Antenna with lacunary distribution network

Abstract

The invention relates to an antenna comprising an array of unitary radiating elements including an array of excitation ports, the antenna comprising a gapy tree distribution network including at least one inactive terminal distribution line electrically connected to a resistive element.

Description

[0001] The invention lies in the field of antennas comprising an array of unitary radiating elements.

[0002] The invention applies to radio frequency antennas, in particular, microwave antennas. Such antennas can be used in various applications such as radar applications in avionics and aerospace, high-speed communication, beacons, and space technologies.

[0003] It is indeed regularly necessary to design different distribution networks which will be coupled to different radiating element networks.

[0004] A solution is proposed in MIMO (Multi-Input Multi-Output) radars, which benefit from a single radiating element as the transmission source. However, such a solution implements various electronic functions, which impact the cost, reliability, power consumption, weight, and lifespan of the antenna.

[0005] We know of a tree-like distribution network that allows electrical signals to be carried from a single distribution input to distribution outputs coupled to a subset of unitary radiating elements.

[0006] The design of such a network can prove to be long and complex given that the distribution network must be impedance-matched with each of the predetermined impedance distribution outputs, which imposes symmetry conditions on the tree.

[0007] Furthermore, it is necessary to design a specific tree network for each network of radiating elements to be excited, which implies a particularly significant design time.

[0008] US 2016 / 197405 A1 describes an array antenna in which the radiating elements are arranged in a two-dimensional matrix of 2Nx2N regions excluding at least one of the four corners of a polygon defined by these regions.

[0009] WANG MENGYI ET AL: "A Ka-Band High-Gain Dual-Polarized Microstrip Antenna Array for 5G Application", 2019 INTERNATIONAL CONFERENCE ON MICROWAVE AND MILLIMETER WAVE TECHNOLOGY (ICMMT), IEEE, May 19, 2019 (2019-05-19), pages 1-3, describes an antenna array where each radiating element is fed by two orthogonal lines to achieve dual polarization.

[0010] One aim of the invention is to limit at least one of the aforementioned disadvantages.

[0011] To this end, the invention relates to an antenna comprising an array of unit radiating elements, the antenna comprising a gap distribution array being an N-ary tree array comprising distribution lines connected to each other at nodes having the same predetermined impedance Z, the distribution lines comprising primary distribution lines, each primary distribution line being connected, at an intermediate node, to N other distribution lines where z is an integer greater than or equal to 1 and N is a prime number greater than 1, and terminal distribution lines, each terminal distribution line being connected to only one other of the distribution lines,terminal distribution lines comprising at least one active terminal distribution line coupled to the unit radiating element array in a first array of at least one excitation port of the unit radiating element array so as to allow the unit radiating element array to be excited simultaneously in at least one excitation port of the first array of at least one excitation port from an electrical signal injected into an input of the distribution network, terminal distribution lines comprising at least one inactive terminal distribution line electrically connected to a resistive element T to a resistive element having an impedance of the resistive element equal to the impedance Z,said antenna being characterized in that the resistive element is located opposite an excitation port of the array of radiating elements not forming part of the first array so that the antenna is devoid of coupling means between the inactive terminal distribution line and a radiating element located opposite the resistive element.

[0012] Advantageously, the antenna includes a first gap distribution network comprising M1 active terminal distribution line(s) coupled to M1 first excitation port(s) of the unit radiating element network, in which M1 is an integer greater than or equal to 1 different from N1 x1< , N1 being a prime number greater than 1 and x1 being an integer greater than or equal to 1, the first gap distribution network being an N1-ary tree network.

[0013] Alternatively or in addition, the antenna includes a second gap distribution network comprising M2 active terminal distribution lines coupled to M2 second excitation ports of the unit radiating element network, in which M2 is equal to N2 x2< , N2 being a prime number greater than 1 and x2 being an integer greater than or equal to 1, the second gap distribution network being an N2-ary tree network.

[0014] In a particular embodiment, the antenna comprises a non-gap distribution network being a tree network comprising distribution lines connected to each other at nodes having the same predetermined impedance, the distribution lines comprising primary distribution lines, each primary distribution line being connected, at an intermediate node, to K other distribution lines where k is an integer greater than or equal to 1 and K is a prime number greater than 1, and terminal distribution lines connected to a unique other distribution line,the terminal distribution lines being active terminal distribution lines coupled to K third excitation ports of the unit radiating element array so as to allow the unit radiating element array to be excited simultaneously at the K third excitation ports from an electrical signal injected into a non-gapful distribution network input.

[0015] In a particular embodiment, the antenna comprises several distribution networks coupled to sub-networks of respective excitation ports distinct from the radiating element network so as to allow the simultaneous transmission or reception of several electromagnetic beams.

[0016] In one particular embodiment, the antenna comprises several sources, the inputs of the distribution networks being connected to separate respective sources or separate respective receivers.

[0017] In one particular embodiment, the antenna comprises sub-arrays of respective excitation ports distributed over concentric rings.

[0018] In a particular embodiment, the antenna is devoid of excitation ports other than the excitation ports of the first array of at least one excitation port.

[0019] Advantageously, each unitary radiating element includes one of the excitation ports of the first array of at least one excitation port.

[0020] In one particular embodiment, the antenna is planar.

[0021] The invention also relates to a method for manufacturing an antenna according to any one of the preceding claims, comprising: a design step of the radiating element array including the first excitation port array, a design step of the gap distribution array so that it allows the unit radiating element array to be excited simultaneously at at least one excitation port of the first array of at least one excitation port when coupled to the first array of at least one excitation port and when an electrical signal is injected at the distribution input of the gap distribution array, a manufacturing step of the gap distribution array designed during the design step, a step consisting of electrically connecting the inactive distribution line to the resistive element,a coupling step of the gap distribution network to the first network of at least one excitation port comprising a coupling step of each active distribution line of the gap distribution network to an excitation port of at least one excitation port of the first network of excitation ports so as to allow the network of radiating elements to be excited at the excitation port when an electrical signal is injected at the distribution input.

[0022] Advantageously, when the excitation port network comprises a first set of M1 first excitation port(s) such that M1 is an integer greater than or equal to 1 different from N1 x1< where N1 is a prime number greater than 1 and x1 is an integer greater than 1, a design step of a first gap distribution network comprising M1 active terminal distribution line(s), a manufacturing step of the first gap distribution network, a coupling step of the first gap distribution network to the M1 first excitation port(s) and a step of electrically connecting the active terminal distribution line to a resistive element.

[0023] When the excitation port network includes a second set of M2 second excitation ports such that M2 is an integer greater than 1 equal to N2 < x2, where N2 is a prime number greater than 1 and x2 is an integer greater than 1, the method comprises: a design step of a second gap distribution network comprising M2 terminal distribution lines, the terminal distribution lines being active, a manufacturing step of the second gap distribution network and a coupling step of the second gap distribution network to the M2 second excitation ports, a step of electrically connecting the inactive terminal distribution line to a resistive element, or, a design step of a non-gap distribution network comprising M2 active terminal distribution lines and at least one inactive terminal distribution line, a manufacturing step of the second non-gap distribution network and a coupling step of the second non-gap distribution network to the M2 second excitation ports.

[0024] Other features, details and advantages of the invention will become apparent from the description provided with reference to the accompanying drawings given by way of example, which represent, respectively: there figure 1 , schematically represents, in exploded view, different planes of a planar antenna, the figure 2 , schematically represents, in top view, a planar antenna comprising an array of radiating elements, the figure 3 , schematically represents radiation patterns (in dB) of different sub-arrays of radiating elements along different directions formed around the central position of the antenna occupying the horizontal plane (90°, -90°), the directions being defined by the angles, in degrees, formed by these directions with the plane of the antenna, in a plane perpendicular to the antenna plane, the figure 4 , schematically represents a first example of a gap distribution network according to the invention coupled to a first sub-network of radiating elements of the network of the figure 2 , there figure 5 , schematically represents a second example of a gap distribution network according to the invention coupled to a second sub-network of radiating elements of the network of the figure 2 , there figure 6 , schematically represents an example of a non-gap distribution network coupled to a central network of radiating elements of the figure 2 , there figure 7 , schematically represents curves representing the desired and actual WRE as a function of an angular opening, the figure 8 , schematically represents another example of a radiating element network comprising several sub-networks of radiating elements, the figure 9 schematically represents a first gapy distribution network coupled to a first sub-network of radiating elements of the network of the figure 8 , there figure 10 schematically represents a non-gap distribution network coupled to the first sub-network of radiating elements of the network of the figure 8 , there figure 11 schematically represents a gapy distribution network coupled to a second sub-network of radiating elements of the network of the figure 11 , there figure 12 schematically represents a gapy distribution network coupled to the third sub-network of radiating elements of the network of the figure 11 , there figure 13 schematically represents a gapy distribution network coupled to a third sub-network of radiating elements of the network of the figure 11 , there figure 14 schematically represents a gapy distribution network coupled to a fourth sub-network of radiating elements of the network of the figure 12 .

[0025] From one figure to another, the same elements are identified by the same references.

[0026] On each of the figures 4 , 6 And 9 à 14 The distribution network shown in this figure is surrounded by a black frame which represents the perimeter of the distribution layer containing this network.

[0027] The invention relates to an antenna comprising an array of unitary radiating elements including an array of excitation ports.

[0028] Each radiating element has a reactive impedance (capacitive and / or inductive).

[0029] The antenna can be a planar array antenna, for example printed, that is to say, comprising an array of unitary radiating elements of the microstrip patch type. The invention also relates to cavity back slot planar array antennas, also called "cavity back slot antennas" in Anglo-Saxon terminology, substrate integrated waveguide (SIW) antennas, as well as ring arrays.

[0030] The invention also applies to non-planar antennas, such as horn antennas, Vivaldi antennas, coaxial dipoles, waveguide apertures and dielectric resonators, whose radiating elements are distributed over a radiating surface and coupled to the distribution network.

[0031] The invention applies to single-beam antennas capable of simultaneously radiating or receiving a single electromagnetic beam, as well as to multi-beam antennas capable of simultaneously radiating and / or receiving several electromagnetic beams.

[0032] Each individual radiating element includes, for example, an excitation port. The antenna therefore comprises an array of excitation ports.

[0033] By excitation port subnetwork we mean a network formed by a subset including at least one of the excitation ports of the excitation port network.

[0034] In general, the antenna includes at least one distribution network for distributing a radio frequency excitation electrical signal, for example microwave, from a distribution input to a distribution output or distribution outputs, and vice versa, coupled to the distribution port or, respectively, to the respective excitation ports of the excitation port network, or of a sub-network of excitation ports of the antenna excitation port network, so as to allow the network of unit radiating elements to be excited at the excitation ports of the sub-network when a signal is injected at the distribution input.

[0035] It should be noted that when a distribution network is capable of exciting the array of unitary radiating elements at the excitation ports of the excitation port array, or at the excitation ports of a sub-array of ports, when a signal is injected at the distribution input, it is necessarily, conversely, capable of generating, at the receiver, an electrical signal at the input of the distribution network from signals simultaneously generated by the excitation ports of the excitation port array, or respectively by the excitation ports of the sub-array of excitation ports. Therefore, for the sake of brevity, we will systematically refer only to the network's ability to excite the excitation ports to which it is coupled from a signal injected at its input, and we will only mention this ability in the claims.

[0036] A multibeam antenna comprises several sub-arrays of excitation ports coupled to separate distribution networks, with the excitation port sub-arrays not sharing any excitation ports. This allows different beams to be radiated and / or received simultaneously using the same array of radiating elements.

[0037] When the antenna comprises multiple distribution networks, these networks are advantageously integrated into several distribution layers stacked along a stacking axis. Advantageously, the different distribution networks occupy separate layers. This avoids crossings between distribution lines from different distribution networks and, consequently, simplifies their design.

[0038] Alternatively, the planar or non-planar antenna includes at least one distribution layer, each distribution layer comprising one or more distribution networks.

[0039] On the figure 1 An exploded view of different planes of a planar antenna A1 is shown, including distribution layers of this antenna. This antenna is multilayered. It comprises a plurality of layers stacked along a z-axis of stacking.

[0040] The planar antenna A1 comprises an RE array of unit radiating elements E distributed over a flat surface of a first layer CO1. The unit radiating elements E are, in the non-limiting example of the figure 1 electrically conductive pellets.

[0041] The first CO1 layer is, for example, made of polytetrafluoroethylene PTFE, based on glass fiber reinforced Teflon, glass fiber reinforced epoxy resin composite or ceramic.

[0042] The antenna comprises a stack of a plurality of distribution layers D1, D2, D3, each comprising a distribution network not visible on the figure 1 .

[0043] The first layer CO1 and the distribution layers D1, D2, D3 are stacked along the z-axis.

[0044] These different layers are separated in pairs by metallic planes serving as ground planes, not shown on the figure 1 The different layers of the antenna are separated in pairs by insulating layers.

[0045] Distribution networks are, for example, coupled to radiating elements by metallized holes also called metallized vias.

[0046] Antenna A1 advantageously, but not necessarily, includes a CE layer containing radio frequency electronics, for example, transmit and / or receive circuits. Distribution layers D1, D2, and D3 are interposed between the first CO1 layer and the CE layer containing the radio frequency electronics, along the z-axis.

[0047] Alternatively, the radio frequency electronics are located outside the stack, for example, on an electronic board interconnected with the stack, particularly with distribution networks, by coaxial cables via connectors such as, for example, coaxial connectors, for example SMA connectors (acronym for the Anglo-Saxon expression SubMiniature version A).

[0048] There figure 2 schematically represents, in top view, an example of the application of an antenna A comprising a network R of radiating elements being a matrix of 32*32 radiating elements E regularly distributed on a flat surface in rows and columns, the rows being perpendicular to the columns.

[0049] In the following text, we assume that each radiating element E of the figure 2 includes a single PE excitation port but all or part of the radiating elements could alternatively include multiple excitation ports.

[0050] In a first embodiment of the invention, the antenna A comprises a set of distribution networks configured to independently excite three sub-networks of excitation ports SC, S1, and S2, respectively distributed on concentric surfaces SUC, SU1, and SU2 centered at C and contiguous. The first surface SU1 completely surrounds the central surface SUC, and the second surface SU2 completely surrounds the first surface SU1. In other words, the surfaces SU1 and SU2 are concentric rings or frames.

[0051] The central sub-network SC consists of four excitation ports arranged at the vertices of a square distributed across the surface SUC. These four ports correspond, for example but not necessarily, to the centers of the four central radiating elements.

[0052] The first excitation port sub-array S1 consists of M=60 excitation ports distributed across the surface SU1. These are, for example, but not necessarily, the centers of the radiating elements forming the eight-row, eight-column matrix including the center C, excluding the radiating elements comprising the ports of the central sub-array SC. The first sub-array S1 has a width of 3 columns and 3 rows of excitation ports.

[0053] The second sub-lattice S2 consists of M2 = 960 excitation ports distributed over the surface SU2. These are the centers of the radiating elements forming the matrix of 32 rows and 32 columns, with the exception of the radiating elements constituting the matrix of eight rows and eight columns including the center C. The second sub-lattice has a width of 12 columns and 12 rows of excitation ports.

[0054] This configuration allows for the emission or reception of concentric beams of different sizes, as seen on the figure 3 representing, respectively from left to right, the radiation patterns of the central sublattice SC, the first sublattice S1, and the second sublattice S2. Excitation of the radiating elements distributed on the surface SUC alone allows, as can be seen on the left of the figure 3 , to radiate or receive a wide beam while the excitation of the radiating elements distributed over the SU1 surface allows, as visible at the center of the figure 3 , to radiate or receive a finer beam and that of the radiating elements distributed on the SU2 surface allows, as visible to the right of the figure 3 to radiate or receive an even finer beam. Exciting all the radiating elements allows for the generation of an even finer beam than that generated by feeding the SU2 surface. This architecture is therefore adaptable to different needs, starting from a network of a predetermined size.

[0055] The shapes and dimensions of the excitation port sub-arrays are not limited. Various shapes can be imagined, adapted according to the requirements in terms of beam shapes, beam apertures, gain, and radiated power. For example, rings formed by one or more rows and columns of excitation ports can be considered.

[0056] There figure 4 schematically represents a first distribution network RP1 configured and coupled to the network R so as to allow the excitation ports of the first subnetwork S1 of M excitation ports distributed on the first surface SU1 to be excited from an excitation signal injected into a first distribution input E1.

[0057] The first distribution network RP1 is an N-ary tree distribution network where N is a prime number greater than 1. N is equal to 2 in the example of the figure 4 .

[0058] A tree-like distribution network connects a single distribution input E1 to a plurality of terminal nodes NF, represented in the figures by squares delineating the positions and shapes of the radiating elements to which the respective terminal nodes NF are coupled. In practice, the terminal nodes NF are, for example, essentially point nodes; alternatively, they can have various shapes and dimensions.

[0059] Preferably, the terminal nodes have dimensions smaller than those of the radiating element.

[0060] The NF terminal nodes are, for example, located opposite the PE excitation ports to which they are respectively coupled, that is, at the centers of the squares of the figure 4 in the non-limiting examples shown in the figures. The terminal nodes NF constitute the distribution outputs of the tree-like distribution network.

[0061] An N-ary tree-like distribution network, or N-ary tree, is defined as a tree-like network or tree consisting of distribution lines connected to each other at nodes NI, NR, NF. The distribution lines include primary distribution lines LP. Each primary distribution line LP is connected, at an intermediate node NI, to a number Nz of other distribution lines, which may be primary distribution lines LP or terminal distribution lines LA, LI, or may include at least one primary distribution line LP and at least one terminal distribution line LA, LI.

[0062] By terminal distribution line LA, LI, we mean a distribution line connected to a single other distribution line in the distribution network.

[0063] This other distribution line is a primary LP distribution line.

[0064] Each terminal distribution line LA, LI connects a terminal node NF, also called a leaf node, to an intermediate node NI.

[0065] In an N-ary tree network, N is a prime number greater than 1 and z is an integer greater than or equal to 1. The different primary rows can be connected to Nz numbers on other, different distribution rows. For example, a binary tree might have nodes where one distribution row is connected to two other distribution rows, and nodes where one distribution row is connected to four other distribution rows.

[0066] Each primary distribution line (LP) connects a parent node to a child node, and each parent node is connected to a primary distribution line and Nz child distribution lines. Each child distribution line can be either a primary or terminal distribution line.

[0067] The tree network includes a first primary line LP connecting the input E1 to a first node called the root node NR which is also an intermediate node.

[0068] The root node NR is located at the center C in the non-limiting example of the figure 4 .

[0069] The first distribution network RP1 is designed so that the nodes NR, NF, NI, of the first distribution network RP1 all have the same predetermined impedance Z.

[0070] The distribution lines are impedance-matched to the network nodes to which they are connected.

[0071] Let Z be the impedance of each node and P = N z< the number of daughter distribution lines of this node. Then, in order to have an impedance Z at each child node of this node, each daughter distribution line must have a characteristic impedance Z0 given by: Z 0 = P − 1 * Z

[0072] Advantageously; the impedance Z is also the impedance of each of the radiating elements E.

[0073] The impedance Z is real and positive.

[0074] In the non-limiting example of the figure 4 The RP1 tree is a binary tree. Alternatively, a tree with an N greater than 2 is perfectly conceivable.

[0075] In the non-exhaustive implementation of the figure 4 The tree is strict. In other words, all nodes have zero or two children and each terminal node has the same depth.

[0076] The height of the tree is the maximum depth of a node in the tree. The depth of a node is its rank, where the rank of the root node (NR) is rank 1 and the rank is incremented at each child node up to a leaf node (NF) by moving only in the direction from the root node (NR) to the leaf node (NF).

[0077] In the non-exhaustive implementation of the figure 4 The tree has a height of 7.

[0078] The first distribution network RP1 is coupled to the M excitation ports of the first subnetwork RP1 of M excitation ports so as to allow the network R of radiating elements to be excited simultaneously at the level of the M excitation ports of the subnetwork by means of an excitation signal injected on the first distribution input E1, and therefore conversely, to generate a reception signal at the level of the first distribution input E1, from electromagnetic signals received simultaneously by each of the M excitation ports.

[0079] For this purpose, the RP1 network is configured to include M terminal distribution lines, called active, LA being each coupled to one of the M excitation ports so as to allow the network of radiating elements to be excited simultaneously at the M excitation ports from a signal injected into the input of the distribution network.

[0080] According to the invention, the antenna comprises a gapy N-ary tree distribution network of which the first distribution network RP1 is an example.

[0081] By lacunary N-ary tree distribution network, we mean an N-ary tree distribution network comprising M active terminal distribution lines LA, and P other terminal distribution line(s), called inactive line(s) LI, with P an integer greater than or equal to 1.

[0082] Each inactive terminal distribution line LI is electrically connected, at the level of the NF terminal node to which it is connected, to a resistive element T, represented by an oval area that masks the NF terminal node on the figure 4 , impedance-matched to the inactive terminal distribution line.

[0083] In other words, the resistive element T presents an impedance, called the impedance of the resistive element, equal to the predetermined impedance Z of the nodes of the NR, NI, NF network.

[0084] The impedance of the resistive element T is resistive. It is, moreover, real.

[0085] The impedance of the resistive element T is equal to its resistance (expressed in ohms).

[0086] The resistive element T presents the impedance that the inactive distribution line LI would have seen if it had been coupled to a radiating element E located opposite the resistive element T.

[0087] At emission, the resistive element T adapts in impedance the inactive distribution line and absorbs, by Joule effect, the energy carried by the inactive terminal distribution line LI.

[0088] Upon reception, the resistive element T adapts the impedance of the inactive terminal distribution line.

[0089] Thus, the resistive element T prevents parasitic energy transfers due to standing waves from the inactive distribution line to the radiating element and vice versa.

[0090] Furthermore, the antenna lacks coupling means of the type enabling the inactive terminal distribution line to be coupled to a radiating element of the network of radiating elements so as to prevent the inactive distribution line from exciting any radiating element of the network from a signal injected into the input of the distribution network.

[0091] Thus, any energy transfer between the inactive terminal distribution line LI and the radiating network is prevented.

[0092] For example, in the realization of figures 2 And 4 , the antenna lacks coupling means between the inactive terminal distribution line LI and a radiating element located opposite the resistive element T, which, coupled with the presence of the resistive element, prevents any energy transfer between this inactive terminal distribution line LI and the radiating element located opposite the resistive element T.

[0093] The resistive element is, for example, an electrical component, also called a resistor, or a resistive layer.

[0094] Each inactive terminal distribution line LI is electrically connected, at the level of the NF terminal node to which it is connected, to a resistive element T, represented by an oval area that masks the NF terminal node on the figure 4 , impedance-matched to the inactive terminal distribution line.

[0095] In the realization of the figure 4 The presence of inactive lines LI arises from the fact that M is different from N x< with x is an integer greater than or equal to 1. Indeed, M is equal to 60 and N equal to 2, M is different from a power of 2.

[0096] The RP1 tree comprises a set of 64 lines, including 60 active LA lines and four inactive LI lines.

[0097] The four active lines LI each comprise a resistive element T located opposite one of the excitation ports of the four central radiating elements (distributed on the central surface SC) of the R array of radiating elements of the figure 2 .

[0098] Each of the active lines LA is coupled to the excitation port of the radiating element E located opposite the inactive line LA so as to allow energy transfer from the inlet of the gapy distribution network to the excitation port, and vice versa.

[0099] The branches of each tree are distribution lines. In the case of a planar antenna, these can be implemented using printed circuit board technologies known to those skilled in the art. Distribution lines can be of the microstrip type, the stripline type, or the integrated waveguide (SIW) type.

[0100] The coupling between the active distribution lines and their respective ports is achieved in a manner known to those skilled in the art. This coupling is, for example, achieved by electromagnetic coupling via a slot. Alternatively, the coupling is achieved by electrically connecting the end of a transmission line to an excitation point, for example, via a metallized via. The coupling can also be performed on the plane of the flat radiating element, or "patch," by directly driving it with a printed microstrip line connected to the edge of the radiating element. Excitation can also be achieved by proximity coupling to a microstrip line printed at a level located between the patch and the layer forming the ground plane.

[0101] Designing an N-ary tree-like distribution network capable of exciting a number of excitation ports other than N<x> is a lengthy and complex process. Introducing inactive lines that prevent these lines from exciting the antenna's radiating elements significantly simplifies this design. The tree is thus implemented as an N-ary tree with N<x< (where x is an integer greater than or equal to 1) distribution lines, and some distribution lines are deactivated by connecting them to a resistive element T.

[0102] In the realization of the figure 4 , the excitation ports of the first sub-network S1 of excitation ports are distributed according to a sub-network having a center of symmetry C.

[0103] In the realization of the figure 4 The radiating element network comprises a central subset SC of radiating elements consisting of Nx < -M radiating elements distributed along a central subnetwork completely enclosed by the first surface. Advantageously, the tree of the first gap distribution network RP1 is initially designed to allow the radiating elements of the first subset S1 and the central subset SC to be simultaneously excited by an excitation signal injected at the first input E1, and vice versa. Certain terminal distribution lines are then made inactive to prevent the RP1 network from exciting the ports of the central subnetwork S. This configuration simplifies the design of a distribution tree.

[0104] Advantageously, the root node of the first network RP1 is located at the center of symmetry C. This makes it easier to trace the distribution network and to easily design a distribution network that excites the M radiating elements in a balanced way (i.e., with signals having the same phase and amplitude).

[0105] Alternatively, the antenna includes a gap distribution network, i.e., of the N-ary tree type, comprising at least one inactive terminal line LI. This gap distribution network, capable of exciting a subset of excitation ports, can include a number of excitation ports equal to Nx (where x is an integer greater than or equal to 1), as we will see later in the text. This also simplifies the design of the N-ary tree.

[0106] There figure 5 schematically represents a second distribution network RP2 configured and coupled to network R so as to be able to simultaneously excite the radiating elements of the second subset of radiating elements S2 distributed over the second surface SU2 visible on the figure 2 , from an excitation signal injected into a second excitation input E2, and vice versa.

[0107] Since the number of unit radiating elements M2 of the second sub-network of radiating elements is different from N x< (with x is an integer greater than or equal to 1), the second distribution network RP2 is advantageously a gap distribution network.

[0108] The second lacunar distribution network RP2 differs from the first lacunar distribution network RP1 in that it is not strict and in its height, due to the higher number M2 of unit radiating elements in the second subset of unit radiating elements. The height of the second distribution network is 10.

[0109] The second gap distribution network RP2 comprises 960 active terminal distribution lines LA and 4 inactive terminal distribution lines LI; each inactive line LI is connected to a resistive element T represented by a white oval area on the figure 5 preventing the inactive line LI from exciting the network R of radiating elements from a signal injected at the second distribution input E2 and from transmitting a signal to the second distribution input when any of the radiating elements receives an electromagnetic signal.

[0110] The four inactive LI lines each include an NF leaf node located opposite the SU1 zone.

[0111] In the realization of the figure 5 The PE excitation ports of the second subset of excitation ports S2 are distributed according to a subnetwork having a center of symmetry C. Advantageously, the root node of the second network RP2 is located at the center of symmetry C. This makes it easier to trace the distribution network.

[0112] The design of the second, sparse distribution network RP2 is relatively simple, and the fact that it is not perfect—that is, that not all the NF leaf nodes have the same height—avoids having to deactivate distribution lines located next to each of the radiating elements of subsets S1 and S2. Indeed, the leaf nodes connected to the inactive LI lines have a lower height than the leaf nodes connected to the active LA lines. This also helps to limit energy losses and the number of resistive elements to be distributed.

[0113] There figure 6 represents a third RS distribution network coupled to the unitary radiating elements of the central SC subnetwork.

[0114] The third RS distribution network is configured and coupled to the R network so as to enable the radiating elements to be excited at the four excitation ports of the S subnetwork when an excitation signal is injected into the third RS distribution network at the third distribution input E3, and conversely, to generate a receive signal at the third receive input from electromagnetic signals received at the four excitation ports of the S subnetwork.

[0115] Advantageously, the third RS distribution network is a tree-like distribution network, also called a non-gap distribution network.

[0116] In this patent application, a non-lacunar K-ary tree distribution network is defined as a network that is a K-ary tree whose terminal distribution lines are all active terminal distribution lines LA. K is a prime number greater than 1.

[0117] Each of the active terminal distribution lines LA is coupled to one of the PE excitation ports of the central subnetwork S so as to allow the network to be excited at the excitation ports of the subnetwork S when an excitation signal is injected into the third distribution network at the third input E3 and vice versa.

[0118] Thus, the RS gap-free distribution network is free of inactive terminal distribution lines. This helps to limit losses in the secondary distribution network.

[0119] A non-gap tree distribution network RS is advantageously provided when the subnetwork of excitation ports to be excited by means of the secondary network comprises L excitation ports, L being a power of K (i.e., L= K k< where k is an integer greater than or equal to 1).

[0120] Advantageously, the non-gap tree distribution network is a perfect tree. By perfect tree, we mean a tree in which all NF leaf nodes have the same height.

[0121] In the non-limiting example of the figure 6 The central subnetwork SC consists of four ports belonging to four respective unit radiating elements. The non-gap distribution network is a perfect binary tree with a height of 3.

[0122] A gap-free distribution network is of relatively simple design and avoids the need to provide inactive lines, which helps to limit radiated power losses when the number of radiating elements or excitation ports is a power of a prime number greater than 1, for example, a power of 2.

[0123] Indeed, at each intermediate node NI, if a resistive element absorbing energy is connected to the end of one of the terminal lines, this corresponds to a loss of half the radiated power, i.e., a loss of radiated power of 3dB (10* log(1-1 / 2)). If this resistive element is not located at the first division but at the second, this corresponds to a loss of 1.25dB (this value being obtained by calculation (10 * log(1- 0.5*0.5)=10*log(0.75)).

[0124] Alternatively and / or in addition, the antenna includes at least one sparse tree distribution network configured and coupled to the network R in such a way as to excite the excitation ports of a subnetwork of L excitation ports having a number such that L = Kk, where K is a prime number greater than 1 and k is an integer greater than or equal to 1. This distribution network then includes inactive lines. This type of distribution network, however, has a higher limit than a non-sporous distribution network.

[0125] In one embodiment, a single source is used to generate the excitation signals injected into the input of respective distribution networks coupled to different respective excitation port sub-networks and / or a single receiver is used to receive the excitation signals generated into the input of the respective distribution networks.

[0126] There figure 7 The diagram schematically represents, on the left, the desired Equivalent Isotropically Radiated Power (EIRP) as a function of the beam's angular aperture, and on the right, the actual EIRP of an antenna as a function of its angular aperture when a single power source is used to excite the different subsets of excitation ports generating the various beams with different apertures. When a single source is used for all beams, the EIRPs, corresponding to the sum of the electrical power applied to the antenna and the antenna's gain, differ for the various apertures. The narrower the beam, the greater the number of excited radiating elements. The radiated power (EIRP) is proportional to the number of radiating elements. The wider the beam, the more the power is distributed over a smaller number of radiating elements, and the lower the EIRP.It is possible to compensate for the amplitudes of the signals applied to the distribution networks of the excitation port subsets in order to generate the respective beams, for example, by using attenuators. This makes it possible, for example, to balance the EIRP of each beam, i.e., to obtain a higher radiated power for the widest beam and a lower radiated power for the narrowest beams.

[0127] The reduction in EIRP is not problematic in some applications. In these cases, it is not necessary to adjust the amplitudes of the signals injected into the different subnetworks to avoid this reduction.

[0128] Alternatively, several independent sources and / or several independent receivers are used to generate the excitation signals injected into the input of the respective distribution networks and / or, respectively, to receive the signals generated at the input of the respective distribution networks. In other words, a first distribution network is connected to a first source or a first receiver, and a second distribution network is connected to a second source distinct from the first source or, respectively, to a second receiver distinct from the first receiver. This allows for easy adjustment of the amplitudes and the generation of concentric beams at different frequencies.

[0129] The invention has been described in the case where the unitary radiating elements are coupled to the distribution networks such that each radiating element is capable of being excited at a single excitation port. In other words, each unitary radiating element is coupled to a single distribution network so that the distribution network is capable of exciting it at a single excitation port.

[0130] Alternatively, at least one radiating element is coupled to the network so that it can be simultaneously excited at multiple excitation ports. Advantageously, the unitary radiating element is coupled to several distribution networks so that each distribution network can excite one of the respective excitation ports of the radiating element. This allows the same radiating element to be excited simultaneously by two different signals. It also allows for dual polarization: either linear (vertical for one port and horizontal for the other) or circular (right-handed for one and left-handed for the other).

[0131] There figure 8 represents different sub-arrays of excitation ports of an array R1 of radiating elements E. The array R1 is a matrix of 8*8 = 64 unit radiating elements arranged regularly in rows and columns. The rows are parallel to each other and perpendicular to each other. Each radiating element E includes an excitation port PE. The excitation ports PE are, for example, but not necessarily, located at the centers of the respective radiating elements E.

[0132] The respective sub-networks P1, P2, P3, P4 of PE excitation ports are distributed over contiguous surfaces comprising a first square surface SC, and three L-shaped surfaces L1, L2 and L3 separated in pairs by dashed lines on the figure 8 .

[0133] The three L-shaped surfaces L1, L2, and L3 surround the first rectangular surface. The first L-shaped surface L1 partially surrounds the first rectangular surface SC. The second L-shaped surface L2 partially surrounds the first L-shaped surface, and the third L-shaped surface L3 partially surrounds the second L-shaped surface L2. Thus, the surface area of ​​the first L-shaped surface L1 is larger than that of the square surface CC and includes more excitation points PE, namely 12, than the square surface CC, which has 4. The surface area of ​​the second L-shaped surface L2 is larger than that of the first L-shaped surface L1 and includes more excitation ports, namely 20, than the first L1 surface. The surface area of ​​the third L-shaped surface L3 is larger than that of the second L-shaped surface L2 and includes more excitation ports, namely 28, than the second L2 surface.

[0134] In the non-limiting example of the figure 8 The excitation points of each L are distributed over two rows forming one branch of the L and over two columns forming the other branch of the L. The number of rows or columns of excitation points per branch of the L can of course be different and vary from one L to another.

[0135] THE figures 9 à 14 represent different possible distribution networks for exciting the respective excitation port sub-networks P1, P2, P3, P4. These distribution networks are binary trees with leaf nodes NF, connected to active distribution lines LA, represented as squares materializing the positions of the radiating elements E to which they are coupled.

[0136] There figure 9 represents a first example of a distribution network RDa coupled to the four PE excitation ports of the first P1 excitation port subnetwork. The RDa distribution network is a gap-based distribution network implemented as a binary tree of height 7 comprising four active terminal distribution lines LA and four inactive terminal distribution lines LI connected to respective resistive elements T represented by ovals on the figures 9 à 14 The distribution network RDa includes a first distribution input Ea. This example exhibits greater radiated power losses than that emitted by a distribution network without gaps. These losses are expressed in 10 ∗ LOG 1 − ∑ n = 1 4 1 2 n where n is the index of each resistive element T. This can be useful when it is necessary to attenuate the radiated power. This avoids the need for attenuators.

[0137] There figure 10 represents a second example of a distribution network RDb coupled to the four PE excitation ports of the first network P1. This second example is more advantageous in terms of radiated power because the distribution network is a gap-free distribution network. More precisely, it is a perfect binary tree with a height of 3. This distribution network was obtained by moving the first distribution input Ea relative to the figure 5 and by positioning the root node at the center of symmetry C1 of the subnetwork P1 while the root node NR of the network Rda was at the center of symmetry C1 of the network R1.

[0138] The excitation ports of the other subnetworks L1, L2, L3, not having a center of symmetry and being made up of respective numbers of distinct excitation ports of a power of two, are advantageously supplied by gap distribution networks being, for example, perfect binary trees.

[0139] There figure 11 This represents a first example of a distribution network RD1a coupled to the twelve excitation ports of the L1 subnetwork. This distribution network RD1a is a gap-type distribution network, which is a perfect binary tree with a height of 7, comprising twelve active final distribution lines LA and three inactive final distribution lines LI connected to their respective resistive elements T. This example exhibits a greater limitation on radiated power. The distribution network RD1a includes a second distribution input E1a and a root node NR located at the center of symmetry C.

[0140] The first two resistive elements T encountered after input E1a limit the radiated power by 6dB compared to that of a complete array. The last resistive element being a quarter array (line divided into four), an additional loss of 1.25dB occurs, so the array implies a loss of 7.25dB, corresponding to 10 ∗ LOG 1 − 1 2 + 1 2 2 + 1 2 4 .

[0141] There figure 12 represents a second example of an RD1b distribution network coupled to the twelve excitation ports of the L1 subnetwork. This distribution network is a gap-type distribution network, which is a perfect binary tree with a height of 5, comprising twelve active terminal distribution lines LA and one inactive terminal distribution line LI. This example exhibits a less significant radiated power limitation than the network of the figure 10 This distribution network was obtained by moving the second distribution input E1b relative to the figure 10 and the root node NR.

[0142] The network implies a limitation of radiated power of 1.25dB due to the single resistive element.

[0143] To excite the L1 subnetwork, it is more advantageous to plan the network of the figure 12 than that of the figure 11 Conversely, if there is a need to attenuate the radiated power, the configuration of the figure 12 allows you to avoid the use of attenuators.

[0144] There figure 13 represents an example of a distribution network RD2 coupled to the twelve excitation ports of the subnetwork L2. This distribution network RD2 is a gap-based distribution network being a perfect binary tree of height equal to 7 comprising 20 active terminal distribution lines LA and five inactive terminal distribution lines LI connected to respective resistive elements T. The distribution network RD2 includes a distribution input ED2.

[0145] There figure 14 represents an example of a distribution network RD3 coupled to the 28 excitation ports of the L2 subnetwork. This distribution network RD3 is a gap distribution network which is a perfect binary tree of height equal to 7 forming 28 active distribution lines LA and 5 inactive distribution lines LI connected to respective resistive elements T. The distribution network RD3 includes a distribution input ED3.

[0146] Advantageously, the antenna includes four feed networks, one of which is from that of the figures 9 And 10 , one of those figures 11 And 12 and those of figures 13 And 14This architecture allows for the simultaneous creation of four beams by supplying the four distribution networks with separate excitation signals, or a single beam by supplying the distribution networks so that the different excitation ports are excited by the same excitation signal. Advantageously, the supply networks are located in separate, stacked layers to avoid line overlap.

[0147] The invention has been described in the case where each gapped or non-gapped distribution network of an antenna is coupled to a sub-network of excitation ports of the antenna's excitation port network.

[0148] The invention also relates to an antenna comprising a gap distribution network coupled to all the excitation ports of the antenna's excitation port network.

[0149] In this case, the antenna may also include radiating elements without excitation ports, i.e. not coupled to a distribution network.

[0150] Alternatively, each radiating element includes one of the excitation ports of the excitation port network coupled to the gap distribution network.

[0151] In this case, the resistive elements T of the excitation port array are, for example, located opposite areas of the radiating element array that are devoid of radiating elements, or the resistive elements T belong to the same radiating surface as the radiating elements; they are, for example, coplanar with the radiating elements in the case of a planar antenna. The invention also relates to an antenna comprising a gap distribution array coupled to a sub-array of excitation ports of the antenna's excitation port array, in which at least one resistive element is located opposite an area of ​​the radiating element array that is devoid of radiating elements, or in which at least one resistive element is coplanar with the radiating elements.

[0152] The invention relates to a method for manufacturing an antenna according to the invention.

[0153] The antenna comprises an array of unitary radiating elements coupled to a distribution network into an array of excitation ports or to a plurality of distribution networks into respective sub-arrays of excitation ports. Each distribution network is coupled to the excitation ports of the network or to the ports of a sub-array of ports in such a way as to allow the radiating elements at the excitation ports of the network or sub-array of excitation ports to be simultaneously excited by an excitation signal injected at the input of the distribution network, and vice versa.

[0154] The manufacturing process includes a design step for the excitation port network or the excitation port sub-network(s).

[0155] This step is advantageously carried out depending on the beam that one wishes to radiate or receive, or the beams that one wishes to be able to radiate or receive independently of each other.

[0156] The process also includes a step of designing the distribution network(s) so that they are capable of exciting the network of unit radiating elements at the level of the network or sub-network of excitation ports or at the level of the respective excitation port sub-networks, and vice versa. This step can, for example, be implemented by computer or performed manually.

[0157] The process includes a manufacturing step of the distribution network(s) designed during the design step and a coupling step of the distribution network to the corresponding excitation port network or sub-network of excitation ports so that it is capable of exciting the radiating element network at the excitation port(s) of the network or respectively of the sub-network or a coupling step of each distribution network to the excitation port(s) of the corresponding excitation port network or respectively sub-network of excitation port(s) so that it is capable of exciting the unitary radiating element network at the excitation port(s) of the network or respectively of the sub-network of excitation port(s) from respective signals injected at their respective inputs, and vice versa.

[0158] The process also includes a manufacturing step of at least one gap distribution network, a coupling step of the gap distribution network, and more particularly of its active distribution lines, to the excitation ports of the network of excitation ports or to the excitation ports of the subnetwork of excitation ports of the network of excitation ports and a step of electrically connecting each inactive terminal distribution line to a resistive element.

[0159] Advantageously, the gapy tree distribution network is connected to a network or subnetwork of primary excitation ports.

[0160] By network subnetwork of primary excitation ports, we mean a network or subnetwork of M1 excitation ports such that M1 is different from N x< where N is a prime number greater than 1 and x is an integer greater than or equal to 1.

[0161] Advantageously, the antenna includes at least one network or subnetwork of primary excitation ports coupled to a gapy tree-like distribution network.

[0162] Advantageously, in the process according to the invention, the network or sub-network of excitation ports, when it is primary, is coupled to a gap distribution network or each sub-network of primary excitation ports is coupled to a respective gap distribution network.

[0163] In an embodiment, the antenna includes at least one array or sub-array of Q secondary excitation ports such that Q = N x < where x is an integer greater than 1.

[0164] The method comprises a step of designing and manufacturing a gap-based, tree-like distribution network intended to excite each excitation port of the network or sub-network of secondary excitation ports, a step of coupling the network or sub-network of secondary excitation ports to the gap-based distribution network, and more specifically to the active terminal distribution lines of the gap-based, tree-like distribution network, and a step of connecting each inactive terminal distribution line of this gap-based, tree-like distribution network to a resistive element. This embodiment may be advantageous for limiting radiated power.

[0165] The method includes, as an alternative or additional step, a design and fabrication step for a gap-free distribution network intended to excite the excitation ports of a sub-network of secondary excitation ports, and a coupling step for the sub-network of secondary excitation ports to the gap-free distribution network by coupling to the active terminal distribution lines of the gap-free network. This solution is more efficient than the previous one in terms of radiated power.

[0166] The manufacturing process according to the invention is simple and robust.

[0167] It allows for the creation of relatively low-cost antennas that do not require discrete, passive or reactive electronic components such as circulators, insulators, etc., or active components such as in the case of a MIMO RADAR with a transmitter / receiver per unit radiating element.

[0168] The process according to the invention is reproducible because it is based on an industrially mastered N-ary tree distribution network technology.

[0169] This process involves relatively simple design steps.

[0170] It allows the creation of multiple beams with identical (concentric) or different centers by dividing the arrays of radiating elements or excitation ports into several sub-arrays. This array can be divided a large number of times, thus creating a large number of independent beams. This process therefore makes it possible to create a variable-sized antenna with the same patch array. It allows different needs to be met from a single array of radiating elements.

[0171] Depending on the characteristics of the desired beam, more or fewer radiating elements are excited.

[0172] The proposed solution allows for the generation or reception of multiple radio beams simultaneously in a relatively inexpensive and compact manner. It notably eliminates the need for components such as duplexers, circulators, power dividers, and isolators. However, these components are expensive and bulky.

Claims

1. Antenna comprising a network of unitary radiating elements, the antenna comprising at least one lacunary distribution network being an N-area tree network comprising distribution lines connected to one another in nodes having one same predetermined impedance Z, the distribution lines comprising primary distribution lines, each primary distribution line being connected, in an intermediate node, at Nz other distribution lines where z is an integer greater than or equal to 1 and N is a prime number greater than 1, and terminal distribution lines, each terminal distribution line being connected to one single other of the distribution lines, the terminal distribution lines comprising at least one active terminal distribution line coupled to the network of unitary radiating elements in a first network of at least one excitation port of the network of unitary radiating elements, so as to enable to excite the network of unitary radiating elements simultaneously in the at least one excitation port of the first network of at least one excitation port from an electric signal injected in an input of the distribution network, the terminal distribution lines comprising at least one inactive terminal distribution line electrically connected to a resistive element having an impedance of the resistive element equal to the impedance Z, said antenna being characterised in that the resistive element is located facing an excitation port of the network of radiating elements not forming part of the first network, such that the antenna has no coupling means between the inactive terminal distribution line and a radiating element located facing the resistive element.

2. Antenna according to the preceding claim, wherein said lacunary distribution network is a first lacunary distribution network comprising M1 active terminal distribution line(s) coupled to M1 first excitation port(s) of the network of unitary radiating elements, wherein M1 is an integer greater than or equal to 1, different from N1x1, N1 being a prime number greater than 1 and x1 being an integer greater than or equal to 1, the first lacunary distribution network being an N1-area tree network.

3. Antenna according to the preceding claim, further comprising a second lacunary distribution network such as defined in claim 1, and comprising M2 active terminal distribution line(s) coupled to M2 second excitation port(s) of the network of unitary radiating elements, wherein M2 is equal to N2x2, N2 being a prime number greater than 1 and x2 being an integer greater than or equal to 1, the second lacunary distribution network being an N2-area tree network.

4. Antenna according to any one of the preceding claims, comprising a non-lacunary distribution network being a tree network comprising distribution lines connected to one another in nodes having one same predetermined impedance, the distribution lines comprising primary distribution lines, each primary distribution line being connected, in an intermediate node, at Kk other distribution lines, where k is an integer greater than or equal to 1 and K is a prime number greater than 1, and terminal distribution lines connected to one single other of the distribution lines, the terminal distribution lines being active terminal distribution lines coupled to K third excitation ports of the network of unitary radiating elements, so as to enable to excite the network of unitary radiating elements simultaneously in the K third excitation ports from an electric signal injected in an input of the non-lacunary distribution network.

5. Antenna according to any one of the preceding claims, comprising several distribution networks according to any one of the preceding claims, and coupled to distinct respective subnetworks of excitation ports of the network of radiating elements, so as to enable to simultaneously emit or receive several electromagnetic beams.

6. Antenna according to the preceding claim, comprising several sources, the inputs of the distribution networks being connected to distinct respective sources or to distinct respective receivers.

7. Antenna according to any one of claims 5 to 6, comprising respective subnetworks of excitation ports distributed over concentric rings, the (i+1)th ring surrounding the ith ring, i = 1 at Nss-networks-1, Nss-networks being the number of said subnetworks.

8. Antenna according to any one of the preceding claims, wherein the antenna has no excitation port, other than the excitation ports of the first network of at least one excitation port.

9. Antenna according to the preceding claim, wherein each unitary radiating element comprises one of the excitation ports of the first network of at least one excitation port.

10. Antenna according to any one of the preceding claims, the antenna being planar.

11. Method for manufacturing an antenna according to any one of the preceding claims, comprising: - a step of designing the network of radiating elements comprising the first network of excitation ports, - a step of designing the lacunary distribution network, such that it enables to excite the network of unitary radiating elements simultaneously in the at least one excitation port of the first network of at least one excitation port, when it is coupled to the first network of at least one excitation port and when an electric signal is injected at the distribution input of the lacunary distribution network, - a step of manufacturing the lacunary distribution network designed during the design step, - a step consisting of electrically connecting the inactive distribution line to the resistive element, - a step of coupling the lacunary distribution network to the first network of at least one excitation port comprising a step of coupling each active distribution line of the lacunary distribution network to an excitation port of the at least one excitation port of the first network of excitation ports, so as to enable to excite the network of radiating elements at the excitation port, when an electric signal is injected at the distribution input.

12. Method for manufacturing, according to the preceding claim, an antenna according to claim 2, wherein when the network of excitation ports comprises a first set of M1 first excitation port(s) such that M1 is an integer greater than or equal to 1, different from N1×1, where N1 is a prime number greater than 1 and x1 is an integer greater than 1, a step of designing a first lacunary distribution network comprising M1 active terminal distribution line(s), a step of manufacturing the first lacunary distribution network, a step of coupling the first lacunary distribution network to the M1 first excitation port(s) and a step consisting of electrically connecting the active terminal distribution line to a resistive element.

13. Method for manufacturing, according to any one of claims 11 to 12, an antenna according to claim 3, and wherein, when the network of excitation ports comprises a second set of M2 second excitation ports, such that M2 is an integer greater than 1 equal to N2x2, where N2 is a prime number greater than 1 and x2 is an integer greater than 1, the method comprising: - a step of designing a second lacunary distribution network comprising M2 terminal distribution lines, the terminal distribution lines being active, a step of manufacturing the second lacunary distribution network and a step of coupling the second lacunary distribution network to the M2 second excitation ports, a step consisting of electrically connecting the inactive terminal distribution line to a resistive element, or, - a step of designing a non-lacunary distribution network comprising M2 active terminal distribution lines, and at least one inactive terminal distribution line, a step of manufacturing the second non-lacunary distribution network and a step of coupling the second non-lacunary distribution network to the M2 second excitation ports.

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