EP0949710A1 - Spherical multilayer focalising lens - Google Patents

Abstract

The focussing lens is simpler and more compact than previous systems.

Description

The invention relates to a multilayer focusing spherical lens capable of to be mounted in a transmit / receive antenna of a system terminal remote transmitter / receiver.

The invention also relates to a transmit / receive antenna. comprising such a lens, as well as a signal transmission / reception terminal radio to and from at least two remote transmitter / receiver systems evolving at different points in the visible space relative to said terminal, this terminal comprising such an antenna.

The invention applies in particular, but not limited to, to high speed data sets to and from a constellation satellites, for public or private use, civil or military.

More generally, the invention relates to any application requiring a lens of simple structure to obtain an antenna compact.

In order to simplify the structure of the lens in an antenna, a first solution is to use a single-layer focusing spherical lens as shown in Figure 1. These lenses have the advantage of being easy to manufacture since they only have a single layer and possibly, as shown, an adaptation layer.

However, for a given dimension, these lenses have a gain fairly low, corresponding to an antenna efficiency of less than 50%. In the example represented in figure 1 in spite of an optimization of the various lens parameters, such as refractive index, diameter and losses by reflection limited by the adaptation layer, the gain remains low taking into account converging rays which represent a loss of energy and disturb the radiation pattern of the antenna in the form of side lobes reassembled. Experience shows that a drop in the refractive index lengthens the focal length, therefore increases the overall volume of the antenna and an increase of this index increases the ohmic losses without improving the focusing of the lens.

To remedy this drawback, a solution would be to oversize the lens to obtain a satisfactory gain, for example of around 31 dB for the applications concerned. However such oversizing is not acceptable because it involves space and additional weight not compatible with a transmission / reception terminal including we seek to minimize the weight and size.

A second solution consists in using a multilayer type lens. Luneberg as shown in Figure 2. These lenses have a plurality concentric spherical layers whose dielectric constant decreases continuously from the center to the edge of the lens. This type of lens has the advantage of having a total spherical symmetry well suited to the realization an antenna aimed at a very wide field of view.

However, for a given dimension, these lenses have also a fairly low gain corresponding to an antenna efficiency of 50 at 60%. Figure 2 shows a divergence of the many rays despite a fairly fine sampling of the theoretical law given by Luneberg. To get a good yield it would be necessary to considerably increase the number layers which represents a totally prohibitive manufacturing cost especially for widely used applications.

Finally the document US 4 307 404 describes a model of multilayer antenna planar and spherical, in which reference is made to an artificial structure spherical.

However, the problem posed in this document concerns the frequency interference. Consequently the deflection of the beam does not applies only for certain frequencies and the antenna described is therefore not very wide band: the beam sweeps mechanically in the same direction to all compatible frequencies of the radiating source.

The invention therefore aims to overcome the disadvantages previously mentioned.

Its object is a focusing spherical lens whose structure is simple and compact and whose manufacturing cost is reduced compared to lenses of the prior art.

The invention further relates to such a lens whose performance especially in terms of yield are better than those of prior art.

To this end, according to a first aspect, the invention proposes a lens focusing multilayer spherical suitable for mounting in an antenna device transmission / reception of a terminal of a remote transmitter / receiver system, and having a concentric focal sphere, characterized in that it comprises two layers, respectively central and peripheral, having constants dielectric values, each dielectric constant value being determined so that the lens focuses the microwave beams parallel to the focal sphere concentric with the lens.

Thus, the bilayer structure of the lens improves focusing and ensures therefore a simplicity of structure while reducing the volume of the lens by compared to that of lenses of the prior art. Of course this supposes to have optimized the two dielectric constant values as well as the radius source position. This gives a yield of 70 to 80% completely satisfactory for the applications concerned.

According to one embodiment, the lens comprises a layer adapter, intended to reduce reflection losses at the dielectric interface of the lens / air.

This adaptation layer has the effect of reducing losses and couplings generated by reflection phenomena on the surface of the spherical lens.

According to another embodiment, the values of the constants dielectric of the two layers are between 2 and 5.

According to a second aspect, the invention proposes an antenna transmission / reception of radio signals from and to at least one system remote transmitter / receiver operating in visible space in relation to said antenna, characterized in that it includes a focusing spherical lens as previously mentioned.

According to a third aspect, the invention proposes a terminal transmission / reception of radio signals from and to at least two remote transmitter / receiver systems operating at different points in the space visible with respect to said terminal, characterized in that it comprises a means for determining the position at a given instant of said remote transmitters / receivers in sight, a means of choosing a transmitter / receiver remote, an antenna according to claim 14, comprising at least two primary sources of transmission / reception, a means of controlling movements primary sources of emission / reception on the focal sphere adapted to avoid that the primary sources only collide and switching means between primary sources.

According to one embodiment of the terminal, each primary source, mounted on a support, is made mobile by the action of at least a couple of motors so as to obtain a displacement of each source on at least the lower half of the focal sphere.

According to a first variant, each primary source is made mobile by the action of a couple of azimuth / elevation motors.

According to a second variant, each primary source is made mobile by the action of a couple of motors called X / Y, the first motor ensuring a rotation of each primary source around a primary axis Ox substantially horizontal and the second motor ensuring rotation of each primary source around a secondary axis Oy made mobile relative to the primary axis by the first motor by being constantly orthogonal to this primary axis.

According to a third variant, a first primary source is rendered mobile by the action of a couple of azimuth / elevation motors and the second source primary is made mobile by the action of a couple of X / Y motors, the motor azimuth of the first primary source also driving the whole the antenna.

According to a fourth variant, each primary source is made mobile by the action of a couple of motors with oblique axes of rotation.

Other characteristics of the invention are explained in a non-explanatory manner. limiting in the following description of embodiments, with reference to attached figures.

Figure 1 is a plan view of a spherical lens focusing monolayer of the prior art.

Figure 2 is a plan view of a spherical lens focusing multilayer known as Luneberg of the prior art.

Figure 3 is a schematic representation of a terminal according to the invention, as well as the elements of the satellite transmission system within of which it is integrated.

Figure 4 is a plan view of a spherical lens focusing bilayer according to the invention.

Figure 5 is a schematic representation of a first mode of creation of a mechanical system for moving primary sources transmission / reception on a portion of the focal sphere of the focusing lens, by pairs of azimuth / elevation motors.

Figure 6 shows an assembly of the tilting electronics of the signals from the primary emission / reception sources of the mechanical system of the figure 5.

FIG. 7 is a variant of the assembly of FIG. 6.

Figure 8 is a schematic representation of a second mode of creation of a mechanical system for moving primary sources transmission / reception on a portion of the focal sphere of the focusing lens, by pairs of azimuth / elevation motors.

Figure 9 is a schematic representation of an embodiment a mechanical system for moving primary sources transmission / reception on a portion of the focal sphere of the focusing lens, by pairs of X / Y motors.

Figure 10 is a schematic perspective representation (Figure 10a) and in section (FIG. 10b) of an embodiment of the primary sources transmission / reception.

Figure 11 is a representation of the mechanism of Figure 8 on which are mounted primary transmission / reception sources conforming to embodiment of FIG. 10.

Figure 12 is a schematic representation of an embodiment a mechanical system for moving primary sources transmission / reception on a portion of the focal sphere of the focusing lens, by pairs of azimuth / elevation and X / Y motors.

Figure 13 is a schematic representation of an embodiment a mechanical system for moving primary sources transmission / reception on a portion of the focal sphere of the focusing lens, by pairs of motors with oblique axes, only one source being active.

Figure 14 is a representation of the embodiment of Figure 13 in which both sources are active.

Figure 15a is a schematic sectional representation of a mode of realization of the lens support.

Figure 15b is an enlarged view of part A of Figure 15a.

Figure 3 shows an antenna 1 for two satellites 2, 3 scrolling on an orbit 4 around the Earth 5. The orbits of the satellites are deterministic and known well in advance. It appears however drifts (limited to about ± 0.1 ° seen from a terminal) linked to the residual atmospheric drag, to the solar radiation pressure, which are corrected at regular intervals by satellite engines. These satellites have reception antennas as well as transmitting antennas 6, 7 transmitting high power signals in directional beams 8, 9.

An individual or a business using the transmission system data is provided with an antenna terminal comprising on the one hand an antenna 1, fixedly installed for example on the roof like a satellite TV antenna classic. This antenna terminal, or transmission / reception terminal comprises by elsewhere, control electronics 10 monitoring the satellites, transmitting and receiving radio signals, and decoding information encrypted for which the user has an authorization (subscription). The antenna terminal is also connected to a microcomputer type computer 11 PC, comprising a non-detailed memory device, a keyboard 12 and a screen 13. The memory device of the microcomputer includes a recording of the information characterizing the orbits of the satellites (updated ephemeris periodically by signals from stations), and software allowing to calculate at a given instant, as a function of this orbit information and the geographic location of the antenna terminal (longitude, latitude), the local geographic angles (azimuth, elevation) of the visible satellites, which are assigned by the station (or gateway) which manages the area concerned.

The antenna terminal can also be connected in another embodiment to a television set 14 for receiving programs on command, said television set can be fitted with a camera 15 allowing applications of videoconference, as well as a telephone 16 and a fax, not shown. Both types of user interfaces (microcomputer or television set) can be present simultaneously; in this case, the various devices requiring the data transfer via the antenna terminal are connected to a box connector 17 possibly integrated into the housing 10 containing the electronics control of the antenna terminal.

In more detail the antenna 1 comprises a spherical lens focusing 21 having a focal sphere S.

According to the invention, this focusing lens has two layers, respectively central 21a and peripheral 21b, having constants dielectric values, each dielectric constant value being determined so that the lens focuses the microwave beams parallel to the focal sphere S concentric with the lens.

The determination of each dielectric constant value can also integrate the fact that the paths of the microwave beams must be equal, that the power density between two consecutive rays sampling the source diagram is constant, namely that the source diagram be adapted to the spatial distribution of the energy received by it, and that the reflections at the interface of the two layers are weak. In the second case this maximizes the gain of the antenna by generating a tube of quasi-uniform energy at the exit of the lens.

It may be necessary to reduce reflections at the dielectric / air interface of the lens if you want to improve the performance of the antenna. A diaper adaptation of a thickness of a quarter wavelength can then advantageously be provided on the periphery of the lens. She is advantageously produced for example in the form of a coating in dielectric index equal to the square root of the layer dielectric index peripheral. Another variant consists in drilling on a thickness of a quarter wavelength a plurality of blind holes, in density such that the average of the index of the remaining dielectric and the index of the air in the holes equals an index equal to the square root of the dielectric index of the peripheral layer 21b. This method, which amounts to "simulating" a dielectric of determined permittivity, is classic. Blind holes can also be replaced by crossed grooves.

The central layers 21a and peripheral 21b of the spherical lens contain low loss, moderate density material.

For example, the central layer 21a is made of glass and the layer peripheral 21b is made of a dielectric material with adjustable constant, such as a foam loaded with calcium titanate or barium, and / or microbeads metallic glass.

So as to optimize the characteristics of the lens 21 and by way of consequence of antenna 1, the values of the dielectric constants of the two central layers 21a and peripheral 21b are between 2 and 5. In the example shown in Figure 4, a couple of optimum value is of the order of 4.5 for the peripheral layer 21b and 3.7 for the central layer 21a.

The antenna 1 also includes two primary sources 23, 24 transmission / reception of spherical wave beams and mechanical assembly represented in FIGS. 5, 8, 10, 11, 12 and 13 for positioning these sources transmission / reception primaries.

The two primary sources 23, 24 of emission / reception of waves spherical are movably arranged on a portion of the focal sphere S of the focusing lens. These are conventional horn antennas in the satellite TV reception for example, for which horns illuminated by parabolic reflectors are used.

The specific characteristics of the cones used here are linked to part at the angle from which they see the focusing lens and secondly at the wavelength used. Regarding data rates, consider for various applications covering interactive games, teleworking, distance education, interactive video, Internet-type data transmission, a maximum transmitted volume of the order of 1 to 5 Mbps, and a maximum received volume of an order of magnitude higher, that is to say from 10 to 50 Mbps. Furthermore, for make a compact antenna the position of the horns is as close as possible of the spherical lens: their useful radiation cone being very wide, the diameter of their mouth will be small, from 20 to 25 mm in the example considered of a system operating in the Ku band, ie 11.7 to 14.3 Ghz.

A simple mechanical assembly allowing to fulfill the function of displacement of the two sources on a portion of the focal sphere, consists in make the two sources mobile by the action of a couple of motors azimuth / elevation for each source.

Two embodiments of this type of assembly are shown in Figures 5 and 8.

FIG. 5 illustrates a mechanical assembly in which the displacement of the two horns is made independently. Source support mainly comprises a concentric double crown 32, 33 and swings 30, 31 supporting the horns 23, 24. To ensure that the portion of sphere determined by the axes of freedom of the horns in this configuration corresponds well to the focal sphere of the focusing lens 21, this is arranged in the center of the double crown, by means of mechanical support not shown here, but of a classic nature.

In this configuration, the first horn 23 is moved by a support "Interior" to the support of the other horn 24. This first horn 23 is attached by its upper part has a swing type support structure 30, made of rigid plastic, the two arms of which are formed in an arc of a part low to avoid hindering the passage of the other swing 31 supporting the second horn 24. The swing 30 is attached along an axis A to a inner crown 32.

The swing of the swing relative to the vertical is achieved by a tilting motor 36, for example of the electric stepping motor type, arranged along the axis A inside the ring 32. This movement allows reach an inclination β ₁ , between -80 ° and + 80 °. This inclination is a function of the elevation of the satellite: it is zero for a satellite located at the zenith of the place, and is ± 80 ° for a satellite located 10 ° above the horizon of the place.

The inner ring 32 is rotated by another electric motor 34, also of the stepping type, the action of which makes it possible to determine an azimuth α ₁ between 0 ° and 360 °. This motor is for example disposed outside of the two crowns, and drives the inner crown in rotation via a toothed crown.

We therefore understand that the combination of the actions of the two engines azimuth 34, tilt 36 allows the first horn 23 to be placed at any point chosen on a cap of the focal sphere with an opening angle of ± 80 °, the horn remaining permanently pointed towards the center of the focusing lens. Control of the two motors 34, 36 makes it possible to follow a traveling satellite, the speed of travel of the satellite corresponding to a movement of the horn by example of an elevation position -80 ° to an elevation + 80 ° in ten minutes about.

Thus the two azimuth 34 and tilt 36 motors constitute a couple of azimuth / elevation motors.

In case the system shares the same frequency bands as geostationary satellites (which is the case in Ku band), non-interference with them is ensured by switching traffic to another satellite, as soon as the one that is pursued approaches less than 10 ° from the geostationary arc, in angle seen from the terminal.

The support for the second horn is very similar to that described above for the first horn. This horn 24 is attached by its lower part to a swing structure 31, of sufficient size so as not to risk hindering the passage of the interior swing. This swing is suspended from an outer ring 33. The angle of azimuth α ₂ of the antenna 24 is determined by the action of an azimuth motor 37, and the angle of inclination β ₂ is obtained by the action of a tilt motor 35 at all points identical to the positioning motors of the other antenna.

Electronic control and supply of stepper motors azimuth and inclination of the horns is not described here but is known to man art.

Regarding the electronic assembly allowing the tilting between the two horns 23, 24, it is illustrated in FIG. 6. A signal channel to emit 42 including an amplifier 46 (“SSPA: Solid State” technology "Power Amplifier": solid state power amplifier), and a signal channel receipt 43 including an amplifier 47 (“LNA: Low Noise” technology Amplifier ”: low noise amplifier) are connected to a circulator 41. This circulator of known nature is a passive component causing the circulation of signal in a given direction between its three ports and allowing decoupling transmission / reception. It is for example made of ferrite. This circulator 41 is connected to a switch 40 for selective connection to one or other of the horns. The switch 40 is connected to the horns by flexible coaxial cables 44, 45. It is of known diode type, and switches in less than a microsecond between the two cones. Additional components not mentioned in this description, such as power supply, are of a conventional nature in this field.

The operating mode of the device comprises several phases. The first is the installation of the device. It includes the mechanical fixing of the antenna on the roof of a building, checking the horizontal axes and the orientation north / south of the antenna. Then the antenna is connected to its power supply, to a pilot microcomputer 11, and to user devices TV 14, camera 15, phone 16.

In the same phase, the ephemeris of the constellation satellites (orbital parameters of position and speed at a given initial time) are entered in memory of the computer intended to serve as host and pilot of the antenna. These data can be provided in the form of a diskette.

After entering the local time and the terrestrial position of the antenna terminal (latitude, longitude), the computer can calculate the current position of the constellation satellites as a function of time since the instant corresponding to the memorized orbital parameters, and compare these positions with the theoretical visibility area from the antenna terminal. A procedure for automatic calibration of the system is possible, with pointing of the 2 horns 23, 24 on the theoretical position of satellites in view, followed for a few instants, and verification from the acquired power level data received and transmitted, the spatial orientation of the antenna, and the quality of monitoring. A diagnosis of corrections to be made to the installation is carried out automatically in based on this calibration data.

In the current use phase, when the user puts the system running (computer running and antenna power supply), the piloting calculates the position of the satellites at this time, and therefore determines which satellites are in sight at this time from this position of the globe. The station him affects one of the satellites in visibility depending on the availability of data data (therefore in bandwidth) of the various satellites at this time. The computer 11 calculates the corresponding position to be taken by a horn on the focal sphere of the focusing lens, sends the movement orders to stepper motors for moving this horn, and selectively connects this horn, corresponding to the most visible satellite, to the transmission and reception. Data transmission and reception are then possible.

The computer then continuously calculates the corrective movements to bring to the position of the horn used to follow the satellite, and pilot the engines position accordingly. Positioning accuracy required for tracking regular spacecraft is determined by the width of the main lobe of the antenna, and the acceptable attenuation rate of the signal before displacement of said antenna. In this case, a 5 ° lobe opening and loss of signal acceptable of 0.2 dB lead to a pointing accuracy of 0.5 ° of the horn by the motors, which corresponds to a typical focal sphere of 20 cm radius at a positioning accuracy of 2 mm. A satellite tracking scrolling at approximately 1500 km then leads to a maximum speed of the horn of one mm per about a second. When tracking a satellite, the horn ensuring the flow of communications has priority when traveling on the other horn, the software ensuring at all times that no collision occurs by moving the second horn off the road of the first.

According to the satellite elevation criterion less than 10 ° (satellite approaching the horizon), or abnormal drop in the received signal (taking into account trees, hills or other local obstacles, permanent or not, or passage in the band near the geostationary arc, in which interference by or to geostationary satellites means that the link must be interrupted), the computer determines the second most visible satellite, after a short dialogue with the station to check the speed availability of this satellite, it positions the second cornet corresponding to this position. Then the selective connection of this horn is carried out and the tracking of this satellite is carried out. Time to switching between the two horn antennas, 1 microsecond in the realization presented, leads, for a volume of data transmitted of 1 Mbps to 50 Mbps maximum, data loss corresponding to about 1 to 50 bits. The reconstruction of lost data is carried out by using error correcting codes transmitted with the signal.

The updating of the ephemeris is carried out periodically in from the station directing the area where the terminal is located, via the network satellite itself.

As seen in the description, the motors used in this mounting are of power adapted to the displacement of a low mass, a few hundred grams at most, which allows the use of motors inexpensive, very conventional in trade. This is an advantage over to the satellite tracking solution using two antennas, for which the motors must be adapted to the precise mass positioning of a few kg, and are therefore more expensive.

The levels of accuracy required in positioning the antenna of a part and the time between two movements on the other hand guarantee that an assembly classical mechanics and simple electronics can reach these levels. It can therefore be seen that the solution chosen is economical to manufacture.

The implementation as it has been described provides both a device for low cost, the various components being of known type or specification undemanding manufacturing, and a compact device.

It should be noted that the motorization and the supports are protected by a cylindrical radome R (figure 8) which ends upwards in half sphere close to the lens; the catch in the wind, indifferent to the direction, then presents a low drag coefficient, which is an advantage over conventional antennas without radome, for which there are problems of movements maintained during gusty winds.

In another variant, the electronic assembly allowing the tilting between the two horns 23, 24, is replaced by an illustrated assembly in FIG. 7. In this arrangement, each horn 23, 24 comprises a circulator 41 ', 41 "to which amplification modules are directly connected on the transmit signals 46 ', 46 "and receive signals 47', 47". Amplifiers emission signals from the two primary sources are connected by two cables coaxial 45 ', 44' to a selective connection device 40 'to which the signal to be transmitted by a channel 42. Similarly, the low noise amplifiers of the received signals are connected by coaxial cables 45 ", 44" to a device selective connection 40 "to which is connected a channel 43 of received signal.

This provision is intended to reduce the impact of signal loss if producing in flexible coaxial cables, and estimated around 1 dB in each cable whose length including the relaxation loops is estimated between 70 and 90 cm. This variant has a higher cost by duplicating amplifiers, but allows for equal amplifier power, improving the Equivalent Isotropic Radiated Power (EIRP) of around 1 dB, and the factor reception merit (G / T) of about 2 dB. With equal antenna performance, this allows a reduction of the dimensions of the spherical lens, therefore of any the antenna.

In a variant relating to the satellite tracking method, a active technique replaces the passive technique described, in which as we the data characterizing the position of the satellites are simply stored in advance in computer memory, and for which it is assumed that we thus position the primary sources in the right place at the right time, without real time control. In the variant envisaged, each horn has several receivers, for example four receivers arranged in a square matrix, and provides output signals corresponding to a sum and a difference signals received by the different receivers. At the start of a given satellite, a horn is positioned according to the data calculated by the computer 11. Then the analysis of the evolution over time of the signals sum and difference makes it possible to determine in which direction the satellite is moves and follow it accordingly. Automatic updating of stored ephemeris, depending on the positions of the satellites actually observed, is possibly performed regularly by the host computer.

In another variant not shown, in which the user does not no microcomputer, satellite tracking software and memory recording systems are integrated into a microprocessor memory, for example integrated in a box to be placed under a TV set, typical size of traditional encrypted TV decoders, and which can be confused with a modulator / demodulator suitable for encrypted broadcasts. A procedure for downloading ephemeris at regular intervals is to all the ways provided automatically, without user intervention.

It should be noted that in all the previous variants, if the strip of operation of the multimedia system is the same as that of television direct by satellites, the two sources can be placed in the positions adapted to target two geostationary satellites: the same antenna terminal is then used alternately for the multimedia application, and for the reception of programs broadcast by these two satellites, these can be changed to will, by moving sources.

In yet another variant, a device similar to that of the invention is no longer installed at the ground terminal, but at a satellite, for example observation satellite to send images to only a few ground stations whose position can be arbitrary. The principle for tracking ground stations is similar for the satellite to that of traveling satellites for a ground terminal. In this application, the size of the ground stations can be very clearly reduced (for example by a factor of 10 if a gain of 20 dB is achieved on the signal received by the antenna) compared to conventional reception antennas suitable for satellites emitting in wide beam, therefore with a power received weak. This can also improve the confidentiality of data sent. Finally, the simplicity of the solution, its low cost (compared to particular to active antennas with very many elements) and its low power consumption make its implementation very favorable on satellite.

According to another embodiment as shown in FIG. 9, the sources of the antenna are printed blocks of the type known as "patches". These cobblestones can either be unique by source, as shown in Figures 10a and 10b, or grouped into small networks (Figure 9) allowing compensate for possible aberrations in the focusing system. This variant to pavers, being more compact, is particularly suitable for the spherical lens because it makes it possible to significantly reduce the overall size of the antenna terminal.

It is also possible to envisage a device with three sources, including one is permanently targeting a geostationary arc satellite. Such a layout allows, with a single antenna, or multimedia applications to high speed of information to the traveling satellites (which require two sources mobile), or the reception of direct television images from a satellite geostationary (even if it uses a different frequency band than the system multimedia), at the user's choice, and without repositioning delay mobile sources.

For example if the lens remains fixed, a source stuck to the lens receives the TV shows, while both mobile sources provide the same time monitoring and switching required for the multimedia mission.

If the lens is rotating, in particular to reduce masking by the supports (assembly of figures 13 and 14), the third source can also be mounted on a mobile support with respect to the lens and the two other sources.

Other embodiments of the mechanical assembly making it possible to fulfill the function of displacement of the two sources on a portion of the sphere focal, will be described below. Of course, the different modes of realization described above of the electronic tilting assembly of the sources, the satellite tracking method and the sources themselves may apply to the following.

FIG. 8 represents a variant of the mechanical assembly with motors azimuth / elevation of figure 5. Each source 23, 24 is mounted on an arm support 50, 51 comprising an arc of a circle 52, 53 concentric with the focal sphere S positioned respectively on one half of the lower part of the sphere focal length and a rotary drive shaft 54, 55 extending parallel to the vertical and being coupled to a motor called azimuth 56, 57. Thus the primary sources 23, 24 are made mobile according to a separate azimuth Az1 and Az2 respectively.

On the other hand, each primary source 23, 24 is guided on its arc of circle 52, 53 in a slide, for its movement in elevation El1, El2, which in the example chosen, is between 1 and 80 °, by elevation motors 58, 59. These elevation movements El1 and El2 make it possible to define the axes of targets S1 and S2 of the two visible satellites.

In another variant of mechanical mounting for supporting the mobile sources, shown in FIG. 9, each primary source 23, 24 is made mobile by the action of a so-called X / Y motor torque. A semi-circular arc 60 is attached at two diametrically opposite points, for example East and West, of the focal sphere. A source 23 is movable along this arc acting as a slide by the action of a secondary electric motor 61 attached to the source. The second source 24 is mounted identically on another arc 62 being guided by a secondary motor 63. Although this is not shown, each semi-circular arc 60 and 62 is rotated around a primary axis Ox by a primary motor constituting the second motor of the X / Y motor couple, the circular arc 60 having a radius less than the circular arc 62. The secondary motors 61 and 63 thus make it possible to make the sources mobile around a secondary axis Oy itself made movable relative to the primary axis by means of the primary motors, the secondary axis Oy always being orthogonal to the primary axis Ox. One of the sources transmits and receives towards the "north" satellites, the other transmits and receives towards the "south" satellites, this to avoid conflicts of position of the sources. Relative repositioning of the two arms where arcs are possible if one passes over the lens.
the assemblies of FIGS. 8 and 9 have an advantage of compactness compared to the assemblies of FIGS. 5 and 7. They are also more suitable for obtaining high angles of illumination of the lens by the sources, this being necessary in the case of using a spherical focusing lens.

In another connection variant of the amplifiers mounted before primary sources, using a mechanical assembly of sources in accordance with Figure 9 and as shown in Figure 11, each hoop is a guide waves, thus carrying the microwave signal, and a conventional rotating joint is mounted at the hinge joint. This arrangement reduces the signal losses and therefore move the amplifiers away from primary sources.

Another variant of replacing cables connected to sources primary consists in using optical fibers to ensure the emission and / or the reception of signals. These fibers have an advantage of flexibility in depending on the movement of the source and amplifier assembly. The support can itself be used as an optical conductor to transmit information from movement of the motor moving the primary source.

The device then includes an electroluminescent diode for the emission of light (on a band of a few hundred MHz) and a photodiode for receiving optical data. A mirror is mounted on the level the point of attachment of the arches, for the transmission of light to the tube optical conductor.

The tube can also be used for the transmission of electric current for the power of the primary source, the amplifier and the motor displacement, having two spaced apart conductive tracks and having contactors at the source for receiving this electric current.

In another variant of mechanical source support mounting mobile, shown in Figure 12 a first primary source 23 is rendered mobile by the action of a couple of azimuth / elevation motors 70, 71 and the second primary source 24 is made mobile by the action of a couple of X / Y motors 72, 73, the azimuth motor 70 of the first primary source further driving the whole antenna.

In another variant of mechanical source support mounting mobile, shown in Figures 13 and 14 each primary source 23, 24 is made mobile by the action of a couple of motors with oblique axes of rotation 80, 81 and 82, 83.

Each primary source support comprises an arm 84, 85 and a forearm 86, 87, the primary source 23, 24 being fixed on a free end 88, 89 of the forearm 86, 87. The first motor 80, 82 drives the arm 84, 85 in rotation about a primary oblique axis O ₁ , O ₂ offset by a primary angle α _o1 , α _o2 , relative to the vertical, the second motor 81, 83 driving the front- arm 86, 87 in rotation relative to arm 84, 85 about a secondary oblique axis O ' ₁ , O' ₂ offset from the vertical by a secondary angle α ' _o1 , α' _o2 greater than the angle primary α _o1 , α _o2 , the primary and secondary axes of each pair of motors extending on either side of the vertical.

We can also provide that the terminal, in which the lens is mounted on a support separate from that of the primary sources, further comprises an additional motor 90 intended to drive the support of the lens of such so that it extends substantially parallel to the beams.

According to another embodiment (Figures 15a and 15b) the support of the lens 21 consists of a substantially cylindrical crown 91 on the one hand mechanically coupled to the lens and on the other fixed to a platform 92. In this embodiment the platform 92 is fixed and is used in particular to place the terminal on the house or the land on which it will be used.

The two arms 84, 85 of the primary sources (FIGS. 13 and 14) are then fixed to this platform 92 either directly or via the motor additional 90 which, in this case, does not drive the lens. This configuration provides primary sources with an additional degree of freedom for monitoring satellites.

The mechanical coupling means of the lens with the crown 91 includes a flange 93 formed on the periphery of the lens. for example the flange 93 can be molded with the lens, in particular in the central zone of the sphere.

The flange 93 cooperates with the crown 91 which for this purpose comprises a angled end 91a on which the collar 93 rests.

The crown 91 can be part of the radome R as described above. in particular with reference to FIG. 8. For this purpose the radome R comprises two respectively upper Ra and lower parts Rb. The lower part Rb forms the crown 91.

According to the embodiment described above, the collar 93 of the lens 21 will then be supported on the lower part Rb. In this case, the part upper Ra can be replaced by a thermoformed plastic envelope thin but rigid enough to play its protective role.

Of course, the invention is not limited to the examples described previously, but can be applied to other embodiments such as by example active scanning antennas, and more generally to any realization using one or more means equivalent to the means described, to perform the same functions, with a view to obtaining the same results, such as for example each primary source, mounted on a support, is made mobile by the action of at least a couple of motors so as to obtain a displacement of each source on at least the lower half of the sphere focal.

Claims (29)

Multilayer focusing spherical lens (21) suitable for mounting in a transmitting / receiving antenna device (1) of a terminal of a system remote transmitter / receiver, and having a concentric focal sphere (S), characterized in that it comprises two layers, respectively central (21a) and peripheral (21b), having different dielectric constants, each value of dielectric constant being determined such that the lens (21) focuses the parallel microwave beams towards the focal sphere (S) concentric to the lens. Spherical focusing lens according to claim 1, characterized in what each dielectric constant value is optimized so that the ray paths representing the propagation of microwave energy are equal. Spherical focusing lens according to claim 1 or 2, characterized in that each dielectric constant value is determined by so that the power density between two consecutive rays is constant. Spherical focusing lens according to any one of Claims 1 to 3, characterized in that each constant value dielectric is determined so that the reflections at the interface of the two layers are weak. Spherical focusing lens according to any one of Claims 1 to 4, characterized in that it comprises a layer adapter (22), intended to reduce reflective losses at the interface dielectric of the lens / air. Spherical focusing lens according to claim 5, characterized in that the adaptation layer (22) is of the quarter wave type. Spherical focusing lens according to claim 6, characterized in that the adaptation layer (22) consists of a dielectric with an index equal to the square root of the dielectric index of the peripheral layer (21b). Spherical focusing lens according to claim 6, characterized in that the adaptation layer (22) has a thickness equal to a quarter of the wavelength used, pierced with a plurality of blind holes with a density of drilling adapted to create an equivalent index equal to the square root of the index of the dielectric of the peripheral layer (21b). Spherical focusing lens according to any one of Claims 1 to 8, characterized in that the layers (21a, 21b) contain a low loss material. Spherical focusing lens according to any one of Claims 1 to 9, characterized in that the central layer (21a) is made of glass. Spherical focusing lens according to any one of claims 1 to 10, characterized in that at least one of the two layers, and in particular, the peripheral layer (21b) contains a dielectric material with adjustable constant, such as a foam loaded with calcium titanate or barium and / or metallized glass microbeads. Spherical focusing lens according to any one of Claims 1 to 11, characterized in that the values of the constants dielectric of the two layers (21a, 21b) are between 2 and 5. Transmission / reception antenna (1) for radio signals from and to at least one remote transmitter / receiver system operating in space visible with respect to said antenna, characterized in that it comprises a focal spherical lens (21) according to any one of claims 1 to 12. Transmitting / receiving antenna (1) according to claim 13, characterized in that it comprises at least one primary source (23, 24) transmission / reception of signals in the form of quasi-spherical wave beams, mobile on a portion of the focal sphere (S), a means control (10) of the position of each primary source transmission / reception in relation to the known position of a system remote transmitter / receiver. Terminal for transmitting / receiving radio signals from and to at least two remote transmitter / receiver systems operating at points different from the visible space with respect to said terminal, characterized in that it includes means for determining the position at a given instant of said remote transmitters / receivers in sight, a means of choosing a transmitter / receiver remote, an antenna (1) according to claim 14, comprising at least two primary sources (23, 24) of transmission / reception, a means of controlling the displacements of the primary sources of emission / reception on the focal sphere (S) suitable for preventing primary sources from colliding and means switching between primary sources. Terminal according to claim 15, characterized in that it comprises besides means for recovering data lost during the time of switching. Terminal according to claim 15 or 16, characterized in that the primary sources (23, 24) take the form of mobile horn antennas on a portion of the focal surface. Terminal according to any one of claims 15 to 17, characterized in that each primary source (23, 24), mounted on a support, is made mobile by the action of at least a couple of motors so as to obtain a displacement of each source on at least the lower half of the sphere focal. Terminal according to claim 18 in which the lens (21) is mounted on a support distinct from that of the primary sources, characterized in that it further comprises an additional motor (90) intended to drive the lens support (21) so that it extends substantially parallel to the beams. Terminal according to claim 18 or 19, characterized in that each primary source (23, 24) is made mobile by the action of a couple of azimuth / elevation motors (34, 35, 56, 57; 36, 37, 58, 59). Terminal according to claim 20, characterized in that each primary source support comprises a means forming a swing (30, 31), on which the primary source (23, 24) is fixedly mounted, each swing being made movable on the one hand along an axis by a motor called azimuth (34, 35) of the couple of motors, and secondly relative to the vertical by the other motor says tilt (36, 37) of the engine torque. Terminal according to claim 20, characterized in that each primary source support comprises an arm (50, 51) forming an arc of a circle concentric with the focal sphere, positioned respectively on one half of the lower part of the focal sphere, each arm being made mobile according to a azimuth by a motor called azimuth (56, 57) of the couple of motors, and each source primary being made movable along the arc by the other motor (58, 59) of the torque engine. Terminal according to claim 18 or 19, characterized in that each primary source is made mobile by the action of a couple of motors known as X / Y, the first motor ensuring rotation of each primary source around with a substantially horizontal primary axis Ox and the second motor (61, 63) ensuring a rotation of each primary source around a secondary axis Oy made movable relative to the primary axis by the first motor by being constantly orthogonal to this primary axis. Terminal according to claim 18 or 19, characterized in that a first primary source (23) is made mobile by the action of a couple of azimuth / elevation motors (70, 71) and the second primary source (24) is rendered mobile by the action of a couple of X / Y motors (72, 73), the azimuth motor (70) of the first primary source (23) further driving the entire antenna (1). Terminal according to claim 18 or 19, characterized in that each primary source (23, 24) is made mobile by the action of a couple of motors (80, 82; 81, 83) with axes of oblique rotation (O ₁ , O ₂ ; O ' ₁ , O' ₂ ). Terminal according to claim 25, characterized in that each primary source support (23, 24) comprises an arm (84, 85) and a forearm (86, 87), the primary source being fixed on a free end (88 , 89) of the forearm, the first motor (80, 82) driving the arm in rotation about a primary axis (O ₁ , O ₂ ) oblique offset by a primary angle (α _o1 , α _o2 ) relative to the vertical, the second motor (81, 83) driving the forearm in rotation relative to the arm about a secondary axis (O ' ₁ , O' ₂ ) oblique offset from the vertical of a secondary angle (α ' _o1 , α' _o2 ) greater than the primary angle (α _o1 , α _o2 ), the primary and secondary axes of each pair of motors extending on either side of the vertical. Terminal according to any one of claims 15 to 26, characterized in that at least one primary source has a module amplification of transmitted and received signals. Terminal according to any one of claims 15 to 27, characterized in that the remote transmitters / receivers are satellites of a constellation, and that the means of determining the position at a given instant satellites in view includes a database of orbital parameters of each satellite at a given time, a means of memorizing the parameters terminal position terrestrial, software for calculating the current position of each satellite from initial orbit parameters and elapsed time from the initial moment, a software for comparing the orbital position with the angular area visible from the position of the terminal and a means of updating regular database of satellite orbital parameters. Terminal according to any one of claims 15 to 28, characterized in that it further comprises a primary source mounted in sight of a remote transmitter / receiver system fixed in visible space with respect to the antenna.

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