HIGH-FREQUENCY TRANSMITTING / RECEIVING SYSTEM, ASSOCIATED EQUIPMENT AND METHOD

Description

[0001] The present invention relates to a radio frequency transmission / reception system, as well as to an associated radio frequency transmission / reception installation and method.

[0002] Patent document WO 2014 / 091274 A1 describes an array of active antennas distributed on a "linear section" support, i.e. forming several sections inclined relative to each other, according to distinct antenna orientation directions. The array includes a module for controlling the antennas so as to depoint a radiofrequency beam from the antenna array.

[0003] Patent document US 2005 / 088358 A1 describes an active antenna array comprising parasitic elements controlled to depoint a radio frequency beam from the antenna.

[0004] In the scientific article by AM Montaser et al. entitled “Circular, Hexagonal and Octagonal Array Geometries for Smart Antenna Systems Using Hybrid CFO-HC Algorithm” published in Journal of Engineering Sciences, vol. 40, no. 16, pp. 1715-1732, November 2012 , A radio frequency transmitting / receiving system is described comprising an octagonal active antenna array and an active antenna array control device designed to control the active antennas so as to emit a 360° multidirectional radiation pattern according to a predefined template.

[0005] This system is particularly restrictive in terms of energy consumption given that the antenna network transmits simultaneously in several directions even in the absence of a mobile terminal to follow in each of these directions.

[0006] Another solution for transmitting in multiple directions is to depoint a unidirectional beam. In this context, the scientific article by S. Han., C.-L. I, Z. Xu and a. C. Rowell, entitled "Large-Scale Antenna Systems with Hybrid Analog and Digital Beamforming for Millimeter Wave 5G" and published in IEEE Communications Magazine, January 2015 , describes a radiofrequency transmission / reception system of the type comprising: an active antenna array comprising a main group of active antennas oriented in a main direction; and a device for controlling the active antenna array designed to: o receive one of several possible misalignment values; and o control the active antennas so as to emit a beam misaligned by the received misalignment value, relative to the main direction.

[0007] In particular, in the state of the art, the antenna array is linear.

[0008] To reduce the energy consumption of such a system, the control device is designed to implement a process aimed at turning off a maximum number of antennas, while respecting a radiation template with the received depointing value.

[0009] However, the inventors found that it was difficult to turn off additional antennas as the beam deflection angle increased (e.g. up to a maximum value of ± 45°).

[0010] It may therefore be desirable to provide a radiofrequency transmission / reception system which makes it possible to overcome at least some of the aforementioned problems and constraints.

[0011] There is therefore proposed a radiofrequency transmission / reception system of the aforementioned type, and according to claim 1.

[0012] Thus, when the beam is depointed in a direction close to the auxiliary direction, the active antennas of the auxiliary group can be preferentially used to form the beam, which advantageously makes it possible to turn off antennas oriented in the main direction.

[0013] Optionally, the main direction and the auxiliary direction form an acute angle, for example between +30° and +50°, preferably equal to +45°± 10° or for example between -50° and -30°, preferably equal to -45°± 10°.

[0014] Also optionally, the system comprises: a first auxiliary group of auxiliary active antennas oriented in a first auxiliary direction, the main direction forming with the first auxiliary direction a first acute angle, for example between +30° and +50°, preferably equal to +45°± 10°; and a second auxiliary group of auxiliary active antennas oriented in a second auxiliary direction, different from the main direction and the first auxiliary direction; the main direction forming with the second auxiliary direction a second acute angle, for example between -50° and -30°, preferably equal to -45°± 10°; the first and second angles (α, β) are of opposite sign and have equal absolute values, preferably 45°± 10°. the first and second angles are of opposite sign and have equal absolute values, preferably 45°± 10°; the first and second auxiliary groups of active antennas have the same number of active antennas;each active antenna comprises a radiating element; the system comprises a support of the radiating elements, in which the support comprises a respective section for each group of active antennas, and in which each section of the support is either linear so that the radiating elements are distributed along a straight line along this support section, or planar so that the radiating elements are distributed according to a two-dimensional matrix on this planar support section; the emitted beam is unidirectional; the system comprises: parasitic elements associated respectively with at least some of the active antennas, so as to modify a directivity of the associated antenna; and control means designed to selectively activate each of the parasitic elements; each parasitic element comprises at least two sub-elements;the system further comprises, for each parasitic element, a PIN diode designed to selectively connect the two sub-elements of the parasitic element, the control means being designed to selectively control each of the PIN diodes; each active antenna comprises a radiating element selected from a planar element and a dipolar element; the radiating elements of antennas of one of the groups are aligned and distributed by alternating a first set of at least one dipolar radiating element and a second set of at least one planar radiating element; the radiating elements of antennas of one of the groups are aligned and alternately planar and dipolar. ;

[0015] A radiofrequency transmission / reception installation is also proposed comprising four systems according to the invention as described above, the active antenna networks of which are arranged in an octagon.

[0016] Also proposed is a radiofrequency transmission / reception installation comprising two systems according to the invention, in which the active antenna arrays of the two systems have auxiliary active antennas in common.

[0017] According to an additional feature, the installation comprises two pairs of systems whose active antenna arrays are arranged in an irregular octagon comprising four main sides on which the main active antennas are distributed and four auxiliary sides on which the auxiliary active antennas are distributed, in which, for each auxiliary side, all the auxiliary antennas are in common with the two adjacent arrays.

[0018] Also provided is a radio frequency transmission / reception method, according to claim 15.

[0019] Optionally, the controlled active antenna array comprises: a first auxiliary group of auxiliary active antennas, oriented in a first auxiliary direction, different from the main direction, the main direction forming with the first auxiliary direction a first acute angle, for example between +30° and +50°, preferably equal to +45°± 10°; and a second auxiliary group of auxiliary active antennas, oriented in a second auxiliary direction, different from the main direction and the first auxiliary direction; the main direction forming with the second auxiliary direction a second acute angle, for example between -30° and -50°, preferably equal to -45°± 10°; the method comprises a step of calculating a set of complex excitations of the active antennas as a function of the first and second angles, so as to determine an input power of each active antenna;parasitic elements associated respectively with at least some of the active antennas are selectively activated by control means so as to modify a directivity of the associated antenna.;

[0020] Also provided is a computer program downloadable from a communications network and / or recorded on a computer-readable medium, characterized in that it comprises instructions for executing the steps of a aforementioned radiofrequency transmission / reception method, when said program is executed on a computer.

[0021] The invention will be better understood with the aid of the following description, given solely by way of example and with reference to the appended drawings in which: [ Fig. 1 ] there figure 1 is a schematic view of the architecture of a radiofrequency transmission / reception system according to a first embodiment of the invention; [ Fig. 2 ] there figure 2 is an example of implementation of a reconfigurable active antenna array according to the first embodiment; [ Fig. 3 ] there figure 3 is an enlarged view of the radiating part of a reconfigurable active antenna according to the figure 2 ; [ Fig. 4 ] there figure 4 illustrates radiation patterns of a reconfigurable active antenna according to the figure 3 in two distinct configurations; [ Fig. 5 ] there figure 5 illustrates a radiofrequency emission method implemented by the system of the figure 1 ; [ Fig. 6 ] there figure 6 is an example of implementation of an alternative embodiment of the invention in which the active antennas of the network are not reconfigurable; [ Fig. 7 ] there figure 7 illustrates an alternation of different radiating elements distributed over a section of the active antenna network according to several variant embodiments of the invention; [ Fig. 8 ] there figure 8 illustrates simulation results comparing the energy consumption of a linear network by sections according to the figure 6 compared to a conventional linear network; [ Fig. 9 ] there figure 9 illustrates simulation results comparing the energy consumption of an active antenna array according to the figure 2 for different configurations of active antennas and for different misalignment values; [ Fig. 10 ] there figure 10 illustrates a radiofrequency transmission installation according to a second embodiment of the invention; and [ Fig. 11 ] there figure 11 illustrates a radiofrequency transmission installation according to a third embodiment of the invention. Premier mode de réalisation

[0022] In reference to the figure 1 , a radiofrequency transmission system 100 according to a first embodiment of the invention will be described.

[0023] This system 100 firstly comprises a network 308 of active antennas {1.n}, this network comprising N elementary antennas called active antennas, where n denotes a natural integer between 1 and N.

[0024] Subsequently, the expression “active antenna” will designate any elementary antenna of the network 308 comprising a radiating element, for example of the planar or dipole type, and an amplifier configured to excite the radiating element. Thus, the term “antenna” will be reserved exclusively to designate the elementary antenna and not the network.

[0025] Each active antenna 1.n of the array 308 comprises a radiating element 5.n and a dedicated amplifier 4.n, such as a transmit power amplifier, to excite the radiating element in amplitude and phase. Generally, several radiating elements could be associated with the same amplification means to be excited in the same way.

[0026] Thus, the network 308 generally makes it possible to generate radiation according to one or more radiofrequency beams.

[0027] In the example described, a single unidirectional radiofrequency beam is intended to be emitted by the network 308. This unidirectional beam thus has a radiation pattern comprising a main lobe oriented in a preferred direction and secondary lobes. This beam is reconfigurable in the sense that its radiation characteristics can be adjusted by modifying the excitations applied to the radiating element of all or part of the active antennas (i.e. amplitude and / or phase weighting law of the associated sources).

[0028] Optionally, each active antenna 1.n is reconfigurable, i.e. it further comprises parasitic elements 6.n respectively associated with the radiating elements 5.n, so as to modify a directivity of the associated radiating element. An example of a parasitic element will be described in more detail with reference to the figure 3 below. In other embodiments, parasitic elements could be provided only for certain radiating elements, the others being devoid of them so that their directivity is not modifiable. Hereinafter, the expression "reconfigurable antenna" will designate an active antenna comprising a parasitic element.

[0029] More specifically, the network 308 comprises a main group A0 of active antennas oriented in a main direction d0, as well as, generally, one or more other groups of active antennas oriented in respective directions different from the main direction d0. Subsequently, these other groups will be referred to as “auxiliary groups”. In the example described, the network 308 comprises two auxiliary groups A1, A2, the respective active antennas of which are oriented in respective so-called auxiliary directions d1, d2. As will be explained in more detail subsequently, the auxiliary directions d1, d2 are different from one another.

[0030] More precisely, the main direction d0 and the first auxiliary direction d1 form a first acute angle α, while the main direction d0 forms a second acute angle β with the second auxiliary direction d2.

[0031] So, α = d 0 → , d 1 → ^ , β = d 0 → , d 2 → ^ , where the function x → , y → ^ provides the value of the trigonometric angle formed between two vectors x and y by assigning a + sign or a - sign to the value of the angle to designate the trigonometric (+) and anti-trigonometric (-) direction respectively. By definition, an acute angle has a value between 0 and 90°.

[0032] In particular, the first acute angle α has a value between +30° and +50°, preferably equal to +45°± 10°, while the second acute angle β has a value between -30° and -50°, preferably equal to -45°± 10°.

[0033] Generally, the first and second angles α and β are of opposite signs, so that the first and second auxiliary directions d1 and d2 are oriented on either side of the main direction d0. Thus, the first and second auxiliary directions are not parallel to each other.

[0034] In the example described, the first and second acute angles α and β have the same absolute value (i.e. |α|=|β|) equal to 45°± 10°. This value may be adjusted according to the radiation pattern of each of the active antennas considered and / or according to a desired maximum depointing value to depoint the beam emitted by the active antenna array relative to the main direction d0.

[0035] Generally, the main group A0 comprises N0 active antennas, while the first and second auxiliary groups A1, A2 comprise N1 and N2 active antennas respectively. Preferably, N1 and N2 are both strictly less than N0. In other words, the auxiliary antennas of each group are fewer in number than the main antennas.

[0036] Each number of auxiliary antennas N1, N2 may be chosen according to the number of main antennas N0, so as to modify the direction of the depointed beam emitted by the network 308.

[0037] In the example described, each active antenna 1.n has a single radiating element 5.n. In this case, we equate each number N0, N1, N2 of antennas to the number of radiating elements respectively in each group A0, A1, A2 of active antennas.

[0038] According to the invention, the number N0 of antennas in the main group A0 and the numbers N1, N2 of auxiliary antennas in the auxiliary groups A1, A2 are determined so that a ratio N1 / N0 and / or N2 / N0 is between 1 / 7 and 1 / 3, such that: [Math1] 1 7 ≤ N 1 N 0 ≤ 1 3 let / ou 1 7 ≤ N 2 N 0 ≤ 1 3

[0039] The constraint relating to the number N1 and / or N2 of auxiliary antennas relative to the number N0 of main antennas as defined in equation [Math1] above is particularly advantageous for facilitating high beam misalignments, i.e. at misalignment angles of the order of ±45° to within ±15°, preferably 45° ±10°, while making it possible to achieve an additional reduction in the energy consumption of the antenna network relative to the case where each of the groups of auxiliary antennas comprises the same number of antennas equal to the number N0 of antennas of the main group A0.

[0040] In the example described, the two auxiliary groups A1, A2 have the same number of antennas N1=N2 designated N12 which is strictly less than N0 and more particularly between 1 / 8 and 1 / 4 of the total number of antennas of the active antenna network Nt=N0+N1+N2=N0+2.N12, such that: [Math2] Nt 8 ≤ N 12 ≤ Nt 4

[0041] In general, the radiating elements are distributed within each group of antennas A0, A1, A2 with a pitch specific to the group, noted respectively p0 for the main group A0 and p1, p2 for the first and second auxiliary groups A1, A2. Subsequently, the term "pitch" will denote the spacing between two consecutive radiating elements in each group of antennas or, equivalently, the distance between two adjacent antennas.

[0042] In the example described, the radiating elements in each group A0, A1, A2 are distributed respectively along a distinct straight line and following the same pitch p, such that p0=p1=p2=0.5λ, where λ denotes the operating wavelength of the antenna or equivalently the wavelength of the beam emitted by the network assuming that each antenna emits at the same wavelength.

[0043] In other embodiments (not shown), the radiating elements of each group of active antennas may be distributed on a flat surface according to a two-dimensional matrix having a respective pitch px, py according to two distinct dimensions.

[0044] Generally, the pitch, the number of active antennas in each group and the number of parasitic elements can be chosen according to the beam to be emitted.

[0045] The system 100, more precisely the network 308, comprises an antenna support 8 designed to fix the radiating elements of the active antennas.

[0046] Generally, the support 8 comprises a respective section for each group of antennas. In the example described, the support comprises a main section 8.0 for the main group A0, a first auxiliary section 8.1 and a second auxiliary section 8.2 respectively for the first and second auxiliary groups A1, A2.

[0047] In an alternative embodiment (not shown), the active antennas are divided into two groups, i.e. a main group A0 and an auxiliary group A1 or A2, so that the support comprises two sections, i.e a main section and an auxiliary section.

[0048] In the example described, each section 8.0, 8.1, 8.2 of the support is linear with respect to the radiating elements, in the sense that the section of the support defines a straight line along which the radiating elements of the corresponding antenna group are distributed. Thus, the linear distribution of all the radiating elements on the multiple sections of the support defines a topology called "linear by sections". Thus, such an array will subsequently be referred to as linear by sections.

[0049] Generally, the main section 8.0 forms with the first auxiliary section 8.1 an angle equal to the first angle α as defined with reference to the figure 1 . The main section 8.0 forms with the second auxiliary section 8.2 an angle equal to the second angle β as defined with reference to the figure 1 Or 2 . In the example described, α=+45° and β=-45°.

[0050] Generally, the radiating elements are mounted perpendicular to the support, so that they extend in a direction perpendicular to the support.

[0051] According to another embodiment (not shown), each section of the support is planar relative to the radiating elements of the active antennas, so that the radiating elements are distributed according to a two-dimensional matrix on this planar support section.

[0052] The system 100 further comprises a control device 3 for the network 308 of active antennas.

[0053] The control device 3 firstly comprises a processing and control module 301 designed to provide radiation parameters for each beam to be transmitted, from data received from one or more mobile operators. In particular, this data includes the radiation direction of the beam and its associated template as well as the data stream to be transmitted. This radiation direction can be expressed in the form of an offset value relative to a default direction, e.g. the main direction d0 of the network 308.

[0054] The control device 3 further comprises a calculation module 303 provided for determining a set of amplitudes and phases for all of the beams intended to feed the active antennas of the network 308. The calculation module 303 is configured to provide, on a first output, the set of amplitudes 304 and on a second output, the set of amplitudes and phases.

[0055] The control device 3 further comprises a polarization module 307 (or power supply module) provided for powering the amplifiers 4.1,...,4.n,...,4.N of the active antenna network 308. This polarization module 307 is designed to determine and apply a polarization voltage V n< DC to each amplifier 4.n.

[0056] The control device 3 further comprises a signal generation module 306 provided to determine the power intended to be applied to the input of each amplifier 4.n, called input power P n< in .

[0057] The control device 3 further comprises a control module 307a provided for selectively controlling each of the parasitic elements by applying a switching voltage to it. For example, this switching voltage is selected from two reference voltages V n< ON and V n< OFF.

[0058] In the example described, the control device 3 comprises a computer comprising a processor 3.1, a main memory 3.2 associated with the processor, for example of the RAM type ( Random Access Memory in English), a hard disk 3.6 on which a computer program P is stored, an input / output port 3.7, a communication interface 3.8 and a communication bus 3.9 connecting these elements.

[0059] The computer program P comprises executable code instructions designed to be loaded into the main memory 3.2 in order to be executed by the processor 3.1 for the implementation of the software modules described above.

[0060] Alternatively, all or part of the preceding modules could be implemented by electronic circuits, for example micro-wired, not involving a computer program.

[0061] There figure 2 illustrates, in three dimensions, the radiating elements 5.1,...5.n,...,5.N and the parasitic elements 6.1,...6.n,...6.N respectively associated. As described above with reference to the figure 1 , the radiating elements are distributed on the support 8 according to a topology called “linear by sections”.

[0062] In this example, the radiating elements 5.1,...,5.n,...,5.N of each group of antennas A0, A1, A2 are dipoles fixed perpendicular to the surface of the support 8.

[0063] The support 8 can be designed as a single block or in several parts arranged together so that the first and second auxiliary sections 8.1, 8.2 are inclined relative to the main section 8.0, respectively according to the first and second angles α, β, as defined previously with reference to the figure 1 .

[0064] The support 8 is designed so that the inclination of the auxiliary sections 8.1, 8.2 relative to the main section 8.0 can be adjusted, for example by means of a deformable junction between each auxiliary section 8.1, 8.2 and the main section 8.0 so as to adjust the value of the first and second angles α, β.

[0065] In the example described, the auxiliary sections 8.1, 8.2 are inclined by 45° relative to the main section 8.0, so that the main direction d0 forms with the first and second auxiliary directions d1, d2, respectively an angle α=+45° and β=-45°. Advantageously, the antennas of the auxiliary sections thus facilitate the depointing of the beam by +45° and -45° relative to the main direction d0, and in practice even beyond these values.

[0066] Generally, the emitted beam F is deflected by an angle φ relative to the main direction d0. The auxiliary directions d1, d2 (respectively the angles α and β) are determined according to the maximum value of the deflecting angle φ, in particular φ=α=β in absolute value.

[0067] As illustrated on the figure 2 , the main section 8.0 comprises twelve dipoles, while the auxiliary sections 8.1, 8.2 each comprise two dipoles, for a total of 16 active antennas. This distribution of antennas is such that N2 / N0=N1 / N0=1 / 6 and verifies the relation 1 7 ≤ N 1 N 0 = N 2 N 0 ≤ 1 3 as stated above.

[0068] The 308 active antenna array has a sufficient number of dipoles in the main 8.0 section to form a beam with radiation properties similar to those which would be obtained by a conventional linear array, particularly in terms of aperture at -3dB ( Half Power Beamwidth in English), directivity and beam scanning. Advantageously, the dipoles of the auxiliary sections 8.1, 8.2. facilitate beam depointing with maximum radiation at +45° for the first auxiliary group A1 and at -45° for the second auxiliary group A2.

[0069] In the example described, each radiating element is a 5.n crossed dipole as illustrated in the figure 3 . This dipole comprises two T-shaped radiating structures intersected at 90° to each other, in which each T-shaped structure is dedicated to a distinct polarization.

[0070] Each of the two T-shaped radiating structures of the 5.n dipole is associated with a separate parasitic element 6.n for each polarization, by means of a support plate 7.n formed of a dielectric material. The parasitic element 6.n may also be called a director element in the sense that it allows the directivity of the 5.n dipole to be modified.

[0071] In order not to overload the figures 2 et 3 , the parasitic element 6.n is shown only for a single polarization, that is to say in association with only one of the two T-shaped structures of the dipole 5.n. In practice, the parasitic element 6.n further comprises a structure similar to that shown but perpendicular to the other T-shaped structure of the dipole 5.n.

[0072] In the example described, the parasitic element 6.n comprises two distinct parasitic sub-elements 6.na, 6.nb arranged on the support plate 7.n, in the same plane as that of the dipole 5.n.

[0073] Each parasitic sub-element 6.na, 6.nb is formed of a metallic surface having a length L approximately equal to 0.4λ and spaced from the dipole 5.n by a distance e approximately equal to 0.3λ, where λ denotes the operating wavelength of the dipole.

[0074] In the illustrated example, each parasitic sub-element 6.na, 6.nb has the shape of an elongated surface. However, other shapes may be used for the parasitic elements, depending on the desired radiation properties. For example, the parasitic element may be segmented or have curved ends.

[0075] For each parasitic element 6.n associated with an active antenna, the sub-elements 6.na, 6.nb are connected to each other by means of a voltage-controlled switch by the control module 307b of the parasitic elements, so as to connect or disconnect the two sub-elements 6.na, 6.nb to each other as a function of the switching voltage V n< ON, V n< OFF applied to the switch and thus reconfigure the radiation pattern of each active antenna so that the radiation of the active antenna is more or less directional.

[0076] In the example shown, the switch is a PIN diode ( Positive Intrinsic Negative in English) 6.nc. The control module 307a described above with reference to the figure 1 is designed to selectively drive each of the PIN diodes. For example, by applying a non-zero DC voltage across the PIN diode 6.nc, the two parasitic sub-elements 6.na, 6.nb are electrically connected to each other and in the absence of this voltage, these two parasitic sub-elements are disconnected from each other.

[0077] The PIN diode behaves like an open or closed switch, depending on the voltage applied to its terminals. Thus, under the application of a switching voltage V n < ON greater than or equal to a threshold voltage (e.g. non-zero) across the terminals of the PIN diode 6.nc, the diode behaves like a closed switch having the effect of electrically connecting the two parasitic sub-elements 6.na, 6.nb which interact by electromagnetic coupling with the radiating element 5.n with which it is associated so as to modify the aperture and the directivity of the radiation pattern of the active antenna concerned.

[0078] On the contrary, when a control voltage V n < OFF lower than or equal to another threshold voltage (eg 0V) is applied to the terminals of the PIN diode 6.nc, the two parasitic sub-elements 6.na, 6.nb are disconnected from each other. Thus, each isolated sub-element is no longer likely to be sufficiently excited to significantly modify the radiation pattern of the associated radiating element due to its too small electrical dimension.

[0079] For example, the application of the switching voltage V ON across the PIN diode 6.nc is carried out by means of a DC voltage source which is for example separate from the power source used to power the amplifiers ( i.e. input power P n< in , bias voltage V n< DC ).

[0080] Advantageously, the implantation of the 6.nc PIN diode in the substrate of the parasitic element 6.n is simple and inexpensive to implement. Furthermore, the 6.nc PIN diode has an ultra-short response time allowing the elementary radiation pattern of each active antenna to be reconfigured very quickly. This property is particularly advantageous in the context of electronic beam scanning between a base station and a mobile terminal on the move where the required latency times are of the order of 10 to 20 µs to reconfigure the beam.

[0081] There figure 4 illustrates the theoretical radiation pattern of a reconfigurable antenna of the type illustrated in figure 3 .

[0082] Each reconfigurable antenna of the network 308 can be considered as an elementary source in the sense that it comprises a radiating element excited by an amplifier and associated with a parasitic element driven by an electrical source as described previously.

[0083] In the example described, the reconfigurable antenna has two directivity states or equivalently two distinct 3 dB apertures (Δφ -3dB).

[0084] By definition, directivity expresses the ability of an antenna to radiate the power supplied to its terminals in preferred directions in space. More precisely, the directivity D(θ, φ), sometimes called directive gain, is defined as the ratio between its radiation intensity in the direction (θ, φ) and that (uniform) of the isotropic antenna which radiates the same power. Generally, the term "directivity" implies the maximum directivity.

[0085] For directional antennas, the maximum directivity is approximated by [Math 3]: D = 4 π Ω A = 41253 Δ − 3 dB θ . Δ − 3 dB φ Or Δ − 3 dB θ , Δ − 3 dB φ are the half-power opening angles respectively in the horizontal plane π θ and the azimuthal plane π φ and expressed in degrees. Thus, the directivity D is inversely proportional to these opening angles.

[0086] As illustrated by the solid curve on the figure 4 , a first radiation pattern of the reconfigurable antenna corresponds to a first opening Δ − 3 dB φ 1 equal to 66° characterizing a first state of directivity of the antenna, when a first switching voltage V n< ON is applied by the control module 307a to the PIN diode 6.nc.

[0087] As illustrated by the dotted line curve, a second radiation pattern of the reconfigurable antenna corresponds to a second aperture Δ − 3 dB φ 2 equal to 90° characterizing a second state of directivity, when a second switching voltage V n< OFF (eg V n< OFF =0V) is applied by the control module 307a to the PIN diode 6.nc.

[0088] Subsequently, the first directivity state of the antenna will be called the more directional mode (S-PD), since it has a smaller aperture than the second directivity state which will then be called the less directional mode (S-MD), i.e. Δ − 3 dB φ 1 < Δ − 3 dB φ 2 . In this case, each antenna reconfigurable according to the more directional mode is assimilated to a more directional elementary source (S-PD) while each antenna reconfigurable according to the less directional mode is assimilated to a less directional elementary source (S-MD) as indicated in the legend of the figure 4 .

[0089] Thus, by applying an appropriate voltage across each PIN diode 6.nc selectively for each active antenna, the radiation pattern of the active antenna is made more or less directional.

[0090] In the example of the figure 4 , the aperture of the radiation pattern of the antenna can be increased by 24°, thus making the antenna less directional. Thus, each active antenna formed by the association of the parasitic element 6.n with the radiating element 5.n is reconfigurable in the sense that the directivity of the active antenna (or its aperture) can be modified as a function of the control voltage received from the control module 307a.

[0091] A radiofrequency emission method according to the invention will now be described with reference to the figure 5 .

[0092] In the example described, the method is implemented in the radiofrequency transmission system 100 described with reference to the figure 1 .

[0093] During an initial step E50, the control device 3 recovers geometric parameters of the network 308 of active antennas, such as the first and second angles α, β, the pitches p0, p1, p2 and the numbers N0, N1, N2 of antennas in each group A0, A1, A2 of active antennas previously stored on the hard disk 3.6.

[0094] During the initial step E50, the control device 3 receives via the communication interface 3.8 parameters relating to the radiation, such as depointing values ​​φ 1 ,...φ m and a radiation template G to be respected for the beam to be emitted as well as effective data to be transmitted by the network 308 of active antennas.

[0095] For example, the radiation template defines for the main radiation lobe, a maximum power level in an undefined preferred direction, and defines for the secondary lobes, a power level over an angular range Δφ SLL on either side of the main lobe.

[0096] For example, a value φ of depointing as described with reference to the figure 2 is received by the control device 3, this value defining the preferred direction of radiation of the beam emitted after application of the depointing.

[0097] The radiation parameters are provided simultaneously as input to the processing and control module 301 and the control module 307a. On the basis of this data, the processing and control module 301 determines at least radiation constraints which it transmits to the calculation module 303.

[0098] Upon receipt of the radiation constraints and the geometric parameters, the calculation module 303 calculates the set of amplitudes and phases {Ai, Φi} 1≤i≤N, also designated by amplitude and phase weighting law, during a calculation step E52.

[0099] During a polarization step E57, the polarization module 307 determines the polarization voltage V n< DC of each amplifier 4.n as a function of the output power P n< out defined as a function of the set of amplitudes {Ai} 1≤i≤N provided 304 by the calculation module 303.

[0100] For this purpose, the polarization module 307 uses a polarization function f Pdc making it possible to calculate a polarization voltage as a function of the power P n< out at the output of the amplifier, such that V n< DC =f Pdc (P n< out ). This function f Pdc is developed beforehand to characterize each amplifier.

[0101] Once the bias voltage is determined, the bias module 307 applies it to the relevant amplifier.

[0102] During a power supply step E53, the signal generation module 306 calculates for each amplifier 4.n the input power P n< in to be applied to the input of the amplifier, taking into account the data to be transmitted.

[0103] For this purpose, the power supply module 306 uses a function f Pin previously stored and specific to each amplifier making it possible to determine the input power P n< in corresponding to the determined output power, such that P a< in =f Pin (P n< out ).

[0104] During a control step E58, the control module 307a determines a switching voltage to be applied selectively to each parasitic element so as to modify the directivity of the active antenna, for example according to the more directional mode or the less directional mode and the control module 307a applies each switching voltage V n< ON or V n< OFF selectively to the PIN diode controlling each parasitic element.

[0105] The switching voltages are calculated by the control module 307a from the number of beams to be transmitted and the depointing value for each beam. For example, the control module 307a is designed to apply the voltage V ON to the parasitic elements of the main antennas on the main section 8.0 and the voltage V OFF to the parasitic elements of the auxiliary antennas on the first and second auxiliary sections 8.1, 8.2. Thus, the main antennas are configured in the more directional mode while the auxiliary antennas are configured in the less directional mode.

[0106] In other alternative embodiments, only a subset of the main antennas and / or a subset of the auxiliary antennas are reconfigured into the more directional or less directional mode.

[0107] At the end of the control step E58, the control module 307a sends to the calculation module 303 information indicating which mode has been applied to each reconfigurable active antenna among the more directional mode or the less directional mode.

[0108] Thus, for each active antenna, the control device 3 provides each amplifier with an input power P n< in =f Pin (P n< out ), a bias voltage V n< DC =f Pdc (P n< out ) and drives the parasitic element of the reconfigurable active antenna by applying a voltage V n< ON or V n< OFF .

[0109] There figure 6 illustrates a variant embodiment of the figure 2 , where no parasitic elements are associated with the dipoles 5.1,...,5.n,...,5.N, so that the antennas are not reconfigurable.

[0110] There figure 7a illustrates an alternative embodiment according to which a section or part of a section of an array 308 of active antennas without parasitic elements has aligned and alternately planar radiating elements ( patch in English) and dipoles. This alternating distribution can be applied to one or more sections of the antenna support, in particular to the main section 8.0 and / or to at least one of the auxiliary sections 8.1, 8.2.

[0111] Thus, one or more sections selected from the main section 8.0, the first and second auxiliary sections 8.1, 8.2 comprise an alternation of planar radiating elements and dipole radiating elements (crossed dipole as described with reference to the figure 6 ).

[0112] In the example described, a first planar radiating element 5.1 without interference belonging to a first active antenna 1.1 is followed by a crossed dipole 5.2 without interference belonging to a second active antenna 1.2 adjacent to the first active antenna 1.1 and so on. The radiating elements are spaced two by two by a constant pitch p, such that p=0.5λ.

[0113] Advantageously, these two types of radiating elements have different radiation properties, particularly in terms of directivity and radiation aperture. An alternating distribution of these types of radiating elements is particularly advantageous for making the active antenna array more energy-efficient, particularly due to the absence of voltage to be applied to the PIN diodes of parasitic elements. This solution constitutes an alternative to the use of parasitic elements, offering the active antenna array reduced energy consumption, favored inter-source decoupling and optimized active impedances.

[0114] In other embodiment variants, the alternation of several sets of radiating elements of different types will be considered, for example, the alternation of a first set comprising one or more radiating elements of dipolar type and a second set comprising one or more radiating elements of planar type.

[0115] There figure 7b illustrates a particular variant according to which the first set 5p comprises two planar radiating elements 5.1, 5.3 and the second set 5d comprises two dipolar radiating elements 5.2, 5.4. These first and second sets are alternately distributed along the same straight line.

[0116] In general, it will be possible to define as many sets as there are types of radiating elements to be used in the active antenna network and to distribute these sets specifically according to the desired radiation properties of the radiofrequency beam, for example by alternation, according to a periodic pattern, or else irregularly. Performances énergétiques (1st embodiment)

[0117] The inventors compared, by means of simulations, the energy consumption of an active antenna network having a linear topology by sections designated by RLS of the first embodiment according to the variant embodiment of the figure 6 (i.e. with non-reconfigurable active antennas not including parasitic elements) to that of a conventional linear network designated by RL, so as to quantify the contribution of the invention (i.e. linear topology by sections) in terms of energy efficiency.

[0118] By "conventional linear array" we mean an array that does not include auxiliary antennas, i.e. no auxiliary sections inclined relative to the main section. The results of these simulations will now be described with reference to the figure 8 .

[0119] The simulation results presented in this document are obtained for the same target radiation pattern of the emitted beam or the same radiation template defined in particular by an equivalent isotropic radiated power (EIRP = 53 dBm), a level of attenuation of the secondary lobes less than -15 dB compared to the main lobe (SLL: Side Lobe Level in English) and a half-power aperture (HPBW: Halt Power BeamWidth in English) less than or equal to 10°. The beam is emitted at a central frequency f 0 =3.6 GHz. The active antenna array comprises 16 radiating elements distributed on the support with a constant pitch p=0.5λ 0 .

[0120] The results are obtained by applying the configuration method developed in the prior patent application FR1912812 for calculating the amplitude weighting law of the active antennas of the network. This configuration method implements an optimization algorithm minimizing a convex norm of a weighting vector.

[0121] The minimization takes into account beam radiation constraints and a power constraint intrinsic to the network amplifiers so that each amplifier operates in a linear regime, possibly taking into account coupling conditions between antennas, active impedance conditions, grouped sparsity conditions for the simultaneous emission of several radiofrequency beams.

[0122] The linear topology by sections of the active antenna array, as proposed in the present invention, makes it possible to reduce the energy consumption of the array. This reduction has been estimated in the particular case where the amplitude weighting law is calculated according to the optimization algorithm of the prior patent application. However, those skilled in the art may expect similar results by applying to the transmission / reception system according to the present invention other optimization methods known from the prior art for calculating the amplitude weighting law.

[0123] These results are shown in the table of the figure 8 (Fig. 8a ), for each type of network (RL, RLS), the number of switched-off antennas ( Antennes Off ) ,the total supply power P dc of the active antenna network expressed in Watts (W), this power corresponding to the sum of the supply powers applied to the amplifiers of the active antennas not switched off and the reduction in energy consumption expressed as a percentage (%) for different beam misalignment values ​​φ: 0°, +15°, +45°, +30°.

[0124] These results also indicate ( Fig. 8b ) for each type of network (RL, RLS), the weighting power expressed in dBm corresponding to the output power P n< out of each amplifier 4.n as determined by the method according to the figure 5 for each of the 16 antennas in the network, this power being applied to the radiating element of the active antenna concerned.

[0125] These results also indicate ( Fig. 8c ) for each type of network (RL, RLS), the radiation patterns obtained with the calculated weighting powers ( Fig. 8b ). These diagrams are represented by the modulus of the electric field on the ordinate, designated by |E| and expressed in dBV / m, as a function of the value of the angle φ expressed in degrees on the abscissa.

[0126] Without beam misalignment, i.e. for a received misalignment value φ equal to 0°, these results demonstrate that the linear sectional topology (RLS) allows a greater number of antennas to be switched off (7 in total) than the classic linear topology (6 in total) as reported in table (a) of the figure 8 . It follows that the total supply power P dc of the network is 12.3 W for the linear sectional topology (RLS), compared to 13.3 W for the classic linear topology (RL).

[0127] Thus, the linear topology by sections allows to achieve a reduction of approximately 8% of the energy consumption of the active antenna network compared to a classic linear topology (RL). These results apply for a misalignment value equal to 0° and more generally to low misalignment values ​​between -10° and 10°, in other words for a misalignment value φ=0°±10°.

[0128] For a received misalignment value φ equal to +15°, the results show that the linear sectional topology (RLS) allows a greater number of antennas to be switched off (6 in total) than the classic linear topology (5 in total) as reported in table (a) of the figure 8 . It follows that the total supply power P dc of the network is 13.5 W for the linear sectional topology (RLS), compared to 14.5 W for the classic linear topology (RL). Thus, the linear sectional topology achieves a reduction of approximately 7% in the energy consumption of the active antenna network compared to a classic linear topology (RL).

[0129] More generally, the inventors have demonstrated that, for low received misalignment values ​​φ, i.e. between 0° and +15° (or between 0° and -15°), the linear network by sections (RLS) according to the principle of the invention makes it possible to switch off more active antennas in comparison with the linear network (RL) making it possible to achieve reductions in energy consumption of the active antenna network of the order of 7 to 8%.

[0130] For a misalignment value φ equal to +45°, the results show that the linear sectional topology (RLS) allows a greater number of antennas to be switched off (in total 2) than the classic linear topology (no antenna switched off). According to the calculated weighting law ( Fig. 8b ), antennas No. 1 and 2 are switched off. It follows that the network according to the linear sectional topology (RLS) consumes a total supply power P dc of 20 W, compared to 22.7 W for the classic linear topology (RS), which corresponds to a 12% reduction in energy consumption in favor of the linear sectional network (RLS).

[0131] These comparisons were developed for equivalent radiation conditions, i.e. such that the radiation pattern of the beam emitted by the active antenna array respects the same radiation template ( Fig. 8c ).

[0132] For a misalignment value φ equal to +30°, the results show that the linear sectional topology (RLS) allows a greater number of antennas to be switched off (in total 5) than the conventional linear topology (in total 4). It follows that the network according to the linear sectional topology (RLS) consumes a total supply power P dc of 15.3 W, compared to 16.4 W for the conventional linear topology (RS), which corresponds to a 7% reduction in energy consumption in favor of the linear sectional network (RLS).

[0133] More generally, it is demonstrated that, for high received misalignment values ​​φ, i.e. between +30° and +45° (or between -30° and -45°), the linear network by sections (RLS) according to the principle of the invention makes it possible to switch off more active antennas in comparison with the linear network (RL) making it possible to achieve reductions in energy consumption of the active antenna network of the order of 7% to 12%.

[0134] Thus, in view of the above, it appears clearly that the particular orientation of the auxiliary antennas relative to the main antennas according to a linear section topology (RLS) according to the principle of the invention advantageously makes it possible to reduce the number of switched-off antennas in the active antenna network and to reduce the energy consumption of the active antenna network all the more so as the beam misalignment value is high compared to a conventional linear topology (RS).

[0135] The inventors also compared, by means of simulations, the energy consumption of an active antenna network having a linear sectional topology (RLS) according to the first embodiment of the figure 2 , for the following two antenna configurations: a homogeneous configuration of the antennas, that is to say where all the active antennas of the network are configured according to the more directional mode of the figure 4 (designated as S-PD); and a mixed antenna configuration, i.e. where only a part of the active antennas is configured according to the more directional mode, while the other antennas are configured according to the less directional mode of the figure 4 (designated as S-MD & S-PD).

[0136] The results of these simulations highlight the contribution of the invention in terms of energy efficiency. These results will now be described with reference to the figure 9 , where the sizes presented correspond exactly to the same as those of the figure 8 as described above.

[0137] In the context of these simulations, we consider: a particular homogeneous configuration, where all the antennas of the array, i.e. the antennas of the main section 8.0 and the antennas of the auxiliary sections 8.1, 8.2. are configured according to the more directional S-PD mode; and a particular mixed configuration, where the antennas of the main section 8.0 are configured according to the less directional S-MD mode while the antennas of the auxiliary sections 8.1, 8.2 are configured according to the more directional S-PD mode.

[0138] Without beam misalignment, i.e. for a received misalignment value φ equal to 0°, the results ( Fig. 9a ) demonstrate that the homogeneous S-PD configuration allows a greater number of antennas to be switched off (7 in total) than the mixed S-MD & S-PD configuration (6 in total). It follows that the total supply power P dc is 12.3 W for the homogeneous S-PD configuration, compared to 13.8 W for the mixed S-MD & S-PD configuration. Thus, the homogeneous configuration of reconfigurable antennas in the more directional mode advantageously allows a reduction of approximately 11% in the network energy consumption compared to the mixed configuration.

[0139] For a received misalignment value φ equal to +15°, the results ( Fig. 9a ) demonstrate that the homogeneous S-PD configuration allows a greater number of antennas to be switched off (6 in total) than the mixed S-MD & S-PD configuration (5 in total). It follows that the total supply power P dc is 13.5 W for the homogeneous S-PD configuration, compared to 15 W for the mixed S-MD & S-PD configuration. Thus, the homogeneous configuration of reconfigurable antennas in the more directional mode advantageously allows a reduction of approximately 10% in the energy consumption of the network compared to the mixed configuration.

[0140] More generally, it is demonstrated that, for low received misalignment values ​​φ, i.e. between 0° and +15°, or between 0° and -15°, by reconfiguring all the reconfigurable active antennas in the more directional mode (S-PD), it is possible to reduce the energy consumption of the network by 10 to 11%.

[0141] For a beam misalignment value φ equal to +45°, the results ( Fig. 9a ) demonstrate that both configurations allow the same number of antennas to be switched off (equal to 2) but that the mixed S-MD & S-PD configuration allows better energy efficiency to be achieved than the homogeneous S-PD configuration.

[0142] Specifically, antennas #1 and 2 are turned off for both configurations ( Fig. 9(a) ) but the weighting powers (dBm) are of the order of 26 dBm for the mixed configuration while they are not higher, i.e. of the order of 27.5 dBm for the homogeneous configuration ( Fig. 9(b) ). It follows that the active antenna array has a total feed power P dc of 19 W for the mixed S-MD & S-PD configuration, compared to 20 W for the homogeneous S-PD configuration, which corresponds to a 5% reduction in the power consumption of the active antenna array in favor of the mixed configuration.

[0143] These comparisons were developed for equivalent radiation conditions, i.e. such that the radiation pattern of the beam emitted by the active antenna array respects the same radiation template ( Fig. 9c ).

[0144] For a received offset value φ equal to +30°, the results ( Fig. 9a ) show that both configurations allow the same number of antennas (equal to 5) to be switched off with the same total supply power P dc of 15.4 W, so that at this misalignment value, the mixed S-PD & S-MD configuration does not allow the energy consumption to be reduced compared to the homogeneous S-PD configuration.

[0145] More generally, the inventors have demonstrated that for high received misalignment values ​​φ, i.e. equal to +45°±10° (or -45°±10°), it is preferable to apply a mixed configuration (S-MD & S-PD) of the reconfigurable active antennas of the network, so as to reduce the energy consumption of the network.

[0146] Thus, in view of the results of the Fig. 9 , it appears clearly that the selective modification of the directivity of each antenna by means of the parasitic elements advantageously makes it possible to further increase the energy efficiency of a linear network by sections to emit a beam according to a given template. In other words, the reconfigurability of the antennas constitutes an additional lever to reduce the total power consumed P dc by the network of active antennas while respecting the given template. Deuxième mode de réalisation

[0147] A second embodiment of the invention will now be described with reference to the figure 10 which illustrates a radio frequency transmitting / receiving installation 1000 designed to simultaneously transmit / receive four radio frequency beams Fa, Fb, Fc, Fd, adapted to cover respectively four distinct coverage areas Za, Zb, Zc, Zd. Within each coverage area, the respective beam has a radiation direction adjustable within the coverage area by electronic scanning. This direction can be adjusted by ±45° relative to a default direction, corresponding respectively to the main direction for each system.

[0148] For this purpose, the installation comprises four systems according to the invention arranged in an octagon. More precisely, each system 100a, 100b, 100c, 100d comprises an array 308a, 308, 308c, 308d of active antennas and a control device 3a, 3b, 3c, 3d of the array of active antennas, as described previously with reference to figures 1 And 2 .

[0149] The four beams Fa, Fb, Fc, Fd can be individually reconfigured by the respective control devices 3a, 3b, 3c, 3d which can be operated independently of each other.

[0150] For each network 308a, 308b, 308c, 308d, the first auxiliary section 8.1a, 8.1b, 8.1c, 8.1d, carrying the radiating elements of the first auxiliary group A1 of auxiliary antennas forms an angle equal to the first angle α=+45° with the main section 8.0a, 8.0b, 8.0c, 8.0d carrying the radiating elements of the main group A0 of antennas.

[0151] Similarly, for each network 308a, 308b, 308c, 308d, the second auxiliary section 8.2a, 8.2b, 8.2c, 8.2d, carrying the radiating elements of the second group A2 of auxiliary antennas forms an angle equal to the second angle β=-45° with the main section 8.0a, 8.0b, 8.0c, 8.0d carrying the radiating elements of the main group A0 of antennas.

[0152] The antenna supports are arranged end to end to form an irregular octagon. More specifically, the main sections 8.0a, 8.0b, 8.0c, 8.0d of each network 308a, 308b, 308c, 308d are of the same length L0 and arranged in parallel two by two so as to form the main sides of the irregular octagon, while the auxiliary sections {8.2a, 8.1b}, {8.1a, 8.2d}, {8.1d, 8.2c}, {8.1c, 8.2b} of two adjacent networks {308a, 308d}, {308a, 308b}, {308c, 308b}, {308c, 308d} are arranged two by two so as to be aligned along a respective straight line to form each of the four auxiliary sides of the octagon, each auxiliary side having the same length L12 less than the length of the main sides, i.e. such that L12 <L0.

[0153] Unlike a regular octagon, the installation 1000 according to the irregular octagonal structure as described below has long sides corresponding to the main sections and short sides corresponding to the auxiliary sections. Advantageously, the installation 1000 according to the invention has great ease of depointing each beam to ±45°, or even beyond ±45° with high directivity while reducing the number of active antennas switched on.

[0154] In the example described, the first and third systems 100a, 100c each comprise seven main active antennas on their main section 8.0a, 8.0c and two auxiliary antennas on each of their two auxiliary sections 8.1a, 8.2a, 8.1c, 8.2c. The second and fourth systems 100b, 100d each comprise seven main active antennas on their main section 8.0b, 8.0d and one auxiliary antenna on each of their two auxiliary sections 8.1b, 8.2b, 8.1d, 8.2d.

[0155] The number of auxiliary antennas distributed over the auxiliary sections of the active antenna arrays will be selected according to the desired scanning, i.e. the aperture covered in depointing. Thus, for each array, this aperture will be all the more extensive as the number of auxiliary antennas arranged on its auxiliary sections is large.

[0156] In alternative embodiments (not shown), the four networks will have an identical number of auxiliary antennas N2=N1 on their auxiliary sections.

[0157] Each array may include parasitic elements so as to modify the directivity (or aperture) of all or part of the active antennas as described previously.

[0158] Each of the four radiofrequency transmission systems operates according to the method as described above with reference to the figure 5 .

[0159] Thus, for each of the four areas to be covered Za, Zb, Zc, Zd, each system 100a, 100b, 100c, 100d receives the actual data streams to be transmitted to mobile terminals located in the respective areas, as well as the number of beams, the radiation template and an associated beam depointing value. Each system controls the active antennas by powering the amplifiers (P n< in , V n< DC ) and possibly by controlling the associated parasitic elements (V n< ON / OFF ), as described above.

[0160] It is clear that a radiofrequency transmission / reception system such as that described above allows the active antenna network to depoint a beam at a lower energy cost, thus making it less energy-intensive while benefiting from increased depointing agility (in particular for depointing values ​​of the order of ± 45°).

[0161] The arrangement of several of these systems to form an installation such as that described above makes it possible to simultaneously point several beams in different coverage areas at lower energy cost. Troisième mode de réalisation

[0162] A third embodiment of the invention will now be described with reference to the figure 11 which illustrates a radio frequency 1100 transmission / reception installation similar to that of the figure 10 , with the difference that all the auxiliary active antennas arranged on each auxiliary side of the irregular octagon are shared between two adjacent networks.

[0163] The installation 1100 comprises four radiofrequency transmission / reception systems as described above. The active antenna arrays 308a', 308b', 308c', 308d' of these four systems are arranged end to end so as to form an irregular octagon. The main active antennas of these arrays are distributed respectively on four main sides of the octagon while the auxiliary active antennas are distributed respectively on four auxiliary sides of the octagon.

[0164] Depending on the misalignment values ​​and the radiation templates received, the control device 3a', 3b', 3c', 3d' of each network 308a', 308b', 308c', 308d' of active antennas calculates the amplitude and phase weighting law of the antennas and determines, for each active antenna, configuration parameters such as the input power P in (n)< and the supply voltage V DC (n)< to be applied to the associated amplifier and in the case where the auxiliary active antenna is reconfigurable, the control voltage of V off / on (n)< applied to the parasitic element as described above.

[0165] Unlike the second embodiment described with reference to the figure 10 , the auxiliary antennas distributed on the auxiliary sides of the octagon are shared for each pair of adjacent networks (308a', 308d'), (308a', 308b'), (308b', 308c'), (308c', 308d').

[0166] Each control device 3a', 3b', 3c', 3d', takes into account the auxiliary antennas shared with each adjacent network for the calculation of the amplitude and phase weighting law used to determine the configuration parameters of the shared auxiliary active antennas.

[0167] Thus, the radiofrequency transmission / reception installation according to the third embodiment is configured so that the auxiliary antennas located along each auxiliary side of the irregular octagon are pooled (or shared) between two adjacent networks, so that these pooled auxiliary antennas are configured so as to contribute to the formation of the beams intended to be emitted respectively in the two adjacent coverage areas.

[0168] In the example described, the network 308a comprises a first auxiliary section 8.1a' comprising a first set M1 of three auxiliary antennas forming an auxiliary side of the irregular octagon. These three auxiliary antennas are shared between the networks 308a' and 308d'. Thus, the amplitude and phase weightings of these three auxiliary antennas are calculated according to a so-called multi-beam mode, so that their radiation jointly contributes to the formation of the beam Fa' emitted by the network 308a' and the beam Fd' emitted by the network 308d' adjacent to the network 308a'.

[0169] For this purpose, the control device 3a' is adapted to coordinate with the control device 3d' of the adjacent network 308d' taking into account the radiation characteristics of the beam Fd' intended to be emitted by the adjacent network 308d for the calculation of the weighting law of its auxiliary antennas and vice versa. Thus, the power applied to each auxiliary antenna corresponds to the cumulative power of the signals applied for the formation of the two beams Fa' and Fd'.

[0170] Likewise, a second set M2 of auxiliary antennas are shared between the network 308a' and the network 308b' adjacent to the network 308a'. Thus, the control device 3a interacts with the control device 3b' of the network 308b' adjacent to the network 308a' so as to calculate a weighting law in amplitudes and phases of the shared auxiliary active antennas M2 adapted to form the beam Fa' and the beam Fb' intended to be emitted by the network 308b' adjacent to the network 308a'.

[0171] The same applies to each other pair of adjacent networks taken two by two, i.e. {308b', 308c'}, {308c', 308a'} with the sets of shared active antennas M3, M4.

[0172] The pooling of auxiliary active antennas between each pair of adjacent networks for the calculation of the weighting laws of the active antennas and the configuration of the active antennas is particularly advantageous for optimizing the energy consumption of the radiofrequency transmission / reception installation by allowing the extinction of additional active antennas compared to the configuration according to the second embodiment.

[0173] Such pooling is particularly advantageous in the case where the radiofrequency transmission / reception installation is used to simultaneously transmit several beams in different directions to ensure extensive coverage, particularly in the case of four beams, each of which is offset by up to ±45° so as to ensure 360° radiofrequency coverage.

[0174] In the example described, the control devices 3a', 3b', 3c', 3d' are interconnected two by two so that the auxiliary antennas can be shared between two adjacent active antenna networks. However, in alternative embodiments, these control devices may be implemented within the same control device common to all of the active antenna networks.

[0175] It will also be noted that the invention is not limited to the embodiments described above. It will indeed appear to those skilled in the art that various modifications can be made to the embodiments described above, in light of the teaching which has just been disclosed to them.

[0176] In particular, the radiofrequency transmission / reception system may be designed for the transmission of several beams simultaneously in a multi-operator mode when the infrastructure is shared by several mobile network operators.

[0177] In the case where the antennas are reconfigurable, the parasitic element of each antenna may be designed so that the antenna can be reconfigured according to more than two configurations corresponding to distinct directivity states, thus making it possible to select the directivity from a plurality of modes.

[0178] In the detailed presentation of the invention given above, the terms used should not be interpreted as limiting the invention to the embodiments set forth in this description, but should be interpreted to include all equivalents whose prediction is within the reach of those skilled in the art by applying their general knowledge to the implementation of the teaching just disclosed to them.

Claims

1. A radiofrequency transmission / reception system (100) comprising: - an array (308; 308a, 308b, 308c, 308d; 308a', 308b', 308c', 308d') of active antennas comprising: • a main group (A0) of active antennas oriented in a main direction (d0); • at least one auxiliary group (A1; A2) of one or more active antennas, referred to as auxiliaries, oriented in an auxiliary direction (d1; d2), different from the main direction (d0); - a control device (3; 3a, 3b, 3c, 3d; 3a', 3b', 3c', 3d') for said active antenna array designed to: • receive a misalignment value (φ) among several possible misalignment values (φi,..,φn) ; • control the active antennas (1.1,..., 1.n, ..., 1.N) so as to emit a beam (F; Fa, Fb, Fb, Fc, Fa', Fb', Fb', Fc') that is misaligned by the received misalignment value (φ), relative to the main direction (d0); characterized in that the main group (A0) comprises a main number (N0) of antennas and said at least one auxiliary group (A1; A2) comprises an auxiliary number (N1; N2) of antennas between 1 / 7 and 1 / 3 of the main number (N0).

2. The system according to claim 1, wherein the main direction (d0) and the auxiliary direction (d1; d2) form an acute angle (α; β), for example between -50° and -30°, or between +30° and 50°, preferably equal to ±45°±10°.

3. The system according to any one of claims 1 to 2, comprising: - a first auxiliary group (A1) of auxiliary active antennas oriented in a first auxiliary direction (d1); and - a second auxiliary group (A2) of auxiliary active antennas oriented in a second auxiliary direction (d2), different from the main direction (d0) and the first auxiliary direction (d1); and wherein, - the main direction (d0) forms a first acute angle (α) with the first auxiliary direction (d1), for example between +30° and +50°, preferably equal to +45°± 10°; and - the main direction (d0) forms a second acute angle (β) with the second auxiliary direction (d2), for example between -50° and -30°, preferably equal to -45°± 10°.

4. The system according to claim 3, wherein the first and second angles (α; β) are of opposite sign and have equal absolute values, preferably 45°± 10°.

5. The system according to claim 3 or 4, wherein the first and second auxiliary groups (A1, A2) of active antennas have the same number (N 12) of active antennas.

6. The system according to one of claims 1 to 5, wherein each active antenna (1.1, ..., 1.n, ..., 1.N) comprises a radiating element (5.1, ..., 5.n, ..., 5.N), the system comprising a support for the radiating elements, wherein the support comprises a respective section (8.0, 8.1, 8.2) for each group (A0, A1, A2) of active antennas, and wherein each section (8.0, 8.1, 8.2) of the support is either linear so that the radiating elements (5.1,... ,5.n,... ,5.N) are distributed along a straight line along this support section, or planar so that the radiating elements are distributed in a two-dimensional matrix on this planar support section.

7. The system according to any one of claims 1 to 6, wherein the beam (F; Fa, Fb, Fc, Fd; Fa', Fb', Fb', Fc') emitted is unidirectional.

8. The system according to any one of claims 1 to 7, comprising: - parasitic elements (6.1,... ,6.n,... ,6.N; 6.na, 6.nb) associated respectively to at least some of the active antennas (1.1,... ,1.n,... 1.N), so as to modify a directivity of the associated antenna; and - control means (307a) designed to selectively activate each of the parasitic elements.

9. The system according to claim 8, wherein each parasitic element (6.n) comprises at least two sub-elements (6.na, 6.nb), the system further comprising, for each parasitic element, a PIN diode (6.nc) designed to selectively connect said at least two sub-elements together and wherein the driving means (307a) are designed to selectively drive each of the PIN diodes (6.nc).

10. The system according to any one of claims 1 to 9, wherein each active antenna comprises a radiating element selected from a planar element (5.1, 5.3) and a dipole element (5.2, 5.4).

11. The system according to claim 10, wherein the antenna radiating elements (5.1,... ,5.n,... ,5.N) of one of the groups (A0, A1, A2) are aligned and distributed by alternating a first set (5d) of at least one dipolar radiating element (5.2, 5.4) and a second set (5p) of at least one planar radiating element (5.1, 5.3).

12. A radiofrequency transmitting / receiving installation (1000) comprising four systems according to claims 4 and 5 taken together, whose active antenna arrays (308a, 308b, 308c, 308d) are arranged in an octagon.

13. The radiofrequency transmitting / receiving installation (1100) comprising two systems according to any one of claims 1 to 11, wherein the active antenna arrays of the two systems have auxiliary active antennas in common.

14. An installation (1100) according to claim 13 comprising two pairs of systems whose arrays (308a'; 308b'; 308c'; 308d') of active antennas are arranged in an irregular octagon comprising four main sides on which the main active antennas are distributed and four auxiliary sides on which the auxiliary active antennas (M1 ; M2; M3; M4), wherein, for each auxiliary side, all the auxiliary antennas (M1; M2; M3; M4) are in common with the two adjacent arrays (308a', 308d'; 308a', 308b'; 308b', 308c'; 308c', 308d').

15. A radiofrequency transmission / reception method, comprising the following steps: - receiving (E50) a misalignment value (φ) from among several possible misalignment values; and - controlling an array (308; 308a, 308b, 308c, 308d; 308a', 308b', 308c', 308d') of active antennas so as to emit at least one beam (F; Fa, Fb, Fb, Fc) misaligned by a received misalignment value with respect to a default direction ; the array (308) of controlled active antennas comprises a main group (A0) of active antennas, known as main antennas, oriented in a main direction (d0) and at least one auxiliary group (A1, A2) of active antennas, known as auxiliary antennas, oriented in an auxiliary direction (d1 ; d2) different from the main direction (d0), characterized in that the main group (A0) comprises a main number (N0) of antennas and said at least one auxiliary group (A1; A2) comprises an auxiliary number (N1; N2) of antennas between 1 / 7 and 1 / 3 of the main number (N0).

16. A computer program downloadable from a communication network and / or recorded on a computer-readable medium, characterized in that it comprises instructions for executing the steps of a radiofrequency transmission / reception method according to claim 15, when said program (P) is executed on a computer of a system according to claim 1.