Classifications

• • 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
  • H01Q9/06—Details
  • H01Q9/14—Length of element or elements adjustable
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01P—WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE
  • H01P1/00—Auxiliary devices
  • H01P1/18—Phase-shifters
  • H01P1/185—Phase-shifters using a diode or a gas filled discharge tube
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01Q—ANTENNAS, i.e. RADIO AERIALS
  • H01Q15/00—Devices for reflection, refraction, diffraction or polarisation of waves radiated from an antenna, e.g. quasi-optical devices
  • H01Q15/24—Polarising devices; Polarisation filters 
  • H01Q15/242—Polarisation converters
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01Q—ANTENNAS, i.e. RADIO AERIALS
  • H01Q15/00—Devices for reflection, refraction, diffraction or polarisation of waves radiated from an antenna, e.g. quasi-optical devices
  • H01Q15/24—Polarising devices; Polarisation filters 
  • H01Q15/242—Polarisation converters
  • H01Q15/244—Polarisation converters converting a linear polarised wave into a circular polarised wave
• • 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
  • H01Q3/44—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 electric or magnetic characteristics of reflecting, refracting, or diffracting devices associated with the radiating element
  • H01Q3/46—Active lenses or reflecting arrays
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01Q—ANTENNAS, i.e. RADIO AERIALS
  • H01Q5/00—Arrangements for simultaneous operation of antennas on two or more different wavebands, e.g. dual-band or multi-band arrangements
  • H01Q5/40—Imbricated or interleaved structures; Combined or electromagnetically coupled arrangements, e.g. comprising two or more non-connected fed radiating elements
  • H01Q5/45—Imbricated or interleaved structures; Combined or electromagnetically coupled arrangements, e.g. comprising two or more non-connected fed radiating elements using two or more feeds in association with a common reflecting, diffracting or refracting device

Definitions

• the present invention relates to a dual-band electronic scanning antenna 5, with active microwave reflector. It applies in particular for microwave applications requiring two emission bands which are moreover subject to very low cost production conditions. It can for example be applied for individual stations of communication with scrolling satellites, and more generally for o many types of multimedia applications.
• antennas comprising an active microwave reflector.
• the latter also called “reflect array” in Anglo-Saxon literature, is a network with electronically controllable phase shifters 5.
• This network extends in a plane and comprises a network of phase control elements, or phase network, disposed in front of reflecting means, constituted for example by a metallic plane forming a ground plane.
• the reflective grating comprises in particular elementary cells each carrying out the reflection and the phase shift, variable on 0 electronic control, of the microwave wave which it receives.
• a primary source for example a horn, placed in front of the reflective network emits microwave waves towards the latter.
• Mass applications can be envisaged for such 5 antennas, in particular with the advent of interactive multimedia activities via satellite communications networks.
• Scrolling satellites are placed around the earth.
• the ground antennas must follow the satellites.
• the antennas 0 transmit and receive on two frequency bands, with different phase shifts between these two bands.
• an object of the invention is to produce a dual-band electronic scanning antenna with a reflecting array intended in particular for mass applications, and therefore of low production cost.
• the invention relates to an electronic scanning antenna, characterized in that it comprises at least two sources microwave emitting in different frequency bands and having opposite circular polarizations, an active reflective network comprising elementary cells illuminated by the sources and a polarization rotator, interposed between the reflective network and the sources, transforming the circular polarizations into two linear polarizations crossed, an elementary cell comprising two transverse phase shifters, the first phase shifter acting on the waves of a linear polarization and the second phase shifter acting on the waves of the other linear polarization.
• FIG. 4 a partial sectional view of an example of active network used in an antenna according to the invention
• FIG. 5 a detailed perspective view of an embodiment of an elementary cell of an active reflective network used in an antenna according to the invention
• FIG. 1 schematically illustrates an exemplary embodiment of an electronic scanning antenna with an active reflective network in which the microwave distribution is for example of the so-called optical type, that is to say for example ensured using a primary source illuminating the reflective network.
• the antenna comprises a primary source 1, for example a horn.
• the primary source 1 emits microwave waves 3 towards the active reflecting network 4, arranged in the Oxy plane.
• This network reflector 4 comprises a set of elementary cells performing the reflection and the phase shift of the waves it receives.
• An antenna according to the invention comprises at least two elementary sources, for example of reverse circular polarizations, to illuminate the active reflector 4 whose elementary cells moreover have a given architecture.
• the two sources emit waves in different frequency bands.
• Figure 2 schematically illustrates such an antenna.
• the latter therefore comprises two sources S D , S Gl, for example horns, with respective right and left polarizations. These horns illuminate an active reflective network 4 as described above.
• a polarization rotation grid 21 is disposed in front of this reflector 4, and interposed between the latter and the sources S 0 , S G.
• the polarization rotation grid transforms the circularly polarized waves emitted by these sources into linearly polarized waves.
• An antenna according to the invention can also include linear elementary sources, of crossed polarizations. In this case, there is no need to use a polarization rotation grid.
• FIG. 3 schematically shows a part of a reflector network 4 in the Oxy plane, by a top view, along F.
• the reflector comprises a set of elementary cells 10 arranged side by side and separated by zones 20, used for microwave decoupling cells. These cells 10 carry out the reflection and the phase shift of the waves they receive.
• An elementary cell 10 comprises a phase-shifting microwave circuit disposed in front of a conducting plane. More specifically, as will appear below, the microwave circuit comprises two transverse phase shifters, each dedicated to linear polarization.
• FIG. 4 is a schematic sectional view, in the Oxz plane, of a possible embodiment of the active reflector 4.
• the reflector 4 consists of a microwave circuit distributed in the elementary cells 10 and of a conducting plane 42, arranged substantially parallel to the microwave circuit 41, at a predefined distance d.
• This microwave circuit receives the incident waves, for example substantially planar, emitted by the aforementioned sources S D , S G.
• the function of the conducting plane 42 is in particular to reflect the microwave waves. It can be formed by any known means, for example parallel wires or a mesh, sufficiently tight, or a continuous plane.
• the microwave circuit 41 and the conductive plane 42 are preferably produced on two faces of a dielectric support 43, for example of the printed circuit type.
• the reflector 4 also comprises, preferably on the same printed circuit 43, which is then a multilayer circuit, the electronic circuit necessary for controlling the phase values.
• FIG 4 there is shown a multilayer circuit whose front face 44 carries the microwave circuit 41, the rear face 45 carries components 46 of the aforementioned electronic control circuit, and the intermediate layers form the conductive plane 42 and for example two component interconnection plans 47 to the microwave circuit 41.
• FIG. 5 shows, schematically, an exemplary embodiment of an elementary cell 10 of an antenna according to the invention.
• a cell comprises a phase-shifting microwave circuit, forming part of the microwave circuit mentioned in relation to FIG. 4.
• the phase-shifting device comprises conductive wires 51, 51 ′ arranged on a support, for example on the front face 44 of the multilayer circuit 43.
• the wires 51 , 51 'each comprise at least two semiconductor elements with two states 521, 521', 522, 522 ', diodes for example.
• the embodiment of Figure 5 consists of two conductive son each having two diodes in series, cross-wired and connected together by a central control conductor 53.
• the conductor central 53 is for example itself connected to a metallized hole 531 which connects the conductive wires 51, 51 ′ to the electronic control circuit arranged on the rear face 45 of the multilayer circuit, via the interconnection circuits.
• the central conductor 53 is connected to the four diodes 521, 521 ', 522, 522' of the phase shifter, by being wired between the two diodes of each of the conductor wires 51.
• the ends of the latter are also each connected to a control conductor 54 connected for example itself to a metallized hole 541 produced in the multilayer circuit 43.
• the ends of the conductive wires 51, 51 ′ are thus connected to the electronic control circuit.
• each of the four diodes can then be controlled by the electronic control circuit.
• Each of the diode wires acts on the only waves whose polarization, that is to say the electric field vector, has a component which is parallel to it.
• the polarization rotation grid 21 transforms for example the right circular polarization into a linear polarization parallel to a conductive wire 51 while it transforms the left circular polarization into a linear polarization parallel to the other conductive wire 51 ', a conductive wire 51 being for example parallel to the direction Ox and the other conductive wire 51 'being for example parallel to the direction Oy.
• the invention provides decoupling zones 20 which separate the cells 10.
• decoupling zones 20 which separate the cells 10.
• a decoupling zone 20 surrounding an elementary cell comprises a conductive strip 62.
• the end conductors 54 which connect the conductive wires to the electronic control circuit are for example preferably located in the conductive strip 62, without however being electrically connected to the latter. For this purpose, provision is made for an interruption of the strip around the end conductors 54.
• the conductive strip 62 is for example produced by metallic deposition on the front face 44, between the cells, parallel to the directions Ox and Oy.
• This strip 62 forms, with the reflective plane 42 which is below, a space of the guide type. wave whose width is the distance d.
• the distance d is chosen so that it is less than ⁇ / 2, knowing that a wave whose polarization is parallel to the bands cannot propagate in such a space.
• the reflector according to the invention operates in a certain frequency band and we choose d so that it is less than the smaller of the wavelengths of the two bands.
• the strip 62 must have a sufficient width for the effect described above to be appreciable. In practice, the width may be of the order of ⁇ / 15.
• the metallized holes 541 for connecting the conductors 54 to the electronic control circuit. Indeed, these being parallel to the polarization of the stray wave, they are equivalent to a conductive plane forming shielding if they are sufficiently close (at a distance from each other much less than the length of operating wave of the reflector), therefore numerous, for the operating wavelengths of the reflector. If this condition is not fulfilled, it is of course possible to form additional metallized holes 61, having no connection function.
• the equivalent circuit relates to a conductive wire 51 and its two diodes 521, 522, in fact what corresponds to a phase shifter, associated with a given polarization and therefore with a given frequency band.
• the incident microwave wave, of linear polarization and parallel to Oy and wires 51 is received on terminals B and B 2 and meets three capacitors C 0l C ,. ,, C, 2 in series, connected in parallel on terminals B ., and B 2 .
• the capacitance C 0 represents the linear decoupling capacitance between the end conductors 54 and the conductive strip 62 of the decoupling zone 20.
• the capacitance C facilitateis the linear capacitance between the end conductor 54 connected to the first diode 521 and the central conductor 53.
• the capacitance C, 2 is the linear capacitance between the end conductor 54 connected to the second diode 522 and the central conductor 53.
• the first diode 521 At the terminals of the capacitor C
• the second diode 522 represented by its equivalent diagram.
• the latter is analogous to that of the first diode 521, its components bearing an index 2.
• the microwave output voltage is taken between terminals B3 and B4, terminals of the capacitors Crj, C
• phase shifter 10 The operation of the phase shifter 10 is explained below by considering, in a first step, the behavior of such a circuit in the absence of the second diode 522, which returns to the equivalent diagram of FIG. 7 to remove the 522 as well as the capacity C
• phase shifter of a cell 10 this phase shifter corresponding to a conducting wire 51, 51 ′, can have four different values for its susceptance Q (denoted Bpi, BQ2. BD3 and BD4) according to the command (direct polarization or inverse) applied to each of the diodes 521, 522.
• These values are a function of the parameters of the circuit of FIG. 7, that is to say of the values chosen for the geometric parameters (dimensions, shapes and spacings of the different conductive surfaces) and electrical (electrical characteristics of the diodes) of the phase shifter.
• the cell's susceptibility Bc is then given by:
• the susceptance Bc can take four distinct values (denoted Bd, Bc2. BC3> and ⁇ C4) corresponding respectively to the four values of BQ, the distance d representing an additional parameter for the determination of the values Bd - Bc4-
• the parameters of the circuit are chosen so that the zero (or substantially zero) susceptances are such that they correspond to the diodes polarized in the forward direction, but that it is of course possible to choose a symmetrical operation in which the parameters are determined for appreciably cancel the susceptibilities B r ; more generally, it is not necessary that one of the susceptances B or B r is zero, these values being determined so that the condition of equal distribution of the phase shifts d ⁇ -
• an elementary cell according to its second conducting wire 51 ′ can be described in a similar manner, for the waves emitted by the second source, for example S G , in another frequency band.
• the active network 4 is illuminated by two sources S D , S G emitting respectively in right and left circular polarization and in two different frequency bands, the polarization rotation grid 21 transforming these two circular polarizations into two crossed linear polarizations allowing the cells of the active network 4 to act independently on two polarizations and in different frequency bands.
• An elementary cell 10 in fact comprises two transverse phase shifters, preferably controllable, the first phase shifter 51, 521, 522 acting on the waves of a linear polarization and the second phase shifter 51 ', 521', 522 'acting on the waves of the other linear polarization.
• a phase shifter and therefore its conducting wire, is substantially parallel to the direction of this polarization.
• the polarization rotation grid 21 is arranged in such a way that the linear polarizations obtained from the circular polarizations are very substantially parallel to the phase shifters concerning them.
• the polarization rotation grid can be any polarization rotator, in particular, it can be a meander grid or a wire grid.
• the invention advantageously makes it possible to operate on two frequency bands and to adjust the phase shifts of the waves reflected by the active network, independently of one band to another. Knowing that these phase shifts determine the direction of the beams emitted by the antenna, it is therefore easy and quick to change the direction of the beam for the two frequency bands. This is particularly well suited for tracking scrolling satellites arranged around the Earth used in particular for all kinds of multimedia applications.
• an antenna according to the invention is well suited for mass use, that is to say intended for a large audience, insofar as it can be produced at low cost. Indeed, it does not contain expensive or complex components to implement.
• the active network consisting of a multilayer printed circuit with components arranged on these front and rear faces, is not costly to produce. In addition, it is perfectly suited to mass production.
• the polarization rotation grid used in particular in the case where the elementary sources have circular polarizations as is the case for example for multimedia applications, is also inexpensive.

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• Physics & Mathematics (AREA)
• Electromagnetism (AREA)
• Variable-Direction Aerials And Aerial Arrays (AREA)
• Aerials With Secondary Devices (AREA)

Applications Claiming Priority (3)

Publications (2)

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• 1999
  • 1999-02-05 FR FR9901378A patent/FR2789521A1/fr not_active Withdrawn
• 2000
  • 2000-01-31 US US09/890,932 patent/US6437752B1/en not_active Expired - Fee Related
  • 2000-01-31 WO PCT/FR2000/000220 patent/WO2000046876A1/fr active IP Right Grant
  • 2000-01-31 AU AU23007/00A patent/AU2300700A/en not_active Abandoned
  • 2000-01-31 DE DE60004174T patent/DE60004174T2/de not_active Expired - Lifetime
  • 2000-01-31 EP EP00901684A patent/EP1157444B1/de not_active Expired - Lifetime

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