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] This disclosure relates to the field of superdirectional antennas. In particular, this disclosure relates to a superdirectional antenna array system operating over a wide frequency band. The invention has applications in wireless communication systems. Previous technique

[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 devices, antennas operating in different bands are increasingly required to coexist in the same environment. Therefore, antennas must be able to emit radiation only in the desired direction, reduce interference on the receiving end by capturing only signals from a preferred direction, and ultimately reduce power consumption and system operating costs. Furthermore, 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 miniaturize the size of the antenna system to limit the overall device volume.

[0004] However, as the dimensions of the antennas 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 it occupies. In other words, the bandwidth decreases as the size decreases. The antenna's directivity is also related to its size. It decreases as the size decreases.

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

[0006] A known solution consists of nesting different conventional networks together to cover a wide frequency band. However, it is often difficult to ensure good isolation between the different frequency bands due to the Interference occurs between the radiation on the transmitting and receiving sides. Furthermore, beamforming capacity is affected by increasing frequency due to the appearance of grating lobes.

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

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

[0009] One object of the present disclosure is to propose a new compact antenna array system architecture with low manufacturing cost using standard printed circuit board techniques. Summary

[0010] This disclosure improves the situation.

[0011] An antenna array system is proposed comprising: - a powered main antenna 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 arranged to form a first envelope by concentrically surrounding the main fed antenna, each parasitic antenna comprising a substrate of dielectric material having one 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 charge, each parasitic antenna being configured to emit a beam directed along a main direction, the reactive charges being configured to selectively activate the electromagnetic coupling between the main fed antenna and a pair of parasitic antennas to modify the directivity of the main fed antenna.

[0012] The features described in the following paragraphs may optionally be implemented independently of each other or in combination with each other:

[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, / , where X is the wavelength of the beam emitted by the main fed antenna and the parasitic antennas.

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

[0016] The main powered antenna comprises two dielectric material substrates crossed 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 right prism, each parasitic antenna comprising a substrate of dielectric material forming one face of a right prism.

[0019] The envelope is in the form of a cylinder, each parasitic antenna comprising a substrate 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 one face of a rectangular parallelepiped. The main fed antenna and the parasitic antennas are capable of being coupled together to emit an electromagnetic beam in four preferred main azimuthal directions (0°, 90°, 180°, and 270°) and in four preferred off-point azimuthal directions (45°, 135°, 225°, and 315°). The reactive loads are configured to selectively activate 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 preferred opposite azimuthal 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 one 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 made 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 piece.

[0026] According to one 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 features, details and advantages will become apparent from reading the detailed description below and from analyzing the accompanying drawings, in which: Fig. 1

[0029] [Fig. 1] Fig. 1 is an exploded perspective view representing an antenna array system operating in a frequency band between 758 MHz and 810 MHz according to an embodiment, comprising a group of four parasitic antennas, each forming one face of a right prism, a rectangular parallelepiped, and a main fed antenna or excitation antenna positioned at the center of the prism, the distance between the excitation antenna and the parasitic antenna being less than 0.2X, each parasitic antenna being connected to parasitic reactive loads: capacitive or inductive, the excitation antenna and the parasitic antennas being capable of being coupled together to emit an electron beam in four preferred main azimuthal directions 0°, 90°, 180° and 270° and in four preferred off-point azimuthal directions 45°, 135°, 225° and 315°,the capacitive or inductive loads being configured to selectively activate coupling between a pair of opposing parasitic antennas or a pair of adjacent antennas with the exciter antenna to orient the electron beam along two preferred opposing azimuthal 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 parasitic antenna of the [Fig.l]. Fig. 3

[0031] [Fig.3] The [Fig.3] is a perspective view showing an example of an embodiment of a main antenna fed from the [Fig. 1]. Fig. 4A

[0032] [Fig.4A] The [Fig.4A] is a perspective view of the antenna array system of the [Fig.1] in an assembled configuration. Fig. 4B

[0033] [Fig.4B] The [Fig.4B] is a top view of the antenna array system of the [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] The [Fig.6] is a perspective view showing another example of an embodiment of a powered main antenna. Fig. 7

[0036] [Fig.7] The [Fig.7] is an exploded perspective view representing 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 one face of a rectangular parallelepiped and a main fed antenna positioned at the center of the prism of the [Fig.6]. Fig. 8

[0037] [Fig.8] The [Fig.8] is a perspective view representing the antenna array system of the [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] The [Fig. 10] is an exploded perspective view representing an antenna array system according to another embodiment, comprising a group of four 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 and arranged on each parasitic antenna. Fig. 11A

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

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

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

[0043] [Fig.12B] [Fig.12B] shows a schematic perspective view of the powered auxiliary antenna of [Fig.12A], 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 powered auxiliary antenna to a feed network printed on the rear face of the substrate. Fig. 13

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

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

[0046] [Fig. 15] The [Fig. 15] is a perspective view of the antenna array system of the [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 central 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 of the frequency in the principal angular sectors and (c) directivity and gain as a function of frequency in the sectors depointed at ± 45°. Fig. 17

[0048] [Fig. 17] The [Fig. 17] shows the specification of the antenna array system of the [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 principal angular sectors and (c) radiation efficiency as a function of frequency. Fig. 18

[0049] [Fig. 18] The [Fig. 18] shows the simulation results and the measured results on a prototype antenna array system of the [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 (d) radiation efficiency as a function of frequency. Fig. 19

[0050] [Fig. 19] The [Fig. 19] is a perspective view representing 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 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 central 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 implementation methods

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

[0054] In this disclosure, the term “radiation efficiency” refers to the losses of an antenna that 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 this disclosure, the term “gain” is defined as the ratio of the radiation intensity to the total power injected into the antenna in a given direction. It is also related to efficiency and directivity.

[0056] In the following description, the expression “exciting antenna” or “main powered antenna” or simply “main antenna” refers to 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 following description, the expression “reconfigurable antenna in directivity” or “reconfigurable antenna” refers to an antenna associated with a parasitic antenna to modify the directivity of the beam emitted in a given direction.

[0058] In the following description, the expression “fed auxiliary antenna” refers to 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 following description, the term “outer face” refers to a substrate face of a parasitic antenna oriented outwards from the envelope formed by the parasitic antennas assembled together surrounding the main fed antenna or the excitation antenna. In other words, the outer faces of the parasitic antennas form the outer face of the envelope. The term “inner face” refers to a substrate face of a parasitic antenna oriented towards the excitation antenna located at the center of the envelope.

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

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

[0062] The distance between the parasitic antenna and the excitation 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 the main fed antenna.

[0063] Figure 2 represents one of the parasitic antennas 10.1 used in the system of Figure 1. The parasitic antenna 10.1 comprises a substrate 13.1 having a shape The substrate is approximately rectangular. 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 0.15X. The substrate is made of a dielectric material. For example, the substrate is made of RT5880 type dielectric material, having a relative permittivity er of 2.2, and a loss tangent tan(φ) of 0.0009. The substrate has one face facing outwards from the envelope and one face facing inwards from the envelope. The parasitic antenna includes a radiating element 11.1 having an M shape formed on the outer 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 along a main azimuthal direction. In the embodiment shown in [Fig. 1], the four parasitic antennas are configured to emit four beams directed along four azimuthal directions, namely 0°, 90°, 180°, and 270°. This unidirectional beam has a radiation pattern comprising a main lobe oriented along 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 disk 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 shown in the figure.

[0066] The excitation antenna 30 is associated with four parasitic antennas whose function is to reconfigure the radiation pattern of the excitation antenna by electromagnetic coupling. The reactive charges 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. 1] operates as follows. The excitation antenna 30 is continuously powered by a source and emits radiation in all directions. For example, the charge 12.1 connected to the radiating element 11.1 takes a predetermined reactive value C1 and the charge 12.3 connected to the radiating element 11.3 takes a predetermined reactive value C2. The two opposing charges activate the radiating elements 11.1 and 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 primarily increase the directivity of the exciter antenna in the principal azimuthal direction 0° and the principal azimuthal direction 180°. Similarly, the reactive value of the two other opposite charges 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 exciter antenna 30 so as to increase the directivity of the exciter antenna in the two other principal azimuthal directions 90°, 270°.

[0068] According to another 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 offpoint directions 45°, 135°, 225°, 315°.

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

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

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

[0072] For example, when the charge 12.1 and the charge 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 back lobe extending in the 180° direction. When the charges 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 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 load pair 12.1, 12.2 simultaneously activates the two parasitic radiating elements 11.1, 11.2 and the load pair 12.3, 12.4 simultaneously activates the two parasitic radiating elements 11.3, 11.4, the latter interact by electromagnetic coupling with the excitatory radiating element of the excitatory antenna so that the radiation pattern of system 1 extends in two opposite depointed directions (45° and 225°), with a main lobe extending in the 45° direction and a back lobe extending in the 225° direction. When the charge pair 12.2,12.3 activates the parasitic radiating elements 11.2,11.3 and the charge pair 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 system 1 extends in two 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 charges so as to selectively activate the parasitic radiating elements to modify the directivity of the radiation. By switching the value of the parasitic reactive charges, it is thus possible to make the beam sweep 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 exhibits an ultra-short response time to an instruction signal transmitted by the circuit, allowing for very rapid reconfiguration of the radiation pattern of the exciter antenna. In particular, the antenna array system can be used in a 5G application between a 5G gateway and a mobile wireless device such as a mobile phone, which requires a latency on the order of tens of microseconds to reconfigure the beam.

[0076] The system in [Fig. 1] allows coverage of 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 excitation antenna to cover other azimuthal directions. It is possible to cover 2N azimuthal directions by providing N parasitic antennas, where N is a natural number.

[0077] Fig. 5 illustrates a variant embodiment of the antenna array system of Fig. 1, where the parasitic antennas form two envelopes by concentrically surrounding the central excitatory antenna 230.

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

[0079] In this embodiment example, 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 example, the parasitic antennas and the excitatory antenna are similar to those in [Fig.1].

[0081] As in [Fig. 2], the parasitic antenna comprises a substrate having a substantially rectangular shape, one face oriented towards the outside of the envelope and one face oriented towards the inside of the envelope. The parasitic antenna comprises a radiating element having a shape M formed on the outer 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 disk 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] Figure 6 illustrates another embodiment of the main excitation antenna 130. The main excitation antenna 130 comprises two dielectric material substrates 131.1, 131.2 crossed at 90° to each other. One of the two substrates includes a central longitudinal slot having dimensions adapted to allow passage of the second substrate 133.2.

[0084] The faces 133.1, 133.2 of the two substrates 131.1, 131.2, which are oriented in the same direction, are each provided with an M-shaped radiating element 132.1, 132.2, similar to those found in parasitic antennas. In [Fig. 6], these two faces are shown in a view arbitrarily referred to herein as the front view. These faces are also provided with a ground plane. In [Fig. 6], the two opposite faces are shown in a view arbitrarily referred to herein as the rear view.

[0085] Fig. 7 illustrates another variant embodiment of the antenna array system of Fig. 1 in which the central exciter antenna used is that of Fig. 6.

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

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

[0088] In this embodiment example, the parasitic antennas are similar to those in [Fig.1].

[0089] The system operates in the same way as that of [Fig. 1]. The value of the parasitic reactive charges 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 charges, it is thus possible to sweep the beam in the eight azimuthal directions.

[0090] Fig. 8 represents the system of Fig. 7 in an assembled configuration. By way of 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] Figure 9 illustrates a top view of the system of Figure 8. Each support has a longitudinal groove on both edges, sized to accommodate an edge of the substrate of a parasitic antenna. Thus, the parasitic antennas are assembled together in pairs via the supports. The antenna array system is in the form of a right prism with an octagonal base. The parasitic antennas and the mechanical supports form the faces of this prism.

[0092] Figure 9 also shows the radiation patterns 102.1, 102.3, 102.2, 102.4 calculated respectively for the four principal azimuthal directions 0°, 180°, 90°, 270° and the radiation patterns 104.1, 104.2, 104.3, 104.4 calculated respectively for the four off-axis directions 45°, 135°, 225°, 315°. For these calculations, the substrate used for the parasitic antenna and the main fed antenna is made of a material known as RT5880, 0.8 millimeters thick, with a height of 142 millimeters and a width of 60 millimeters.

[0093] Fig. 10 is an exploded perspective view representing 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 one face of a right prism, and a main fed antenna 330 positioned at the center of the prism. The main fed antenna 330 and the parasitic antennas form a first superdirectional antenna array configured to operate in a first frequency band between 780 MHz and 810 MHz. The loads associated with the parasitic antennas allow the orientation of the radiation emitted by this first superdirectional array to be selectively modified in the eight azimuthal directions. The operation of this superdirectional array is similar to that of [Fig. 1].

[0095] In order 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 enclosures and optimal performance for each band, the network system in [Fig. 10] further includes four groups of auxiliary powered antennas, each arranged on a parasitic antenna. These auxiliary antennas are configured to operate in a frequency band different from that of the main powered antenna 330. The auxiliary antennas operate in a frequency band between 2.4 GHz and 3.8 GHz.

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

[0097] Figure 11A illustrates an example of the 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 powered auxiliary antennas are arranged on the outer face of the substrate 313.1 of the parasitic antenna 310.1. In the described embodiment, the four powered auxiliary antennas are distributed in the form of an array.

[0098] Figure 1 IB illustrates an example of an embodiment of a passive feed network 319 implemented on the inner face of the substrate of the parasitic antenna 310.1. The feed network is connected to a power supply 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 uniformly fed or excited by the feed network 319.

[0099] Figure 12A illustrates an example of a powered auxiliary antenna used to form the group of four auxiliary antennas in Figure 11A. The auxiliary antenna 340.1 used is a patch antenna. It comprises a radiating element 342.1 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 37.3 x 53.6 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.12B], the patch is provided with a power supply point 343.1 which is connected to the power supply point 345.1 of the power supply network via a coaxial connector 344.1. The patch is separated from the ground plane by a distance d which is for example on the order of 9 mm.

[0101] Advantageously, and thanks to the single-sided structure of the parasitic antenna having one side equipped 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 parasitic antenna substrate and to implement the 319 feed network on the rear face of the parasitic antenna substrate. 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 overall size.

[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 piece.

[0103] Figure 13 schematically illustrates a top view of the antenna array system of Figure 10 in an assembled configuration. In this embodiment, the mounting piece 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 array 319 located on the inner face of the substrate 313.1 of the parasitic antenna.

[0104] According to another embodiment not shown, the system may include at least two groups of auxiliary antennas arranged on each parasitic antenna. By way of example, the system includes a first group of fed auxiliary antennas as described above and a second group of unpowered auxiliary antennas electromagnetically coupled to the first group of auxiliary antennas. Each unpowered auxiliary antenna comprises only a rectangular radiating element or patch with a U-shaped slot. This unpowered radiating element may be remotely attached to the powered radiating element of the powered auxiliary antenna by means of a fastening piece such as a foam layer or a mechanical part.

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

[0106] In this 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 is substantially square in shape. Each connector comprises two sections perpendicular to each other, forming an “L” in a cross-sectional plane. The long edges of the connector have a vertical groove configured to insert an edge of the substrate of the parasitic antenna. Thus, the parasitic antennas are assembled together in pairs 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] By way of example, the system has a compact cubic geometric shape. Its dimensions are 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] Figure 15 also shows the radiation patterns 303.1, 303.3, 303.2, 303.4 calculated respectively for the four principal azimuthal directions 0°, 180°, 90°, 270° and the radiation patterns 302.1, 302.2, 302.3, 302.4 calculated for the four off-point directions 45°, 135°, 225°, 315°. For these calculations, the substrate used for the parasitic antenna and the main fed antenna is made of a material known as RT5880, 0.8 millimeters thick, with a height of 142 millimeters and a width of 60 millimeters.

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

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

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

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

[0113] [Tables 1] Frequency band 5 GHz N7 N28 N38 N41 N53 N78 Frequency (MHz) 2500 - 269 0 770-825 2570-262 0 2496-2696 2483-249 5 3300-3800 Gain >12 dBi > 7 dBi >12 dBi > 12 dBi > 11 dBi > 12.8 dBi Radiation Efficiency >90% >90% >90% >95% >95% >95%

[0114] Figure 18 shows the measurement results obtained for a prototype of the array antenna system of Figure 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 right prism, and a main fed antenna positioned at the center of the prism, with a group of four auxiliary fed antennas operating in a frequency band between 2.4 GHz and 3.8 GHz 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 one face of a right prism, and a main fed antenna 430 positioned at the center of the prism. The main fed antenna 430 and the parasitic antennas 410.1, 410.2, 410.3 form a first superdirectional antenna array configured to operate in a first frequency band between 780 MHz and 810 MHz. The reactive loads associated with the parasitic antennas allow the orientation of the radiation emitted by this first superdirectional array to be selectively modified in the eight azimuthal directions.

[0117] In order 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 enclosures and optimal performance for each band, as in the case of [Fig. 15], the network system of [Fig. 19] further includes three groups of powered auxiliary antennas, each arranged on a parasitic antenna. These powered auxiliary antennas are configured to operate in a frequency band different from that of the main powered antenna 430. They operate specifically in a frequency band between 2.4 GHz and 3.8 GHz.

[0118] Figure 20 is a top view of the antenna array system of Figure 19. In this embodiment, as in the system of Figure 8, the system further comprises three mechanical supports 401.1, 401.2, and 40.3 that 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] Radiation diagrams have also been shown in [Fig.21] 402.1, 402.3, 402.3 calculated respectively for the three principal azimuthal directions 0°, 120°, 240° and the radiation diagrams 404.1, 404.2, 404.3 calculated respectively for the three off-point directions 60°, 180°, 300°.

[0120] A known application example concerns a local customer or 5G gateway device for providing high-speed fixed radio broadband access (FWA). It enables rapid deployment at speeds sufficient for the needs of home users at competitive prices compared to fiber optics. It is an economical alternative in rural areas where fiber installation is too expensive, and in urban and suburban areas where fiber installation can be difficult. The user equipment typically consists of an outdoor antenna connected on one side to a base station via radio waves and on the other side to an internal unit via an Ethernet cable. The internal unit then distributes the received signals to the various connected home devices. The internal unit can, for example, be equipped with an antenna array system according to an embodiment described above.

[0121] The antenna array system of this disclosure also simplifies 5G installation. Indeed, thanks to the superdirectivity and the wide frequency band in which the antenna array system operates, it is no longer necessary to install an external antenna placed in direct line of sight of the 5G access point and connect it to the internal 5G box via cable, which dictates the choice of location for the 5G gateway.

[0122] The use of a single indoor device (or 5G gateway) simplifies installation costs, simplifies equipment, and allows for greater flexibility in choosing the location of the 5G gateway. Such a device can operate in frequency bands below 6 GHz and combine carrier aggregation technologies with beamforming antenna technologies. It helps to limit losses related to indoor penetration, multipath propagation, and interference. Furthermore, the specific architecture allows for miniaturization, facilitating its integration into the 5G equipment.

[0123] This disclosure is not limited to the embodiments described above, which have been given by way of example. It is evident that these embodiments can be modified, in particular to encompass all the variations that a person skilled in the art may consider in the context of the protection sought, particularly with regard to the number of parasitic antennas and the number of active antennas, the materials used for the substrate, and the shape of the active radiating element of the active antenna.

Claims

Demands

1. 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 parasitic antenna comprising a substrate of dielectric material (13.1, 13.2, 13.3, 13.4) having one face oriented outwards from 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 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 (30) and a pair of parasitic antennas to modify the directivity of the main fed antenna (30); - the distance between the main fed 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) being equal to or less than 0.2 X, / . being the wavelength of the beam emitted by the main fed antenna (30, 130, 230, 330, 430) and the parasitic antennas.

2. Antenna array system according to claim 1, wherein the parasitic antenna set (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. Antenna array system according to any one of claims 1 to 2, wherein the main fed antenna (30) comprises a radiating element (32) in the form of a disk mounted remotely on a cylindrical ground plane (31).

4. Antenna array system according to any one of claims 1 to 2, wherein the main fed antenna (130) comprises two substrates (133.1, 133.2) of dielectric material intersected at 90° to each other, the faces of the substrates oriented in the same direction each being provided with a radiating element (132.1, 132.2) and a ground plane.

5. Antenna array system according to any one of the preceding claims, wherein the parasitic radiating element has an M shape.

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

7. An antenna array system according to any one of claims 1 to 5, wherein the first envelope is in the form of a cylinder, each parasitic antenna comprising a substrate of dielectric material forming part of the cylindrical wall.

8. Antenna array system according to any one of claims 1 to 7, wherein the main fed antenna and the parasitic antennas operate in a first frequency band between 718 MHz and 810 MHz.

9. Antenna array system according to any one of the preceding claims, wherein the parasitic antenna set 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 one 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 principal azimuthal preferred directions 0°, 90°, 180° and 270° and in four azimuthal preferred off-point directions 45°, 135°, 225° and 315°, the reactive charges being configured to selectively activate coupling between a pair of opposite 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°).

10. An antenna array system according to any one of the preceding claims, further comprising for each parasitic antenna, a group of powered 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.

11. Antenna array system according to claim 10, wherein the powered 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.

12. Antenna array system according to claim 10 or 11, 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 array (319) made on the inner face of the substrate of the parasitic antenna.

13. Antenna array system according to any one of claims 10 to 12, wherein each powered 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 piece (302.1).

14. Antenna array system according to any one of claims 10 to 13, wherein the auxiliary antennas of the same group have identical dimensions.

15. Antenna array system according to any one of claims 10 to 13, wherein the auxiliary antennas of the same group have different dimensions.

Images