WO2010149605A1

WO2010149605A1 - Method of helping to steer an antenna, power-assisted steering antenna using this method and mobile terminal comprising such an antenna

Info

Publication number: WO2010149605A1
Application number: PCT/EP2010/058700
Authority: WO
Inventors: Gérard Raguenet; Nicolas Chuberre; Olivier Courseille
Original assignee: Thales
Priority date: 2009-06-26
Filing date: 2010-06-21
Publication date: 2010-12-29
Also published as: EP2446507A1; FR2947388B1; ES2527217T3; EP2446507B1; FR2947388A1

Abstract

The method for helping to steer an antenna consists in using an antenna comprising a plurality of radiating elements distributed over a surface of a radiating panel, and furthermore consists: in a first step, in activating only first radiating elements located in a first central portion of the radiating panel; manually presteering the antenna in elevation and in azimuth, in a direction corresponding to a maximum level for receiving a signal transmitted by a satellite; in a second step, in then activating simultaneously the first radiating elements and at least the second radiating elements located in a second portion of the radiating panel surrounding the first central portion; and manually refining the steering direction of the antenna in elevation and in azimuth. Application to the field of satellite communications, especially for applications using mobile terminals.

Description

Method of assisting the pointing of an antenna, assisted pointing antenna implementing this method and mobile terminal comprising such an antenna

The present invention relates to a method of assisting the pointing of an antenna and an assisted pointing antenna implementing this method. It applies in particular to the field of satellite communications and more particularly for broadband applications using nomadic terminals, that is to say transportable, but usable in a fixed position.

Satellite data communication systems require the use of antennas that are correctly oriented relative to the satellite. In the case of Ka-band applications using nomadic terminals equipped with a directional antenna of a format such as A5 (15 * 21 cm) or A4 (21 ^* 29.7 cm), the pointing of the antenna must be realized with a precision of the order of the degree, even a few tenths of a degree, which can not be achieved manually without using means of pointing aid.

There are antennas whose pointing is aided by mechanical means. A rough score is manually performed by the user, for example by operating the antenna in rotation so as to pre-position it with respect to the satellite. Then the user performs a small scan in site and azimuth to determine the maximum level of signal received from the satellite. The antenna is equipped with a sound signal generator whose frequency is proportional to the level of the received signal. Intuitively, the user locates the maximum reception level corresponding to the center of the antenna lobe. This technique is implemented on terminals operating in Ku-band and equipped with bulky parabolic antennas whose size is of the order of 60 to 70 cm in diameter.

Other flat antennas are equipped with an electronic pointing mechanism, such as, for example, antennas using the process known as "conical scan". According to this known method, a rough score is manually made by the user, for example in rotating the antenna so as to pre-position it with respect to the satellite. The manual pointing thus achieved is located in an estimated error cone of the order of plus or minus ten degrees around the actual position of the satellite. To refine this score, a pointing aid is then performed electronically by an automated algorithm that successively scans all the angular domains included in the uncertainty cone, and calculates for each domain, the energy level received with respect to the noise. to derive the precise direction of the satellite. The search for the satellite is done via a signal received on a radiofrequency channel of the satellite or a signal coming from a beacon and makes it possible to define the angles of pointing in site and in azimuth which must be given as set the attenuators and phase shifters of the electronic antenna in order to point the antenna beam correctly. This technique makes it possible to perform a pointing aid and acquisition of the carrier of the satellite in a correct way, but has the disadvantage of requiring a large number of controls with an antenna comprising a large number of phase shift modules and formation of bundles and be very complex and very expensive to implement, which is unacceptable for use with low-cost terminals such as desktops.

The object of the invention is to provide a method of assisting the pointing of an antenna, preferably of planar type, not having the drawbacks of known methods and assisted pointing antennas, comprising means for assisting pointing. simple to implement and at a lower cost and to achieve a fine score, quickly and reliably.

For this, the invention relates to a method of assisting the pointing of an antenna, consisting in using an antenna comprising a plurality of radiating elements distributed over a surface of a radiating panel, characterized in that it consists of:

in a first step, to activate only first radiating elements situated in a first central part of the radiating panel, to manually provide a pre-score of the antenna in elevation and in azimuth, in a direction corresponding to a maximum level of reception of a signal emitted by a satellite; in a second step, then simultaneously activating the first radiating elements and at least the second radiating elements situated in a second part of the radiating panel surrounding the first central portion and manually refine the pointing direction of the antenna in elevation and in azimuth.

Advantageously, the second step comprises at least two sub-steps of successively activating an increasing number of radiating elements from the first central part towards the second part and then towards a peripheral part of the radiating panel surrounding the second part up to the second part. acttvation of all the radiating elements of the antenna and, at each substep, manually refine the pointing direction of the antenna in site and in azimuth.

Advantageously, the activation of the radiating elements of the antenna is achieved by manually actuating at least two switching means.

Advantageously, the pointing direction of the antenna is adjusted at each step by actuating verniers adjusting in rotation about two axes respectively in elevation and in azimuth.

Preferably, the maximum level of reception of the signal emitted by the satellite is determined by viewing a light signal or by hearing a sound signal, the light signal - or sound depending on the reception level.

The invention also relates to an assisted pointing emission and reception antenna for implementing the method according to one of the preceding claims, the antenna comprising a plurality of radiating elements distributed over a surface of a radiating panel. , characterized in that it further comprises at the reception: first activation means for activating only first radiating elements situated in a first central part of the radiating panel,

at least second activation means for at least second radiating elements located in a second part of the radiating panel surrounding the first central part, and at least a first means for combining the signals received by the radiating elements activated by the first and the second activation means, manual adjustment means for pre-pointing the antenna and for fine-tuning the pointing in azimuth and in a direction corresponding to a maximum level of reception of a transmitted signal by the satellite.

Advantageously, the first and second activation means are microwave switches.

Advantageously, the adjustment means are step verniers.

Advantageously, the antenna further comprises, on reception, third activation means for activating third radiating elements situated in a third peripheral part of the radiating panel surrounding the second part and at least one second means for combining the signals received by the radiating elements activated by the first, the second and the third activation means.

The invention also relates to a mobile terminal comprising an assisted pointing antenna.

Other features and advantages of the invention will become clear in the following description given by way of purely illustrative and non-limiting example, with reference to the attached schematic drawings which represent: FIG. 1 a, 1 b: two diagrams of an example of an antenna comprising a radiating panel, according to the invention; FIG. 2a: a diagram of an enlargement of the central part of the antenna of FIG. 1, according to the invention; FIGS. 2b, 2c, 2d: a diagram of an example of a spot radiated by the central part of the antenna and two corresponding radiation patterns, according to two orthogonal planes between them, according to the invention; FIG. 3a: a diagram of an enlargement of the central part and of an intermediate part of the antenna activated simultaneously, according to the invention; FIGS. 3b and 3c: two radiation patterns in two planes orthogonal to each other, corresponding to the central part and to the intermediate part of the antenna activated simultaneously, according to the invention; FIGS. 4a and 4b: two radiation patterns in two planes orthogonal to one another, corresponding to the activation of all the radiating elements of the antenna, according to the invention; FIG. 5: an example of architecture of an antenna, according to the invention.

The method of assisting the pointing of an antenna according to the invention comprises at least two successive steps, the first step makes it possible to acquire a signal derived from a satellite, for example of the geostationary type, and to realize pre-pointing the antenna in the direction corresponding to a maximum energy level of this signal. During this first step, the pre-pointing is achieved by activating only a few radiating elements of the antenna located at the center of the radiating panel so as to obtain a radiated beam, called a spot, having a broad radiation pattern, and therefore not very directional, and a low gain, which makes it possible to obtain a fast but coarse manual score with a low precision, so with a large margin of error.

The second step makes it possible to refine the pointing direction and thus reduce the margin of error. In this second step, the score is refined by activating a greater number of radiating elements from the center to the periphery of the radiating panel of the antenna, so as to obtain a finer spot and therefore more directional.

Opttonnellement, the second step can be split into several successive sub-steps. In this case, the number of radiating elements activated from the center to the periphery is, from one substep to the next, successively more and more important until the activation of the complete antenna, which allows to obtain more and more directive spots and to refine more and more the score achieved in successive sub-stages. Typically, two or three steps are sufficient.

In the exemplary embodiment described below, the pointing aid method is applied to an antenna of A4 format. In this example, three steps are sufficient to obtain a positioning of the radio axis of the antenna towards the satellite with a precision of the degree. The antenna example diagrammatically shown in FIG. 1a comprises a radiating panel 10 consisting of an array of radiating elements 12 of patch type. FIG. 1b shows an example of distribution of the radiating elements of the antenna into fifteen subassemblies, called base bricks 11, each base brick 11 comprising thirty two radiating elements 12 arranged in a rectangular configuration. By way of nonlimiting example, the directivity of each radiating element may be of the order of 9 dBi and the directivity of a basic brick may be of the order of 24 dBi.

In the first step of the method according to the invention, only the central portion 13 of the antenna corresponding to the central base brick is activated. Figure 2a shows an enlargement of the activated portion of the antenna. In this first step, the pre-pointing of the antenna is done manually using for example a receiver type GPS (in English: Global Positioning System) and a compass. The GPS receiver is used to determine the local geographic coordinates of the terminal, ie longitude and latitude, and to calculate the angular orientation required in site and azimuth so that the antenna can receive a signal from the satellite to acquire whose longitude is known by the terminal when it is first implemented. The longitude of the satellite is given by the operator when offering services. The signal received from the satellite can come either from a beacon on board the satellite or as a carrier transmitted in a satellite communication channel. The compass gives the direction of the geographic North which allows to orient, approximately, the antenna in site and in azimuth.

The method then consists in aligning the direction of the maximum radiation of the central base brick of the antenna with respect to the direction of the satellite. The radiation pattern of the beam radiated by this central part of the antenna, for example at a frequency of 20 GHz as shown in FIGS. 2c and 2d, gives the order of magnitude of the pointing accuracy that it is possible to 'get. Due to a choice of a rectangular central zone, the spot radiated by this central zone, represented for example in FIG. 2b, is elliptical and its widths at -1OdB according to two perpendicular sectional planes XZ and YZ ₁ are respectively equal. at approximately 24 ° and 12 °, Z being the direction of an axis normal to the surface of the radiating panel, X and Y being orthogonal axes located in the plane of the radiating panel and respectively corresponding to the main axes of the antenna in site and in azimuth

When the antenna has hooked up the signal coming from the satellite, from this initial hooking position, the alignment procedure of the antenna with respect to the satellite is continued by using verniers of adjustment of the rotating antenna around of the two X and Y axes and energy level indicators of the signals received by a receiver of the antenna, so as to position the antenna in the direction of the maximum energy of the radiation pattern of the central part of the antenna. 'antenna. The energy level indicators can be, for example, light signals emitted by light-emitting diodes or sound signals emitted by a buzzer. The adjustment verniers preferably comprise a stepwise rotation drive device.

At the end of this first step, setting the detection sensitivity of the signa! from the satellite at 0.5dB level deviations, the accuracy of the normalization of the antenna to the satellite is about 6 ° in the XZ plane, and 3 ° in the YZ plane, as shown in Figures 2c and 2d.

In the second step of the method according to the invention, the central part of the antenna corresponding to the central base brick and an intermediate part of the antenna comprising four additional bricks surrounding the central brick are activated simultaneously. As shown in Figure 3a, these five bricks form, in this example, a cross-shaped design. The directivity of the operational part of the antenna is then improved and of the order of 31 dBi with respect to the directivity of the only central part used in the first step and consisting of a single basic brick which is the order of 24 dBi. As represented in FIGS. 3b and 3c, the fact of using a larger part of the antenna makes it possible to obtain a more directional radiation pattern, hence with an amplitude comprising greater variation slopes which will make it possible to refine again the score.

From the optimum position obtained at the end of the first step, the alignment procedure of the antenna with respect to the satellite is continued by using the verniers of adjustment of the antenna in rotation around the two axes X and Y and the level indicators of the signals received by a receiver of the antenna, so as to position the antenna in the direction of the maximum of the radiation pattern of the activated zone of the antenna comprising the central part and the intermediate part.

At the end of this second step, by setting the detection sensitivity of the signal from the satellite to O ₁ SdB level deviations, the accuracy of the normal alignment of the antenna towards the satellite is approximately 2.6 ° according to the XZ plane, and 1, 3 ° according to the YZ plane, as shown in Figures 3b and 3c.

In the third step of the method according to the invention, the complete panel of the antenna comprising the fifteen basic bricks is activated. The directivity of the complete panel is improved compared to the cases of the two previous steps where only part of the panel is activated. In the embodiment described, the directivity of the complete panel is of the order of 35.8 dBi. As shown in FIGS. 4a and 4b, the fact to activate all the radiating elements of the antenna panel makes it possible to obtain a more directional radiation pattern than in the preceding steps and to refine the pointing once more.

From the optimum position obtained at the end of the second step, the alignment procedure of the antenna with respect to the satellite is continued using the same method of adjustment as in the previous steps, by means of the adjustment verniers and received signal levels so as to position the antenna in the direction of the maximum of the radiation pattern of the complete radiating panel. The final accuracy of the alignment of the antenna normal toward the satellite is about 1 ° in the XZ plane, and 0.8 ° in the YZ plane, as shown in Figures 4a and 4b. Overall, the precision obtained is of the order of 1 °. At this point, the antenna is considered correctly pointed towards the satellite with a final pointing accuracy of plus or minus 0.5 ° according to the two axes in elevation and in azimuth.

This pointing assistance strategy is very simple since each step uses only information delivered by a signal receiver and is performed manually by the user, iteratively and with increasing accuracy depending on the size of the antenna, only by actuating verniers of rotational adjustments around the two axes site and azimuth of the antenna in accordance with indications of level of the received signal. The number of steps used depends on the desired pointing accuracy and the operating frequency used. Typically, two or three steps are sufficient. The different parts of the radiating panel and the base bricks may have different shapes from those chosen in the embodiment described, but they must be made to form sets of radiating elements that can be activated successively from the center to the periphery of the radiating panel of the antenna.

FIG. 5 represents an example of antenna architecture implementing the pointing aid method. This architecture has no search calculator of the optimum pointing direction. The activation of the different parts of the antenna to go from a step of the pointing assist method to the next step is controlled only by means of microwave switches whose position change is activated manually by the user, which limits the complexity and cost of realization of the antenna. Depending on the position of the different switches, signal combiners make it possible to combine the signals received by at least two different parts of the antenna.

In the exemplary embodiment shown, the pointing aid method comprises three successive steps and the radiating elements mounted on the radiating panel of the antenna are thus configured in three concentric subassemblies respectively constituting a central portion 1 of the antenna, an intermediate portion 2 surrounding the central portion 1, and an outer peripheral portion 3 surrounding the intermediate portion 2. For a method having a number of steps other than three, the number of parts of Pantenne is modified accordingly. The antenna comprises a transmission path and a reception path connected via diplexers 21, 22, 23, to each of the three portions of the radiating panel. The diplexers conventionally provide for the separation of the transmission channels. and reception. At the output of the diplexers the signals received on each of the channels are amplified in respective amplifiers 41, 42, 43 before being transmitted to a receiver 30. The reception channel comprises a signal receiver 30 connected to the different parts of the radiating panel of the antenna via a plurality of microwave switches 31, 32, 33, 34 and signal combiners 35, 36. The output of the receiver is connected to a modulation and demodulation interface 37.

In the architecture example shown in FIG. 5, the central part 1 of the antenna is connected to a first switch 31 having a first position connected to the receiver 30 via a second switch 32 and a second position. connected to a first signal combiner 35. The first signal combiner 35 has two inputs connected respectively to the intermediate part 2 and to the central part 1 of the antenna when the first switch 31 is in the second position and an output connected to the receiver 30 through a third switch 33 having a first position connected to the second switch 32 and a second position connected to a second signal combiner 36.

The second signal combiner 36 has two inputs respectively connected to the outer peripheral part 3 of the antenna and to the output of the first signal combiner 35 when the third switch 33 is in the second position and an output connected to the receiver 30 by the intermediate of a fourth switch 34 and the second switch 32.

In a reception mode operation, during the initial phase of acquiring the signal of a satellite and pointing the antenna towards the satellite, the successive activation of each of the three subassemblies 1, 2, 3 of radiating elements of the antenna is performed by the user only by successively changing the position of one or more microwave switches 31, 32, 33, 34 connected to the signal receiver 30. The terminal has the authorization of only when the antenna is correctly pointed.

On transmission, when the antenna is correctly pointed, the modulation and demodulation interface 37 which is intended to shape a signal! to be transmitted, is connected to an amplifier 38, then to a signal divider 39 which divides the signal to be transmitted into three components respectively applied at the input of each of the three parts 1, 2, 3 of the antenna via the diplexers respective 21, 22, 23.

Although the invention has been described in connection with particular embodiments, it is obvious that it is not limited thereto and that it includes all the technical equivalents of the means described and their combinations if they are within the scope of the invention.

Claims

A method of assisting the pointing of an antenna, comprising using an antenna comprising a plurality of radiating elements distributed on a surface of a radiating panel, characterized in that it consists of:

in a first step, to activate only the first radiating elements situated in a first central part of the radiating panel, to ensure, by means of manual adjustment means, a pre-pointing of the antenna in elevation and azimuth, in a direction corresponding to a maximum level of energy in reception of a signa! transmitted by a satellite, in order to position the antenna in a first optimal position,

in a second step, the antenna being in the optimum position at the end of the first step, then simultaneously activating the first radiating elements and at least the second radiating elements located in a second part of the radiating panel surrounding the first part; central and to refine, the direction of pointing of the antenna in site and in azimuth corresponding to a maximum level of reception.

2. Method according to claim 1, characterized in that the second step comprises at least two substeps of successively activating an increasing number of radiating elements of the first central part, towards the second part, then to a peripheral part of the radiating panel surrounding the second part until the activation of all the radiating elements of the antenna and, at each sub-step, manually refine the pointing direction of the antenna in elevation and in azimuth.

3. Method according to one of claims 1 or 2, characterized in that, to move from one pointing direction to another, the activation of the radiating elements of the antenna is achieved by manually operating at least two means of switching.

4. Method according to one of claims 1 to 3, characterized in that the pointing direction of the antenna is adjusted at each step by actuating rotary adjusting verniers around two axes respectively in elevation and in azimuth.

5. Method according to one of the preceding claims, characterized in that the maximum level of reception of the signal emitted by the satellite is determined by viewing a light signal or by hearing a sound signal, the light signal or sound dependent reception level.

An assisted pointing emission and reception antenna for carrying out the method according to one of the preceding claims, the antenna comprising a plurality of radiating elements distributed over a surface of a radiating panel, characterized in that it also includes at the reception:

first activation means for activating only first radiating elements situated in a first central part of the radiating panel,

at least second activation means for at least second radiating elements located in a second part of the radiating panel surrounding the first central part, and at least a first means for combining the signals received by the radiating elements activated by the first and the second activation means,

manual adjustment means for pre-pointing the antenna and for fine-tuning the pointing in elevation and in azimuth, in a direction corresponding to a maximum level of reception of a signal emitted by the satellite.

7. Antenna according to claim 6, characterized in that the first and the second activation means are microwave switches.

8. Antenna according to one of claims 6 or 7, characterized in that the adjusting means are stepping verniers.

9. Antenna according to claim 6, characterized in that it further comprises, on reception, third activation means for activating third radiating elements located in a third peripheral portion of the radiating panel surrounding the second part and at least a second means for combining the signals received by the radiating elements activated by the first, the second and the third activation means.

10. nomadic terminal, characterized in that it comprises an antenna according to one of claims 6 to 9.