WO2015004186A1 - Antenne orientable et son procédé de commande - Google Patents

Antenne orientable et son procédé de commande Download PDF

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Publication number
WO2015004186A1
WO2015004186A1 PCT/EP2014/064718 EP2014064718W WO2015004186A1 WO 2015004186 A1 WO2015004186 A1 WO 2015004186A1 EP 2014064718 W EP2014064718 W EP 2014064718W WO 2015004186 A1 WO2015004186 A1 WO 2015004186A1
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WO
WIPO (PCT)
Prior art keywords
antenna
steerable
group
antenna elements
elements
Prior art date
Application number
PCT/EP2014/064718
Other languages
English (en)
Inventor
Farshad KESHMIRI
Christophe CRAEYE
Shambhu Nath JHA
Maxime DROUGUET
Original Assignee
Universite Catholique De Louvain
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
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Application filed by Universite Catholique De Louvain filed Critical Universite Catholique De Louvain
Publication of WO2015004186A1 publication Critical patent/WO2015004186A1/fr

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q19/00—Combinations of primary active antenna elements and units with secondary devices, e.g. with quasi-optical devices, for giving the antenna a desired directional characteristic
    • H01Q19/28—Combinations of primary active antenna elements and units with secondary devices, e.g. with quasi-optical devices, for giving the antenna a desired directional characteristic using a secondary device in the form of two or more substantially straight conductive elements
    • H01Q19/32—Combinations of primary active antenna elements and units with secondary devices, e.g. with quasi-optical devices, for giving the antenna a desired directional characteristic using a secondary device in the form of two or more substantially straight conductive elements the primary active element being end-fed and elongated
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q3/00—Arrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system
    • H01Q3/24—Arrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system varying the orientation by switching energy from one active radiating element to another, e.g. for beam switching
    • H01Q3/242—Circumferential scanning

Definitions

  • the invention relates to a steerable antenna. According to a second aspect, the invention relates to a method for controlling a steerable antenna.
  • Directivity measures the power density that an antenna radiates in the direction of its strongest emission, normalized with respect to the power density radiated by an ideal isotropic radiator that emits uniformly in all directions and that radiates the same total power. Directivity is generally expressed in decibels over isotropic, dBi.
  • Phased array antennas are directive and comprise an array with several antenna elements. Phased array antennas allow producing a non- isotropic radiation pattern that can be scanned in different directions. Phased array antennas use antenna elements that are all active all the time. Phased array antennas thus require providing sophisticated controlled feeds to the various antenna elements. Therefore, phased array antennas have a complex configuration and are costly to manufacture. Moreover, they are heavy and bulky. These drawbacks are even more apparent when the number of active antenna elements is large.
  • ESPAR Electroically Steerable Passive Array Radiator
  • antennas comprise one active antenna element and several passive (or parasitic) antenna elements located on a circumference of a circle around the active antenna element.
  • passive antenna elements located on a circumference of a circle around the active antenna element.
  • a controller changes the directivity of the antenna by changing the reactive loading (inductor or capacitor) terminating each passive antenna element.
  • the voltage applied to each voltage-tunable capacitor connected to the passive antenna elements is varied.
  • ESPAR antennas do require a less complex feeding network and are cheaper than phased array antennas.
  • the directivity of the ESPAR antennas is limited. There is therefore a need to provide a steerable antenna that presents a higher directivity than an ESPAR antenna.
  • the invention relates to a steerable antenna comprising:
  • N antenna elements N >1 , said N antenna elements being arranged along a closed outer contour line and surrounding the M antenna elements of the first antenna group.
  • said steerable antenna comprises switching means coupled to the N antenna elements of the second antenna group; in that
  • said steerable antenna comprises a controller programmed for controlling said switching means for switching to be active at different times one different antenna subgroup comprising Na antenna elements of the second antenna group, 1 ⁇ Na ⁇ N-1 , while switching to be passive at same different times N- Na other antenna elements of the second antenna group; in that
  • said steerable antenna further comprises L inner termination groups, 1 ⁇ L ⁇ M, each of them comprising a plurality of (at least two) different termination loads; in that
  • said switching means comprise L inner termination switches, each of them being connected in between one antenna element of said first antenna group and the different termination loads of one different of said L inner termination groups;
  • said controller is also programmed for controlling said L inner termination switches for connecting and disconnecting each of L antenna elements of first antenna group to and from the termination loads of one different inner termination group.
  • the controller for controlling the switching means is programmed such that, in use, at least one antenna element of the second antenna group is switched to be active at different times while the other antenna element(s) of the second antenna group is (are) switched to be passive at same different times.
  • the controller is also programmed for connecting and disconnecting at different times said N-Na other passive antenna elements of second antenna group to and from different termination loads.
  • Na antenna elements of the second antenna group are active at each time t when the steerable antenna of the invention is in operation.
  • the other N-Na antenna elements of the second antenna group are passive (hence in a parasitic state) when the Na antenna elements of the second antenna group are active.
  • the second antenna group only comprises passive antenna elements.
  • the M antenna elements of the first antenna group collectively play the role of an intelligent reflector that leads to an increase in directivity of the steerable antenna. In other words, the M antenna elements of the first antenna group provide a collective scattering effect.
  • the antenna of the invention also comprises L inner termination groups, 1 ⁇ L ⁇ M, each of them comprising a plurality of termination loads, L inner termination switches connected as explained above, and the controller for controlling said inner termination switches as exposed above.
  • L inner termination groups 1 ⁇ L ⁇ M, each of them comprising a plurality of termination loads, L inner termination switches connected as explained above, and the controller for controlling said inner termination switches as exposed above.
  • This allows modulating or adapting the termination loads of the antenna elements of first antenna group for further increasing the directivity of the steerable antenna.
  • the termination loads of L antenna elements of first antenna group are modulated depending on the direction of main radiation lobe (desired direction of maximum radiation).
  • the steerable antenna of the invention allows obtaining a higher directivity with respect to the one of an ESPAR antenna.
  • the steerable antenna of the invention has other advantages. It is easy to fabricate and easy to implement, in particular in comparison with a phased array antenna.
  • the steerable antenna of the invention is well suited for mass production and is lighter than a phased array antenna. It is also robust and has a long life cycle. Faulty components can be replaced and repairing the steerable antenna of the invention is simple.
  • the steerable antenna of the invention is well suited in different applications of radio communications and wireless localization.
  • the steerable antenna of the invention is a good trade-off between a phased array antenna that presents a high directivity and an ESPAR antenna that does not require sophisticated fabrication, implementation steps and that is relatively cheap.
  • the antenna of the invention By choosing passive antenna elements for the first antenna group, one does indeed obtain a steerable antenna that is less sophisticated than a phased array antenna and almost as cheap as an ESPAR antenna, while maintaining a high directivity and a possibility to steer the beam in an azimuthal plane.
  • no individual reflector element is necessary, but one could add such a reflector element.
  • the antenna of the invention one does not need to use a large number of antenna elements for having good properties, in particular for having good directivity. In particular, one does not need to have a large number (larger than fifty for instance) of antenna elements for first antenna group.
  • the antenna of the invention preferably relies on the use of only two antenna groups, even if one could use more antenna groups.
  • the different antenna elements are located in a same plane, most of the corresponding planar surface is not covered by an antenna element.
  • the M antenna elements of first antenna group do not constitute of 'forest' of parasitic elements. Thanks to the modulation of termination loads of L antenna elements of first antenna group notably, high directivity can be obtained with few antenna elements. Hence, the antenna of the invention is not expensive and it can be small.
  • the azimuthal plane is perpendicular to these electrical monopoles.
  • the antenna elements of the first antenna group are protruding from a same plane.
  • the antenna elements of the second antenna group are located in a same plane.
  • the antenna elements of the first and the second antenna groups are located in a same plane.
  • the steerable antenna of the invention provides maximum radiation at an elevation angle that is comprised between 10° and 40°, and more preferably close to 30°, with respect to a plane comprising the different antenna elements.
  • the steerable antenna comprises a structure comprising a dielectric material and the antenna elements of first and second antenna groups are mechanically coupled to said dielectric material.
  • said structure comprising a dielectric material is substantially planar.
  • at least one antenna element of the first antenna group is passive.
  • said controller is programmed and said termination loads of the L inner termination groups are chosen for imposing a symmetry in termination load of different antenna elements of first antenna group with respect to a main radiation lobe of said steerable antenna.
  • said steerable antenna further comprises K outer termination groups, 1 ⁇ K ⁇ N, each of them comprising a plurality of different termination loads;
  • said switching means comprise K outer termination switches each of them being connected in between one antenna element of said second antenna group and the different termination loads of one different outer termination group;
  • said controller is programmed for controlling the K outer termination switches for connecting and disconnecting each of K antenna elements of the second antenna group to and from the termination loads of one different outer termination group.
  • said controller is programmed and said termination loads of the K outer termination groups are chosen for imposing symmetry in termination load of different antenna elements of second antenna group with respect to a main radiation lobe of said steerable antenna.
  • said M antenna elements of said first antenna group are all passive permanently. Any diffractive element known by the one skilled in the art can be used for obtaining a permanent passive antenna element.
  • the cost of fabrication of the antenna is particularly low as first antenna group only comprises permanent passive antenna elements, while maintaining high directivity.
  • said switching means are connected to antenna elements through transmission lines of different lengths so as to improve directivity properties of said steerable antenna.
  • L M
  • the different termination loads of the L inner termination groups can comprise non-zero real parts (up to the order of 20 Ohms for instance).
  • e r is a relative permittivity of a structure of dielectric material including the antenna elements.
  • This preferred embodiment represents a good trade-off between directivity and size of the antenna.
  • e r 1.
  • element of second antenna group is equal to—— .
  • the steerable antenna comprises a total number of antenna elements comprised between 10 and 32.
  • the cost and size and the antenna can be further reduced.
  • This preferred embodiment represents also a good trade-off between good radiation properties and cost/size.
  • the antenna of the invention comprises a total number of antenna elements comprised between 12 and 24 (and still more preferably between 16 and 20).
  • M N
  • This preferred embodiment allows reducing modifications of the radiation diagram when it rotates. In other words, the global shape of the radiation pattern then does not change significantly when direction of maximum of radiation rotates. It is even possible, with this preferred embodiment, to cancel any modification of the radiation pattern as it rotates.
  • said closed outer contour line is a circle.
  • said M antenna elements of first antenna group are arranged along a closed inner contour line.
  • this closed inner contour line is a circle. Then, it is possible to further decrease any modification of the radiation diagram as it rotates, thanks to the circular symmetry.
  • said closed inner contour line and said closed outer contour line are concentric circles. Then, it is possible to further decrease any modification of the radiation diagram as it rotates, thanks to the circular symmetry.
  • the steerable antenna only comprises antenna elements along said inner and outer contour lines.
  • said first antenna group comprises between three and twelve antenna elements, 3 ⁇ M ⁇ 12.
  • said first antenna group comprises between three and twelve antenna elements, 3 ⁇ M ⁇ 12.
  • the first antenna group could comprise four, five, six, seven, eight, nine, ten, or more antenna elements.
  • said second antenna group comprises between three and twelve antenna elements, 3 ⁇ N ⁇ 12.
  • the second antenna group could comprise four, five, six, seven, eight, nine, ten, or more antenna elements.
  • said switching means are electrically connected to the six antenna elements of the second antenna group for sequentially switching to be active at different times one different antenna subgroup comprising three antenna elements of the second antenna group while switching to be passive at same different times the other three antenna elements of said second antenna group.
  • This preferred embodiment is a good trade-off between good properties of the antenna (in particular, its directivity and the possibility of having a radiation pattern that undergoes few changes when it rotates) and its cost of fabrication.
  • At least one antenna element of the steerable antenna is an electrical monopole. More preferably, all the antenna elements of the steerable antenna are electrical monopoles. Cost of the antenna can be further reduced with this preferred embodiment as it is easy and cheap to design and fabricate an electrical monopole. A compact antenna can also be obtained with this preferred embodiment as an electrical monopole can be made small.
  • the steerable antenna comprises an additional passively terminated antenna elements that is located near (ie preferably within about 0.2 working wavelength) the center of inner and outer contour lines. This allows further increasing the directivity of the steerable antenna.
  • the invention relates to a method for controlling a steerable antenna comprising:
  • N antenna elements N>1 , said N antenna elements being disposed along a closed outer contour line and surrounding the M antenna elements of said first antenna group;
  • Said method comprises the step of sequentially switching to be active and at different times Na antenna elements of the second antenna group, 1 ⁇ Na ⁇ N- 1 , while switching to be passive and at same different times N-Na other antenna elements of the second antenna group.
  • the method of the invention further comprises the step of connecting L antenna elements of first antenna group, 1 ⁇ L ⁇ M, to different termination loads of L inner termination groups as main radiation lobe of said steerable antenna rotates.
  • the method of the invention further comprises the step of connecting K antenna elements of first antenna group, 1 ⁇ K ⁇ N, to different termination loads of K inner termination switches as main radiation lobe of said steerable antenna rotates.
  • Fig.1 shows a top view of a preferred embodiment of a steerable antenna according to the invention at a time t1
  • Fig.2 shows a top view of same preferred embodiment of a steerable antenna according to the invention at a time t2 > t1 ;
  • Fig.3 shows a top view of another preferred embodiment of a steerable antenna according to the invention.
  • Fig.4 shows a top view of another preferred embodiment of a steerable antenna according to the invention at a time t1 ;
  • Fig.5 shows same preferred embodiment of a steerable antenna according to the invention at a time t2 > t1 ;
  • Fig.6 shows a top view of another preferred embodiment of a steerable antenna according to the invention .
  • Fig.7 shows a top view of another preferred embodiment of a steerable antenna according to the invention at a time t1 ;
  • Fig.8 shows a top view of same preferred embodiment of a steerable antenna according to the invention at a time t2 > t1 ;
  • Fig.9 shows a comparison between simulated radiation patterns (radial scale in dB) obtained with an ESPAR antenna and with an antenna according to the invention
  • Fig.10 shows a comparison between simulated and measured radiation patterns (radial scale in dB) obtained with an antenna according to the invention
  • Fig.1 1 shows measured radiation patterns (radial scale in dB) obtained with an antenna according to the invention
  • Fig.12 shows a comparison between simulated radiation patterns (radial scale in dB) obtained with an ESPAR antenna and with an antenna according to the invention
  • Fig.13 shows a top view at a given time of a preferred embodiment of the steerable antenna
  • Fig.14 shows a calculated radiation pattern for the preferred embodiment of previous figure, at same given time
  • Fig.15 shows a top view at a given time of a preferred embodiment of the steerable antenna
  • Fig.16 shows a calculated radiation pattern for the preferred embodiment of previous figure, at same given time.
  • the drawings of the figures are neither drawn to scale nor proportioned. Generally, identical components are denoted by the same reference numerals in the figures.
  • Figures 1 and 2 show a top view of a preferred embodiment of a steerable antenna 1 according to the invention at two different times t1 and t2, with t2 > t1 .
  • the term 'steerable' is known by the one skilled in the art.
  • a steerable antenna is a directional antenna whose main radiation lobe can be readily shifted in direction.
  • the main radiation lobe of an antenna is the radiation lobe containing the maximum power in a polar radiation diagram.
  • a directional antenna or beam antenna is an antenna which radiates more power in one or more directions with respect to the others.
  • a directional antenna does not present isotropic properties and allows obtaining increased transmitting and receiving performances in some directions.
  • An example of directional antenna is a YAGI antenna.
  • the steerable antenna 1 of the invention comprises a first antenna group comprising M antenna elements 5, M > 1 .
  • the steerable antenna 1 of the invention also comprises a second antenna group comprising N antenna elements 5 with N > 1 .
  • the antenna elements 5 of the second antenna group are disposed or arranged along a closed outer contour line 21 and they surround the antenna elements 5p of the first antenna group.
  • the antenna elements 5 of the second antenna group are preferably substantially uniformly disposed along the closed outer contour line 21 .
  • the antenna elements 5 are preferably supported by (or mechanically coupled to) a structure of dielectric material that is not shown in figures 1 and 2. More preferably, such a structure of dielectric material is substantially planar. Then, this structure is preferably printed on a dielectric material.
  • An antenna element 5 is an element that can support electric currents (or equivalent electric / magnetic currents) which contribute to radiation.
  • an antenna element 5 can be an antenna array comprising several elements. Therefore, an antenna element 5 could be a small entity comprising different elements.
  • the antenna elements 5 are terminated by a given port, for instance by a generator (sometimes named transmitter), a receiver, an inductive load, or a capacitive load. Other termination ports are possible.
  • a generator sometimes named transmitter
  • a receiver sometimes named inductive load
  • capacitive load or a capacitive load.
  • Other termination ports are possible.
  • equivalent electric current and equivalent magnetic currents are known by the one skilled in the art.
  • the antenna elements 5 of the steerable antenna 1 can be made of different types of materials. Preferably, the antenna elements 5 are metallic. An antenna element 5 can have different electromagnetic functions. Examples of antenna elements 5 that can be used for the invention are: electrical monopole, electrical dipole, magnetic dipole. The antenna elements 5 of the steerable antenna 1 of the invention can be different or identical.
  • An antenna element 5 can be passive or active.
  • the term 'passive' is known by the one skilled in the art, and is also sometimes referred to as parasitic.
  • An example of antenna that uses passive antenna elements is the YAGI antenna.
  • a passive antenna element 5p is an antenna element 5 that is not connected to a receiver or a generator.
  • Receiver and generator are known by the one skilled in the art.
  • a receiver is an electronic device that receives or absorbs electromagnetic waves traveling along a line and that converts those waves in usable form, into a varying voltage for instance.
  • a generator is an electronic device that generates an alternating current for instance, said alternating current exciting the active antenna elements 5a that thereafter radiate electromagnetic waves.
  • Passive antenna elements 5p are preferably electrically connected to ground, or left open, or terminated into a capacitive or inductive load.
  • the load of passive antenna elements 5p preferably involves a small resistive part.
  • An active antenna element 5a is an antenna element 5 that is connected to a receiver or a generator, generally through a transmission line (or feed line).
  • An active antenna element 5a is capable of transmitting or receiving electromagnetic waves (or radio signals): they are therefore sometimes named as driven antenna elements.
  • passive antenna elements 5p The purpose of passive antenna elements 5p is generally to modify the radiation pattern of the electromagnetic waves emitted by the active antenna elements 5a, directing them in one direction, and increasing the directivity of an antenna.
  • a passive antenna element 5p does this by acting as a passive resonator, on which electric currents (or equivalent electric and magnetic currents) are excited in the presence of the active antenna elements 5a, with those excited currents re-radiating such fields with a different phase, as compared to the field generated by the active antenna elements 5a.
  • the waves from the different antenna elements 5 interfere, strengthening the radiation of the antenna in the desired direction, and cancelling out the waves in undesired directions. Any scattering element can be used as passive antenna element 5p.
  • the steerable antenna 1 of the invention comprises switching means 100 and a controller 1 10.
  • the switching means 100 are coupled to the N antenna elements 5 of the second antenna group (N > 1 ).
  • the switching means are electrically connected to the antenna elements 5 of the second antenna group.
  • they are connected to the antenna elements 5 of the second antenna group through transmission lines 70.
  • the controller 1 10 allows controlling the switching means 100 and is programmed such that, in use, Na antenna elements 5 are switched at different times to be active, while N-Na other antenna elements 5 of the second antenna group are switched to be passive at same different times.
  • Na can take any integer value between 1 and N-1 .
  • FIG. 1 and 2 In the preferred embodiment shown in figures 1 and 2,
  • the switching means 100 sequentially connect at different times at least one antenna element 5 of the second antenna group to a receiver or a generator 60 of microwave signals, while disconnecting at the same time the other antenna element(s) of the second antenna group from said receiver or a generator 60 of microwave signals.
  • the preferred steerable antenna 1 shown in figures 1 and 2 is a transmitting (or emitting) antenna comprising a generator 60.
  • a transmission line 70 drawn with solid line segments stands for an 'active' transmission line 70. This means that the antenna element 5 connected at one end of this transmission line 70 is active.
  • the switching means 100 connect such an 'active' transmission line 70 and the antenna element 5 connected at one end of this 'active' transmission line 70 to the generator 60.
  • a transmission line 70 drawn with dashed line segments stands for a 'passive' transmission line 70 which means that the antenna element 5 connected at one end of the transmission line 70 is passive.
  • the switching means 100 disconnect such a 'passive' transmission line 70 and the antenna element 5 connected at one end of this 'passive' transmission line 70 from the generator 60.
  • Na is equal to 2 for both t1 and t2. Nevertheless, Na could change between the different time intervals.
  • Na could be equal to one for a time t1 , to three for a time t2 > t1 , and to two for a time t3 > t2.
  • the lengths of transmission line can be adjusted in order to produce appropriate phase shifts between (equivalent) current on the different active antenna elements 5a and, in turn, to increase the directivity of the whole antenna.
  • switching means 100 can be used as it is known by the one skilled in the art. Examples of switching means are: integrated switches, diodes. Other types of switching means could be used.
  • the controller 1 10 is preferably a microcontroller.
  • the steerable antenna 1 further comprises L inner termination groups 215, 1 ⁇ L ⁇ M, each of them comprising a plurality of different termination loads 220 (not shown in figures 1 and 2).
  • the switching means 100 comprise L inner termination switches 205 (not shown in figures 1 and 2), each of them being connected in between one antenna element 5 of first antenna group and the different termination loads 220 of one different of said L inner termination groups 205.
  • the controller 1 10 is programmed for controlling the L inner termination switches 205 for connecting and disconnecting each of L antenna elements of first antenna group to and from the termination loads 220 of one different inner termination group 215.
  • two or three antenna elements 5 of the second antenna group are switched to be active at the same time: Na > 1 .
  • the term 'gain' is known by the one skilled in the art.
  • the gain, G is given by the following equation:
  • the controller 1 10 is programmed such that the switching means 100 sequentially switch all the antenna elements 5 of the second antenna group to be active at different times. If it is not wanted that the radiation pattern performs a 360° rotation, the controller 1 10 can indeed be programmed such that the switching means 100 switch only some of the antenna elements 5 of the second antenna group to be active during a period. A period is the duration between two different times at which a same antenna element 5 has been switched from a passive state to an active state. For instance, if a 270° rotation of the radiation pattern is wanted with the preferred embodiment shown in figures 1 and 2, only three antenna elements 5 of the second antenna group need to be switched sequentially to be active. Moreover, it is possible to have other antenna elements 5 disposed along the closed outer contour line 21 and that are not coupled to the switching means 100. The second antenna group only comprises N antenna elements 5 that are coupled to the switching means 100.
  • FIG 3 shows a top view of another preferred embodiment of the steerable antenna 1 according to the invention.
  • the antenna elements 5 of first (respectively second) antenna group are arranged along a closed inner (respectively outer) contour line 1 1 (respectively 21 ).
  • the switching means 100 and the controller 1 10 are not depicted for clarity reasons.
  • Figures 4 and 5 show two top views of another preferred embodiment of the steerable antenna 1 of the invention at two different times, t1 and t2, when the steerable antenna 1 is in operation (t2 > t1 ).
  • the switching means 100 and the controller 1 10 are not depicted in these two figures.
  • the antenna elements 5 of first (respectively second) antenna group are arranged along a closed inner (respectively outer) contour line 1 1 (respectively 21 ).
  • all the antenna elements 5 of the first antenna group are always passive (or passive permanently).
  • antenna elements are therefore denoted by 5p in figures 4 and 5.
  • the switching means 100 have switched three antenna elements of the second antenna group and denoted by 5a in figure 4 to be active.
  • the steerable antenna 1 therefore presents by symmetry a main transmitting or receiving direction parallel to the horizontal black arrow shown at figure 4.
  • the switching means 100 have switched three antenna elements denoted by 5a in figure 5 to be active, while switching the other antenna elements 5p of figure 5 to be passive.
  • the main transmitting or receiving direction (represented by a black arrow) of the steerable antenna 1 has rotated between t1 and t2 as the set of active antenna elements 5a has changed between t1 and t2. In the example shown in these two figures, this main transmitting or receiving direction has rotated counterclockwise between t1 and t2.
  • the roles of some antenna elements 5 of the second antenna group have changed between active and passive, and conversely, for inducing the radiating diagram of the steerable antenna 1 to rotate.
  • the switching means 100 are coupled to some or all the antenna elements 5 of the first antenna group.
  • signals from the generator 60 (also named transmitter) or toward the receiver are obtained or combined through the use of a splitter circuit.
  • the generator 60 is thus not directly connected to the switching means 100 as shown in figures 1 and 2, but rather through such a splitter circuit.
  • the switching means 100 switches several antenna elements 5 of the second antenna group to be active at a same time (as for the example shown in figures 1 , 2, 4 and 5) : Na > 1 . Then, it is preferred that the distance between the two active antenna elements 5a that are the farthest from each other is comprised between the radius and the largest diameter of the closed outer contour line 21 .
  • the antenna elements are separated by a minimum
  • e r is the relative permittivity of the structure of dielectric material supporting the antenna elements 5.
  • the length (or largest dimension) of the antenna is the length (or largest dimension) of the antenna
  • a phase shifting technique between the antenna elements 5 active at same times is preferably used for obtaining a still higher directivity.
  • Phase shifting technique among signals radiated by or received from different active antenna elements 5a is achieved either through the use of transmission lines of different lengths or through the use of phase shifting circuits.
  • the steerable antenna 1 comprises at least one inner termination group 215 (L inner termination groups 215, with L e [1 , M]), each of said at least one inner termination group 215 comprising at least two (or a plurality of) different termination loads 220;
  • the switching means 100 comprise at least one (L with L e [1 , M]) inner termination switch 205, each of the at least one inner termination switch 205 coupled to one of the at least one antenna element 5 of the first antenna group and coupled to the at least two different termination loads 220 of one different of the at least one inner termination group 215; and
  • controller 1 10 is also programmed for controlling the at least one inner termination switch 205 for connecting and disconnecting at least one of the at least one antenna element 5 of the first antenna group to and from the termination loads 220 of one different inner termination group 215.
  • the steerable antenna 1 of the invention further comprises K outer termination groups 210, K e [1 , N], each outer termination group 210 comprising at least two different termination loads 220;
  • the switching means 100 comprise K outer termination switches 200 each coupled to one different antenna element 5 of the N antenna elements 5 of the second antenna group and each coupled to the at least two different termination loads 220 of one different outer termination group 210; and - the controller 1 10 is also programmed for controlling the K outer termination switches 200 for connecting and disconnecting each of K antenna elements 5 of the second antenna group to and from the termination loads 220 of one different outer termination group 210.
  • Examples of inner 205 and outer 200 termination switches are: integrated switches and switching diodes. Other types of switching devices could be used.
  • An example of the combination 'switch + termination load 220' is a varicap diode that is known by the one skilled in the art.
  • the switching means comprise six outer termination switches 200, and six inner termination switches 205.
  • N 6
  • Each outer termination group 210 comprises two different termination loads 220 (for clarity reasons, only some 220 reference signs are shown in figure 6).
  • Each inner termination group 215 comprises two different termination loads 220 (for clarity reasons, only some 220 reference signs are shown in figure 6).
  • the termination loads 220 are preferably open transmission lines of different lengths. Depending on the length of these open transmission lines, they behave as different types of impedances.
  • these open transmission lines can behave as an inductance, a capacitor, or as an open circuit (impedance tending to infinity). Other ways of realizing the termination loads could be exploited.
  • the controller 1 10 is not shown in figure 6.
  • the lengths of open transmission lines determine the impedance provided as an antenna load. Let us define by Ag the wavelength of the waves propagating in the transmission line. Approximately, for open-ended lines, the load at the antenna level will be capacitive if the line length is less than Ag/4 and inductive if it is between Ag/4 and Ag/2; these correspond to purely imaginary impedances. Some real (i.e. resistive) part of the load may appear because of the losses in the transmission line. The switches also modify a little the real and imaginary parts of the impedance. The dependence of the load on line length is described by classical transmission- line theory.
  • FIGS 7 and 8 show two top views of another preferred embodiment of the steerable antenna 1 at two successive times t1 and t2, with t2 > t1 .
  • the steerable antenna 1 comprises six outer termination groups 210 each comprising two different termination loads: 220a and 220b. For clarity reasons, these reference signs (220a and 220b) are not shown for all the outer termination groups 210.
  • the steerable antenna 1 also comprises six inner termination groups 215. Each inner termination group 215 comprises three different termination loads: 220c, 220d, and 220e.
  • the controller controls the outer termination switches 200 coupled to the three active antenna elements 5a for disconnecting them from any termination load 220.
  • the termination loads 220 that are disconnected from any antenna element 5 are represented by dashed line segments in figures 7 and 8.
  • the termination loads 220 that are connected to an antenna element 5 are represented by solid line segments in figures 7 and 8.
  • the passive antenna elements 5p of the second antenna group are each connected to a termination load 220 so as to obtain load symmetry with respect to the main direction of radiation.
  • this main direction of radiation is depicted by a black arrow. Therefore, two passive antenna elements 5p of the second antenna group are connected to a same second termination load 220b, whereas the other passive antenna elements 5p of the second antenna group that is located in between these two passive antenna elements 5p is connected to a first termination load 220a.
  • the passive antenna elements 5p of the first antenna group are connected to different termination loads 220 also in order to obtain load symmetry with respect to the main direction of radiation. Therefore, the most left-side passive antenna element 5p is connected to a fourth termination load 220d.
  • the two passive antenna elements 5p adjacent to said most left-side passive antenna element 5p are also connected to said fourth termination load 220d.
  • the most right-side passive antenna element 5p of the first antenna group is connected to a fifth termination load 220e, whereas the two passive antenna elements 5p adjacent to said most right-side passive antenna element 5p are connected to a third termination load 220c.
  • the main direction of radiation has rotated clockwise.
  • the active and passive roles of the antenna elements 5 of the second antenna group have changed.
  • the controller has also changed the states of the outer 200 and inner 205 termination switches in order to keep load symmetry with respect to the main direction of radiation: hence, the states of the outer 200 and inner 205 termination switches have also rotated clockwise.
  • This specific loading of the different antenna elements 5 of the steerable antenna 1 that impose load symmetry with respect to the main direction of radiation (or reception) allows having a still higher directivity.
  • three active antenna elements 5a of the second antenna group are disconnected from any termination load 220.
  • Two passive antenna elements 5p of the second antenna group are connected to a same second termination load 220b.
  • the passive antenna element 5p that is positioned in between these two passive antenna elements 5p is connected to a first termination load 220a.
  • Three passive antenna elements 5p of the first antenna group are connected to a same fourth termination load 220d.
  • Two passive antenna elements 5p of the first antenna group are connected to a same third termination load 220c, and the passive antenna element 5p that is positioned in between these two passive antenna elements 5p is connected to a fifth termination load 220e.
  • the antenna elements 5 can be of various shapes, of various sizes, and with different electromagnetic functions. Examples of shapes for the antenna elements 5 are: a loop, a rod, a hollow cylinder, a U-shape. Other shapes are possible. All the antenna elements 5 can have a same shape or can have different shapes. All the antenna elements 5 can have a same size or the antenna elements 5 can have different sizes.
  • the antenna elements 5 can be made of different types of materials. Preferably, the antenna elements 5 are metallic. More preferably, they are made of copper.
  • the antenna elements 5 can be for instance: electrical monopoles, electrical dipoles, magnetic dipoles.
  • the antenna elements 5 can be different or identical. So, for instance, it is possible to have an antenna element 5 that is an electrical monopole and another antenna element 5 that is an electrical dipole. Other combinations are possible.
  • the antenna elements 5 comprise a cylindrical element that is electrically insulated from a grounding plate.
  • outer conductors of coaxial cables or microstrips or striplines
  • the central conductors of these coaxial cables are connected to one end of the cylindrical elements.
  • the features of the steerable antenna 1 apply whether it is used for transmitting or receiving.
  • the properties are the same for both the receiving and transmitting modes. Therefore, no confusion should result from a description that is made in terms of one or the other mode of operation and it is well understood by those skilled in the art that the invention is not limited to one or the other mode.
  • the steerable antenna 1 of the invention is used in the following frequency range, 433 MHz - 24 GHz, and more preferably, in the range 800 MHz - 12 GHz.
  • FIG. 9 shows a comparison between two simulated radiation diagrams in an azimuthally plane, between 0° and 360° (radial scale in dB). These two radiation diagrams are normalized to 15 dB.
  • FIG. 1 is a radiation diagram of an optimized ESPAR antenna comprising one central active antenna element surrounded by six passive antenna elements. From figure 9, we can see that the directivity increases with the steerable antenna 1 according to the invention. In particular, the back lobe of the radiation pattern of the ESPAR antenna is not present in the radiation diagram of the steerable antenna 1 according to the invention. In fact, simulated directivity values as high as 12 dBi can be obtained with the steerable antenna 1 of the invention and according to the above-mentioned preferred embodiment (the dBi unit is known by the one skilled in the art).
  • the steerable antenna 1 according to the invention is approximately 5 dBi more directive than the ESPAR antenna.
  • FIG. 10 shows two radiation patterns in an azimuthal plane, between 0° and 360° for a steerable antenna 1 according to the invention and for the same preferred embodiment as the one in relation with the results shown in figure 9. Dashed curve represents a measured radiation pattern in an anechoic chamber, whereas solid curve is a simulated radiation pattern. The patterns are normalized to 25 dB. This figure shows a relatively good correspondence between simulation and measurement. A small difference in the measured sidelobes can be attributed to the fact that the fabricated prototype comes with losses in the switches and transmission lines in the PCB boards used to get the switched reactances.
  • Figure 1 1 shows, at six different times (see the six different positions in the legend of figure 1 1 ), measured radiation patterns obtained with the preferred embodiment of the steerable antenna 1 that has been described in relation to figure 9. From this figure, we clearly see the rotation of the radiation pattern between the six different times.
  • simulated directivity is around 7.3 dBi for the steerable antenna 1 of the invention
  • the simulated directivity is around 7 dBi for an ESPAR antenna.
  • Figure 12 shows different simulated radiation patterns (310, 320, and 330) in an azimuthal plane between 0° and 360°. Pattern 310 relates to the radiation pattern of an ESPAR antenna.
  • CST Computer Simulation Technology, www.cst.com
  • Figure 13 shows a top view of a steerable antenna 1 according to a preferred embodiment of the invention.
  • This figure also relates to a configuration of the steerable antenna 1 when main radiation lobe (or main radiation) is directed along the black arrow of figure 13.
  • All antenna elements of first antenna group are passive permanently. The points represent the antenna elements.
  • Radius of inner contour line 1 1 is 0.3348 wavelengths, that of the outer contour line 21 is 0.6696 wavelengths.
  • three antenna elements of second antenna group with a termination load equal to 50-jO are active. All the other antenna elements are passive. From this figure, we can see that the termination loads of the different antenna elements are chosen so as to have symmetry in termination loads for the different antenna elements. For the geometry of figure 13, this corresponds to symmetry with respect to a horizontal line passing through the black arrow.
  • the corresponding radiation pattern in the plane containing the array of antenna elements, as calculated with the Method of Moments, assuming that the antenna elements are monopoles protruding from a perfectly conducting plane is given in figure 14. This corresponds to a narrow main-beam and high sidelobes.
  • FIG. 15 shows a top view of a steerable antenna 1 according to another preferred embodiment of the invention.
  • This figure also relates to a configuration of the steerable antenna 1 when main radiation lobe (or main radiation) is directed along the black arrow of figure 15.
  • All antenna elements of first antenna group are passive permanently.
  • the points represent the antenna elements.
  • the values of the termination loads of the different antenna elements are written on figure 15 in Ohms for a working frequency of 2.45 GHz, and assuming that a 50 Ohm generator is used for feeding the steerable antenna 1 .
  • Radius of inner contour line 1 1 is 0.49 wavelengths, that of the outer contour line 21 is 0.735 wavelengths.
  • Steerable antenna 1 comprising: a first antenna group comprising M antenna elements 5, M > 1 , a second antenna group comprising N antenna elements 5, N >1 , said N antenna elements 5 being arranged along a closed outer contour line 21 and surrounding the M antenna elements 5 of the first antenna group.
  • the steerable antenna 1 further comprises: switching means 100 coupled to the N antenna elements 5 of the second antenna group and a controller 1 10 programmed for controlling said switching means 100 for sequentially switching to be active and at different times successive antenna subgroups, each antenna subgroup comprising Na antenna elements 5 of the second antenna group, 1 ⁇ Na ⁇ N-1 , while switching at same different times N-Na other antenna element 5 of the second antenna group to be passive.
  • the steerable antenna 1 also comprises L inner termination groups 215 and L inner termination switches 205, 1 ⁇ L ⁇ M, allowing modifying the termination loads of the antenna elements 5 of first antenna group for improving the directivity of the steerable antenna 1 .
  • N is preferably equal to two, three, four, five, six, seven, eight, nine or ten.
  • the antenna elements of the first antenna group are connected through switching means to passive loads.
  • the antenna elements 5 of second antenna group are also connected to different passive loads at same different times through switching means.

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  • Variable-Direction Aerials And Aerial Arrays (AREA)

Abstract

La présente invention concerne une antenne orientable (1) comprenant : un premier groupe d'antenne comprenant M éléments d'antenne (5), un second groupe d'antenne comprenant N éléments d'antenne (5), lesdits N éléments d'antenne (5) entourant les M éléments d'antenne (5) du premier groupe d'antenne, un moyen de commutation (100) couplé aux N éléments d'antenne (5) du second groupe d'antenne ainsi qu'un dispositif de commande (110) programmé de manière à basculer de manière séquentielle, en mode actif et à différentes heures, des sous-groupes d'antenne successifs du second groupe d'antenne, tout en basculant aux mêmes différentes heures d'autres éléments d'antenne (5) du même second groupe d'antenne en mode inactif et de manière passive sous différentes charges possibles. L'antenne orientable (1) comprend également L groupes de terminaison internes (215) et L commutateurs terminaux internes (205), 1 ≤ L ≤ M, permettant ainsi de modifier les charges de terminaison des éléments d'antenne (5) du premier groupe d'antenne.
PCT/EP2014/064718 2013-07-10 2014-07-09 Antenne orientable et son procédé de commande WO2015004186A1 (fr)

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GB1312349.2 2013-07-10
GB201312349A GB201312349D0 (en) 2013-07-10 2013-07-10 Steerable antenna and method of controlling said steerable antenna

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WO2015004186A1 true WO2015004186A1 (fr) 2015-01-15

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WO2017043921A1 (fr) * 2015-09-10 2017-03-16 엘지전자 주식회사 Procédé et dispositif pour réaliser une communication avec un terminal virtuel dans un système de communication sans fil
CN111384593A (zh) * 2018-12-26 2020-07-07 现代自动车株式会社 天线装置及其驱动方法
EP4270637A1 (fr) * 2022-04-26 2023-11-01 KATHREIN Sachsen GmbH Dispositif d'antenne pour la lecture de signaux rfid uhf

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US5294939A (en) * 1991-07-15 1994-03-15 Ball Corporation Electronically reconfigurable antenna
US6317092B1 (en) * 2000-01-31 2001-11-13 Focus Antennas, Inc. Artificial dielectric lens antenna
US20050174298A1 (en) * 2002-09-17 2005-08-11 Ipr Licensing, Inc. Low cost multiple pattern antenna for use with multiple receiver systems

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Publication number Priority date Publication date Assignee Title
US5294939A (en) * 1991-07-15 1994-03-15 Ball Corporation Electronically reconfigurable antenna
US6317092B1 (en) * 2000-01-31 2001-11-13 Focus Antennas, Inc. Artificial dielectric lens antenna
US20050174298A1 (en) * 2002-09-17 2005-08-11 Ipr Licensing, Inc. Low cost multiple pattern antenna for use with multiple receiver systems

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2017043921A1 (fr) * 2015-09-10 2017-03-16 엘지전자 주식회사 Procédé et dispositif pour réaliser une communication avec un terminal virtuel dans un système de communication sans fil
US10631275B2 (en) 2015-09-10 2020-04-21 Lg Electronics Inc. Method and device for performing communication with virtual terminal in wireless communication system
CN111384593A (zh) * 2018-12-26 2020-07-07 现代自动车株式会社 天线装置及其驱动方法
EP4270637A1 (fr) * 2022-04-26 2023-11-01 KATHREIN Sachsen GmbH Dispositif d'antenne pour la lecture de signaux rfid uhf

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