Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01Q—ANTENNAS, i.e. RADIO AERIALS
  • H01Q21/00—Antenna arrays or systems
  • H01Q21/24—Combinations of antenna units polarised in different directions for transmitting or receiving circularly and elliptically polarised waves or waves linearly polarised in any direction
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01Q—ANTENNAS, i.e. RADIO AERIALS
  • H01Q1/00—Details of, or arrangements associated with, antennas
  • H01Q1/12—Supports; Mounting means
  • H01Q1/22—Supports; Mounting means by structural association with other equipment or articles
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01Q—ANTENNAS, i.e. RADIO AERIALS
  • H01Q1/00—Details of, or arrangements associated with, antennas
  • H01Q1/12—Supports; Mounting means
  • H01Q1/22—Supports; Mounting means by structural association with other equipment or articles
  • H01Q1/2208—Supports; Mounting means by structural association with other equipment or articles associated with components used in interrogation type services, i.e. in systems for information exchange between an interrogator/reader and a tag/transponder, e.g. in Radio Frequency Identification [RFID] systems
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01Q—ANTENNAS, i.e. RADIO AERIALS
  • H01Q9/00—Electrically-short antennas having dimensions not more than twice the operating wavelength and consisting of conductive active radiating elements
  • H01Q9/04—Resonant antennas
  • H01Q9/0407—Substantially flat resonant element parallel to ground plane, e.g. patch antenna
  • H01Q9/0421—Substantially flat resonant element parallel to ground plane, e.g. patch antenna with a shorting wall or a shorting pin at one end of the element
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01Q—ANTENNAS, i.e. RADIO AERIALS
  • H01Q9/00—Electrically-short antennas having dimensions not more than twice the operating wavelength and consisting of conductive active radiating elements
  • H01Q9/04—Resonant antennas
  • H01Q9/30—Resonant antennas with feed to end of elongated active element, e.g. unipole
  • H01Q9/42—Resonant antennas with feed to end of elongated active element, e.g. unipole with folded element, the folded parts being spaced apart a small fraction of the operating wavelength

Definitions

• the invention relates to an isotropic antenna capable of transmitting or receiving an electromagnetic field over a wide frequency spectrum.
• the invention also relates to a physical magnitude measuring sensor which comprises an antenna according to the invention.
• the invention applies to communicating objects whose size is small compared to the wavelengths used for communication.
• the objects concerned by the invention are terminals having dimensions of the order of a few centimeters operating in the ISM (Industrial Scientific Medical), UHF (UHF for Ultra High Frequency), VHF ( VHF for "Very High Frequency”), SHF (SHF for "Super High Frequency”), EHF (EHF for "Extremly High Frequency”).
• the antennas that equip such terminals have reduced dimensions compared to operating wavelengths ⁇ (typically less than 0.5 ⁇ ). This specificity of the antennas defines a category of antennas commonly called "miniature antennas".
• the proposed antenna is an antenna that applies, among other things, to low-range, low-speed and low-power applications such as, for example: - wireless networks of scattered sensors: building monitoring, environmental monitoring, sensors used in industrial settings; - home automation: switches, remote controls, etc. ;
• the applications mainly concerned by the invention are applications for which the orientation of one or more devices intended to communicate together is random and changing.
• the quality of the radio link must however remain constant regardless of the orientation.
• an antenna whose radiation characteristics are substantially isotropic is therefore ideally sought.
• the purpose of the proposed invention is to answer this problem.
• the antennas used to date in the applications mentioned above are omnidirectional type but it is noted, however, that they always have directions in which the radiation is zero. Transmission is impossible in these directions.
• a second aspect affecting the quality of the transmission is the polarization mismatch of the waves transmitted or received by the antenna. When the polarization of the waves is linear, tilting the antennas relative to each other can lead to orthogonal polarization directions. In such a case, the transmitted power becomes zero.
• FIG. 1 represents a first example of miniature antenna structure of the known art.
• Two dipoles D1, D2 of half-wave length are arranged orthogonally.
• the supply signals V1 and V2 respective dipoles D1 and D2 are applied at the intersection of the two dipoles.
• the power supplies are in quadrature phase:
• V2 Vl e D ⁇ / 2
• the radiation of a dipole is generated by a current distribution which is established along the dipole, in a half-wave resonance mode.
• the produced radiation is then maximum in the direction orthogonal to the dipole and it is zero in the direction of the dipole. Due to the cross arrangement of the two dipoles and their phase quadrature power supply, the direction of the maximum radiation of one corresponds to the zero radiation direction of the other.
• the set of two dipoles radiates in all directions. The radiation is thus almost isotropic in power.
• the characteristics of the emitted radiation are as follows: the difference between the minimum and the maximum power emitted is typically 4.7 dB (which is considered a "good" isotropy in power;
• the polarization of the transmitted waves is circular in the direction perpendicular to the plane of the dipoles and rectilinear in the plane of the dipoles; the typical bandwidth of the transmitted waves is substantially equal to 10% of the central frequency.
• FIGS. 2A and 2B show a second example of miniature antenna structure of the known art.
• the antenna shown in FIGS. 2A and 2B is an inverted F antenna commonly called IFA antenna (IFA for "Inverted F - Antenna").
• An IFA antenna consists of an electrically conductive plane 1 (ground plane), a wired or planar metal part 2, commonly called “roof" of the antenna, arranged most often parallel to the ground plane (but can also not being parallel to the ground plane), an electrically conductive connection 3 placed at a first end of the roof, in a first plane perpendicular to the ground plane and which bypasses the roof and the ground plane, and an excitation means 4, for example a wire probe, placed in a second plane perpendicular to the ground plane and which is connected to an RF radiofrequency source which creates a potential difference between the roof and the ground plane.
• the second end of the roof 2 is in open circuit.
• the ground plane 1 preferably has dimensions larger than the roof so that, from a geometric point of view, the projection of the roof on the ground plane lies entirely within the ground plane.
• the roof 2, the short-circuit 3 and the excitation means 4 draw, seen in profile, an inverted F which is at the origin of the name of the antenna (see Figure 2A).
• the length 12 of the roof 2 is substantially equal to ⁇ g / 4, where ⁇ g is the guided wavelength of the antenna.
• the distance h separating the roof 2 from the ground plane 1 is on average equal to a small fraction of the wavelength ⁇ g, for example ⁇ g / 20, and the distance d which separates the plane in which the ground is placed.
• circuit of the plane in which is placed the excitation means is chosen to match the impedance of the antenna to the RF source.
• a quarter-wave resonance mode is established between the roof 2 and the ground plane. Such an antenna is not isotropic.
• the difference between the minimum and the maximum power emitted by the antenna varies from 9.5 dB to 28 dB.
• the value of 9.5 dB is obtained for a small mass plane
• the polarization As far as the polarization is concerned, it is close to a linear state on the whole radiation pattern, except for two reduced aperture lobes for which the polarization is quasi-circular. The uniformity in circular polarization is therefore quite bad.
• the bandwidth is typically equal to 1.25% of the center frequency.
• Miniature antennas of the known art have many disadvantages.
• the miniature antenna of the invention does not have these disadvantages.
• the invention relates to an antenna which comprises four elementary IFA antennas, each elementary IFA antenna comprising a ground plane, a roof, a short circuit between the ground plane and the roof and a means of excitation, the four antennas IFA elementary elements being distributed around an axis in a first set of two IFA antennas having essentially equivalent far-field elementary radiations and a second set of two IFA antennas having substantially equivalent far-field elementary radiations, the two IFA antennas of the first set being aligned along a first alignment axis substantially perpendicular to the axis and the two IFA antennas of the second set being aligned along a second alignment axis substantially perpendicular to the axis, the first alignment axis and the second axis of alignment.
• the excitation means of the four elementary IFA antennas being fed by radio frequency signals of the same amplitude, the phases of which follow a progressive law substantially in quadrature by rotation around the axis (0 °, 90 °, 180 °, 270 °).
• the two elementary IFA antennas of the same set of two antennas are identical and symmetrical with respect to the axis.
• the four elementary IFA antennas are all identical.
• the roofs of the four elementary IFA antennas are distributed on a flat surface substantially perpendicular to the axis. According to yet another additional feature of the invention, the roofs of the four elementary IFA antennas are substantially inscribed in a circle. According to yet another additional characteristic of the invention, the roofs of the four elementary IFA antennas are substantially inscribed in an ellipse.
• the roofs of the four elementary IFA antennas are distributed over a substantially conical closed surface.
• the roofs of the four elementary IFA antennas are distributed on a cylindrical surface whose generator is parallel to the axis.
• the cylindrical surface is a cylindrical surface whose directrix curve draws a circle, or a square, or a rectangle.
• the roofs of the four elementary IFA antennas are formed by metallizations carried out on the same substrate.
• the ground planes of the four elementary IFA antennas are formed by the same conductive layer.
• the antenna comprises means for switching the progressive law in quadrature between a first direction of rotation about the axis and a second direction of rotation about the axis, opposite the first direction of rotation. meaning .
• the invention also relates to a physical quantity measuring sensor comprising means for measuring the physical quantity and a transmitter equipped with an antenna able to transmit the measurement of the physical quantity in the form of a modulation of an electromagnetic wave. emitted by the transmitter, characterized in that the antenna is an antenna according to the invention.
• An antenna according to the invention consists of a combination of four elementary IFA antennas.
• an antenna according to the invention comprises a single ground plane, four electrically conductive patterns placed above the ground plane and each forming an IFA antenna roof, four short-circuit connections and four excitation means. .
• the four elementary IFA antennas are grouped according to two sets of two antennas, the two IFA antennas of the same set being designed so that their elementary radiations in far field are equivalent.
• Two IFA antennas have equivalent far-field elemental radiations when, being placed independently in the same frame with the same orientation, they radiate in the band of useful frequencies, a wave of the same amplitude and of the same phase in each direction of space.
• a simple way to obtain two IFA antennas with equivalent elementary radiations consists in producing identical antennas, that is to say having the same geometry (same shape and same dimensions). It is this embodiment that will be mainly described in the following patent application, as a preferred embodiment of the invention. It is possible, however, to make two IFA antennas having different shapes or dimensions and still having equivalent elemental radiations. Examples of such antennas will be described later with reference to FIGS. 10A and 10B.
• the ground plane of an antenna of the invention consists of a conductive element whose surface may admit, if necessary, metallization spares and electronic components.
• the surface of the ground plane may be a circular, elliptical, square, rectangular planar surface, a conical surface, a cylindrical, cubic, or parallelepipedic, cylindrical surface, and so on.
• the surface that defines the ground plane has a symmetry with respect to an axis.
• the surface of the ground plane is of dimension greater than or equal to the surface in which the electrically conductive patterns forming roofs are integrated so that, from a geometrical point of view, the projection, on the ground plane, of the surface in which the motifs are integrated electrically conductive roofs lies entirely within the ground plane.
• the radiation of the antenna is all the more isotropic in power that the ground plane is small. This is why the ground plane will preferably be chosen of dimensions equal to the dimensions of the surface in which the electrically conductive patterns forming roofs are integrated. The ground plane will most often be larger when it has, for integration reasons, a circuit support function such as, for example, the RF circuit that supplies the elementary IFA antennas.
• the RF circuit that supplies the four power supply connections can indeed be made on the upper or lower side of the ground plane.
• the influence of its presence on the radiation of the antenna is negligible when properly designed.
• Different possibilities of realization of the supply circuit are possible in the form of a parallel network or series of microstrip line including or not localized elements (couplers, phase shifters, etc.).
• the patterns forming roofs may be son or flat elements whose contours can have very varied shapes: rectangular, trapezoidal, elliptical, arched or not, rounded at the ends or not, the general shape of a pattern and its dimensions strongly determining the radiation characteristics of the antenna, in particular its operating frequency.
• the patterns are arranged either parallel to the ground plane, or inclined at an angle to it (the angle of inclination of the patterns can be equal, for example, to 30 ° and can reach 45 ° or more).
• the patterns may be made on substrate by printed circuit techniques or by machining conductive parts, for example metal.
• the patterns are grouped into a first pair of identical patterns and a second pair of identical patterns.
• the patterns of a pair of identical patterns are aligned along an alignment axis perpendicular to the Oz axis of the antenna, the two alignment axes of the two pairs of patterns intersecting at right angles to the axis of the antenna. 'antenna.
• the two conductive connections forming a short circuit between the ground plane and the ends of the conductive patterns of a pair of conductive patterns are arranged symmetrically with respect to the axis Oz. It is the same of the two excitation means associated with the two conductive patterns of the same pair of conductive patterns.
• the four excitation means supply the four IFA antennas with signals of substantially equal amplitude, phase-shifted according to a progressive phase-quadrature law, so that, for antennas al-a4 which follow one another about the axis Oz (in clockwise or anti-clockwise), it comes:
• Two IFA antennas aligned along an axis perpendicular to the axis of the antenna are strongly coupled (typically -3 to -4 dB). Their power supplies are in phase opposition (180 °) but, because of their opposite orientations, their resonances are in phase.
• the coupling phenomenon is beneficial here because it advantageously allows a reduction in the length L of the roofs of the two IFA antennas which are facing each other compared to the case of a single isolated IFA having the same operating frequency.
• the dimension L can thus be less than ⁇ / 4.
• the set is smaller than the simple combination of dipoles cross, which is an advantage of the invention.
• the coupling between two elementary IFA antennas of the invention whose roofs are perpendicular to each other is important. (-2 to -3dB).
• the concentrated electric field between the ground plane and the roof of the antenna is oriented in the normal direction to the ground plane.
• two IFA antennas are arranged on the same ground plane, their field lines are oriented in the same direction perpendicular to the ground plane. There is then a strong coupling between them.
• This coupling is a function of the distance between the antennas and depends little on their orientations. For this reason, it is impossible to have two IFA antennas crosswise according to the principle of operation of the dipoles in cross. The strong coupling would not allow to feed the IFA antennas independently in quadrature phase.
• an isotropic antenna according to the invention advantageously has the following characteristics:
• Circular polarization in the normal direction to the plane of the antenna
• the bandwidth relative to -1OdB is between 1 and 20% depending, in particular, on the RF circuit used power supply and the characteristics of elementary IFA antennas.
• FIG. 1 already described represents a first example of a miniature antenna structure of the known art
• FIGS. 2A and 2B already described represent a second example of a miniature antenna structure of the known art
• FIG. 3 represents a view from above of a first antenna example according to the preferred embodiment of the invention.
• FIG. 4 represents a view of a second antenna example according to the preferred embodiment of the invention
• FIG. 5 represents a perspective view of a third antenna example according to the preferred embodiment of the invention
• FIG. 6 represents a perspective view of a fourth antenna example according to the preferred embodiment of the invention.
• FIG. 7 represents a perspective view of a fifth antenna example according to the preferred embodiment of the invention
• FIGS. 8A and 8B show, respectively, a perspective view and a top view of a sixth antenna example according to the preferred embodiment of the invention
• - Figures 9A and 9B show, respectively, a perspective view and a top view of a seventh antenna example according to the preferred embodiment of the invention
• FIGS. 10A and 10B respectively show a perspective view and a top view of examples of miniature antennas according to a different embodiment of the preferred embodiment of the invention.
• Figures HA and HB show comparative curves antenna covers of the prior art and an antenna according to the invention
• FIG. 12 represents a comparative histogram of the coverage gain at 90% in rectilinear polarization of antennas of the prior art and of an antenna of the invention
• FIG. 13 shows a side view of an embodiment of the sensor according to the invention.
• FIG. 14 represents an application of the sensor of the invention to motion capture.
• FIGS 3-9B illustrate different examples of antennas according to the preferred embodiment of the invention.
• the roof patterns of the IFA antennas are identical in pairs, two identical patterns being aligned along an alignment axis perpendicular to the axis of the antenna.
• FIG. 3 represents a first example of an antenna according to the preferred embodiment of the invention.
• the four conductive patterns 2 forming roofs IFA antennas are all identical (for example, in the form of rectangle) and inscribed in a circle C.
• the conductive connections that connect the conductive patterns forming roofs to the ground plane are placed at the outer ends of the grounds (ie substantially on the periphery of the circle C), in planes perpendicular to the plane of the figure.
• the roof patterns may be discrete metallic elements or conductive elements made on the same substrate.
• FIG. 4 represents a view from above of a second antenna example according to the preferred embodiment of the invention.
• the four rectangular-shaped conductor patterns 2 are distributed over an ellipse E.
• the conductive patterns 2 may be discrete elements or elements made on the same substrate.
• FIG. 5 represents a perspective view of a third antenna example according to the preferred embodiment of the invention.
• the conductive patterns forming roofs 2 are in the form of parallelepipeds. Patterns 2 are here formed on a same substrate S. They could also be discrete elements.
• FIG. 6 represents a perspective view of a fourth antenna example according to the preferred embodiment of the invention.
• the ground plane 1 has a conical surface and the conductive patterns 2 are arranged on a substrate which also has a conical shape.
• the axis of symmetry Oz is here the axis of the cones.
• FIG. 7 represents a perspective view of a fifth antenna example according to the preferred embodiment of the invention.
• the roof patterns of IFA antennas are distributed on a cylindrical surface whose generator is parallel to the axis of symmetry of the antenna and whose directing curve draws a square.
• FIGS. 8A and 8B show two views of a sixth antenna example according to the preferred embodiment of the invention.
• the roof patterns of the IFA antennas are located in the same plane perpendicular to the axis of the antenna and are bent to be inscribed in a square surface.
• FIGS. 9A and 9B show two views of a seventh antenna example according to the preferred embodiment of the invention.
• the roof patterns of the IFA antennas are located in the same plane perpendicular to the axis of the antenna and are folded to be inscribed in a circular surface.
• the patterns 2 are folded, for example, in the form of spirals.
• the patterns 2 are distributed on a substrate Circular S placed next to a circular mass plane.
• the circles defined by the ground plane and the substrate S are parallel and their centers are aligned along the axis Oz.
• FIGS. 10A and 10B represent, respectively, a perspective view and a top view of examples of miniature antennas according to a different embodiment of the preferred embodiment of the invention.
• the two IFA antennas of a set of two aligned antennas have substantially equivalent far-field radiations but their geometries are not identical.
• FIG. 10A represents an example where two aligned elementary IFA antennas have roofs of different lengths Ia, Ib and different heights h, hb with respect to the ground plane.
• FIG. 10B shows another example where each pair of two aligned elementary IFA antennas comprises an antenna whose roof is of rectangular shape (2a, 2c) and another antenna whose roof is of elliptical shape (2b, 2d).
• the roof patterns are made by photolithography.
• the ground connections 3 are located at the outer ends of the patterns 2.
• the connections 3 are copper wires 0.6 mm in diameter, one end of which is welded to the pattern 2 and the other end to the ground plane.
• the supply wires 4 are also 0.6mm diameter copper wires. The ends of the ground wires 3 and the supply wires 4 which are located on the side of the substrate S are distributed on a circle X.
• the distance which separates, on the same pattern 2, the end of the ground wire 3 of the end of the feed wire 4 is substantially equal to 3.6mm.
• the distance separating the ground plane 1 from the substrate S is substantially equal to 4 mm.
• the diameter of the substrate S is substantially equal to 25 mm and the diameter of the ground plane is greater than the diameter of the substrate S, for example equal to 30 mm.
• other values of the diameter of the ground plane can be envisaged if the condition is respected by a diameter greater than or equal to the diameter of the substrate S.
• the antenna described above has an operating frequency substantially equal to 2.5GHz.
• the bandwidth and the exact frequency of impedance matching also depend on the power supply network used.
• the difference between the minimum and the maximum of the power emitted by the antenna is typically 5.6 dB, which corresponds to a good isotropy in power.
• the polarization of transmitted waves is circular along the axis Oz and rectilinear in the plane of the patterns 2.
• the average axial ratio diagram is substantially 49%.
• the table below shows the typical performances of the difference between maximum and minimum of the directivity and mean diagram on the axial ratio diagram for the antenna of the invention and two antennas of the prior art. That is, the combination of cross dipoles and the IFA antenna alone.
• the difference between the maximum and the minimum of the directivity diagram makes it possible to quantify the isotropy in power.
• the average of the axial ratio diagram makes it possible to quantify the uniformity of the polarization with respect to the circular state. An average of 100% means that the antenna radiates with a perfectly circular polarization in all directions.
• This criterion makes it possible to compare antennas with each other. This criterion is the coverage of antennas.
• the coverage of an antenna is the proportion of orientation / inclination covered by the antenna as a function of the minimum power it receives when it is illuminated by an incident plane wave of unit power density.
• FIG. 12 represents a comparative histogram of the 90% coverage gain, in rectilinear polarization, for the three antennas considered: the gain G 1 corresponds to the half-wave dipoles, the gain G 2 corresponds to a single IFA antenna and the gain G3 corresponds to an antenna according to the invention.
• Curves C1, C2, C3 of Figures HA and HB are the typical typical coverage curves of an antenna according to the invention (typical size ⁇ / 5), an IFA antenna alone and a combination of cross dipoles. (typical size ⁇ / 2).
• FIG. 13 represents a profile view of an embodiment of a sensor provided with an antenna according to the invention.
• the antenna is, for example, an antenna as described in FIGS. 9A-9B.
• the sensor comprises a multilayer printed circuit board CI consisting of an insulating layer 5 on which are deposited, on one side, a conductive layer 6 which constitutes the ground plane and, on the other side, a substrate 7 on which are integrated different circuits xl, x2, x3 such as integrated circuits, battery, sensor, RF power supply network, etc.
• the dimensions of the sensor are small, so that the antenna is the largest component.
• the diameter D of the sensor is thus typically equal to ⁇ / 5 or ⁇ / 4. This dimension is to be compared to the diameter ⁇ / 2 half-wave dipoles cross.
• the realization of the sensor in printed circuit technology advantageously allows mass production at low costs.
• the combination of electronic circuits and the antenna advantageously allows the realization of an autonomous sensor. Components and devices placed under the ground plane disturb the radiation very little.
• An example of use of the isotropic antenna of the invention will now be described, in the context of a TDMA network (TDMA for Time Division Multiple Access), with reference in Figure 14.
• the TDMA network is a star network for motion capture that includes a master node NM and a set of slave nodes N1-N14 that are moving relative to the master node. Each slave node of the network is placed a sensor which comprises an antenna according to the invention.
• the slave nodes are distributed as follows:
• the node N1 is a point of a tennis racket
• the node N2 is a point of a tennis ball
• N3-N14 nodes are points of the body of a tennis player.
• This star network orchestrated by the master node, makes it possible to recover, at determined time intervals, the data delivered by the various sensors whose positions vary over time.
• Each sensor located at a slave node is optimized in terms of size, integration and power consumption. It consists of a physical measurement sensor and its conditioning, a processing unit and a radio transmitter / receiver connected to an isotropic antenna according to the invention. Autonomous, it has an on-board power source.
• the sensor located at the master node is less subject to constraints of size and consumption but also has a radio transmitter / receiver and a processing unit.
• the antenna that equips the sensor located at the master node may be an isotropic antenna according to the invention or a dipole antenna. All the advantage of the antenna according to the invention in this context lies in its radiation pattern which covers the entire space, in its circular polarization state which optimizes the radio transmission whatever the inclination of the sensors and in its low volume requirement.
• the antenna according to the invention which equips each sensor located at a slave node has an isotropic radiation power in all directions and an optimized circular polarization so that there is no direction for which the transmission between a slave node and the master node would be interrupted.
• the antenna according to the invention equipping the slave nodes is circularly polarized, and the antenna equipping the master node is polarized rectilinearly. Thus, the transmission can not be interrupted due to polarization mismatch.
• the antenna according to the invention increases very little the overall dimensions of the sensors because its planar form factor with a ground plane on one of these faces allows easy integration on the sensor.
• the antenna can be made with the same printed technology as the rest of the sensor circuit.
• the functions of the sensor and the battery integrate multilayer under the ground plane of the antenna as previously mentioned.
• the master node transmits a time synchronization word and information addressed to the slave nodes, as well as a cyclic redundancy code also known as CRC code (CRC for "Cyclic Redundancy Code”). ").
• CRC code Cyclic Redundancy Code
• the sensors of the invention advantageously make it possible to ensure a robust radio frequency communication link to the variations of positions. Fewer errors are detected and the use of the information retrieval procedure is much less necessary, helping to optimize real-time throughput and limit sensor consumption.
• Different variants of antennas can be made in the context of the invention, namely, for example, reconfigurable antennas, diversity antennas or antennas with limited coverage at half-spaces.
• Reconfigurable antennas include means for switching phase states. A first phase state can then correspond to a 0 ° -> 90 ° -> 180 ° -> 270 ° phase progression between the different elementary antennas, whereas a second phase state corresponds to a 0 ° phase progression.
• the diversity antennas are made, when the coupling level between elementary IFA antennas allows it, by feeding them by two channels or by four independent channels.

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• 2006
  • 2006-07-21 FR FR0653071A patent/FR2904148B1/fr not_active Expired - Fee Related
• 2007
  • 2007-07-17 WO PCT/EP2007/057351 patent/WO2008009667A1/fr active Application Filing
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