling between the electromagnetic waves and the set of phase-shifting cells; the electromagnetic coupling zone comprises a set of electrically conductive elements, arranged to form an outline of a resonant cavity guiding the electromagnetic waves towards the electromagnetic lens, the set of electrically conductive elements comprising first tracks electrically connected to the polarization lines. Definitions

[0014] By "radiating source" is meant any system (preferably a focal system) adapted to emit electromagnetic waves. By "electromagnetic lens" is meant a transmitting network. By "phase-shifting cell" is meant an elementary cell of a transmitting network. For example, an elementary cell may comprise at least: a first planar antenna (called a receiving antenna), arranged to receive an incident wave emitted by the radiating source(s); a second planar antenna (called a transmitting antenna), arranged to transmit with a phase shift the incident wave received by the first antenna.

[0015] Other elementary cell architectures can also be used, such as multilayer structures based on the concept of frequency-selective surfaces, or on the concept of Fabry-Pérot cavities. Radiating elements such as dipoles, slots, etc. can also be used at the elementary cell level. By "switches" we mean elements that allow or prohibit the flow of an electric current, for example between two separate radiating surfaces of the transmitting antenna of the phase shifting cell. By "polarization lines" we mean tracks made of an electrically conductive material. By "electrically conductive" we mean an element having an electrical conductivity at 300 K greater than 10 2 < S / cm. By "electromagnetic coupling" we mean a coupling (i.e. a transfer of energy) by electromagnetic field between the electromagnetic waves emitted by the radiating source(s) and the phase shifting cells (more precisely with the radiating surface of the receiving antenna of the phase shifting cells).

[0016] Thus, such an antenna according to the invention makes it possible to facilitate the excitation of the phase-shifting cells over a large aperture, when a high antenna gain is desired, thanks to such an electromagnetic coupling zone which allows excitation of the phase-shifting cells in the near field. The size and shape of the resonant cavity can be adapted to optimize the radiation received by the phase-shifting cells, for example to homogenize the amplitude and the phase and increase the coupling efficiency.

[0017] The use of electromagnetic coupling then makes it possible in particular to obtain an antenna with a reduced thickness compared to a slotted antenna, to avoid a significant decrease in the electromagnetic field received by the phase-shifting cells located on the edges of the electromagnetic lens, or even to overcome a (frequency) dependence of the electromagnetic radiation received by the phase-shifting cells during beam defocusing.

[0018] Furthermore, such a resonant cavity makes it possible not to lose energy on the lateral parts of the antenna, which makes it possible to increase the quality of the radiation transmitted by the phase-shifting cells located on the edges of the electromagnetic lens, and to control the illumination law of the electromagnetic lens (apodization or " aperture taper " in English). Examples include the increase in radiation efficiency, thanks to the reduction of the " spill» (part of the emitted radiation which does not reach the phase-shifting cells, a phenomenon present if the resonant cavity is permissive to electromagnetic waves), the reduction of the levels of the secondary lobes (SLL for “ Side Lobe Level » in English) etc.

[0019] The set of electrically conductive elements, forming a contour of the resonant cavity, allows electromagnetic shielding in the vicinity of the lateral parts of the transmitting array antenna.

[0020] Finally, the fact that the set of electrically conductive elements comprises first tracks electrically connected to the polarization lines makes it possible to consider moving the control electronics of the switches (for example under the antenna) so as to minimally disturb the radiation emitted by the radiating source(s), and the radiation transmitted by the phase-shifting cells.

[0021] The antenna according to the invention may comprise one or more of the following characteristics.

[0022] According to a characteristic of the invention, the resonant cavity comprises: a first open end, opening onto the electromagnetic lens; a second open end, opposite, opening onto the emissive zone; a lateral part, connecting the first and second open ends, the outline of which is formed by the set of electrically conductive elements.

[0023] According to a characteristic of the invention, the electromagnetic coupling zone extends in a dielectric medium.

[0024] Thus, an advantage provided is to avoid electromagnetic disturbances in the electromagnetic coupling zone. The dielectric medium can be air.

[0025] According to a characteristic of the invention, the electromagnetic coupling zone comprises a dielectric substrate, comprising interconnection levels; the first tracks being formed on the interconnection levels; and the set of electrically conductive elements comprises first interconnection holes, arranged to electrically connect the first tracks between the interconnection levels. Definition

[0026] By "dielectric substrate" is meant that the substrate has an electrical conductivity at 300 K of less than 10 -8< S / cm. By "via hole" (" via " in English), we mean a metallized hole allowing an electrical connection to be established between different levels of interconnection.

[0027] Thus, an advantage provided is to consider an integration of the resonant cavity within the dielectric substrate.

[0028] According to a characteristic of the invention, the set of electrically conductive elements comprises second tracks electrically connected to the polarization lines.

[0029] According to a feature of the invention, the second tracks are formed on the interconnection levels; and the set of electrically conductive elements comprises second interconnection holes, arranged to electrically connect the second tracks between the interconnection levels.

[0030] According to a characteristic of the invention, the antenna comprises switching means configured to switch between the first and second tracks, the first or second non-switched tracks being at floating electrical potential. Definition

[0031] By "floating electrical potential" we mean that the unswitched traces are not subject to a reference electrical potential at the antenna operating frequency.

[0032] Thus, an advantage provided is to add a degree of freedom to adjust the electromagnetic behavior of the resonant cavity. More precisely, there is a first resonant cavity whose contour is formed by the first tracks and the first vias. Similarly, there is a second resonant cavity whose contour is formed by the second tracks and the second vias. The switching means therefore make it possible to switch between the first resonant cavity and the second resonant cavity. As non-limiting examples, the first resonant cavity can be configured (size, shape) to widen the bandwidth, while the second resonant cavity can be configured (size, shape) to increase the depointing range.

[0033] According to a characteristic of the invention, the set of electrically conductive elements is arranged so that the contour of the resonant cavity has a cross section increasing from the emissive zone towards the electromagnetic lens. Definitions

[0034] By "cross-section" is meant a section perpendicular to an axis corresponding to the normal to a plane defined by the electromagnetic lens. By "increasing" is meant that the area of ​​the cross-section increases from the emissive zone towards the electromagnetic lens.

[0035] Thus, an advantage provided by such a shape of the resonant cavity is to promote a significant gain for the antenna.

[0036] According to a characteristic of the invention, the set of electrically conductive elements is arranged so that the contour of the resonant cavity has axial symmetry. Definition

[0037] By "axial symmetry" we mean a symmetry along an axis corresponding to the normal to a plane defined by the electromagnetic lens.

[0038] Thus, one advantage provided by such a shape of the resonant cavity is to promote the directivity of the antenna, that is, the ability of the antenna to concentrate the radiated energy in a solid angle or in a specific direction.

[0039] According to a characteristic of the invention, the emissive zone is planar.

[0040] Thus, an advantage provided is to allow a monolithic integration of the emissive zone to the resonant cavity when the resonant cavity is formed in a dielectric substrate.

[0041] According to a characteristic of the invention, the electromagnetic lens is planar.

[0042] Thus, an advantage provided is to allow monolithic integration of the electromagnetic lens to the resonant cavity when the resonant cavity is formed in a dielectric substrate.

[0043] According to a characteristic of the invention, the emissive zone, the electromagnetic coupling zone and the electromagnetic lens are monolithic. Definition

[0044] By "monolithic" we mean that the emissive zone, the electromagnetic coupling zone and the electromagnetic lens share a common substrate, in the sense that the emissive zone, the electromagnetic coupling zone and the electromagnetic lens are formed on the same substrate.

[0045] Thus, one advantage is to simplify the manufacturing of the antenna with a monolithic technology, for example a PCB technology (“ Printed Circuit Board » in English) or LTCC (“ Low Temperature Co-fired Ceramic» in English). These technologies allow monolithic implementations, with substrate thicknesses typically between 100 µm and 10 mm, and are particularly suitable when the antenna operating frequency is between 1 GHz and 1 THz, with low substrate thicknesses being suitable for frequencies in the GHz range, while high substrate thicknesses are suitable for frequencies in the THz range.

[0046] According to a characteristic of the invention, the resonant cavity has a thickness between λ and 10 λ, where λ is the wavelength of the electromagnetic waves.

[0047] Thus, one advantage provided is to obtain a compact cavity.

[0048] The invention also relates to a passive antenna, comprising: an emissive zone, comprising at least one radiating source arranged to emit electromagnetic waves; an electromagnetic lens, comprising: a set of phase shifting cells, configured to introduce a phase shift to the electromagnetic waves, a ground plane; an electromagnetic coupling zone, arranged between the emissive zone and the electromagnetic lens to generate an electromagnetic coupling between the electromagnetic waves and the set of phase shifting cells; the electromagnetic coupling zone comprises a set of electrically conductive elements, arranged to form an outline of a resonant cavity guiding the electromagnetic waves towards the electromagnetic lens, the set of electrically conductive elements comprising tracks electrically connected to the ground plane. Definitions

[0049] By "passive antenna" is meant that the phase shifting cells do not include active electronic components to introduce a phase shift to the electromagnetic waves. The phase shift can be achieved, for example, by different geometric configurations of the receiving and transmitting antennas of the phase shifting cell. By "ground plane" is meant an electrically conductive surface, preferably metallic, forming an electrical ground plane so as to define a reference potential for the electromagnetic waves.

[0050] Thus, such an antenna according to the invention makes it possible to facilitate the excitation of the phase-shifting cells over a large aperture, when a high antenna gain is desired, thanks to such an electromagnetic coupling zone which allows excitation of the phase-shifting cells in the near field. The size and shape of the resonant cavity can be adapted to optimize the radiation received by the phase-shifting cells, for example to homogenize the amplitude and the phase and increase the coupling efficiency.

[0051] Furthermore, such a resonant cavity makes it possible not to lose energy on the lateral parts of the antenna, which makes it possible to increase the quality of the radiation transmitted by the phase-shifting cells located on the edges of the electromagnetic lens, and to control the illumination law of the electromagnetic lens (apodization or " aperture taper" in English). Examples include the increase in radiation efficiency, thanks to the reduction of the " spillover » (part of the emitted radiation which does not reach the phase-shifting cells, a phenomenon present if the resonant cavity is permissive to electromagnetic waves), the reduction of the levels of the secondary lobes (SLL for “ Side Lobe Level » in English) etc.

[0052] The set of electrically conductive elements, forming a contour of the resonant cavity, allows electromagnetic shielding in the vicinity of the lateral parts of the transmitting array antenna. Brief description of the drawings

[0053] Other features and advantages will become apparent in the detailed description of various embodiments of the invention, the description being accompanied by examples and references to the accompanying drawings. Figure 1 is a schematic perspective view of an antenna according to the invention. Figure 2is a schematic exploded perspective view of an antenna according to the invention, illustrating a first embodiment of the resonant cavity. The dielectric medium is not shown to facilitate visualization. Figure 3 is a schematic perspective view of an antenna according to the invention, illustrating a second embodiment of the resonant cavity. The dielectric medium is not shown to facilitate visualization. Figure 4 is a schematic sectional view of a passive antenna according to the invention. The arrow indicates the direction of the radiation transmitted by the electromagnetic lens. Figure 5 is a schematic sectional view of a reconfigurable antenna according to the invention, illustrating a first form of the resonant cavity. The arrow designates the direction of the radiation transmitted by the electromagnetic lens. Figure 6is a schematic sectional view of a reconfigurable antenna according to the invention, illustrating a second form of the resonant cavity. The arrow designates the direction of the radiation transmitted by the electromagnetic lens. Figure 7 is a schematic sectional view of a reconfigurable antenna according to the invention, illustrating an embodiment where it is possible to switch between a first resonant cavity and a second resonant cavity of different shape. The arrow designates the direction of the radiation transmitted by the electromagnetic lens.

[0054] The figures are not drawn to scale for readability and to simplify their understanding. Detailed description of the implementation methods

[0055] Identical elements or those providing the same function will bear the same references for the different embodiments, for the sake of simplification.

[0056] An object of the invention is a reconfigurable antenna 1, comprising: an emissive zone ZE, comprising at least one radiating source S arranged to emit electromagnetic waves; an electromagnetic lens 2, comprising: a set of phase-shifting cells 20, comprising switches 200 configured to introduce a phase shift to the electromagnetic waves, polarization lines BL, arranged to polarize the switches 200; an electromagnetic coupling zone ZC, arranged between the emissive zone ZE and the electromagnetic lens 2 to generate an electromagnetic coupling between the electromagnetic waves and the set of phase-shifting cells 20; the electromagnetic coupling zone ZC comprises a set of electrically conductive elements, arranged to form an outline of a resonant cavity 3 guiding the electromagnetic waves towards the electromagnetic lens 2, the set of electrically conductive elements comprising first tracks P1 electrically connected to the polarization lines BL. Emitting zone

[0057] The emissive zone ZE is advantageously planar, so that each radiating source S is equidistant from the electromagnetic lens 2.

[0058] The or each radiating source S is advantageously configured to operate at a frequency between 1 GHz and 1 THz, preferably between 10 GHz and 300 GHz.

[0059] The emissive zone ZE is advantageously electrically connected to a transceiver (“ Transceiver » in English), located at the rear of antenna 1 or under antenna 1. Electromagnetic lens

[0060] The electromagnetic lens 2 is advantageously planar.

[0061] Each phase-shifting cell 20 can comprise: a first planar antenna (called reception antenna, not shown), arranged to receive the incident wave emitted by the radiating source(s) S; a second planar antenna Tx (called transmission antenna), arranged to transmit with a phase shift the incident wave received by the first planar antenna.

[0062] The first planar antenna and the second planar Tx antenna are advantageously arranged on either side of a ground plane (not shown, except in Figure 4for a passive, non-reconfigurable antenna). The ground plane is preferably made of a metallic material, more preferably copper. As a non-limiting example, the ground plane may have a thickness of around 17 µm when the operating frequency of the transmitting array antenna is 29 GHz.

[0063] The second planar antenna Tx advantageously has first and second disjointed radiation surfaces, in the sense that they are separated from each other by a separation zone so as to be electrically insulated from each other. For this purpose, a slot is advantageously formed in the second planar antenna Tx to electrically isolate the first and second disjointed radiation surfaces. The slot defines the separation zone. The slot is preferably annular, with a rectangular section. Of course, other shapes are conceivable for the slot, such as an elliptical or circular shape. According to an alternative embodiment, the electrical insulation of the first and second radiation surfaces of the second planar antenna can be ensured by a dielectric material.

[0064] Each phase shifting cell 20 advantageously comprises a phase shifting circuit comprising first and second switches 200 respectively having an alternating on state and a blocked state, the on or blocked states corresponding to a flow of a current, respectively authorized or blocked, between the first and second disjointed radiation surfaces of the second planar antenna Tx. By "alternating", it is meant that the first switch 200 alternates between the on state and the blocked state, while, simultaneously, the second switch 200 alternates between the blocked state and the on state. In other words, at any time, the first and second switches 200 belonging to the same phase shifting circuit have two opposite states, either on / off, or blocked / on. The on / off or blocked / blocked states are not authorized.

[0065] As non-limiting examples, the switches 200 of the phase-shifting cells 20 may be pin-type diodes, MEMS (“ Micro Electro-Mechanical Systems » in English), NEMS (“ Nano Electro-Mechanical Systems » in English). The pin-type diodes can be made of AlGaAs. Other embodiments are possible for the switches 200. As non-limiting examples, radiofrequency switches of the diode, transistor, photodiode, phototransistor type are possible. The choice of a device for controlling the switches 200 depends on the technology chosen. As examples, the following devices can be used: an optical fiber for a photoelectric switch, a laser beam generated by external means and exciting a photoelectric switch, an electromagnetic wave according to the principles of remote power supply known from the field of RFID (" Radio Frequency Identification » in English).

[0066] The polarization lines BL are electrically conductive tracks, forming means for controlling the switches 200 of the phase-shifting cells 20. The polarization lines BL are preferably made of a metallic material, more preferably copper. The polarization lines BL can be electrically connected to the set of electrically conductive elements, and to the second planar antenna Tx, via transmission lines LT.

[0067] Other phase-shifting cell architectures 20 may also be used, such as multi-layer structures based on the concept of frequency-selective surfaces, or on the concept of Fabry-Pérot cavities. Electromagnetic coupling zone

[0068] The electromagnetic coupling zone ZC advantageously extends in a dielectric medium.

[0069] The electromagnetic coupling zone ZC advantageously comprises a dielectric substrate 4, comprising interconnection levels. By way of non-limiting example, the dielectric substrate 4 may be made of a commercial material such as RT / duroid ®< 6002. The dielectric substrate 4 has a thickness typically between 100 µm and 1500 µm for an operating frequency of the antenna between 10 GHz and 300 GHz. By way of non-limiting example, the dielectric substrate 4 may have a thickness of the order of 4 mm when the operating frequency is 60 GHz.

[0070] The first tracks P1 are advantageously formed on the interconnection levels. The set of electrically conductive elements advantageously comprises first vias V1, arranged to electrically connect the first tracks P1 between the interconnection levels.

[0071] The set of electrically conductive elements may comprise second tracks P2 electrically connected to the polarization lines BL. The second tracks P2 are advantageously formed on the interconnection levels. The set of electrically conductive elements advantageously comprises second vias V2, arranged to electrically connect the second tracks P2 between the interconnection levels. The antenna 1 advantageously comprises switching means 5 configured to switch between the first and second tracks P1, P2, the first or second non-switched tracks P1, P2 being at floating electrical potential. For this purpose, additional switching means 5' may be provided on the polarization lines BL so that the first or second non-switched tracks P1, P2 are at floating electrical potential.

[0072] The resonant cavity 3 advantageously comprises: a first open end 30, opening onto the electromagnetic lens 2; a second open end 31, opposite, opening onto the emissive zone ZE; a lateral part 32, connecting the first and second open ends 30, 31, the outline of which is formed by the set of electrically conductive elements.

[0073] The resonant cavity 3 is therefore delimited by the emissive zone ZE, the electromagnetic lens 2 and the set of electrically conductive elements. According to one embodiment, the resonant cavity 3 is delimited by the emissive zone ZE, the electromagnetic lens 2, the first tracks P1 and the first via holes V1. In other words, the first tracks P1 and the first via holes V1 form the outline of the lateral portion 32 of the resonant cavity 3. According to another embodiment, the resonant cavity 3 is delimited by the emissive zone ZE, the electromagnetic lens 2, the second tracks P2 and the second via holes V2. In other words, the second tracks P2 and the second via holes V2 form the outline of the lateral portion 32 of the resonant cavity 3.

[0074] The resonant cavity 3 advantageously has a thickness of between λ and 10 λ, where λ is the wavelength of the electromagnetic waves. The size and shape of the resonant cavity 3 are defined by the template of the first and second tracks P1, P2 and the first and second interconnection holes V1, V2. The template is determined by electromagnetic simulations according to the desired properties of the antenna 1.

[0075] According to one embodiment, the set of electrically conductive elements is arranged so that the contour of the resonant cavity 3 has a cross section increasing from the emissive zone ZE towards the electromagnetic lens 2.

[0076] According to one embodiment, the set of electrically conductive elements is arranged so that the contour of the resonant cavity 3 has axial symmetry. Monolithic integration

[0077] The emissive zone ZE, the electromagnetic coupling zone ZC and the electromagnetic lens 2 are advantageously monolithic, within the dielectric substrate 4.

[0078] The antenna 1 can be manufactured with a planar technology allowing a monolithic implementation, preferably selected from: a PCB technology (“ Printed Circuit Board » in English), an LTCC technology (“ Low Temperature Co-fired Ceramic » in English), a WLP technology (“ Wafer-Level Packaging » in English). Passive antenna (fixed beam)

[0079] An object of the invention is also a passive antenna 1, comprising: an emissive zone ZE, comprising at least one radiating source S arranged to emit electromagnetic waves; an electromagnetic lens 2, comprising: a set of phase-shifting cells 20, configured to introduce a phase shift to the electromagnetic waves, a ground plane PM; an electromagnetic coupling zone ZC, arranged between the emissive zone ZE and the electromagnetic lens 2 to generate an electromagnetic coupling between the electromagnetic waves and the set of phase-shifting cells 20; the electromagnetic coupling zone ZC comprises a set of electrically conductive elements, arranged to form an outline of a resonant cavity 3 guiding the electromagnetic waves towards the electromagnetic lens 2, the set of electrically conductive elements comprising tracks P electrically connected to the ground plane PM.

[0080] The PM ground plane is preferably made of a metallic material, more preferably copper. As a non-limiting example, the PM ground plane may have a thickness of the order of 17 µm when the operating frequency of the transmitting array antenna is 29 GHz.

[0081] Each phase-shifting cell 20 can comprise: a first planar antenna (called reception antenna, not shown), arranged to receive the incident wave emitted by the radiating source(s) S; a second planar antenna Tx (called transmission antenna), arranged to transmit with a phase shift the incident wave received by the first planar antenna.

[0082] Other phase-shifting cell architectures 20 may also be used, such as multi-layer structures based on the concept of frequency-selective surfaces, or on the concept of Fabry-Pérot cavities.

[0083] The first planar antenna and the second planar Tx antenna are arranged on either side of the PM ground plane. The PM ground plane can be electrically connected to the set of electrically conductive elements via LT transmission lines.

[0084] The electromagnetic coupling zone ZC advantageously comprises a dielectric substrate 4, comprising interconnection levels. The P tracks are advantageously formed on the interconnection levels. The set of electrically conductive elements advantageously comprises interconnection holes V, arranged to electrically connect the P tracks between the interconnection levels.

[0085] The resonant cavity 3 advantageously comprises: a first open end 30, opening onto the electromagnetic lens 2; a second open end 31, opposite, opening onto the emissive zone ZE; a lateral part 32, connecting the first and second open ends 30, 31, the outline of which is formed by the set of electrically conductive elements.

[0086] The resonant cavity 3 advantageously has a thickness between λ and 10 λ, where λ is the wavelength of the electromagnetic waves.

[0087] The invention is not limited to the embodiments disclosed. Those skilled in the art are able to consider their technically effective combinations.

Claims

1. Reconfigurable antenna (1), comprising: - an emissive region (ZE), comprising at least one radiating source (S) designed to emit electromagnetic waves; - an electromagnetic lens (2), comprising: a set of phase-shifting cells (20), comprising switches (200) configured so as to introduce a phase shift to the electromagnetic waves, bias lines (BL), designed to bias the switches (200); - an electromagnetic coupling region (ZC), arranged between the emissive region (ZE) and the electromagnetic lens (2) in order to generate electromagnetic coupling between the electromagnetic waves and the set of phase-shifting cells (20); the electromagnetic coupling region (ZC) comprises a set of electrically conductive elements, arranged so to form a profile of a resonant cavity (3) guiding the electromagnetic waves towards the electromagnetic lens (2), the set of electrically conductive elements comprising first tracks (P1) electrically connected to the bias lines (BL).

2. Reconfigurable antenna (1) according to Claim 1, wherein the resonant cavity (3) has: - a first open end (30), opening onto the electromagnetic lens (2); - an opposing second open end (31), opening onto the emissive region (ZE); - a lateral part (32), connecting the first and second open ends (30, 31), the profile of which is formed by the set of electrically conductive elements.

3. Reconfigurable antenna (1) according to Claim 1 or 2, wherein the electromagnetic coupling region (ZC) extends in a dielectric medium.

4. Reconfigurable antenna (1) according to one of Claims 1 to 3, wherein the electromagnetic coupling region (ZC) comprises a dielectric substrate (4), comprising interconnect levels; the first tracks (P1) being formed on the interconnect levels; and the set of electrically conductive elements comprises first vias (V1), designed to electrically connect the first tracks (P1) between the interconnect levels.

5. Reconfigurable antenna (1) according to one of Claims 1 to 4, wherein the set of electrically conductive elements comprises second tracks (P2) electrically connected to the bias lines (BL).

6. Reconfigurable antenna (1) according to Claim 5 in combination with Claim 4, wherein the second tracks (P2) are formed on the interconnect levels; and the set of electrically conductive elements comprises second vias (V2), designed to electrically connect the second tracks (P2) between the interconnect levels.

7. Reconfigurable antenna (1) according to Claim 5 or 6, comprising switching means (5) configured so as to switch between the first and second tracks (P1, P2), the non-switched first or second tracks (P1, P2) being at floating electrical potential.

8. Reconfigurable antenna (1) according to one of Claims 1 to 7, wherein the set of electrically conductive elements is arranged such that the profile of the resonant cavity (3) has a cross section that increases from the emissive region (ZE) towards the electromagnetic lens (2).

9. Reconfigurable antenna (1) according to one of Claims 1 to 8, wherein the set of electrically conductive elements is arranged such that the profile of the resonant cavity (3) exhibits axial symmetry.

10. Reconfigurable antenna (1) according to one of Claims 1 to 9, wherein the emissive region (ZE) is planar.

11. Reconfigurable antenna (1) according to one of Claims 1 to 10, wherein the electromagnetic lens (2) is planar.

12. Reconfigurable antenna (1) according to one of Claims 1 to 11, wherein the emissive region (ZE), the electromagnetic coupling region (ZC) and the electromagnetic lens (2) are monolithic.

13. Reconfigurable antenna (1) according to one of Claims 1 to 12, wherein the resonant cavity (3) has a thickness between λ and 10 λ, where λ is the wavelength of the electromagnetic waves.