Dual-band radio antenna

Abstract

Dual-band radio antenna. This description relates to a dual-band radio antenna (100) comprising a single antenna array (103) including: – a first active antenna element (107A), intended to be excited by a radio frequency signal; and – parasitic second antenna elements (107P) having identical geometries with each other and different from that of the first antenna element, each second antenna element being connected: A) to a reconfigurable parasitic load; or B) to a filtering and / or non-Foster parasitic load. Figure for the abbreviation: Fig. 1B

Description

Title of the invention: Dual-band radio antenna technical field

[0001] This description relates generally to electronic devices, and more particularly to radio antennas. This description specifically concerns dual-band antennas, that is, antennas capable of communicating on two different frequency bands, and circularly polarized antennas, in other words, antennas designed to transmit and / or receive waves with circular polarization. Previous technique

[0002] Circularly polarized antennas are used in many application areas, such as GNSS (Geolocation and Navigation Satellite System) satellite positioning systems. In these applications, the antennas are subject to very strict dimensional and economic constraints, resulting from the desire to integrate these antennas into more compact and less expensive wireless communication devices. Furthermore, the antennas used in these applications generally operate in multi-band, for example dual-band, to be able to process waves simultaneously transmitted or received in different frequency bands. This improves the performance of navigation systems, notably by enabling the acquisition of more reliable and accurate location data.

[0003] Other applications, such as so-called Cognitive Radio (CR) systems, use reconfigurable antennas capable of adapting to the wireless environment. These applications could benefit from reconfigurable circularly polarized antennas to modify the communication frequency according to available propagation channels while reducing losses.

[0004] Furthermore, fifth and sixth generation mobile telephony networks (5G and 6G) ​​are likely to implement base stations incorporating circularly polarized antennas and exhibiting reconfigurable radiation patterns.

[0005] Among existing circularly polarized radio antennas, compact antennas with dimensions smaller than half the antenna's transmission wavelength have been proposed. These antennas can be implemented in various ways, including by forming structures called microarrays comprising several sub-wavelength antennas arranged and controlled to be able to simultaneously transmit and / or receive circularly polarized radio waves.

[0006] A first category of microarray radio antennas includes fully driven antennas, in which all the elements of the array are directly excited by radio frequency signals. These signals may, for example, have the same amplitude but are out of phase with each other. In this category, arrays comprising four inverted-F antennas (IFAs), each inverted-F antenna being directly excited by a signal 90° out of phase with the adjacent antennas, have been proposed. Inverted-F antennas are used in this type of application because of their low profile and their predominantly sectoral radiation pattern above the antenna. These characteristics are particularly required for GNSS applications.Other arrays comprising N inverted F antennas directly excited by signals phase-shifted by 360° / N, for example three inverted F antennas directly excited by signals phase-shifted by 120°, have also been implemented. This allows for phase rotation to generate circular polarization. Antennas in this category have the advantage of broadband operation, achieved, however, at the expense of simplicity, compactness, and antenna efficiency, primarily due to the presence of complex excitation circuits.

[0007] A second category of microarray radio antennas comprises so-called parasitic element antennas, in which only certain active elements of the array are directly excited by a radio frequency signal. The other elements, called parasitic elements, are excited indirectly by coupling with the active elements directly excited by the radio frequency signal. In this category, dual-band antennas whose array comprises eight identical inverted-F antennas arranged in two concentric groups of four antennas have been proposed. In these dual-band antennas, only one of the inverted-F antennas is an active antenna directly excited by the radio frequency signal, the other inverted-F antennas being connected to parasitic loads optimized so that the array emits or receives a circularly polarized wave.Each group of antennas in an inverted F configuration allows communication using a different frequency band than the other group of antennas.

[0008] Parasitic element antennas are simpler and less expensive to produce, but have a narrower bandwidth than fully fed antennas, particularly in the case of compact antennas with a radiation pattern sensitive to variations in parasitic charges as a function of the antenna's transmission frequency. Summary of the invention

[0009] There is a need to overcome all or part of the drawbacks of existing radio antennas. In particular, it would be desirable to develop circularly polarized dual-band antennas capable of achieving performance similar to that of existing antennas, while having a smaller size, lower weight, and lower manufacturing cost.

[0010] To this end, one embodiment provides a dual-band radio antenna comprising a single antenna array including: - a first active antenna element, designed to be excited by a radio frequency signal; and - second parasitic antenna elements having identical geometries with each other and different from that of the first antenna element, each second antenna element being connected: A) to a reconfigurable parasitic load; or B) to a parasitic filtering and / or non-Foster load.

[0011] According to one embodiment, the second antenna elements each comprise an inverted F antenna.

[0012] According to one embodiment, the first antenna element comprises an inverted F antenna.

[0013] According to one embodiment, the first antenna element and the second antenna elements are formed on a tubular-shaped support substrate.

[0014] According to one embodiment, the support substrate is a flexible substrate intended to be rolled up on itself to present said tubular shape.

[0015] According to one embodiment, the first antenna element and the second antenna elements are disjoint and distributed around the perimeter of the same circle.

[0016] According to one embodiment, the antenna further comprises a support and interconnection substrate, the support substrate having an axis of revolution substantially orthogonal to a face of the support and interconnection substrate.

[0017] According to one embodiment, the reconfigurable parasitic load or the filtering and / or non-Foster parasitic load connected to each second antenna element is located on the upper face of the support and interconnection substrate.

[0018] According to one embodiment, the antenna comprises exactly two second antenna elements.

[0019] According to one embodiment, the first antenna element is a monopolar wire-plate antenna.

[0020] According to one embodiment, the second antenna elements surround the first antenna element.

[0021] According to one embodiment, each reconfigurable parasitic load comprises: - a first parasitic load exhibiting a first reactance; - at least one second parasitic load exhibiting a second reactance; and - a switch configured to select the first parasitic load or one of the second parasitic loads. Brief description of the drawings

[0022] These features and advantages, as well as others, will be described in detail in the following description of particular embodiments, given by way of non-limiting example, in relation to the accompanying figures, among which:

[0023] [Fig.1A] is an isometric, schematic and partial view, illustrating an example of a radioelectric antenna according to one embodiment;

[0024] [Fig.1B] is a schematic and partial top view of the antenna of [Fig.1A];

[0025] [Fig.1C] is a schematic and partial side and cross-sectional view of a support substrate on which elements of the antenna of [Fig.1A] are formed;

[0026] [Fig.1D] is a schematic and partial top view of the planar substrate supporting [Fig.1C];

[0027] [Fig.2] is an equivalent electrical diagram of a radio antenna according to one embodiment;

[0028] [Fig.3] is a graph illustrating variations in the axial ratio of a radio antenna as a function of a communication frequency;

[0029] [Fig.4] is an equivalent electrical diagram of a radio antenna according to one embodiment;

[0030] [Fig.5] is a graph illustrating variations in the axial ratio of a radio antenna as a function of a communication frequency;

[0031] [Fig. 6] is a schematic and partial top view of a radio antenna according to one embodiment; and

[0032] [Fig.7] is a schematic and partial top view of a radio antenna according to one embodiment. Description of the implementation methods

[0033] The same elements have been designated by the same reference numerals in the different figures. In particular, the structural and / or functional elements common to the different embodiments may have the same reference numerals and may have identical structural, dimensional and material properties.

[0034] For the sake of clarity, only the steps and elements useful for understanding the described embodiments have been shown and are detailed. In particular, the circuits for generating, filtering, amplifying, etc., radio frequency waves emitted and / or received by the described antennas will not be detailed, as the described antennas are compatible with all or most commonly used circuits. in communication systems using antennas, possibly with adaptations within the reach of the person in the trade upon reading this description.

[0035] Furthermore, the manufacturing processes for the antennas described will not be detailed, as the production of these antennas is within the reach of a person skilled in the art using the indications in this description, for example by implementing standard radio frequency printed circuit manufacturing techniques.

[0036] Unless otherwise specified, when referring to two elements connected together, this means directly connected without intermediate elements other than conductors, and when referring to two elements coupled together, this means that these two elements can be connected or linked through one or more other elements.

[0037] In the following description, when reference is made to absolute position qualifiers, such as the terms "front", "back", "top", "bottom", "left", "right", etc., or relative position qualifiers, such as the terms "above", "below", "superior", "inferior", etc., or to orientation qualifiers, such as the terms "horizontal", "vertical", etc., reference is made, unless otherwise specified, to the orientation of the figures.

[0038] Unless otherwise specified, the expressions "approximately", "about", "substantially", and "in the order of" mean within 10%, preferably within 5%.

[0039] In the following description, the terms "insulating" and "conducting" mean, unless otherwise specified, electrically insulating and electrically conductive respectively.

[0040] Fig. 1A is an isometric, schematic and partial view, illustrating an example of a radio antenna 100 according to one embodiment.

[0041] In the example shown, the antenna 100 comprises a support and interconnection substrate 101 on which a single antenna array 103 is arranged. For the sake of simplicity, the antenna array 103 is symbolized in [Fig. 1A] by a hollow cylinder, or a tube, of substantially circular cross-section and whose axis of revolution is substantially orthogonal to a face of the support and interconnection substrate 101 (the upper face of the substrate 101, in the orientation of [Fig. 1A]). Although not detailed in [Fig. 1A], the support and interconnection substrate 101 is, for example, a printed circuit board. The support and interconnection substrate 101 comprises, for example, metallic layers located on either side of an insulating layer. Contact resumption elements and conductive tracks, not detailed in [Fig.1A], are for example formed in the metallic layers of the support and interconnection substrate 101.

[0042] Fig. 1B is a schematic and partial top view of antenna 100 of Fig. 1A.

[0043] In the example shown, the antenna array 103 comprises a support substrate 105 around the periphery of which are arranged an active antenna element 107A and two parasitic antenna elements 107P. The support substrate 105 has, for example, as illustrated in [Fig. 1B], a generally hollow cylindrical or tubular shape. The substrate 105 has, for example, a substantially circular circumference and an axis of revolution substantially orthogonal to the upper face of the support and interconnection substrate 101. This example is not, however, limiting; the substrate 105 may, alternatively, have any general shape, for example, a tubular shape with an oval, triangular, rectangular, square, etc., cross-section.

[0044] The active antenna element 107A is intended to be excited by a radio frequency signal, for example directly, while the parasitic antenna elements 107P are intended to be excited indirectly by the active antenna element 107A. Figure 1B illustrates an example in which the antenna array 103 comprises two parasitic antenna elements 107P. This example is not limiting, however; the antenna array 103 may, alternatively, have any number, strictly greater than two, of parasitic antenna elements 107P.

[0045] According to one embodiment, the parasitic antenna elements 107P have identical geometries with each other and different geometries from those of the active antenna element 107A. To facilitate understanding of the drawing, the active antenna element 107A has been symbolized, in [Fig. 1B], by a shape comprising a circular arc with a thicker line than the parasitic antenna elements 107P, in order to highlight the fact that the geometry of the active antenna element 107A is different from that of the parasitic antenna elements 107P. In the example shown, the active antenna element 107A and the parasitic antenna element 107P are separate and distributed around the circumference of the same circle.

[0046] In the example illustrated in [Fig.1B], each active antenna element 107A or parasitic antenna element 107P comprises an inverted F-shaped antenna. In this example, the vertical bar of the F formed by the antenna, contained in the plane of [Fig.1B], is symbolized by an arc of a circle following the curvature of the outer face of the support substrate 105, and the central horizontal bar of the F formed by the antenna, extending along a direction orthogonal to the plane of [Fig.1B], is symbolized by a disk, for the active antenna element 107A, or by a circle, for each parasitic antenna element 107P. In this description, the term "central horizontal bar" refers to a portion of the F-shaped antenna substantially orthogonal to the vertical bar of the F formed by the antenna and distinct from the upper horizontal bar of the F, it being understood that the central horizontal bar of the F does not necessarily intersect the vertical bar of the F in its middle.In the example shown, the central horizontal bar of each inverted F antenna is substantially orthogonal to the upper face of the support and interconnection substrate 101.

[0047] In the example shown, the antenna 100 is intended to transmit and / or receive waves having circular polarization.

[0048] For the sake of clarity, the antenna elements 107A and 107P have not been shown in [Fig. 1B] in contact with the outer wall of the support substrate 105. However, in practice, the antenna elements 107A and 107P can be located on and in contact with the outer wall of the support substrate 105. Alternatively, the antenna elements 107A and 107P can be located inside the tube formed by the support substrate 105, and are then, for example, located on and in contact with the inner wall of the support substrate 105.

[0049] Although not illustrated in [Fig. 1B], the radio antenna 100 may further include a connector, for example an SMA (SubMiniature version A) connector, for connecting the antenna 100 to a communication circuit (not shown), for example a circuit for transmitting signals intended to be emitted by the antenna 100 as waves and / or for receiving signals from waves received by the antenna 100. In this case, the connector is located, for example, on the side of a face of the support and interconnect substrate 101 opposite the antenna array 103 (the underside of the substrate 101, in the orientation of [Fig. 1B]). By way of example, the connector is connected to the center bar of the F of the active antenna element 107A by a microstrip line formed on the support and interconnect substrate 101.

[0050] The [Fig.lC] is a schematic and partial side and cross-sectional view of the support substrate 105 on which the active antenna element 107A and the parasitic antenna elements 107P of the antenna 100 of the [Fig.lA] are formed.

[0051] In the example shown, the support substrate 105 is coated with a conductive layer 109. The conductive layer 109 is, in the orientation of [Fig.1C], located on and in contact with the upper face of the support substrate 105. By way of example, the conductive layer 109 is made of a metal, for example copper, or of a metal alloy.

[0052] The antenna elements 107A and 107P are for example formed in the conductive layer 109, for example by photolithography and then etching of the layer 109. As an alternative, the antenna elements 107A and 107P can be formed on and in contact with the upper face of the support substrate 105 by selective deposition of a conductive material.

[0053] In the illustrated example, the conductive layer 109 is covered by an insulating layer 111. In this example, the insulating layer 111 is located on and in contact with a face of the conductive layer 109 in which the antenna elements 107A and 107P are formed (the upper face of the conductive layer 109, in the orientation of [Fig. 1C]). By way of example, the insulating layer 111 is a so-called covering layer (A coverlay) designed to protect the antenna elements 107A and 107P from mechanical and / or chemical damage. In the example shown, the antenna elements 107A and 107P are interposed vertically between the support substrate 105 and the insulating layer 111.

[0054] By way of example, the support substrate 105 and the layers 109 and 111 have thicknesses of approximately 70 pm, 35 pm and 38 pm respectively.

[0055] The substrate 105 is, for example, a flexible substrate (“flex”) designed to be wound upon itself to form a tubular structure, for example as previously described in relation to Figures IA and IB, and then fixed to the support and interconnecting substrate 101 in order to mechanically secure it to the latter and maintain it in the form of a tube. By way of example, the support substrate 105 is wound so that layers 109 and 111 are located on the outside of the tube formed by the substrate 105. Alternatively, the support substrate 105 can be wound so that layers 109 and 111 are located on the inside of the tube formed by the substrate 105.

[0056] Fig.1D is a schematic and partial top view of the planar support substrate 105 of Fig.1C.

[0057] In the example shown, the support substrate 105 has, in top view, a substantially rectangular perimeter, it being understood that the substrate 105 may, alternatively, have any shape. In the illustrated example, the antenna elements 107A and 107P are inverted F-shaped antennas. The horizontal bars of the Fs formed by the antenna elements 107A and 107P, arranged vertically in the orientation of [Fig. 1D], are substantially parallel to each other and substantially orthogonal to the length of the rectangle formed by the substrate 105, and the vertical bars of the Fs formed by the antenna elements 107A and 107P, arranged horizontally in the orientation of [Fig. 1D], are substantially parallel to each other and substantially parallel to the length of the rectangle formed by the substrate 105.As an example, the antenna elements 107A and 107P include bands of a conductive material extending laterally in directions substantially parallel to the upper face of the support substrate 105.

[0058] In the example illustrated in [Fig. 1D], the end of the upper horizontal bar of the F formed by each antenna element 107A and 107P, opposite the vertical bar of the F, is located on and in contact with a protruding portion of the support substrate 105. This allows, for example, the support substrate 105 to be fixed to the support and interconnecting substrate 101, for example by welding the protruding portions of the substrate 105 to the underside of the substrate 101. By way of example, notches or slots for cooperating with the protruding portions of the support substrate 105 are formed in the thickness of the support and interconnecting substrate 101. In In the example shown, each part of the support substrate 105 forming a protrusion extends parallel to the width of the substrate 105 over a distance LB for example equal to approximately 2.5 mm.

[0059] Denoting Xo as a wavelength of emission and / or reception of the antenna 100: - the support substrate 105 has for example a length Lsub equal to approximately 0.6 Xo and a width Wsub equal to approximately 0.11 Xo; - the F formed by the active antenna element 107A, for example, has a height HA equal to approximately 0.16 Xo and a width WA equal to approximately 0.11 Xo; and - the F formed by each parasitic antenna element 107P has for example a height HP equal to about 0.2 Xo and a width WP equal to about 0.09 Xo.

[0060] In a case where the wavelength Xo is expressed in meters, the dimensions Lsub, Wsub, Ha, Wa, Hp and WP above are expressed in millimeters.

[0061] By way of example, in a case where the wavelength Xo is equal to approximately 0.19 m, corresponding to a frequency of approximately 1.575 GHz: - the length Lsub is approximately 150 mm; - the Wsub width is approximately 28 mm; - the height HA is approximately 40 mm; - the WA width is approximately 26 mm; - the HP height is approximately 50 mm; and - the WP width is approximately 22 mm.

[0062] Figure 2 is an equivalent electrical diagram of a radio antenna, by For example, antenna 100 described above in relation to figures IA to 1D, according to one embodiment. The electrical diagram 200 of [Fig. 2] illustrates more precisely an example in which antenna 100 exhibits reconfigurable dual-band operation.

[0063] In the example shown, the radio antenna 100 is symbolized by an impedance matrix [ZA]3x3 connected to a signal source 201. The signal source 201 is, for example, configured to produce a radio frequency signal to be emitted by the radio antenna 100.

[0064] In the illustrated example, one of the parasitic antenna elements 107P is connected either to a parasitic charge of reactance X2, or to a parasitic charge of reactance X'2, different from reactance X2. Similarly, the other parasitic antenna element 107P is connected either to a parasitic charge of reactance X3, or to a parasitic charge of reactance X'3, different from reactance X3.

[0065] In the example shown, each parasitic antenna element 107P includes a switch 203 for activating the parasitic load with reactance X2, X3 or the parasitic load with reactance X'2, X'3. The switches 203 are, for example, of the type SPDT (“Single Pole Double Throw” in English) and each have an input connected to a node applying a potential Vref, for example ground, an output connected to the parasitic load of reactance X2, X3, and another output connected to the parasitic load of reactance X'2, X'3. Each switch 203 is for example controlled by a control circuit, not shown in [Fig.2].

[0066] Activating the parasitic charges with reactances X2 and X3 allows, for example, the antenna 100 to emit a wave at a first frequency fb, and activating the parasitic charges with reactances X'2 and X'3 allows the antenna 100 to emit a wave at a second frequency f2, different from the first frequency fb. In the example shown, the parasitic charges with reactances X2 and X'2 and the switch 203 connected to these charges form a reconfigurable parasitic charge 205-2. Similarly, the parasitic charges with reactances X3 and X'3 and the switch 203 connected to these charges form a reconfigurable parasitic charge 205-3.

[0067] The values ​​of the reactances X2, X'2, X3 and X'3 of the parasitic charges are defined for example by simulation, for example by the implementation of a process called "SWE" (from the English "Spherical Wave Expansion" - development in spherical waves), for example as described in the publication by H. Jaafar et al. entitled "Synthesis of Circularly Polarized Parasitic Micro-Array Using Spherical Wave Expansion" and published in "Proc. 15th European Conference on Antennas and Propagation (EuCAP 2023)", Florence, Italy, March 2023, pp. 1-4.

[0068] By way of example, for first and second frequencies fi and f2 respectively equal to approximately 1.225 GHz, corresponding to the GPS-L2 band, and 1.575 GHz, corresponding to the GPS-L1 band: - reactances X2 and X3 are respectively equal to approximately -21 Q and -43 Q; and - reactances X'2 and X'3 are equal to approximately -120 Q each.

[0069] The parasitic charges of reactances X2, X'2, X3 and X'3 are for example formed on the upper face of the support and interconnection substrate 101, and the node of application of the potential Vref corresponds to a ground plane formed on the side of the lower face of the substrate 101.

[0070] Fig. 3 is a graph 300 illustrating variations of an axial ratio AR, expressed for example in decibels (dB), of a radio antenna, for example antenna 100 of figures IA to 1D including reconfigurable parasitic loads 205-2 and 205-3, as a function of a communication frequency f, expressed for example in gigahertz (GHz).

[0071] In the example shown, a curve 301 illustrates variations in the axial ratio AR of the antenna 100 as a function of the frequency f in the case where the parasitic reactance charges X2 and X3 are connected to the parasitic antenna elements 107P. The Curve 301 corresponds to the first usable frequency band for antenna 100. Furthermore, in this example, curve 303 illustrates variations in the axial ratio AR of antenna 100 as a function of frequency f when parasitic reactance loads X'2 and X'3 are connected to parasitic antenna elements 107P. Curve 303 corresponds to a second, higher frequency band than the first, usable by antenna 100.

[0072] The equivalent diagram 200 and the graph 300 correspond, for example, to a case in which the antenna 100 is intended to be used in a Cognitive Radio (CR) device.

[0073] Figure 4 is an equivalent electrical diagram 400 of a radio antenna, for example the antenna 100 described above in relation to Figures IA to 1D, according to one embodiment. The electrical diagram 400 of Figure 4 illustrates more precisely an example in which the antenna 100 exhibits dual-band operation.

[0074] The electrical diagram 400 of [Fig. 4] includes elements common to the electrical diagram 200 of [Fig. 2]. These common elements will not be described again hereafter. The electrical diagram 400 differs from the electrical diagram 200 in that the electrical diagram 400 includes filtering and / or non-Foster parasitic loads of impedances ZL2 and ZL3 instead of the reconfigurable parasitic loads 205-2 and 205-3.

[0075] In the present description, the expression "parasitic filtering load" refers to a load whose reactance grows in an optimized way with frequency to achieve desired impedance variations, and the expression "non-Foster load" refers to a non-Foster type load, that is, a load whose reactance decreases with frequency.

[0076] Fig. 5 is a graph 500 illustrating variations of an axial ratio AR, expressed for example in decibels (dB), of a radio antenna, for example antenna 100 of figures IA to 1D including the parasitic filtering and / or non-Foster loads of impedances ZL2 and ZL3, as a function of a communication frequency f, expressed for example in gigahertz (GHz).

[0077] In the example shown, a curve 501 illustrates variations in the axial ratio AR of the antenna 100 as a function of the frequency f in the case where the two parasitic filtering and / or non-Foster loads have reactances substantially equal to the reactances X2 and X3 respectively at the frequency fb. Curve 501 corresponds to a first frequency band usable by the antenna 100. Furthermore, in this example, a curve 503 illustrates variations in the axial ratio AR of the antenna 100 as a function of the frequency f in the case where the parasitic filtering and / or non-Foster loads have reactances substantially equal to the reactances X2 and X3 respectively. X'2 and X'3 at frequency f2. Curve 503 corresponds to a second frequency band, higher than the first frequency band, usable by antenna 100. Curves 501 and 503 of graph 500 are for example identical or analogous to curves 301 and 303 of graph 300.

[0078] Furthermore, graph 500 includes curves 505 and 507 illustrating, respectively, the frequency variations of the reactances in the case of non-Foster parasitic loads. In the example shown, the reactance of one of the loads, for example the load with impedance ZL 2, decreases between the value X2, for the first frequency band centered around the frequency fb, and the value X'2, for the second frequency band centered around the frequency f2. Moreover, in this example, the reactance of the load with impedance ZL 3 decreases between the value X3, for the first frequency band, and the value X'3, for the second frequency band.

[0079] The equivalent diagram 400 and the graph 500 correspond, for example, to a case in which the antenna is intended to be used in a satellite positioning device of the "GNSS" type (Geolocation and Navigation by Satellite System) exploiting the first and second bands L1 and L2.

[0080] Fig. 6 is a schematic and partial top view of a radio antenna 600 according to one embodiment.

[0081] Antenna 600 of [Fig. 6] includes elements in common with antenna 100 of Figures IA to 1D. These common elements will not be described again hereafter. Antenna 600 differs from antenna 100 in that antenna 600 comprises one fed antenna element 607A and three parasitic antenna elements 607P.

[0082] The active antenna element 607A and parasitic antenna element 607P of antenna 600 are, for example, analogous respectively to the active antenna element 107A and parasitic antenna element 107P of antenna 100. By way of example, each antenna element 607A, 607P comprises an inverted F-shaped antenna. In the example shown, the active antenna element 607A and parasitic antenna element 607P are disjoint and distributed around the perimeter of the same square, for example, on the periphery of a support substrate analogous to the support substrate 105.

[0083] One advantage of the 600 antenna over the 100 antenna is that the 600 antenna has a strictly greater number of parasitic elements 607P than the parasitic elements 107P of the 100 antenna. This allows the 600 antenna to emit a wave with a purer circular polarization than the polarization of the wave emitted by the 100 antenna.

[0084] Fig. 7 is a schematic and partial top view of a radio antenna 700 according to one embodiment.

[0085] Antenna 700 of [Fig. 7] includes elements in common with antenna 100 of Figures IA to 1D. These common elements will not be described again hereafter. Antenna 700 differs from antenna 100 in that antenna 700 comprises one fed antenna element 707A and five parasitic antenna elements 707P.

[0086] The fed antenna elements 707A and parasitic antenna elements 707P of antenna 700 are, for example, analogous respectively to the active antenna elements 107A and parasitic antenna elements 107P of antenna 100. By way of example, the active antenna element 707A comprises a central radiating disc element, and each parasitic antenna element 707P comprises an inverted F-shaped antenna. The fed antenna element 707A is, for example, more precisely a "wire-plate" type antenna comprising a circular roof constituting a capacitive load, allowing the antenna to be miniaturized, for example, an antenna of the type described in European patent application EP 3671953A1. Placing the active antenna element 707A at the center of the antenna 700 allows the quasi-omnidirectional radiation emitted by the element 707A to be coupled in a substantially equivalent way with the parasitic antenna elements 707P.In the illustrated example, the parasitic antenna elements 707P surround the active antenna element 707A. In the example shown, the parasitic antenna elements 707P are disjoint and distributed on the faces of the same pentagon, for example at the periphery of a support substrate analogous to the support substrate 105. The active antenna element 707A is, for example, placed substantially at the center of the pentagon formed by the parasitic antenna elements 707P.

[0087] One advantage of antenna 700 over antenna 100 is that antenna 700 has a number of parasitic elements 707P strictly greater than the number of parasitic elements 107P of antenna 100. This allows antenna 700 to emit a wave with a purer circular polarization than the circularly polarized wave emitted by antenna 100.

[0088] One advantage of the 100, 600, and 700 antennas described above is that these antennas operate in dual-band mode and each has only one antenna array. This allows them to be less complex, smaller, and less expensive than existing fully fed antennas and dual-band parasitic element antennas.

[0089] Various embodiments and variations have been described. Those skilled in the art will understand that certain features of these various embodiments and variations could be combined, and other variations will become apparent to those skilled in the art. In particular, those skilled in the art are able to adjust the number of parasitic elements of the antenna according to the intended application.

[0090] Furthermore, although the above description takes as an example cases in which each reconfigurable parasitic load 205-2, 205-3 comprises two loads The parasitic loads are not limited to this example. As an alternative, each reconfigurable parasitic load can include any number, strictly greater than two, of parasitic loads.

[0091] Finally, the practical implementation of the described embodiments and variants is within the grasp of a person skilled in the art, based on the functional specifications given above. In particular, a person skilled in the art is able to define the impedance values ​​of the parasitic loads, especially their reactances, according to the intended application, based on the specifications above.

Claims

Demands

1. Dual-band radioelectric antenna (100; 600; 700) comprising a single antenna array (103) having: - a first active antenna element (107A; 607A; 707A), intended to be excited by a radio frequency signal and comprising an inverted F antenna; and - parasitic second antenna elements (107P; 607P; 707P) each comprising an inverted F antenna and having identical geometries with each other and different from that of the first antenna element, each second antenna element being connected: A) to a reconfigurable parasitic load (205-2, 205-3); or B) to a parasitic filtering and / or non-Foster load, wherein the first antenna element (107A; 607A) and the second antenna elements (107P; 607P) are formed on a tubular support substrate (105).

2. Antenna (100; 600) according to claim 1, wherein the support substrate (105) is a flexible substrate intended to be wound upon itself to present said tubular shape.

3. Antenna (100) according to claim 1 or 2, wherein the first antenna element (107A) and the second antenna elements (107P) are disjoint and distributed around the perimeter of the same circle.

4. Antenna (100; 600) according to any one of claims 1 to 3, further comprising a support and interconnection substrate (101), the support substrate (105) having an axis of revolution substantially orthogonal to a face of the support and interconnection substrate.

5. Antenna (100; 600) according to claim 4, wherein the reconfigurable parasitic load (205-2, 205-3) or the filtering and / or non-Foster parasitic load connected to each second antenna element (107P; 607P) is located on the upper face of the support and interconnect substrate (101).

6. Antenna (100; 600) according to any one of claims 1 to 5, comprising exactly two second antenna elements (107P; 607P).

7. Antenna (100; 600; 700) according to any one of claims 1 to 6, in its option A), wherein each reconfigurable parasitic load (205-2, 205-3) comprises: - a first parasitic charge exhibiting a first reactance (X2, X3); - at least one second parasitic charge exhibiting a second reactance (X'2, X'3); and - a switch (203) configured to select the first parasitic load or one of the second parasitic loads.

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