Multi-band, superdirectional antenna array system

Abstract

Antenna array system (1) comprising: - a powered main antenna (30) configured to emit a beam directed along a plurality of main directions, said powered main antenna operating in a first frequency band; - an array of parasitic antennas (10.1, 10.2, 10.3, 10.4) arranged to form a first envelope concentrically surrounding the main fed antenna (30), each antenna comprising a substrate of dielectric material (13.1, 13.2, 13.3, 13.4) having one face oriented outwards from the envelope provided with a parasitic radiating element (11.1, 11.2, 11.3, 11.4) and provided with a ground plane, the parasitic radiating element (11.1, 11.2, 11.3, 11.4) being connected to the ground plane via a reactive load (12.1, 12.2, 12.3, 12.4), each parasitic antenna being configured to emit a beam directed along a principal direction, the reactive loads (12.1, 12.2, 12.3, 12.4) being configured to selectively activate electromagnetic coupling between the main fed antenna and a pair of parasitic antennas to modify the directivity of the main fed antenna. Abstract figure: Figure 1.

Description

Title of the invention: Multi-band and superdirectional antenna array system Technical field

[0001] The present disclosure relates to the field of superdirectional antennas. In particular, the present disclosure relates to a superdirectional antenna array system operating in a wide frequency band. The invention finds applications in wireless communication systems. Prior art

[0002] The rapid development of wireless communication systems requires the design of an antenna system operating in one or more communication bands while offering high data rates.

[0003] With the rise of the Internet of Things (IoT) and the proliferation of connected objects, antennas operating in different bands are required to coexist in the same environment. Also, the antennas must be able to emit radiation only in the desired direction, and reduce interference on the receiving side by capturing only signals from a preferred direction, and finally reduce the power consumption and operating cost of the system. In addition, the antenna system operating in these frequency bands must occupy a limited space to optimize its integration into wireless equipment. In this case, it is necessary to be able to miniaturize the size of the antenna system to limit the volume of the device.

[0004] However, as antenna dimensions decrease, the bandwidth and efficiency also decrease, and the radiation tends to become omnidirectional. Indeed, the quality factor for an antenna is inversely proportional to the space occupied. In other words, the bandwidth decreases as the size decreases. The directivity of the antenna is also related to its size. It decreases as the size decreases.

[0005] It is known to design an antenna array to achieve directional radiation while maintaining compact dimensions. By forming an array of closely spaced antennas (d < 0.25 X), it is possible to achieve a directivity referred to as superdirectivity. However, such a superdirective array generally provides a narrow operating bandwidth.

[0006] A known solution is to nest different conventional networks together to be able to cover a wide frequency band. However, it is often difficult to ensure good isolation between the different frequency bands due to the interference between the radiation on the transmitting and receiving side. In addition, the beamforming capability is affected by the increase in frequency due to the occurrence of grating lobes.

[0007] Another solution is to design a wideband antenna system nesting sub-arrays without array lobes, with similar radiation patterns and having low levels of side lobes. However, these arrays have large dimensions compared to the wavelength and do not allow the optimization of their integration into a wireless communication device, such as for example a 5G gateway or 5G box.

[0008] An object of the present disclosure is to propose a novel superdirectional antenna array system architecture, capable of scanning a plurality of directions in the azimuthal plane, which provides a wide frequency band ranging from 780 MHz to 4.5 GHz, while maintaining optimal performance in each band.

[0009] An object of the present disclosure is to provide a novel compact antenna array system architecture having low manufacturing cost with standard printed circuit techniques. Summary

[0010] The present disclosure improves the situation.

[0011] An antenna array system is proposed comprising: - a powered main antenna configured to emit a beam directed in a plurality of main directions, said powered main antenna operating in a first frequency band; - a set of parasitic antennas arranged so as to form a first envelope by concentrically surrounding the fed main antenna, each parasitic antenna comprising a substrate made of dielectric material having a face oriented towards the outside of the envelope provided with a parasitic radiating element and a ground plane, the parasitic radiating element being connected to the ground plane via a reactive load, each parasitic antenna being configured to emit a beam directed in a main direction, the reactive loads being configured to selectively activate the electromagnetic coupling between the fed main antenna and a pair of parasitic antennas to modify the directivity of the fed main antenna.

[0012] The features set out in the following paragraphs may, optionally, be implemented, independently of one another or in combination with one another:

[0013] The set of parasitic antennas are arranged so as to form at least a second envelope by concentrically surrounding the main fed antenna.

[0014] The distance between the main fed antenna and the parasitic antennas is equal to or less than 0.2 X, / . being the wavelength of the beam emitted by the main fed antenna and the parasitic antennas.

[0015] The main fed antenna comprises a radiating element in the form of a disc remotely mounted on a cylindrical ground plane.

[0016] The main fed antenna comprises two substrates made of dielectric material intersected at 90° to each other, the faces of the substrates oriented on the same side each being provided with a radiating element and a ground plane.

[0017] The parasitic radiating element has an M shape.

[0018] The envelope is in the form of a straight prism, each parasitic antenna comprising a substrate made of dielectric material forming one face of a straight prism.

[0019] The envelope is in the form of a cylinder, each parasitic antenna comprising a substrate made of dielectric material forming part of the cylindrical wall.

[0020] The main powered antenna and the parasitic antennas operate in a first frequency band between 718 MHz and 810 MHz.

[0021] The parasitic antenna assembly comprises four parasitic antennas each forming a face of a rectangular parallelepiped, the main fed antenna and the parasitic antennas being capable of being coupled together to emit an electromagnetic beam in four main azimuthal preferred directions 0°, 90°, 180° and 270° and in four azimuthal depointed preferred directions 45°, 135°, 225° and 315°, the reactive loads being configured to selectively activate the coupling between a pair of opposing parasitic antennas or a pair of adjacent antennas with the main fed antenna to selectively modify the directivity of the main fed antenna in two opposite azimuthal preferred directions chosen from the four pairs of opposite azimuthal directions (0, 180°), (90, 270°), (45°, 225°) or (135°, 315°).

[0022] According to another particularly advantageous embodiment, the antenna array system further comprises, for each parasitic antenna, a group of powered auxiliary antennas operating in a second frequency band different from the first frequency band, said powered auxiliary antennas being mounted at a distance from the outer face of the substrate of each parasitic antenna.

[0023] Preferably, the powered auxiliary antennas are configured to operate in a second frequency band between 2.4 GHz and 3.8 GHz.

[0024] According to an exemplary embodiment, the fed auxiliary antennas are formed by a rectangular patch antenna with a U-shaped slot, each group of fed auxiliary antennas associated with a parasitic antenna being fed uniformly by a feed network produced on the inner face of the substrate of the parasitic antenna.

[0025] Preferably, each powered auxiliary antenna is held in position relative to the outer face of the substrate of the associated parasitic antenna by means of a fixing part.

[0026] According to a variant, the auxiliary antennas of the same group have identical dimensions.

[0027] According to another variant, the auxiliary antennas of the same group have different dimensions. Brief description of the drawings

[0028] Other characteristics, details and advantages will appear on reading the detailed description below, and on analyzing the attached drawings, in which: Fig.l

[0029] [Fig.l] [Fig.l] is an exploded perspective view showing an antenna array system operating in a frequency band between 758 MHz and 810 MHz according to one embodiment, comprising a group of four parasitic antennas each forming a face of a right prism, a rectangular parallelepiped and a main fed antenna or exciter antenna positioned at the center of the prism, the distance between the exciter antenna and the parasitic antenna being less than 0.2X, each parasitic antenna being connected to parasitic reactive loads: capacitive or inductive, the exciter antenna and the parasitic antennas being able to be coupled together to emit an electron beam in four main azimuthal preferred directions 0°, 90°, 180° and 270° and in four azimuthal depointed preferred directions 45°, 135°, 225° and 315°,the capacitive or inductive loads being configured to selectively activate the coupling between a pair of opposing parasitic antennas or a pair of adjacent antennas with the exciter antenna to steer the electron beam in two opposite azimuthal preferred directions [0, 180°], [90, 270°], [45°, 225°] or [135°, 315°] among the eight chosen or selected azimuthal directions. Fig. 2

[0030] [Fig.2] [Fig.2] is a schematic view showing an example of an embodiment of a parasitic antenna of [Fig.l]. Fig. 3

[0031] [Fig.3] [Fig.3] is a perspective view showing an exemplary embodiment of a main antenna fed from [Fig.l]. Fig. 4A

[0032] [Fig.4A] [Fig.4A] is a perspective view of the antenna array system of [Fig.l] in an assembled configuration. Fig. 4B

[0033] [Fig.4B] [Fig.4B] is a top view of the antenna array system of [Fig.4A]. Fig. 5

[0034] [Fig.5] [Fig.5] is a perspective view showing an antenna array system according to another embodiment, comprising two groups of four parasitic antennas, each group forming the four faces of a right prism and a main fed antenna positioned at the center of the prism. Fig. 6

[0035] [Fig.6] [Fig.6] is a perspective view showing another embodiment of a fed main antenna. Fig. 7

[0036] [Fig.7] [Fig.7] is an exploded perspective view showing an antenna array system operating in a frequency band between 758 MHz and 810 MHz according to another embodiment, comprising a group of four parasitic antennas each forming a face of a rectangular parallelepiped and a main fed antenna positioned at the center of the prism of [Fig.6]. Fig. 8

[0037] [Fig.8] [Fig.8] is a perspective view showing the antenna array system of [Fig.7] in an assembled configuration. Fig. 9

[0038] [Fig.9] [Fig.9] is a top view of the system of [Fig.8] with the radiation patterns calculated for the eight azimuthal directions. Fig. 10

[0039] [Fig. 10] [Fig. 10] is an exploded perspective view showing an antenna array system according to another embodiment, comprising a group of four parasitic antennas each forming a face of a right prism and a main fed antenna positioned at the center of the prism, a group of four auxiliary fed antennas operating in a frequency band between 2.4 GHz and 3.8 GHz and arranged on each parasitic antenna. Fig. 11A

[0040] [Fig. 1 IA] [Fig. 1 IA] is a schematic view showing the front face of a parasitic antenna of [Fig. 10] and a group of four fed auxiliary antennas arranged on the front face of the parasitic antenna of [Fig. 10]. Fig. 11B

[0041] [Fig. 1 IB] [Fig. 1 IB] is a schematic view showing the rear face of a parasitic antenna of [Fig. 10] and a feed network configured to feed the group of four powered auxiliary antennas. Fig. 12A

[0042] [Fig.l2A] [Fig.l2A] shows a schematic view of an exemplary embodiment of a high frequency fed auxiliary antenna used to form the group of four fed auxiliary antennas of [Fig. 11 A]. Fig. 12B

[0043] [Fig.l2B] [Fig.l2B] shows a schematic perspective view of the fed auxiliary antenna of [Fig.l2A], showing the radiating element namely the patch with a U-shaped slot positioned at a distance d from the ground plane formed by the front face of the substrate of the parasitic antenna, a coaxial connector connecting the radiating element of the fed auxiliary antenna to a feed network printed on the rear face of the substrate. Fig. 13

[0044] [Fig. 13] [Fig. 13] is a top view of the antenna array system of [Fig. 10] in an assembled configuration. Fig. 14

[0045] [Fig. 14] [Fig. 14] is a perspective view of the antenna array system of [Fig. 10] in an assembled configuration. Fig. 15

[0046] [Fig. 15] [Fig. 15] is a perspective view of the antenna array system of [Fig. 10] in an assembled configuration with the radiation patterns calculated for the eight azimuthal directions in the frequency band between 758 MHz and 810 MHz for the centrally fed main antenna whose directivity is modified by the four parasitic antennas and the four azimuthal directions in the frequency band between 2.4 GHz and 3.8 GHz for the four groups of fed auxiliary antennas. Fig. 16

[0047] [Fig. 16] [Fig. 16] shows the specification of the antenna array system of [Fig. 15] in the frequency band between 760 MHz and 900 MHz: (a) reflection coefficient as a function of frequency, (b) directivity and gain as a function of frequency in the main angular sectors and (c) directivity and gain as a function of frequency in the sectors deflected at ± 45 °. Fig. 17

[0048] [Fig. 17] [Fig. 17] shows the specification of the antenna array system of [Fig. 15] in the frequency band between 2 GHz and 4 GHz: (a) reflection coefficient as a function of frequency, (b) directivity and gain as a function of frequency in the main angular sectors and (c) radiation efficiency in function of frequency. Fig. 18

[0049] [Fig. 18] [Fig. 18] shows the simulation results and the measured results on a prototype antenna array system of [Fig. 15] in the frequency band between 3 GHz and 4.5 GHz: (a) directivity as a function of frequency (b) reflection coefficient as a function of frequency, (c) gain as a function of frequency and (c) radiation efficiency as a function of frequency. Fig. 19

[0050] [Fig. 19] [Fig. 19] is a perspective view showing an antenna array system according to another embodiment, comprising a group of three parasitic antennas each forming one face of a right prism and a main fed antenna positioned at the center of the prism, a group of four auxiliary fed antennas operating in a frequency band between 2.4 GHz and 3.8 GHz being arranged on the substrate of each parasitic antenna. Fig. 20

[0051] [Fig.20] [Fig.20] is a top view of the antenna array system of [Fig.19], Fig. 21

[0052] [Fig.21] [Fig.21] is a top view of the antenna array system of the [Fig.19] with the radiation patterns calculated for the six azimuthal directions in the frequency band between 758 MHz and 810 MHz for the centrally fed main antenna whose directivity is modified by the three parasitic antennas and the three azimuthal directions in the frequency band between 2.4 GHz and 3.8 GHz for the three groups of fed auxiliary antennas. Description of the embodiments

[0053] In the present disclosure, the term “directivity” refers to a parameter that quantifies how a direction of radiation is favored. The directivity of an antenna in a given direction is defined as the ratio of the radiation intensity in that direction to the intensity of an isotropic antenna radiating the same power.

[0054] In the present disclosure, the term “radiation efficiency” refers to the losses of an antenna which can be quantified based on its radiation and total efficiencies. Radiation efficiency is defined as the ratio of the total power radiated to the power accepted by the antenna.

[0055] In the present disclosure, the term “gain” is defined as the ratio of the radiation intensity to the total power injected into the antenna in a direction given. It is also related to efficiency and directionality.

[0056] In the remainder of the description, the expression “exciter antenna” or “powered main antenna” or even “main antenna” designates an antenna comprising an exciting radiating element powered by a source and capable of emitting a beam in a plurality of directions.

[0057] In the remainder of the description, the expression “directivity-reconfigurable antenna” or “reconfigurable antenna” designates an antenna associated with a parasitic antenna to modify the directivity of the beam emitted in a given direction.

[0058] In the remainder of the description, the expression “fed auxiliary antenna” designates an antenna of an array comprising a radiating element fed by a source and capable of emitting radiation in a single given direction.

[0059] In the remainder of the description, the expression “outer face” designates a face of the substrate of a parasitic antenna oriented towards the outside of the envelope formed by the parasitic antennas assembled together surrounding the main fed antenna or the exciter antenna. In other words, the outer faces of the parasitic antennas form the outer face of the envelope. The expression “inner face” designates a face of the substrate of a parasitic antenna oriented towards the exciter antenna located in the center of the envelope.

[0060] With reference to [Fig.l], the antenna array system 1 according to a first embodiment is described below.

[0061] The antenna array system 1 comprises an excitation antenna or powered main antenna 30 configured to emit a beam of wavelength X and directed in a plurality of main directions and a set of four parasitic antennas 10.1, 10.2, 10.3, 10.4 arranged so as to form an envelope by concentrically surrounding the main antenna 30.

[0062] The distance between the parasitic antenna and the exciter antenna is equal to or less than 0.2 X so as to be in the conditions of superdirectivity, X being the operating frequency of the parasitic antennas and of the main powered antenna.

[0063] [Fig. 2] represents one of the parasitic antennas 10.1 used in the system of [Fig. 1]. The parasitic antenna 10.1 comprises a substrate 13.1 having a substantially rectangular shape. For example, it has a length of 142 mm, a width of 60 mm and a thickness of 0.8 mm. The width is approximately equal to 0.15X. The substrate is made of dielectric material. For example, the substrate is made of dielectric material of the RT5880 type, having a relative permittivity er equal to 2.2, and a loss tangent tan(δ) equal to 0.0009. The substrate has a face oriented towards the outside of the envelope and a face oriented towards the inside of the envelope. The parasitic antenna comprises a radiating element 11.1 having a shape M produced on the outside face of the substrate which is also provided with a ground plane. The radiating element 11.1 is connected to the ground plane via a reactive load 12.1. This load can be inductive or capacitive.

[0064] Each parasitic antenna is configured when activated by electromagnetic coupling with the main antenna to emit a beam directed in a main azimuthal direction. In the exemplary embodiment of [Fig.l], the four parasitic antennas are configured to emit four beams directed in four azimuthal directions, namely 0°, 90°, 180° and 270°. This unidirectional beam has a radiation pattern comprising a main lobe oriented in one direction and secondary lobes.

[0065] In this embodiment and as illustrated in [Fig. 3], the excitation antenna 30 comprises a radiating element 32 in the form of a disc mounted at a distance from a cylindrical ground plane 31. The radiating element 32 is connected to the ground plane 31 by a coaxial probe 35. The excitation antenna 30 is powered by a source not illustrated in the figure.

[0066] The excitation antenna 30 is associated with the four parasitic antennas which have the function of reconfiguring the radiation pattern of the excitation antenna by electromagnetically coupling. The reactive loads 12.1, 12.2, 12.3, 12.4 are configured to selectively activate the electromagnetic coupling between the excitation antenna and a pair of parasitic antennas so as to modify the directivity of the beam emitted by the excitation antenna in two opposite azimuthal directions [0, 180°], [90, 270°], [45°, 225°] or [135°, 315°] among the eight selected azimuthal directions.

[0067] The system of [Fig.l] operates as follows. The excitation antenna 30 is continuously powered by a source and emits radiation in all directions. For example, the load 12.1 connected to the radiating element 11.1 takes a predetermined reactive value C1 and the load 12.3 connected to the radiating element 11.3 takes a predetermined reactive value C2, the two opposite charges will activate the radiating element 11.1 and the radiating element 11.3 which interact by electromagnetic coupling with the excitation element 30. The values ​​of the reactive charges C1 and C2 are predetermined so as to mainly increase the directivity of the excitation antenna in the main azimuthal direction 0° and the main azimuthal direction 180°. In the same way, the reactive value of the other two opposite loads 12.2, 12.4 connected respectively to the parasitic radiating elements 11.2, 11.4 can take a predetermined value to activate the two associated radiating elements which interact by electromagnetic coupling with the excitation antenna 30 so as to increase the directivity of the excitation antenna in the two other main azimuthal directions 90°, 270°.

[0068] According to another exemplary embodiment, the adjacent charges (12.1,12.2), (12.2,12.3), (12.3,12.4) and (12.4, 12.1) can take appropriate values ​​to selectively activate the associated radiating elements which interact with the excitation antenna 30 so as to increase the directivity of the excitation antenna in the four azimuthal offset directions 45°, 135°, 225°, 315°.

[0069] Thus, by switching the desired value of the four loads, it is thus possible to selectively modify the directivity of the radiation pattern of the central exciter antenna in the eight azimuthal directions.

[0070] Advantageously, the excitation antenna and the parasitic antennas are antennas configured to operate in the frequency band between 758 MHz and 810 MHz, also called the N28 band.

[0071] [Fig.4A] is a perspective view of the antenna array system of [Fig.1] in an assembled configuration and [Fig.4B] is a top view of the antenna array system of [Fig.4A]. The envelope formed by the four antennas 10.1, 10.2, 10.3, 10.4 has the shape of a rectangular parallelepiped. More specifically, the substrate 13.1, 13.2, 13.3, 13.4 of each parasitic antenna forms one face of a rectangular parallelepiped.

[0072] For example, when the load 12.1 and the load 12.3 activate the associated parasitic radiating elements 11.1, 11.3, the latter interact by electromagnetic coupling with the exciter radiating element of the exciter antenna 30 so that the radiation pattern of the system 1 extends in two opposite directions (0 and 180°), with a main lobe extending in the 0° direction and a weaker rear lobe extending in the 180° direction. When the loads 12.2, 12.4 activate the associated parasitic radiating elements 11.2, 11.4, the latter interact by electromagnetic coupling with the exciter radiating element of the exciter antenna so that the radiation pattern of the system 1 extends in two opposite directions (90 and 270°), with a main lobe extending in the 90° direction and a weaker back lobe extending in the 270° direction.

[0073] For example, when the pair of loads 12.1, 12.2 simultaneously activates the two parasitic radiating elements 11.1, 11.2 and the pair of loads 12.3, 12.4 simultaneously activates the two parasitic radiating elements 11.3, 11.4, the latter interact by electromagnetic coupling with the exciter radiating element of the exciter antenna so that the radiation pattern of the system 1 extends in two opposite depointed directions (45° and 225°), with a main lobe extending in the 45° direction and a rear lobe extending in the 225° direction. When the pair of charges 12.2, 12.3 activates the parasitic radiating elements 11.2, 11.3 and the pair of charges 12.4, 12.1 activates the radiating elements 11.4, 11.1, the latter interact by electromagnetic coupling with the exciter radiating element of the exciter antenna so that the radiation pattern of the system 1 extends in two di opposite depointed directions (135° and 315°), with a main lobe extending in the 135° direction and a secondary lobe extending in the 315° direction.

[0074] An electronic circuit (not shown) is provided to control the value of the parasitic reactive loads so as to selectively activate the parasitic radiating elements to modify the directivity of the radiation. By switching the value of the parasitic reactive loads, it is thus possible to scan the beam in the eight azimuthal directions.

[0075] Advantageously, the implantation of the parasitic load in the substrate of the parasitic antenna is simple and inexpensive to implement. Furthermore, the load has an ultra-short response time when receiving an instruction signal transmitted by the circuit making it possible to very quickly reconfigure the radiation pattern of the exciter antenna. In particular, the antenna array system can be used in the context of a 5G application between a 5G gateway and mobile wireless equipment such as a mobile telephone which requires a latency time of the order of tens of microseconds to reconfigure the beam.

[0076] The system of [Fig.l] makes it possible to cover eight azimuthal directions, capable of covering four pairs of opposite angular sectors. If it is desired to cover more angular sectors, it is possible to add parasitic antennas around the exciter antenna to cover other azimuthal directions. It is possible to cover 2N azimuthal directions by providing N parasitic antennas, N being a natural whole number.

[0077] [Fig.5] illustrates an alternative embodiment of the antenna array system of [Fig.l], where the parasitic antennas form two envelopes concentrically surrounding the central exciter antenna 230.

[0078] The antenna array system 200 comprises an excitation antenna 230 configured to emit a beam of wavelength X and directed in a plurality of main directions, a first set of four parasitic antennas 210.1, 210.2, 210.3, 210.4 arranged to form a first envelope by surrounding the excitation antenna 230, a second set of four parasitic antennas 220.1, 220.2, 220.3, 220.4 arranged to form a second envelope by surrounding the excitation antenna 230. The two envelopes concentrically surround the excitation antenna 230.

[0079] In this exemplary embodiment, the distance between the parasitic antennas of the second envelope which are the antennas furthest from the excitation antenna and the excitation antenna must be equal to or less than 0.2 X so as to be in the conditions of superdirectivity.

[0080] In this embodiment, the parasitic antennas and the excitation antenna are similar to those of [Fig.l].

[0081] As in [Fig.2], the parasitic antenna comprises a substrate having a substantially rectangular shape having a face oriented towards the outside of the envelope and a face oriented towards the inside of the envelope. The parasitic antenna comprises a radiating element having an M shape made on the outside face of the substrate and a ground plane on the same face. The radiating element is connected to the ground plane via a reactive load.

[0082] As illustrated in [Fig.3], the excitation antenna 230 comprises a radiating element in the form of a disc mounted at a distance from a cylindrical ground plane. The radiating element is connected to the cylindrical ground plane by a coaxial connector. The excitation antenna 230 is powered by a voltage source.

[0083] [Fig.6] illustrates another example of the embodiment of the main exciter antenna 130. The main exciter antenna 130 comprises two dielectric material substrates 131.1, 131.2 intersected at 90° to each other. One of the two substrates comprises a central longitudinal slot having a dimension adapted to allow the second substrate 133.2 to pass through.

[0084] The faces 133.1, 133.2 of the two substrates 131.1, 131.2 which are oriented on the same side are each provided with an M-shaped radiating element 132.1, 132.2, similar to those present in parasitic antennas. In [Fig.6], these two faces are illustrated according to a view arbitrarily called here the front view. These faces are also provided with a ground plane. In [Fig.6], the two opposite faces are illustrated according to a view arbitrarily called here the rear view.

[0085] [Fig.7] illustrates another alternative embodiment of the antenna array system of [Fig.l] in which the central excitation antenna used is that of [Fig.6].

[0086] The antenna array system 100 comprises the excitation antenna 130 configured to emit a beam of wavelength X and directed in a plurality of main directions, a set of four parasitic antennas 110.1, 110.2, 110.3, 110.4 arranged so as to form an envelope surrounding the excitation antenna 130.

[0087] In this exemplary embodiment, the distance between the parasitic antennas and the excitation antenna must be equal to or less than 0.2 X so as to be in the conditions of superdirectivity.

[0088] In this embodiment, the parasitic antennas are similar to those of [Fig.l].

[0089] The system operates in the same way as that of [Fig.l]. The value of the parasitic reactive loads is controlled so as to selectively activate the parasitic radiating elements to change the direction of the radiation. By switching the value of the parasitic loads, it is thus possible to scan the beam in the eight azimuthal directions.

[0090] [Fig.8] shows the system of [Fig.7] in an assembled configuration. For example, the parasitic antennas 110.1, 110.2, 110.3, 110.4 are assembled together by mechanical supports 101.1, 101.2, 101.3, 101.4.

[0091] [Fig.9] illustrates a top view of the system of [Fig.8]. Each support includes on its two edges a longitudinal groove having a dimension adapted to insert an edge of the substrate of a parasitic antenna. Thus, the parasitic antennas are assembled together two by two via the supports. The antenna array system has the form of a right prism with an octagonal base. The parasitic antennas and the mechanical supports form the faces of this prism.

[0092] In [Fig.9] the radiation patterns 102.1, 102.3, 102.2, 102.4 calculated respectively for the four main azimuthal directions 0°, 180°, 90°, 270° and the radiation patterns 104.1, 104.2, 104.3, 104.4 calculated respectively for the four depointed directions 45°, 135°, 225°, 315° have also been shown. For these calculations, the substrate used for the parasitic antenna and the main fed antenna is made of a material known under the name RT5880 with a thickness of 0.8 millimeters, a height of 142 millimeters and a width of 60 millimeters.

[0093] [Fig. 10] is an exploded perspective view showing an antenna array system according to another embodiment.

[0094] The antenna array system 300 comprises a group of four parasitic antennas 310.1, 310.2, 310.3, 310.4 each forming a face of a right prism and a fed main antenna 330 positioned at the center of the prism. The fed main antenna 330 and the parasitic antennas form a first superdirectional antenna array which is configured to operate in a first frequency band between 780 MHz and 810 MHz. The loads which are associated with the parasitic antennas make it possible to selectively modify the orientation of the radiation emitted by this first superdirectional array in the eight azimuthal directions. The operation of this superdirectional array is similar to that of [Fig.l].

[0095] In order to be able to provide a network system that can operate in a wide range of 5G frequencies from N28 to N78 while maintaining dimensions comparable to existing housings and optimal performance for each band, the network system of [Fig. 10] further comprises four groups of auxiliary fed antennas each arranged on a parasitic antenna. These auxiliary antennas are configured to operate in a frequency band different from the frequency band in which the main fed antenna 330 operates. The auxiliary antennas operate in a frequency band between 2.4 GHz and 3.8 GHz.

[0096] In [Fig. 10], only the groups of auxiliary antennas associated with the parasitic antennas 310.1 and 310.2 are visible.

[0097] [Fig. 11 A] illustrates an exemplary embodiment of the four auxiliary antennas 340.1, 340.2, 340.3, 340.4 arranged on the outer face of one of the four parasitic antennas referenced 310.1. The fed auxiliary antennas are arranged on the outer face of the substrate 313.1 of the parasitic antenna 310.1. In the exemplary embodiment described, the four fed auxiliary antennas are distributed in the form of an array.

[0098] [Fig. 1 IB] illustrates an exemplary embodiment of a passive feed network 319 produced on the inner face of the substrate of the parasitic antenna 310.1. The feed network is connected to a power source 315. In the illustrated example, the fed auxiliary antennas 340.1, 340.2, 340.3, 340.4 are respectively connected to the feed points 345.1, 345.2, 345.3, 345.4 of the network. The four auxiliary antennas are thus fed or excited uniformly by the feed network 319.

[0099] [Fig. 12A] illustrates an example of a fed auxiliary antenna used to form the group of four auxiliary antennas of [Fig. 11 A]. The auxiliary antenna 340.1 used is a patch antenna. It comprises a radiating element 342.1 provided with a “U” shaped slot. The radiating element is a patch here having a substantially rectangular shape. For example, the dimensions of the radiating element are 37.3x53.6 mm2. The “U” shaped slot has a width of 22.1 mm and a height of 22.8 mm. The thickness of the slot is 2.6 mm.

[0100] As illustrated in [Fig.l2B], the patch is provided with a feed point 343.1 which is connected to the feed point 345.1 of the feed network via a coaxial connector 344.1. The patch is separated from the ground plane by a distance d which is for example of the order of 9 mm.

[0101] Advantageously and thanks to the single-sided structure of the parasitic antenna having a face provided with a parasitic radiating element and a ground plane, it is possible to arrange the four patches 342.1, 342.2 342.3, 342.4 on the outer face of the substrate of the parasitic antenna and to produce the feed network 319 on the rear face of the substrate of the parasitic antenna. It is therefore possible to use a single ground plane for the four auxiliary antennas to simplify the structure of the antenna array system. The specific structure of the auxiliary antenna allows it to be nested on the parasitic antenna while limiting the size of the assembly.

[0102] Generally, each auxiliary antenna is held in position relative to the outer face of the substrate of the associated parasitic antenna by means of a fixing part.

[0103] [Fig. 13] schematically illustrates a top view of the antenna array system of [Fig. 10] in an assembled configuration. In this exemplary embodiment, the fixing part is formed by a foam layer 302.1 interposed between the patch 342.1 of the auxiliary antenna 340.1 and the outer face of the substrate 313.1 of the associated parasitic antenna 310.1. The coaxial connector 344.1 passes through the foam layer to connect the radiating element 342.1 and the feed point of the feed network 319 located on the inner face of the substrate 313.1 of the parasitic antenna.

[0104] According to another exemplary embodiment not illustrated, the system may comprise at least two groups of auxiliary antennas arranged on each parasitic antenna. By way of example, the system comprises a first group of auxiliary antennas fed as described above and a second group of auxiliary antennas not fed and electromagnetically coupled to the first group of auxiliary antennas. Each auxiliary antenna not fed comprises only a rectangular radiating element or patch with a “U” shaped slot. This unfed radiating element may be fixed remotely on the radiating element fed of the auxiliary antenna fed by means of a fixing part such as a foam layer or a mechanical part.

[0105] [Fig. 14] shows the system of [Fig. 10] in an assembled configuration. For example, the parasitic antennas 310.1, 310.2, 310.3, 310.4 are assembled together by a mechanical support 301.

[0106] In this exemplary embodiment, the mechanical support 301 comprises a base 304 and four connectors 301.1, 301.2, 301.3, 301.4 extending vertically from the base 304 which here has a substantially square shape. Each connector comprises two sections perpendicular to each other forming an “L” in a section plane. The long edges of the connector are provided with a vertical groove configured to insert an edge of the substrate of the parasitic antenna. Thus, the parasitic antennas are assembled together two by two via the mechanical support 301. The antenna array system has the shape of a right prism with a rectangular base. The parasitic antennas form the faces of this right prism.

[0107] As an example, the system has a compact cubic geometric shape. Its dimension is 175x175x131 mm3 which is comparable to the dimensions of existing 5G boxes on the current market, with higher performance, and in particular higher directivity.

[0108] In [Fig.15] the radiation patterns 303.1, 303.3, 303.2, 303.4 calculated respectively for the four main azimuthal directions 0°, 180°, 90°, 270° and the radiation patterns 302.1, 302.2, 302.3, 302.4 calculated for the four off-axis directions 45°, 135°, 225°, 315° have also been shown. For these calculations, the substrate used for the parasitic antenna and the main fed antenna is made of a material known under the name RT5880 with a thickness of 0.8 millimeters, a height of 142 millimeters and a width of 60 millimeters.

[0109] [Fig. 16] shows the radio frequency specification of the antenna array system of [Fig. 15] in the frequency band between 760 MHz and 900 MHz. Graph (a) represents the reflection coefficient as a function of frequency. Graph (c) represents the directivity and gain as a function of frequency in the main angular sectors. Graph (c) represents the directivity and gain as a function of frequency in the sectors depointed at ± 45 °. The simulation results obtained for the antenna array system of [Fig. 15] show that the proposed system achieves a radiation efficiency greater than 95% and a gain between 7 and 9.4 dBi for the main directions and a gain between 6 and 7.8 dBi for the depointed directions.

[0110] [Fig. 17] shows the specification of the antenna array system of [Fig. 15] in the frequency band between 2 GHz and 4 GHz. Graph (a) represents the reflection coefficient as a function of frequency, graph (b) represents the directivity and gain as a function of frequency in the main angular sectors and graph (c) represents the radiation efficiency as a function of frequency. The simulation results obtained for the antenna array system of [Fig. 15] show that the proposed system achieves a radiation efficiency greater than 90% and a gain between 11.9 and 14 dBi in the bands N7, N38, N41 and N78.

[0111] Tables 1 and 2 below indicate the performance results achieved by an antenna array system of [Fig. 15].

[0112] Tables 1 and 2 below indicate the performance results achieved by an antenna array system of [Fig.5].

[0113] [Tables 1] 5G Frequency Band N7 N28 N38 N41 N53 N78 Frequency (MHz) 2500- 2690 770-825 2570-262 0 2496-2696 2483-249 5 3300-3800 Gain >12 dBi > 7dBi >12 dBi > 12 dBi > 11 dBi > 12.8 dBi Radiation Efficiency >90% >90% >90% >95 % >95 % >95%

[0114] [Fig. 18] shows the measurement results obtained for a prototype of the array antenna system of [Fig. 15]. The measurement results show satisfactory results, close to those of the simulation in the N78 band.

[0115] [Fig. 19] illustrates a variant of [Fig. 15] in which the antenna array system comprises three parasitic antennas each forming one face of a prism straight and a main fed antenna positioned at the center of the prism, a group of four auxiliary fed antennas operating in a frequency band between 2.4 GHz and 3.8 GHz being arranged on the substrate of each parasitic antenna.

[0116] The antenna array system 400 comprises three parasitic antennas 410.1, 410.2, 410.3 each forming a face of a right prism and a fed main antenna 430 positioned at the center of the prism. The fed main antenna 430 and the parasitic antennas 410.1, 410.2, 410.3 form a first superdirectional antenna array which is configured to operate in a first frequency band between 780 MHz and 810 MHz. The reactive loads which are associated with the parasitic antennas make it possible to selectively modify the orientation of the radiation emitted by this first superdirectional array in the eight azimuthal directions.

[0117] In order to be able to propose a network system that can operate in a wide range of 5G frequencies from N28 to N78 while preserving dimensions comparable to existing boxes and optimal performances for each band, as in the case of [Fig. 15], the network system of [Fig. 19] further comprises three groups of fed auxiliary antennas each arranged on a parasitic antenna. These fed auxiliary antennas are configured to operate in a frequency band different from the frequency band in which the fed main antenna 430 operates. They operate precisely in a frequency band between 2.4 GHz and 3.8 GHz.

[0118] [Fig.20] is a top view of the antenna array system of [Fig.19]. On In this embodiment, as in the case of the system of [Fig.8], the system further comprises three mechanical supports 401.1, 401.2, 40.3 which allow the three parasitic antennas to be assembled together. The antenna array system is in the form of a right prism with a hexagonal base. The parasitic antennas and the mechanical supports form the faces of this prism.

[0119] In [Fig.21] the radiation diagrams 402.1 have also been represented, 402.3, 402.3 calculated respectively for the three main azimuthal directions 0°, 120°, 240° and the radiation patterns 404.1, 404.2, 404.3 calculated respectively for the three depointed directions 60°, 180°, 300°.

[0120] A known example application relates to a 5G customer premises equipment or gateway to provide high-speed fixed radio broadband access (“FWA”). It allows rapid deployment at speeds sufficient for the needs of domestic users at prices competitive with optical fiber. It is a cost-effective alternative solution in rural areas where fiber installation is too expensive, and in urban and peri-urban areas where fiber installation can be difficult. The user equipment typically consists of an outdoor antenna connected on one side with a base station via radio waves and on the other side with an internal box via an Ethernet cable. The internal box then ensures the broadcasting of the received signals for the various domestic devices connected to it. The internal box can for example be equipped with an antenna network system according to an embodiment described above.

[0121] The antenna array system of the present disclosure also makes it possible to simplify the 5G installation. Indeed, thanks to the superdirectivity and the wide frequency band in which the antenna array system operates both in the frequency band, it is no longer necessary to install an external antenna placed in direct view of the 5G access point and to connect it to the internal 5G box via the cable, which imposes the choice of the location of the 5G gateway.

[0122] The use of a single indoor device (or 5G gateway) makes it possible to simplify the installation cost, simplify the equipment and make the choice of location of the 5G gateway more flexible. Such equipment makes it possible to operate in frequency bands below 6 GHz and combine carrier aggregation technologies with those of beamforming antennas. It makes it possible to limit losses linked to indoor penetration and multi-path, and interference. The specific architecture also allows miniaturization to facilitate its integration into 5G equipment.

[0123] The present disclosure is not limited to the embodiments described above which have been given as examples. It is obvious that these embodiments can be modified, in particular to encompass all the variants that a person skilled in the art may envisage within the framework of the protection sought, in particular as regards the number of parasitic antennas and the number of active antennas, the materials used for the substrate, the shape of the active radiating element of the active antenna.

Claims

Claims

1. An antenna array system (1) comprising: - a powered main antenna (30) configured to emit a beam directed in a plurality of main directions, said powered main antenna operating in a first frequency band; - a set of parasitic antennas (10.1, 10.2, 10.3, 10.4) arranged so as to form a first envelope by concentrically surrounding the fed main antenna (30), each parasitic antenna comprising a substrate made of dielectric material (13.1, 13.2, 13.3, 13.4) having a face oriented towards the outside of the first envelope provided with a parasitic radiating element (11.1, 11.2, 11.3, 11.4) and a ground plane, the parasitic radiating element (11.1, 11.2, 11.3, 11.4) being connected to the ground plane via a reactive load (12.1, 12.2, 12.3, 12.4), each parasitic antenna being configured to emit a beam directed in a main direction, the reactive loads (12.1, 12.2, 12.3, 12.4) being configured to selectively activate the electromagnetic coupling between the main fed antenna (30) and a pair of parasitic antennas to modify the directivity of the main fed antenna (30).

2. An antenna array system according to claim 1, wherein the set of parasitic antennas (220.1, 220.2, 220.3, 220.4) are arranged to form at least a second envelope by concentrically surrounding the main fed antenna (230).

3. An antenna array system according to claim 1 or 2, wherein the distance between the fed main antenna (30, 130, 230, 330, 430) and the parasitic antennas (10.1, 10.2, 10.3, 10.4, 110.1, 110.2, 110.3, 110.4, 210.1, 210.2, 210.3, 210.4, 220.1, 220.2, 220.3, 220.4, 310.1, 310.2, 310.3, 310.4, 410.1, 410.2, 410.3) is equal to or less than 0.2 X, X being the wavelength of the beam emitted by the main powered antenna (30, 130, 230, 330, 430) and the parasitic antennas.

4. An antenna array system according to one of claims 1 to 3, wherein the fed main antenna (30) comprises a radiating element (32) in the form of a disc remotely mounted on a cylindrical ground plane (31).

5. An antenna array system according to one of claims 1 to 3, wherein the fed main antenna (130) comprises two substrates (133.1, 133.2) made of dielectric material intersected at 90° to each other, the faces of the substrates oriented on the same side each being provided with a radiating element (132.1, 132.2) and a ground plane.

6. An antenna array system according to one of the preceding claims, wherein the parasitic radiating element has an M shape.

7. An antenna array system according to any preceding claim, wherein the first envelope is in the form of a straight prism, each parasitic antenna comprising a substrate of dielectric material forming one face of a straight prism.

8. An antenna array system according to one of claims 1 to 6, wherein the first envelope is in the form of a cylinder, each parasitic antenna comprising a substrate of dielectric material forming a part of the cylindrical wall.

9. An antenna array system according to one of claims 1 to 8, wherein the main fed antenna and the parasitic antennas operate in a first frequency band between 718 MHz and 810 MHz.

10. An antenna array system according to one of the preceding claims, wherein the set of parasitic antennas comprises four parasitic antennas (10.1, 10.2, 10.3, 10.4, 110.1, 110.2, 110.3, 110.4, 210.1, 210.2, 210.3, 210.4, 220.1, 220.2, 220.3, 220.4, 310.1, 310.2, 310.3, 310.4) each forming a face of a rectangular parallelepiped, the main fed antenna and the parasitic antennas being capable of being coupled together to emit an electromagnetic beam in four main azimuthal preferred directions 0°, 90°, 180° and 270° and in four azimuthal depointed preferred directions 45°, 135°, 225° and 315°, the reactive loads being configured to selectively activate the coupling between a pair of opposing parasitic antennas or a pair of adjacent antennas with the main fed antenna to selectively modify the directivity of the main fed antenna in two opposite azimuthal preferred directions chosen from the four pairs of opposite azimuthal directions (0, 180°), (90, 270°), (45°, 225°) or (135°, 315°).

11. An antenna array system according to one of the preceding claims, further comprising for each parasitic antenna, a group of fed auxiliary antennas (340.1, 340.2, 340.3, 340.4) operating in a second frequency band different from the first frequency band, said powered auxiliary antennas being mounted at a distance from the outer face of the substrate of each parasitic antenna.

12. An antenna array system according to claim 11, wherein the fed auxiliary antennas (340.1, 340.2, 340.3, 340.4) are configured to operate in a second frequency band between 2.4 GHz and 3.8 GHz.

13. An antenna array system according to claim 11 or 12, wherein the fed auxiliary antennas (340.1, 340.2, 340.3, 340.4) are formed by a rectangular patch antenna with a U-shaped slot, each group of fed auxiliary antennas associated with a parasitic antenna being fed uniformly by a feed network (319) made on the inner face of the substrate of the parasitic antenna.

14. An antenna array system according to one of claims 11 to 13, wherein each fed auxiliary antenna (340.1, 340.2, 340.3, 340.4) is held in position relative to the outer face of the substrate of the associated parasitic antenna (310.1, 310.2, 310.3, 310.4) by means of a fixing part (302.1).

15. Antenna array system according to one of claims 11 to 14, wherein the auxiliary antennas of the same group have identical dimensions.

16. Antenna array system according to one of claims 11 to 14, wherein the auxiliary antennas of the same group have different dimensions.

Images