EP0519855A1 - Compact active antenna for weather satellite - Google Patents

Abstract

The subject of the invention is a meterological antenna. It includes one or more correctly-phased directional antennas (2, 3) of the QUAGI type with a mechanical gain of more than 15 dBd, the said antennas (2, 3) are equipped with a directional device and are activated and amplified by means of a low-noise preamplifier (4) arranged at the entrance to the plastic protection (1) so as to be able to place the receiver any distance from the meteorological antenna. The directional antennas (8, 9, 10, 11) are actuated by three servomotors (12, 13, 14), two servomotors (12, 13) control the antenna as a function of the geographical position of the boat and the third servomotor (14) is slaved to an electronic compass, and the meteorological antenna assembly is provided with a self-stabilising device. Antenna for weather satellite for mobile or maritime installation. <IMAGE>

Description

The subject of the invention is an active antenna of small bulk for meteorological satellite.

Currently the state of the art can be defined by the following patents:

- FR-A-2.627.330: the present invention relates to a multifrequency antenna comprising a first printed antenna operating at one or more frequencies, and a second antenna disposed in front of the first antenna using the same radiating surface and operating at a different frequency .

Application in particular to the field of space telecommunications.

- FR-A-2.625.327: the radar, of the type with quasi-linear modulation of the frequency of the signal transmitted during the pulse, comprises a transmission chain provided with a high frequency oscillator, a transmitting-receiving antenna and a reception chain provided with a pulse compression member. According to the invention, in the transmission chain, an Impatt diode from a combiner to a diode generates directly at microwave a synchronization signal from the oscillator (pulses modulated according to negative frequency ramps). For this purpose, a clock generator controls in conduction, for each pulse to be transmitted, a switch arranged in series on the supply conductor at substantially constant current of the Impatt diode.

Application to cartography or meteorology.

- FR-A-2.587.548: reflector comprising load-bearing branches articulated on a support slightly spaced from the latter close radially in the deployed state, carrying a reflective network and pivotable upwards for folding.

Between adjacent load-bearing branches are arranged folding elements which are essentially transverse to them and fixed at preselectable intervals to the reflective network, the folding being effected by successively shortening the intervals between the fixing points.

The invention applies in particular to astronautical antenna reflectors.

- FR-A-2.643.511: the antenna system for direct broadcast satellite reception consists of a parabolic reflector associated with source means, the reflector being positioned and held by means of a support leg formed by a hollow tubular body fixed in its upper part to the rear central zone of the reflector and articulated in its lower part on a base around a horizontal axis to define the elevation of the antenna.

The base has a mobile part in rotation to define the azimuth of the antenna. The tubular body of the support leg has a section sufficient to contain all the circuits associated with the antenna.

Application, in particular, to the reception of satellites whose radiated powers are greater than 50 dBW.

- FR-A-2,584,872: the field of the invention is that of antennas intended to receive and / or radiate electromagnetic waves in circular polarization, produced by the technology of printed circuits.

The problem solved consists in allowing the realization of a low cost antenna, with a wide frequency band, with good efficiency, and the possibility of being used either alone or in a network.

According to the invention, the antenna consists of at least one wire or micro-ribbon conductor so as to form a continuous cruciform circuit arranged parallel to a conductive plate from which it is separated by a dielectric layer.

The invention finds a preferential application for the equipment of mobile land terminals with satellite communication link.

- GB A-207.657 RADIO LEADER: This patent describes a device antenna comprising an antenna for receiving a television broadcast signal and an amplifier located very close to the antenna, connected to the latter to amplify a remote-controlled signal received by the antenna. This is a Yagi antenna in a network of periodic logarythms. The antenna and the amplifier are inserted into an installation, said installation completely inserting the antenna and the amplifier and being highly waterproof. The installation is not electrically conductive, it is made of plastic. It includes a base supporting the antenna and the amplifier as well as an upper closure. A means of electrical supply to the amplifier is incorporated into the installation.

This is a so-called "active antenna" for television. It is active in a very wide band, less than 800 mega HZ.

It is not described and certainly not suggested a directional device for directional antennas, the assembly is not mounted on a self-stabilizing device. This invention has little to do with the invention.

- EP-A-0.142.397: The device usable on merchant ships having only a heading reference, comprises, on a base, a mount provided with means of orientation in bearing and carrying a gyroscopic assembly with two degrees of freedom whose external dial has an axis of rotation X, perpendicular to the bearing axis and whose internal gimbal has an axis of rotation Y, orthogonal to the axis X and which is linked in pointing to the antenna. The gyroscopic assembly includes a single flywheel of significant angular moment compared to the inertia of the antenna. Each dial is fitted with a torque motor controlled by a loop, the reaction signal of which is supplied by an orientation sensor on the other gimbal. The orientation means around the bearing axis are provided to approximately ensure the average pointing of the antenna in bearing and, consequently, to maintain the gyroscopic assembly near the canonical position. This patent describes a gyroscope using known self-stabilizing means such as sensors, servomotors, etc.

The combination of technical characteristics is not found in this patent. The purpose and application are very different.

Currently, the meteorological satellites called METEOSAT and GOES send at a continuous rate photographs of the earth intended for meteorology, seen at 36500 km in height on two radio channels at 1.691 and 1.694 GHZ. The signal is of low power, it can only be received by specific satellite dishes of 1.2 meters in diameter or more.

These specific antennas are not a problem for fixed installations, for example, for military or scientific installations.

For use on boats, it is necessary that these already have a large size to be able to accommodate such antennas with such dimensions.

Increasingly, the use of meteorological information on mobile installations or on small units is becoming apparent. It is therefore necessary to have a specific portable or at least small footprint antenna.

The antenna according to the invention tends to solve all these problems.

The antenna targets two applications, according to two embodiments.

One is a portable antenna, the other is an antenna for mobile maritime use on small units.

In addition, the antenna according to the invention reduces the cost of manufacturing this type of antenna.

Space-saving meteorological antenna intended for the reception of geostationary meteorological satellites working on the band 1.68 to 1.7 GHZ, of the type housed in a plastic protection with low absorption, the preamplification device being supplied with direct current by a cable coaxial which connects the meteorological antenna to the receiver, characterized in that it comprises one or more directional antennas of the QUAGI type correctly put in phase with a mechanical gain of more than 15 Dbd, said antennas are equipped with a directional device and are activated and amplified by means of a low noise preamplifier placed at the input of the plastic protection so that the receiver can be placed at any distance from the antenna meteorological.

In the case of a mobile maritime application, the directional antennas are actuated by three servomotors, two servomotors adjust the antenna according to the geographic position of the boat and the third servomotor is slaved to an electronic compass, the whole of the weather antenna is provided with a self-stabilization device.

The directional device of the directional antennas is actuated by three servomotors; the set of antennas is integral with a first fork supporting the four antennas; this first fork supports the antennas at the periphery of a disc or of a plate cross; this first fork is controlled in rotation to rotate the disc or cross plate by a servomotor or geared motor which controls the rotation about the axis of polarization from 0 to 360 degrees; said first fork is also articulated at its ends to a second fork arranged in a perpendicular plane and the rotation of which is actuated by a geared motor controlling the elevation axis from 0 to 90 degrees; this second range is also controlled by another geared motor which regulates the rotation of the azimuth axis from 0 to 360 degrees; this azimuth axis is located at the base of the second range.

The antenna is mounted on a self-stabilizing device, on a horizontal plane; this device is composed of a fork with vertical branches; this fork receives, at the end of its vertical branches facing upwards, an articulated circle which is itself articulated along an axis diametrically opposite to the plastic protection which forms the dome; all of the directional antennas are integral with this self-stabilizing device by the fork which is fixed by its base to the base of the fork along an axis.

The attached drawings are given as indicative and non-limiting examples. They represent a preferred embodiment according to the invention. They will allow the invention to be easily understood.

FIG. 1 is a schematic view of a meteorological antenna seen in perspective showing the various elements which constitute said antenna.

Figure 2 is a schematic view of an antenna meteorological suitable for maritime use highlighting the antennas and the self-stabilization device.

Figure 3 is a view according to Figure 2 of the weather antenna, on which the self-stabilizing means of the antenna is shown.

The embodiment shown in Figure 1 is a space-saving weather antenna particularly intended to be placed on a mobile vehicle.

The weather antenna shown in Figure 1, is housed in a protection 1 of low absorption plastic. It has two directional antennas 2, 3 of the QUAGI type.

QUAGI 2 and 3 antennas are correctly phased with a mechanical gain of more than 15 Dbd. Said antennas 2, 3 are activated and amplified by means of a low noise preamplifier 4 arranged with the plastic protection 1 and this, so as to be able to place the receiver not shown in FIG. 1, at any distance from l weather antenna.

The preamplification device 4 is continuously supplied by a coaxial cable 5 which connects the weather antenna to the receiver.

In the embodiment shown in FIG. 3, which is particularly intended for a mobile maritime application of the antenna, said meteorological antenna is provided with a three-dimensional self-stabilization device for the whole of the antenna and of three servomotors for directional antennas 8, 9 and 10, 11 of the QUAGI type.

Said antenna 6 is housed in a protection 7 with low absorption in the form of a small diameter ball or cylinder, for example 53 cm in diameter.

The base of this plastic protection 7 has a truncated cone shape.

Said base is fixed to the superstructure of the boat and electrically connected by a cable, not shown in the figures, to protection 7 and to the electrical network.

In this embodiment, there are four antennas 8, 9, 10 and 11. These antennas are activated in the same way by a preamplification device not shown in the figure.

The antennas 8, 9, 10, 11 are provided with a three-dimensional directional device actuated by three servomotors 12, 13 and 14.

The set of antennas is integral with a first fork 15 supporting the four antennas 8, 9 and 10, 11.

This first fork supports the antennas 8, 9, 10, 11 at the periphery of a disc 16 or of a plate cross mounted in rotation on the base of the fork 15.

This first fork 15 is controlled in rotation to rotate the disc 16 or plate cross by a servomotor or geared motor 12 which controls the rotation about the axis of polarization E, F from 0 to 360 degrees.

Said first fork 15 is also articulated at its ends to a second fork 17 arranged in a perpendicular plane and whose rotation is actuated by the geared motor 13 controlling the elevation axis A-B from 0 to 90 degrees.

This second fork 17 is also controlled by another geared motor 14 which regulates the rotation of the azimuth axis C-D.

This azimuth axis C-D is located at the base of the second range 17.

This directional device of the directive antennas 8, 9 and 10, 11 can thus keep the said antennas pointed towards the satellite, by means of the electric compass in combination with the servomotors or geared motors 12, 13 and 14 (which control the rotation about the axis of polarization and rotation around the elevation axis).

The assembly of the meteorological antenna is mounted, as shown in FIG. 3, on a self-stabilizing device, on a horizontal plane. This device is composed of a fork 18 with vertical branches 19, 20. This fork 18 receives, at the end of its vertical branches 19, 20 oriented upwards, an articulated circle 21 which is itself articulated along an axis XY diametrically opposite to the plastic protection 7 which forms the dome.

All of the directional antennas 8, 9 and 10, 11 are integral with this self-stabilizing device by the fork 17 which is fixed, by its base 22, to the base of the fork 18, along an axis 23.

REFERENCES

• 1. Protection of plastic mobile antenna
• 2, 3. QUAGI antennas
• 4. Preamplifier
• 5. Coaxial cable
• 6. Maritime mobile antenna
• 7. Plastic protection for maritime mobile antenna
• 8, 9, 10, 11. Antennas
• 12, 13, 14. Servomotors or gearmotor
• 15. First fork
• 16. Cross disc or plate
• 17. Second fork
  • AB Elevation axis
  • CD Azimuth axis
  • EF Polarization axis
• 18. Fork
• 19, 20 Vertical branches of the fork 18
• 21. Articulated circle
• 22. Base of fork 17

Claims (4)

Space-saving meteorological antenna intended for the reception of geostationary meteorological satellites working on the band (2) 1.68 to 1.7 GHZ, of the type housed in a protection (1) of low-absorption plastic, the preamplification device being supplied in direct current by a coaxial cable (5) which connects the weather antenna to the receiver, characterized by the fact
that it includes one or more antennas (2, 3) directives of the QUAGI type correctly aligned with a mechanical gain of more than 15 Dbd, said antennas (2, 3) are equipped with a directional device and are activated and amplified by means of a low noise preamplifier (4) placed at the entrance to the plastic protection (1) so that the receiver can be placed at any distance from the weather antenna. Space-saving weather antenna according to claim 1 characterized in that
that in the case of a mobile maritime application, the directional antennas (8, 9, 10, 11) are actuated by three servomotors (12, 13, 14), two servomotors (12, 13) regulate the antenna according to the geographic position of the boat and the third servomotor (14) is controlled by an electronic compass, the entire weather antenna is provided with a self-stabilizing device. Space-saving weather antenna according to claim 2 characterized in that
that the directional device of the directional antennas is actuated by three servomotors (12, 13 and 14); the set of antennas is integral with a first fork (15) supporting the four antennas (8, 9, 10, 11); this first fork supports the antennas (8, 9, 10, 11) at the periphery of a disc (16) or of a plate cross; this first fork (15) is controlled in rotation to rotate the disc (16) or plate cross by a servomotor or geared motor (12) which controls the rotation around the axis of polarization (EF) from 0 to 360 degrees; said first fork (15) is also articulated at its ends to a second fork (17) disposed in a perpendicular plane and the rotation of which is actuated by a geared motor (13) controlling the elevation axis (AB) from 0 to 90 degrees ; this second fork (17) is also controlled by another geared motor (14) which regulates the rotation of the azimuth axis (CD) from 0 to 360 degrees; this azimuth axis (CD) is located at the base of the second range (17). Space-saving weather antenna according to claim 1 characterized in that
that it is mounted on a self-stabilizing device, on a horizontal plane; this device is composed of a fork (18) with vertical branches (19, 20); this fork (18) receives, at the end of its vertical branches (19, 20) oriented upwards, an articulated circle (21) which is itself articulated along an axis (XY) diametrically opposite to the plastic protection (7) which forms the dome; the set of directional antennas (8, 9) and (10, 11) is integral with this self-stabilizing device by the fork (17) which is fixed by its base (22) to the base of the fork (18) along an axis (23).

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