Antenna for transmitting and / or receiving an electromagnetic wave, and system comprising this antenna

Abstract

An antenna for transmitting and / or receiving an electromagnetic wave, comprising a radiating element, an adaptable surface with variable impedance, and a controller that is linked to the adaptable surface and controls it based on a desired direction of the electromagnetic wave. The radiating element and the adaptable surface are integrated within a housing, the housing forming a recess for the waves and comprising an opening in order for the electromagnetic wave to be emitted to the outside.

Description

TECHNICAL FIELD

[0001] The present invention relates to antennas for emitting and / or receiving an electromagnetic wave in a desired direction. These antennas are said to be directional, that is to say, they emit and / or receive a beam of electromagnetic waves, this beam being orientable. STATE OF PRIOR ART

[0002] More specifically, the invention relates to an antenna comprising: a radiating element adapted to emit and / or receive said electromagnetic wave, an adaptable surface comprising a plurality of adjustable elements adapted to modify an impedance of said adaptable surface and to modify the way in which the electromagnetic wave is reflected by said adaptable surface, and a controller connected to the adaptable surface and which controls the adjustable elements thereof from parameters, said parameters being determined from the desired direction of the electromagnetic wave.

[0003] Furthermore, the antenna is advantageously configured so that: the radiating element and the adaptable surface are integrated inside a housing forming a cavity, and said housing comprising an opening adapted so that the electromagnetic wave is emitted outwards or is received from outside the housing, through said opening, and towards / from a far field.

[0004] An antenna is isotropic if it emits and / or receives an electromagnetic wave in the same way in all directions. An antenna is directional if it emits and / or receives an electromagnetic wave in a specific direction. These directional antennas are characterized by a radiation pattern, that is, the amplitude of the electromagnetic wave as a function of a direction in a horizontal and / or vertical plane. Such a radiation pattern is generally established with respect to an angle in each plane; it is therefore a polar curve that represents the wave amplitude as a function of the angle between 0° and 360°. This curve generally includes protrusions called lobes, which are angular directions in which the antenna emits more or receives more (is more sensitive).An antenna is therefore directional if its radiation pattern has a main lobe of large amplitude in a determined direction, and other secondary lobes of lower amplitude than that of the main lobe.

[0005] Next, to control the direction of a directional antenna, there are many techniques.

[0006] For example, there are phased array antennas which are composed of a network of radiating elements, each controlled in phase and amplitude to generate overall directional radiation with an inclinable direction.

[0007] In this type of antenna, there are numerous radiating elements, each connected to a controlled amplifier. The antenna is therefore complex and consumes a lot of energy.

[0008] For example, there are reflect array type antennas such as the antenna in US patent 2004 / 263408 which uses a horn-type radiating element, known to have a directional and concentrated radiation pattern in one direction, and an adaptable surface positioned in front of the horn to reflect the electromagnetic wave in a direction determined by the states of the adjustable elements of this adaptable surface.

[0009] The radiating element (horn) has a main radiation lobe with a fixed direction, but by changing the states of the adjustable elements, the antenna controller modifies the amplitude and / or phase of the wave reflected by each adjustable element of the adaptive surface, and thus changes the direction of the reflected electromagnetic wave. The adaptive surface therefore allows the main lobe generated by the radiating element to be tilted.

[0010] In this type of antenna, the adaptable surface is positioned at a distance from the radiating element. The antenna is therefore generally very large (not very compact) and has a limited spatial radiation range because the adaptable surface generates a significant shadow area.

[0011] US document 2013 / 201 068 A1 shows an antenna circuit comprising a source, a high-impedance surface, and a programmable surface.

[0012] US document 2017 / 352 952 A1 shows an antenna with an adaptable focusing reflector.

[0013] US document 2018 / 076 521 A1 shows an antenna aperture impedance matching device. DESCRIPTION OF THE INVENTION

[0014] The present invention aims to improve steerable beam antennas.

[0015] For this purpose, the adaptable surface is positioned on one or more internal walls of the case and is separated from the opening, so that the electromagnetic wave is reflected several times inside the case to impact several times adjustable elements of the adaptable surface.

[0016] Thanks to these arrangements, the electromagnetic wave generated by the radiating element is reflected several times within the cavity and by the adaptable surface before being emitted through the aperture (direct or semi-reflective) to the outside of the housing. This electromagnetic wave is then more easily controlled before its far-field emission. In particular, it is possible to simultaneously create, with any type of radiating element, a directional antenna with a large-amplitude main lobe that can be tilted in any direction.

[0017] Furthermore, electromagnetic radiation losses outside the adaptive surface are avoided. The wave emitted by the radiating element is almost entirely reflected by the adaptive surface, and therefore almost all of the emitted wave can be controlled to be concentrated into a single beam, i.e., a high-energy main lobe. The antenna is thus more efficient.

[0018] In addition, all paths between the radiating element and the adaptable surface are contained within the volume of the cavity, i.e. inside the housing, and the antenna is more compact.

[0019] Finally, the adjustable elements of the adaptable surface can be distributed in any way within the cavity because the multiple reflections ensure that they sweep across the internal surface of the housing and thus impact all the adjustable elements.

[0020] In various embodiments of the antenna according to the invention, one may optionally also use one and / or the other of the following arrangements: According to one aspect, a screen positioned in the cavity between the radiating element and the opening to limit direct electromagnetic wave radiation from the radiating element to the outside of the housing and / or to reflect the waves towards the adaptable surface.

[0021] According to one aspect, the opening consists of several elementary openings, these elementary openings being on one face of the case or on a plurality of faces of the case.

[0022] According to one aspect, the opening is made up at least partially of one or more semi-reflective elements.

[0023] According to one aspect, the semi-reflective element is made of a thin metallic film.

[0024] According to one aspect, the semi-reflective element is made by a network of holes in a metallic element or a network of metallic shapes, a hole or shape being distant from another neighbor by a distance less than half the wavelength of the electromagnetic wave.

[0025] According to one aspect, the semi-reflective element has an electromagnetic transmission property that varies in the surface of the aperture.

[0026] According to one aspect, the electromagnetic transmission property includes the transmission amplitude and / or the transmission phase.

[0027] According to one aspect, the semi-reflective element includes one or more adjustable aperture elements adapted to modify the way in which the electromagnetic wave is reflected and / or transmitted by said aperture, the controller being connected to the adjustable aperture elements to control them from aperture parameters.

[0028] According to one aspect, the radiating element is positioned in the housing to emit and / or receive an electromagnetic wave mainly directly towards the adaptable surface, by orientation of said element in the housing.

[0029] According to one aspect, the radiating element is impedance-matched to the cavity impedance, to meet a critical coupling condition.

[0030] According to one aspect, the radiating element is chosen from a list including a monopole, a dipole, a waveguide, a radiating waveguide, and a planar antenna.

[0031] Depending on one aspect, the adaptable surface covers all the interior faces of the case, or a portion of the interior faces of the case, or one or more of the interior faces of the case.

[0032] According to one aspect, the adaptable surface consists of adjustable elements distributed throughout the housing without periodicity.

[0033] According to one aspect, the adaptable surface comprises first adjustable elements tuned to a first frequency and second adjustable elements tuned to a second frequency, the first frequency being different from the second frequency.

[0034] In one aspect, the first and second adjustable elements are spatially mixed.

[0035] According to one aspect, the adaptable surface includes adjustable elements tuned to a plurality of different frequencies within a predetermined bandwidth.

[0036] According to one aspect, the casing comprises a main face, and the casing has a thickness dimension in a direction perpendicular to said main face that is less than the other dimensions of the casing, and the thickness dimension is greater than half the wavelength of the electromagnetic wave.

[0037] According to one aspect, the case comprises a main face, and the main face is semi-spherical in shape.

[0038] In one aspect, the controller also determines the parameters based on a desired polarization.

[0039] Depending on one aspect, the controller determines the parameters from parameter values ​​pre-recorded in memory, or by calculating a model or by an iterative process using additional information.

[0040] According to one aspect, the additional information comes from signals from external sensors located outside the casing and adapted to receive the electromagnetic wave.

[0041] According to one aspect, the antenna further includes one or more internal sensors adapted to receive the electromagnetic wave, said internal sensors being integrated inside the housing, and the controller determines the parameters from a desired direction of the electromagnetic wave and values ​​of the electromagnetic wave received by the internal sensors at certain predetermined periods.

[0042] According to one aspect, the antenna comprises a plurality of radiating elements integrated inside the housing.

[0043] The invention also relates to a radio communication system Suitable for transmitting audio, video, messages, or data. This radio communication system includes an antenna as shown above.

[0044] The invention also relates to a radar detection system Adapted for locating objects in a space. This radar detection system includes an antenna as shown above. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Other features and advantages of the invention will become apparent during the following description of one of its embodiments, given by way of non-limiting example, with regard to the accompanying drawings.

[0046] Regarding the drawings: there figure 1 is a schematic view of a first embodiment of an antenna according to the invention, the figure 2a shows radiation from the antenna of the figure 1 without parameter optimization, the figure 2b shows radiation from the antenna of the figure 1 after optimization of the parameters by the controller, the figure 3a is a radiation pattern of the antenna of the figure 1 without parameter optimization, the figure 3b is a radiation pattern of the antenna of the figure 1 after optimization of the parameters by the controller, the figure 4a is another radiation pattern of the antenna figure 1with parameters optimized to emit at a 90° angle, the figure 4b is another radiation pattern of the antenna figure 1 , with parameters optimized to emit at a 60° angle, the figure 5a is a schematic view of a variant of the antenna of the figure 1 , comprising an opening made up of several elementary openings on one face of the casing, the figure 5b is a schematic view of a variant of the antenna of the figure 1 , comprising an opening composed of several elementary openings on several faces of the casing, the figure 6 is a schematic view of a variant of the antenna of the figure 1 with a dome-shaped casing, the figure 7 is a side cross-sectional view of an antenna according to the figure 1 including a screen and reflecting devices, and the figure 8 shows a second embodiment of a spherical antenna not part of the claimed invention. DETAILED DESCRIPTION

[0047] There figure 1 shows a first embodiment of the invention of an antenna 10 according to the invention. The antenna 10 is an antenna for emitting and / or receiving an electromagnetic wave in a desired direction.

[0048] Antenna 10 includes: a radiating element 20 for emitting and / or receiving the electromagnetic wave, an adaptable surface 30 comprising a plurality of adjustable elements 31 for modifying an impedance of the adaptable surface and for modifying the way in which the electromagnetic wave is reflected and / or transmitted by said adaptable surface, and a controller 40 connected to the adaptable surface and which controls the adjustable elements of the latter from parameters, the parameters being determined from the desired direction of the electromagnetic wave. Such an antenna can be used, for example, in: a radio communication system suitable for transmitting audio, video, messages or data, or a radar detection system suitable for locating objects in space

[0049] Variants of known adaptable surfaces are described, for example, in the aforementioned US document 2004 / 263408 or in the US document 2016 / 0233971. Many techniques are known for realizing such adaptable surfaces, sometimes called adaptable impedance surfaces, meta-surfaces, wave-shaping devices, reflection gratings.

[0050] For the antenna 10 according to the invention, the radiating element 20 and the adaptable surface 30 are integrated inside a housing 11, often called a "radome" in this technical field. However, here, the housing not only serves to protect the antenna, but the housing 11 also forms a cavity 12 (an electromagnetic cavity) for the We waves emitted and / or received by the radiating element 20. The housing 11 is thus adapted so that these We waves are reflected once or several times inside the housing and possibly reflected once or several times by adjustable elements 31 of the adaptable surface 30.

[0051] For example, the casing 11 is made of a material transparent to electromagnetic waves and its internal surface is at least partially metallized or covered with a metallic (metallized) layer suitable for reflecting the We waves emitted by the radiating element 20.

[0052] More generally, the housing 11 includes a means for reflecting the We waves once or several times inside the housing so that these waves impact adjustable elements 31 of the adaptable surface 30 once or several times. Thanks to these multiple reflections on adjustable elements, these waves can be controlled with a very wide variety of settings.

[0053] Furthermore, the casing 11 is a three-dimensional enclosure that temporarily encloses the We waves. This enclosure has, for example, a parallelepiped shape comprising, for example, a lower face, an upper face, and lateral faces. These faces include the aforementioned means for reflecting the waves.

[0054] Alternatively, the 11 case has a semi-spherical or spherical shape.

[0055] For example, the faces or surfaces of the housing 11 are covered with a suitable material so that the wave We emitted and / or received by the radiating element 20 is reflected by the faces of this 3-dimensional housing 11. The suitable material is, for example, a metallic or metallized material or a material loaded with metallic particles.

[0056] The housing 11 includes an aperture 13 so that the electromagnetic wave We is emitted outwards or received from outside the housing 11, through this aperture 13, as an externally propagating electromagnetic wave Wa. Once emitted from the housing 11, this electromagnetic wave Wa, emitted by the antenna 10, then propagates towards a far field. Conversely, the housing 11 acts as a sensor that absorbs, through the aperture 13, electromagnetic waves Wa originating from a far field so that the radiating element 20 in the housing receives a large quantity of We waves internal to the cavity.

[0057] This opening 13 is an opening in the electromagnetic sense: The housing 11 may be physically closed and sealed, but there is an electromagnetic opening 13 that allows electromagnetic waves to leak at least partially to the outside of the housing. For example, it is sufficient for a portion of the housing to be unmetallized.

[0058] The antenna 10 according to the invention is therefore made up of an electromagnetic cavity delimited by a housing 11 in which is located an adaptable surface 30 with controllable property, and a radiating element 20 which is a source oriented towards the adaptable surface 20 and which is screened from the outside of the housing 11 by a metallic interface.

[0059] It should be noted that the adaptable surface 30 is not positioned in the opening 13 because this would reduce the performance and controllability of the antenna 10, but is positioned on one or more internal walls of the housing 11.

[0060] Thanks to the integration of a radiating element 20 and an adaptable surface 30 within an electromagnetic cavity, the antenna 10 is capable of simultaneously transforming any electromagnetic radiation from the radiating element into directional radiation (focused on a single direction) and into tiltable (orientable) radiation in all directions. Furthermore, this antenna is compact and highly efficient.

[0061] Furthermore, unlike previous phase-array or reflective-array antenna techniques, which impose fixed distances between adjustable elements by their operating principle, the adjustable elements 31 of the adaptable surface can be distributed in any way within the cavity 12. Indeed, the multiple reflections in the cavity 12 ensure that the entire internal surface of the housing 11 is swept and thus that all the adjustable elements 31 are impacted.

[0062] The parameters allow the states of each adjustable element 31 of the adaptable surface 30 to be determined, that is to say how each one modifies its impedance and how the electromagnetic wave We is reflected and / or transmitted in the cavity 12. A set of parameters determines the set of these states and therefore the characteristic of the antenna.

[0063] It is possible to find a set of parameters that optimizes the transmission and / or reception (reciprocally) of the electromagnetic wave Wa from the antenna, that is, that allows obtaining a main lobe L1 of high amplitude and secondary lobes L2 of low amplitude, as represented in figures 2a and 2b which show the change between an emission beam for a set of non-optimized parameters ( figure 2a ) then for a set of optimized parameters ( figure 2bIn particular, in the optimized mode, the L2 side lobes have an amplitude less than half that of the L1 primary lobe. Preferably, the antenna will be designed to achieve L2 side lobe amplitudes less than 1 / 4 of the L1 primary lobe amplitude. Ideally, a ratio of 1 / 10 for these amplitudes should be sought.

[0064] This results in a highly efficient directional antenna (beam concentrated in one direction), particularly from any type of radiating element, and not just a horn as presented in document US 2004 / 263408.

[0065] THE figures 3a and 3b show normalized radiation patterns at an amplitude of 1 of the antenna 10 with parameters of the Figures 3a and 3b, respectively. These diagrams show that changing the parameters improves the directivity of antenna 10, since in the first set of parameters the diagram shows two lobes of almost the same amplitude ( figure 3a ), whereas in the second, optimized set of parameters, the diagram shows a large-amplitude main lobe at the angular position of 0° ( figure 3b ). This main lobe actually has an amplitude greater than 4 times the amplitude of the other lobes, the secondary lobes.

[0066] Next, it is also possible to find a set of parameters that modifies the orientation of the primary lobe L1 of antenna 10. In fact, we are looking for a set of parameters optimized in directivity for each orientation or direction, as represented in figures 4a and 4b . There figure 4a shows a radiation pattern optimized for a 90° orientation or direction, and the figure 4bThis shows a radiation pattern optimized for a 60° orientation or direction. The inventors found on the antenna they developed that it was possible to obtain optimized parameter sets for a wide angular transmission / reception range. For example, this angular range is on the order of + / - 60° relative to a direction normal to the aperture, and this in both perpendicular planes, i.e., the horizontal and vertical planes.

[0067] We therefore simply obtain a highly efficient (sensitivity) adjustable-orientation radiation antenna.

[0068] The controller 40 can determine the parameters for the adaptable surface 30 according to the desired direction of the electromagnetic wave Wa for the antenna 10.

[0069] Following the previous explanations, it is clear that parameter set values ​​can be stored in the controller's memory for a plurality of directions, for example, a set of angular direction pairs based on an angle in the horizontal plane (azimuth) and an angle in the vertical plane (elevation). For example, the controller will choose the parameter set whose direction is closest to the desired direction. Optionally, the controller can perform interpolations on several parameter sets with similar directions.

[0070] Alternatively, a model of the parameter sets could be established, and the controller 40 will determine the parameters by calculation with this model and the desired direction.

[0071] Alternatively, the controller 40 will determine the parameter set to be used through an iterative optimization process, the optimization being carried out, for example, using additional information provided to the controller. This additional information may come from signals from one or more external sensors connected to said controller 40 by a direct or indirect, wired or wireless link. Optionally, this additional information may come from another system, for example, a user system of the antenna 10. This additional information relates to the electromagnetic wave Wa emitted and / or received by the antenna 10, in the near field of the antenna and / or in the far field of the antenna.

[0072] In particular, this additional information can serve as feedback information for determining the adjustment parameters of the adaptable surface 30.

[0073] The antenna 10, according to the embodiment presented above, can then have several variants of its components. These variants can be independent or implemented in combination.

[0074] According to initial versions Regarding the aperture 13 of the antenna 10, the aperture 13 includes a semi-reflective (or semi-transparent) element for electromagnetic waves. Thus, electromagnetic waves can partially pass through these semi-reflective elements in the direction of the entry or exit of the housing 11, the untransmitted portion of these electromagnetic waves being reflected back into the cavity to undergo one or more further reflections. These reflections within the cavity then direct the electromagnetic wave onto the adaptive surface 30, which thus controls a portion of it each time.

[0075] Optionally, the semi-reflective element is made from a thin metallic film.

[0076] Optionally, the semi-reflective element is made by a network of holes in a metallic element or a network of metallic shapes, a hole or shape being distant from another neighbor by a distance less than half the wavelength of the electromagnetic wave.

[0077] The semi-reflective element may have an electromagnetic transmission property (i.e., transmittance) that varies across the internal surface of aperture 13. In other words, this electromagnetic transmission property is not constant throughout aperture 13, and some parts of aperture 13 allow more waves to pass through than others. The electromagnetic transmission property includes, for example, the transmission amplitude and / or the transmission phase through the semi-reflective element, depending on its material and / or structural characteristics.

[0078] Optionally, the semi-reflective element includes one or more adjustable aperture elements designed and controlled to modify how the electromagnetic wave is reflected and / or transmitted by this adjustable aperture element, thus actively modulating the transparency of the aperture 13. The controller is then connected to the adjustable aperture elements to control them based on aperture parameters. These adjustable aperture elements may be similar to or different from the adjustable elements of the adaptable surface 30. The aperture parameters are different from the parameters of the adaptable surface 30.

[0079] Possibly, the 13th opening is made up of several elementary 131 ... 136 openings as represented in Figures 5a and 5b .These elementary openings are located on a single face of the housing 11 or on a plurality of faces of the housing 11. These elementary openings may have identical or different shapes, whether on one face or on several faces of the housing 11.

[0080] According to second variants Regarding the housing 11 of the antenna 10, the housing 11 has a parallelepiped shape as shown in figure 1 , or not parallelepiped. For example, the housing 11 can have a cylindrical or spherical shape or any other shape whatsoever.

[0081] Optionally, the housing 11 includes a main face that has the largest surface area of ​​the housing faces. The main face optionally includes the opening 13 or a portion of the opening 13 (at least one elementary opening).

[0082] The housing 11 then has a dimension in a direction perpendicular to the main face that is smaller than the other dimensions of the housing 11.

[0083] Possibly, the thickness dimension is greater than half the wavelength of the electromagnetic wave.

[0084] Optionally, the main face is semi-spherical. This face may advantageously include the aperture 13 to more easily provide a homogeneous radiation pattern in the horizontal plane over 360° around the normal to said main face. The housing 11 then has, for example, a dome shape as shown in figure 6 with a semi-spherical main face F1 for transmission / reception and a secondary face F2 in the opposite direction to the main face. The secondary face F2 is substantially flat and circular.

[0085] For example, the radiating element 20 is placed inside the housing 11 at the center of the main face F1, i.e. in this semi-spherical shape, and the adaptable surface can be placed on the secondary face F2 opposite the radiating element 20. An opening 13, possibly composed of elementary openings, is located on the main face F1, around the radiating element 20.

[0086] According to third variants Regarding the radiating element 20 of the antenna 10, the radiating element 20 integrated into the housing 11 of the antenna 10 is itself directional, that is to say, it generates a beam of electromagnetic wave We concentrated in one direction.

[0087] Optionally, the radiating element 20 is positioned in the housing 11 relative to the adaptable surface 30 in such a way as to emit and / or receive an electromagnetic wave We mainly directly towards the adaptable surface 30, by a predetermined orientation of the radiating element 20.

[0088] The radiating element 20 can be a monopole, a dipole, a waveguide, a radiating waveguide, or a planar antenna. In fact, integrating the radiating element 20 and the adaptable surface 30 into a cavity 12 allows the use of any type of radiating element.

[0089] Optionally, the radiating element 20 may be composed of a plurality of active elements. These active elements may be specialized: one or more of them are electromagnetic wave emission elements We, and one or more of them are electromagnetic wave reception elements.

[0090] The radiating element 20 can be specified for a particular wave frequency or several frequencies or a bandwidth between two frequencies.

[0091] Advantageously, the radiating element 20 is impedance-matched to the impedance of the cavity 12, that is, the cavity including all its elements, e.g., the aperture 12 and the adaptable surface 30, and others. In particular, it is often desirable to maintain a critical coupling condition for this impedance matching. The quality factor of the radiating element 20 and the cavity 12 are similar or identical.

[0092] According to fourth variants Regarding the adaptable surface 30, this adaptable surface 30 covers all the faces or internal surfaces of the housing 11. Optionally, it covers only a portion of the faces or internal surfaces of the housing 11.

[0093] Optionally, the adaptable surface 30 consists of adjustable elements 31 distributed within the housing 11 without periodicity. That is to say, they do not form a regular matrix. In fact, they can be distributed almost randomly or in predetermined locations for any reason. A great deal of freedom exists. This possibility is impossible in prior art phase-array or reflection-array antennas, which require either periodicity or the concentration of elements in a restricted area for illumination.

[0094] Optionally, the adaptable surface 30 may include first adjustable elements tuned to a first frequency and second adjustable elements tuned to a second frequency. The first frequency is different from the second frequency.

[0095] Most importantly, these first and second adjustable elements can be spatially mixed inside the cavity, whereas in prior art antennas this possibility is impossible due to the distance constraints between the adjustable elements for the operation of these antennas.

[0096] In particular, for satellite applications, it is possible to have a compact antenna adapted to two frequencies such as the first frequency of 20 GHz for transmission and the second frequency of 30 GHz for reception.

[0097] The adaptable surface 20 includes both types of adjustable elements distributed within the cavity of the housing.

[0098] Optionally, the adaptable surface 30 includes adjustable elements tuned to a plurality of different frequencies within a predetermined bandwidth so that the antenna can operate throughout that bandwidth.

[0099] Optionally, the adaptable surface 30 can be ordered to obtain selected polarizations of the electromagnetic wave Wa. In particular, it is possible to obtain with the adaptable surface 30 a horizontal polarization, a vertical polarization, or any combination of horizontal and vertical polarization, and therefore a circular polarization.

[0100] Thus, the controller 40 can also determine the parameters according to a desired polarization, whether horizontal, vertical or circular.

[0101] According to fifth variants, The antenna 10 may include within the cavity other elements, such as one or more protective screens 14 or one or more reflecting devices 15 or internal walls, as shown in figure 7 .

[0102] A screen 14 can be advantageously positioned in the cavity 12 between the radiating element and the opening 13 to limit direct electromagnetic wave radiation from the radiating element 20 to the outside of the housing and / or to reflect the waves towards the adaptable surface 30.

[0103] A reverberating device 15 can also be positioned in the cavity 12 to complicate the reflections of electromagnetic waves in the cavity 12.

[0104] Thanks to these arrangements, it is ensured that the We waves make one or more reflections inside the cavity 12 of the antenna 10, which ensures that they impact the adaptable surface 30 at least once, and preferably several times on a multitude of adjustable elements 31.

[0105] Optionally, internal partitions are located inside the housing 11 and divide the cavity 12 into a plurality of compartments. The adaptable surface 30, or a portion thereof, i.e., adjustable elements 31, can be placed on these internal partitions.

[0106] The antenna 10 may also include, within cavity 12, one or more internal sensors adapted to receive the electromagnetic wave. These internal sensors generate feedback signals which are measurements or values ​​of the electromagnetic wave received by the internal sensors at certain predetermined intervals.

[0107] The controller 40 then determines the parameters of the adaptable surface 30 from the desired direction, as before, but also from these values ​​of the internal sensors.

[0108] These internal sensors allow antenna 10 to maintain its directivity and electromagnetic wave tilt accuracy over the long term. Antenna 10 is thus more robust to temporal variations and external disturbances.

[0109] There figure 8 shows an antenna 10 not forming part of the claimed invention. This antenna comprises the same elements as the antenna 10 of the first embodiment, and may have the same variants independently or in combination with each other.

[0110] This antenna 10 has a spherical housing 11 and a spherical adaptable surface 20 with a diameter smaller than that of the housing, said adaptable surface 20 being positioned inside and at the center of the housing 11. The housing 11 includes a very large aperture 13 covering almost its entire surface. In fact, as already explained, the aperture 13 is defined in an electromagnetic sense; that is to say, it is a part of the housing that is transparent or semi-reflective to electromagnetic waves so that these waves can enter and / or exit the housing 11. It is sufficient that this aperture be made of a material having this property. In this case, the aperture 13 is advantageously semi-reflective such that the electromagnetic waves are reflected several times between the adaptable surface 30 and the housing 11 before exiting the housing 11 or reaching the radiating element 20.

[0111] The radiating element 20 is for example located near the inner surface of the housing 11. Advantageously, this radiating element 20 is protected from the outside by a screen 15: the housing 11 is reflective behind the radiating element.

[0112] Thanks to these arrangements, the antenna 10 of this embodiment is capable of emitting and / or receiving electromagnetic waves over 360° and even in any direction of space.

[0113] As shown, the antenna 10 can comprise two or more radiating elements 20, which improves its angular capabilities.

[0114] Finally, upon reading this detailed description, the person skilled in the art understands that many variations of a steerable antenna are possible, whether in shape, frequencies, directivity performance, depending on each application.

[0115] Numerous applications in communication transmission and radar detection are possible.

[0116] For example, in radio communication, such antennas, having high electromagnetic beam steering capabilities, can be used in pairs. The antennas can self-adjust their directivity to direct their beams towards each other and greatly improve the quality and bandwidth of the transmission between the two antennas.

[0117] For example, the antenna technology according to the invention may be of great interest in satellite antenna applications due to its compactness and multi-frequency capabilities.

Claims

1. Antenna (10) suitable for transmitting and / or receiving an electromagnetic wave in a desired direction, comprising: - a radiating element (20) suitable for emitting and / or receiving said electromagnetic wave, - a tunable surface (30) comprising a plurality of adjustable elements that are suitable in order to modify an impedance of said tunable surface and to change the manner in which the electromagnetic wave is reflected by said tunable surface, and - a controller (40) connected to the tunable surface and which controls the adjustable elements thereof based on parameters, said parameters being determined based on the desired direction of the electromagnetic wave, the radiating element (20) and the tunable surface (30) are integrated inside a housing (11) forming a cavity (12), and said housing (11) forming a cavity (12) adapted so that the electromagnetic wave is reflected several times inside the housing in order to strike the adjustable elements of the tunable surface (30) several times, said housing (11) comprising an opening (13) for the electromagnetic wave to be transmitted to outside the housing or be received from outside the housing, through said opening, and to / from the far field, the tunable surface (30) is positioned on one or a plurality of inner surfaces of the housing and is separated of the opening (13), so as the electromagnetic wave is reflected several times inside the housing in order to strike the adjustable elements of the tunable surface (30) several times.

2. Antenna according to claim 1, further comprising a screen (15) positioned in the cavity (12) between the radiating element and the opening, to limit direct radiation of the electromagnetic wave from the radiating element to outside the housing and / or to reflect the waves towards the tunable surface.

3. Antenna according to claim 1 or claim 2, wherein the opening (13) consists of several elementary openings, these elementary openings being on one face of the housing or on a plurality of faces of the housing.

4. Antenna according to one of claims 1 to 3, wherein the opening (13) at least partially consists of one or more semi-reflective elements.

5. Antenna according to claim 4, wherein the semi-reflective element is implemented by a thin metal film.

6. Antenna according to claim 4, wherein the semi-reflective element is implemented by a network of holes in a metal element or a network of metal shapes, a hole or shape being distanced from a neighboring one by a distance that is less than half the wavelength of the electromagnetic wave.

7. Antenna according to claim 4, wherein the semi-reflective element has an electromagnetic transmission property which varies within the surface of the opening.

8. Antenna according to claim 7, wherein the electromagnetic transmission property comprises the transmission amplitude and / or the transmission phase.

9. Antenna according to one of claims 1 to 8, wherein the semi-reflective element comprises one or more adjustable opening elements suitable in order to change the manner in which the electromagnetic wave is reflected and / or transmitted by said opening, the controller being linked to the adjustable opening elements in order to control them based on opening parameters.

10. Antenna according to one of claims 1 to 9, wherein the radiating element (20) is positioned in the housing so as to emit and / or receive an electromagnetic wave primarily directly towards the tunable surface (30), by orientation of said element within the housing.

11. Antenna according to one of claims 1 to 10, wherein the radiating element (20) is impedance matched with the impedance of the cavity, in order to satisfy a critical coupling condition.

12. Antenna according to one of claims 1 to 11, wherein the radiating element (20) is selected from a list comprising a monopole, a dipole, a waveguide, a radiating waveguide, and a planar antenna.

13. Antenna according to one of claims 1 to 12, wherein the tunable surface (30) covers all the inside faces of the housing (11) or a portion of the inside faces of the housing or one or more of the inside faces of the housing.

14. Antenna according to one of claims 1 to 13, wherein the tunable surface (30) consists of adjustable elements distributed within the housing without periodicity.

15. Antenna according to one of claims 1 to 14, wherein the tunable surface (30) comprises first adjustable elements tuned to a first frequency and second adjustable elements tuned to a second frequency, the first frequency being different from the second frequency.

16. Antenna according to claim 15, wherein the first and second adjustable elements are distributed spatially intermixed.

17. Antenna according to one of claims 1 to 16, wherein the tunable surface (30) comprises adjustable elements tuned to a plurality of different frequencies within a predetermined bandwidth.

18. Antenna according to one of claims 1 to 17, wherein the housing (11) comprises a main face, and wherein the housing has a thickness dimension in a direction perpendicular to said main face that is smaller than the other dimensions of the housing, and the thickness dimension is greater than half the wavelength of the electromagnetic wave.

19. Antenna according to one of claims 1 to 18, wherein the housing (11) comprises a main face, and wherein the main face is semi-spherical in shape.

20. Antenna according to one of claims 1 to 19, wherein the controller (40) determines the parameters also as a function of a desired polarization.

21. Antenna according to one of claims 1 to 20, wherein the controller (40) determines the parameters based on parameter values previously stored in a memory, or by calculating a model, or by an iterative process using additional information.

22. Antenna according to claim 21, wherein the additional information is obtained from signals from external sensors located outside the housing and capable of receiving the electromagnetic wave.

23. Antenna according to one of claims 1 to 22, further comprising one or more internal sensors capable of receiving the electromagnetic wave, said internal sensors being integrated inside the housing, and the controller determines the parameters based on a desired direction of the electromagnetic wave and on values of the electromagnetic wave received by the internal sensors at certain predetermined periods.

24. Antenna according to one of claims 1 to 23, comprising a plurality of radiating elements integrated inside the housing.

25. Radio communication system capable of communicating communications of audio, video, messages, or data, said radio communication system comprising an antenna according to one of claims 1 to 24.

26. Radar detection system suitable for locating objects within a space, said radar detection system comprising an antenna according to one of claims 1 to 24.

Images