Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01Q—ANTENNAS, i.e. RADIO AERIALS
  • H01Q25/00—Antennas or antenna systems providing at least two radiating patterns
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01Q—ANTENNAS, i.e. RADIO AERIALS
  • H01Q1/00—Details of, or arrangements associated with, antennas
  • H01Q1/27—Adaptation for use in or on movable bodies
  • H01Q1/28—Adaptation for use in or on aircraft, missiles, satellites, or balloons
  • H01Q1/288—Satellite antennas
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01Q—ANTENNAS, i.e. RADIO AERIALS
  • H01Q21/00—Antenna arrays or systems
  • H01Q21/06—Arrays of individually energised antenna units similarly polarised and spaced apart
  • H01Q21/061—Two dimensional planar arrays
• • 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
  • H01Q3/02—Arrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system using mechanical movement of antenna or antenna system as a whole
  • H01Q3/08—Arrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system using mechanical movement of antenna or antenna system as a whole for varying two co-ordinates of the orientation
• • 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
  • H01Q3/26—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 relative phase or relative amplitude of energisation between two or more active radiating elements; varying the distribution of energy across a radiating aperture
• • 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
  • H01Q3/26—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 relative phase or relative amplitude of energisation between two or more active radiating elements; varying the distribution of energy across a radiating aperture
  • H01Q3/28—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 relative phase or relative amplitude of energisation between two or more active radiating elements; varying the distribution of energy across a radiating aperture varying the amplitude
• • 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
  • H01Q3/26—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 relative phase or relative amplitude of energisation between two or more active radiating elements; varying the distribution of energy across a radiating aperture
  • H01Q3/30—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 relative phase or relative amplitude of energisation between two or more active radiating elements; varying the distribution of energy across a radiating aperture varying the relative phase between the radiating elements of an array
  • H01Q3/34—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 relative phase or relative amplitude of energisation between two or more active radiating elements; varying the distribution of energy across a radiating aperture varying the relative phase between the radiating elements of an array by electrical means
  • H01Q3/40—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 relative phase or relative amplitude of energisation between two or more active radiating elements; varying the distribution of energy across a radiating aperture varying the relative phase between the radiating elements of an array by electrical means with phasing matrix

Definitions

• the present invention relates to an antenna for a telecommunications system, in particular by satellite.
• antennas intended to receive signals from a mobile source or to transmit signals to a mobile receiver (or target).
• a mobile receiver or target
• active antennas made up of stationary radiating elements are used but the direction of the radiation diagram can be varied by varying the phase of the signals supplying the radiating elements. .
• This technique does not make it possible to obtain satisfactory radiation patterns for large deflection angles, that is to say for directions deviating significantly from the mean direction of emission and / or reception.
• the tracking of a source or a receiver can be carried out using a conventional antenna and motors controlling the movement of this antenna.
• Neither of these two types of antennas makes it possible to correctly resolve the problem of communication between the antenna and a plurality of sources or receivers located in a large area, in particular a ground area, communication to remain confined in the zone despite the change of posi ⁇ of the antenna relative to the zone.
• each satellite has groups of receive and transmit antennas, each group being dedicated to a given area.
• the receiving antennas receive the signals from a station in the area and the transmitting antennas retransmit the received signals to another station in the same area.
• the antennas of a group remain constantly oriented towards the area as long as it remains in the field of vision of the satellite.
• a region of the earth is divided into n zones and when it travels over a region, each zone is assigned a group of transmit and receive antennas which remain constantly oriented towards this area.
• the low altitude of the satellites minimizes the propagation times, which is favorable to communications of the interactive type, in particular for so-called "multimedia” applications.
• the invention provides an antenna which can be mechanically orientated by means of motor means and which further comprises radiating elements controlled to modify the radiation diagram as a function of the relative orientation of the antenna relative to the area, source or target, in order to adapt this diagram to the form in which the antenna sees the target or source area.
• an antenna on board the satellite sees the zone in the form of a circle when the satellite is at the nadir of the zone.
• the antenna sees the area in elliptical form.
• the radiating elements intended for transmission and the radiating elements intended for reception are located on the same panel displaceable by the same motor means.
• the modification of the diagram is obtained by modification of the amplitudes of the signals supplied to the radiating elements.
• the radiating elements are distributed over a surface having a shape which corresponds substantially to the desired radiation pattern for the most distant zones, sources or targets, that is to say the sources providing the weakest signal levels or the targets to which it is necessary to send maximum power.
• the radiating elements are arranged to adapt to the most unfavorable case.
• FIG. 1 is a diagram showing a telecommunication system between stations or land mobiles using a satellite system
• FIG. 2 is a diagram illustrating a distribution of traffic in the context of the telecommunications system to which the invention applies
• FIG. 3 is a diagram of a transmitting and receiving antenna, in accordance with the invention, mounted on board a satellite
• Figure 4 is a diagram showing the control of a transmitting antenna of Figure 3
• Figure 4a is a diagram of a radiating panel
• Figure 5 is a diagram showing the control of a receiving antenna of the figure 3.
• the example which will be described concerns a telecommunication system using a constellation of satellites with low orbit, approximately 1300 km above the surface 10 (FIG. 1) of the earth.
• the system must establish communications between users 12, 14, 16 via one or more connection station (s) 20. It also establishes communications between users and service providers (not mon- very) connected at a connection station. These communications are carried out via a satellite 22.
• the TXF signals of the satellite 22 to the users there are four types of signals, namely: the TXF signals of the satellite 22 to the users, the RXR signals from the users 12, 14, 16 to the satellite 22, the TXR signals from the satellite 22 to the connection station 20 and the RXF signals from the connection station to the satellite 22.
• the suffix F means “forard” or to go (from the connection station to the user sator) and R means “return” or return (from the user to the connection station).
• TX means "transmission”
• RX means "reception”.
• transmission and reception with respect to the satellite.
• Each zone 26i has the shape of a circle with a diameter of about 700 km.
• Each region 24 is delimited by a cone 70 centered on the satellite and an angle at the top determined by the altitude of the satellite. A region is thus the part of the earth visible from the satellite.
• the apex angle is approximately 104 °.
• the satellite comprises groups of transmit and receive antennas assigned to each zone 26. Each group is such that, when the satellite moves, this group remains pointed towards the same zone. In other words, the radiation pattern of each antenna always remains directed towards the same terrestrial area 26 ⁇ in principle as long as the satellite sees this area.
• the antenna requirement is a maximum of 4n: four types of signals per zone.
• the invention - provides, as will be seen below, that the total number of antennas is substantially less than 4n.
• the satellite is used for communication between users and between users and the connection station within each zone 26 ⁇ .
• the communication between zones is carried out using terrestrial means, for example using cables arranged between the connection stations of the various zones forming part of the same region or of different regions.
• the number and arrangement of satellites are such that at any given moment, an area 26- ⁇ sees two or three satellites.
• the traffic requirement is measured, for example, by the average amount of information that is transmitted per unit of time and per unit of area.
• the traffic in part 28 of region 24 (FIG. 2) the traffic is light, while in another part 30 the traffic is heavy.
• High traffic corresponds, for example, to urban areas of a developed country, while low traffic corresponds, for example, to rural or underdeveloped areas.
• signal resources is meant a polarization characteristic and a carrier frequency band characteristic.
• the polarization is either of the right circular type (P Q ) or of the left circular type (P Q ) and two separate bands of carrier frequencies are provided: ⁇ F ⁇ _ and ⁇ F 2 .
• each zone is allocated all the resources A, B, C and D.
• cha ⁇ area is assigned a single resource A, B, C or D.
• the resource allocation signals is such that two adjacent areas do not contain identical resource .
• the zones to which the same resource is assigned are separated by at least one zone where the resource is different.
• zone 26 ⁇ o of resource A (right circular polarization signal PTJ and band ⁇ F ⁇ _) is separated from zone 26_ comprising the same resource, by zone 26 ⁇ to which resource B is assigned (right circular polarization Pp, but band ⁇ F 2 ).
• the carrier frequency bands ⁇ Fi and ⁇ F 2 are either of the same extent, or of a different extent. For example if, in part 28, certain zones require more traffic than other zones, the carrier frequency band ⁇ F will be more important than the carrier frequency band ⁇ F ⁇ .
• the antennas can be made in such a way that they can receive or transmit only signals with a right circular polarization Pp. It is thus possible to use simplified equipment.
• the antenna systems must be capable of generating the two circular polarizations (right and left), without interference between the signals.
• each antenna follows a zone and must carry out a scanning at an angle between 100 ° and 120 ° from the entry of the zone into the field of vision. from satellite to exit.
• shape of the radiation pattern must vary during the movement of the satellite because, for the antenna, an area which is vertical to the satellite is seen without deformation, that is to say as a circle, but an area lying on the edge of a region, for example area 26 ⁇ or 26 2 , is seen in the form of an elongated ellipse of smaller dimensions .
• active traffic areas are assigned to areas with low traffic, that is to say antennas which are electronically pointable and reconfigurable, and areas with heavy traffic are assigned steerable antennas mechanically and electronically reconfigurable.
• all the zones are provided with antennas of the latter type.
• FIG. 3 represents an antenna intended for areas with heavy traffic. It allows transmission and reception.
• This antenna comprises a plate 72 housing two panels of radiating elements, respectively 74 and 76.
• the panel 74 is intended for transmission while the panel 76 is intended for reception.
• the support plate 72 which, in FIG. 3, is shown in the horizontal direction, is pivotable about a horizontal axis 78, parallel to the plane of the plate 72, thanks to a motor 80 called the elevation motor, the pivoting around the axis 78 effecting the elevation orientation.
• Another motor 82 of vertical axis 84, is provided under the motor 80.
• the rotation around the axis 84 allows orientation in azimuth.
• the panel 74 of radiating elements intended for emission has a general elliptical shape with a long axis 86.
• This elliptical shape corresponds to the shape in which the antenna sees an area close to the horizon, when this antenna is pointed towards this zone, that is to say when the vertical axis 88 of the plate 72 is directed towards the zone at the edge of the horizon.
• the elliptical shape is adapted to the shape of an area to be covered corresponding to a pointing angle of approximately 50 ° while the maximum pointing angle is 54 °.
• the axis 86 is perpendicular to the major axis of the ellipse under which an area is seen for such a pointing of 50 °.
• the panel 76 intended for reception has, like the panel 74, the general shape of an ellipse of major axis 90, parallel to the major axis 86 of panel 74.
• Panel 74 is intended for both TXF and TXR signals. Likewise, panel 76 is intended for RXF and RXR signals.
• FIG. 4 is a diagram of a control circuit intended for the transmission panel 74.
• three carrier frequency sub-bands intended for the TXF signals (transmission to the users) are provided and a single carrier frequency band for TXR signals (to the connection station).
• three amplifiers 92, 94 and 96 are assigned to the TXF signals and an amplifier 98 is provided for the TXR signals.
• the circuit of FIG. 4 is not limited to this distribution into three sub-bands for the TXF signals and a band for the TXR signals. Other distributions are possible such as two bands for THF signals and two bands for TXR signals.
• the outputs of amplifiers 92 to 98 are applied to the inputs of a multiplexer 100 which delivers signals to the radiating elements of the panel 74 via a beam-forming circuit or network 102.
• this network 102 adapts the radiation pattern to the position of the satellite with respect to the area to which the antenna is assigned.
• the axis 88 is directed towards the corresponding zone, thanks to the azimuth motor 82 and to the elevation motor 80 (FIG. 3), and to this "mechanical" pointing direction corresponds an electronic control 102 of so as to adapt the beam to the relative position of the antenna and the area.
• the beam is of circular section when the satellite is at the nadir of the area and it is of elliptical section when the area is at the edge of the horizon.
• the circuit 102 comprises, in the example, q power distributors 104 ⁇ to 104g. These distributors are reconfigurable; they are also at low losses because they are located after amplifiers 92 to 98.
• the power distributors 104i affect the amplitude of the signals supplied to the radiating elements of the panel 74 but not their phase. Indeed the radiating elements do not intervene for pointing; it is therefore not necessary to vary the phase of the signals applied to them.
• the number q of power distributors is a sub-multiple of the number of elements. radiant elements.
• the number of radiating elements is 64 or 80 while the number q is 16.
• FIG. 4a shows an example of a panel of radiating elements arranged in an elongated shape. Each radiating element is represented by a circle 140. Inside each radiating element, a number or index has been indicated, from 1 to 16. The identical numbers correspond to an excitation of the same level of amplitude. Thus, for example, the four elements of index 1 in the center are all excited with the same amplitude. Furthermore, in this FIG.
• FIG. 5 represents the circuit intended to exploit the signals received by the panel of radiating elements 76 assigned to reception.
• This circuit includes filters 110, low noise amplifiers 112 of the variable attenuators 114 and variable dephasers 115.
• the role of the attenuators 114 and the dephasers 115 is the same as that of the attenuators 104 of FIG. 4, namely adapt the radiation pattern to the relative position of the satellite with respect to the area.
• the use of phase shifters at reception makes it possible to optimize the formation of the beam; it does not penalize the link budget because the phase shifters are located downstream of the low noise amplifiers 112.
• the attenuators 114 are controlled as a function of the relative position of the satellite relative to the area. Furthermore, a passive combiner 116 performs the sum of the signals supplied by the attenuators 114.
• the output signals from the combiner 116 are supplied to a multiplexer 120 which separates the RXF and RXR signals.
• a multiplexer 120 which separates the RXF and RXR signals.
• three bands of RXF signals and one band of RXR signals are provided in a similar manner to that which is provided in the example in FIG. 4.
• the distribution between the bands for the RXF and RXR signals can be different.
• the cables or electrical conductors pass through a rotating joint 130, 132 and that these cables are subjected to rotations corresponding to the adjustments in elevation and in azimuth.
• the reconfiguration of the radiation diagram as a function of the elevation is ensured by a beam forming network based on ferrite or MMIC (monolithic integrated circuit for microwaves, "Monolithic Microwave Integrate Circuit” in English).
• MMIC monolithic integrated circuit for microwaves, "Monolithic Microwave Integrate Circuit" in English.
• a ferrite-based circuit is preferably used, such a circuit being better suited to the formation of beams with low losses after the power amplification.
• This power amplification is carried out using SSPA amplifiers which have a low efficiency and therefore dissipate a large amount of heat.
• this circuit It is therefore preferable to move this circuit away from the panel 72 which, in general, has few means of heat dissipation; this circuit is therefore installed under the panel 134 called "earth" ( Figure 3) always oriented towards the center of the earth and which has more significant heat dissipation means.
• the beam forming network is, for reception, in MMIC technology. Low noise amplifiers are located near the radiating panel to minimize ohmic losses due to connections.
• the mechanical pointing of the plate 72 is, compared to an electronic pointing, particularly advantageous because it it is not necessary to oversize the radiating element panels 74 and 76.
• the absence of electronic pointing allows the best use of signal resources to form the beams over a large bandwidth.
• the absence of electronic pointing results in the absence of frequency dispersion which is linked to the absence of phase slope for pointing.
• the pitch of the array of radiating elements can be of the order of 0.9 ⁇ . This easily prevents the formation of network lobes. In addition, this distance between adjacent radiating elements facilitates the installation of the various control elements and limits coupling. Furthermore, for a given size of panels 74, 76, compared with an active antenna for which the pitch of the array is approximately 0.6 ⁇ , the number of radiating elements is reduced, which limits the checks and the cost.
• the mechanical pointing of the panel on the useful area makes it possible to limit to ⁇ 12 ° the useful area of the elementary diagram in which the signals are emitted by a panel of radiating elements. In this way, in a zone, it is possible to correctly isolate the right circular polarization signals from the left circular polarization signals and, thus, to achieve a polarization isolation greater than 20 dB.

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• Physics & Mathematics (AREA)
• Engineering & Computer Science (AREA)
• Astronomy & Astrophysics (AREA)
• General Physics & Mathematics (AREA)
• Remote Sensing (AREA)
• Aviation & Aerospace Engineering (AREA)
• Variable-Direction Aerials And Aerial Arrays (AREA)
• Radio Relay Systems (AREA)

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• 1997
  • 1997-06-26 FR FR9708014A patent/FR2765405B1/fr not_active Expired - Fee Related
• 1998
  • 1998-06-25 AU AU83442/98A patent/AU8344298A/en not_active Abandoned
  • 1998-06-25 CA CA002290676A patent/CA2290676A1/fr not_active Abandoned
  • 1998-06-25 US US09/446,418 patent/US6404385B1/en not_active Expired - Fee Related
  • 1998-06-25 WO PCT/FR1998/001347 patent/WO1999000868A1/fr not_active Application Discontinuation
  • 1998-06-25 JP JP50533199A patent/JP2002506589A/ja active Pending
  • 1998-06-25 EP EP98933719A patent/EP1016161A1/fr not_active Withdrawn

Non-Patent Citations (1)

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