Transmit-array antenna comprising a mechanism for reorienting the direction of the beam

Abstract

The present invention relates to a transmit-array radiofrequency antenna comprising: a support; a transmit-array arranged in a plane, called a transmission plane; at least one focal source fixed on the support and arranged at the focal length from the array; and a displacement mechanism for moving the transmit-array, the mechanism being connected to the support and being adapted to translationally move the transmit-array in at least one of the two directions in the transmission plane.

Claims

1. A transmit-array radiofrequency antenna comprising: a support; a transmit-array arranged in a transmission plane, the transmit-array comprising a printed circuit and a plurality of basic cells produced in a central zone of the printed circuit, at least one focal source, fixed on the support and arranged at the focal length from the array; a displacement mechanism for moving the transmit-array, the mechanism being connected to the support and being adapted to translationally move the transmit-array in at least one of the two directions in the transmission plane, the displacement mechanism being connected to the printed circuit in its peripheral zone; wherein the displacement mechanism comprises: two servomotors; two first pantograph devices, each comprising two deformable parallelograms each formed by four articulation segments connected pairwise by a flexible articulation forming a pivot link and one of the segments of which is common to the two parallelograms, in which displacement mechanism, the common segment of each of the two first pantograph devices is connected to one of the two servomotors, whereas one of the segments parallel to the common segment is fixed on the printed circuit in its peripheral zone and the other one of the segments parallel to the common segment is fixed on the support, the connection between each of the common segments with one of the two servomotors being carried out such that one of the servomotors may move the common segment of one of the two first devices and hence move the printed circuit in approximately one of the two directions (X) in the transmission plane, whereas the other one of the servomotors may move the common segment of one of the two first devices and hence move the printed circuit in approximately the other one of the two directions (Y) in the transmission plane.

2. The transmit-array radiofrequency antenna according to claim 1, wherein the displacement mechanism is adapted to translationally move the transmit-array in the two directions of the transmission plane.

3. The transmit-array radiofrequency antenna according to claim 1, wherein the basic cells are patch antennae.

4. The transmit-array radiofrequency antenna according to claim 1, wherein each of the two common segments is connected by a shaft to one of the two servomotors, which shaft is adapted to slide in an opening produced in the support, the shape of the opening being adapted to move the printed circuit in approximately one of the directions (X or Y) in the transmission plane.

5. The transmit-array radiofrequency antenna according to claim 1, wherein the displacement mechanism further comprises: two other pantograph devices, each comprising two deformable parallelograms each formed by four articulation segments connected pairwise by a flexible articulation forming a pivot link and one of the segments of which is common to the two parallelograms, in which displacement mechanism: the common segment of each of the two other pantograph devices is free; one of the other parallel segments is fixed on the printed circuit in its peripheral zone; the other one of the parallel segments is fixed on the support in its peripheral zone; and the four pantograph devices are distributed at 90 to each other around the central zone of the printed circuit.

6. The transmit-array radiofrequency antenna according to claim 1, wherein each pantograph device is a one-piece part.

7. The transmit-array radiofrequency antenna according to claim 6, wherein the one-piece part is made of thermoplastic.

8. The transmit-array radiofrequency antenna according to claim 1, wherein the focal source is of the horn antenna type.

9. An antenna array comprising a plurality of radiofrequency antennae according to claim 1.

10. The transmit-array radiofrequency antenna according to claim 7, wherein the thermoplastic comprises polypropylene.

Description

DETAILED DESCRIPTION

(1) Further advantages and features of the invention will become more clearly apparent upon reading the detailed description of embodiments of the invention, which is provided by way of a non-limiting example, with reference to the following figures, in which:

(2) FIG. 1 is a schematic view of a reflector-array antenna according to the prior art;

(3) FIG. 2 is a perspective view of a reflector-array antenna according to the invention provided with its four-pantograph mechanism for moving the transmit-array;

(4) FIG. 3 is a side view of the antenna according to FIG. 2;

(5) FIG. 4 is a perspective view of one of the pantograph devices of the mechanism for moving the reflector-array according to the invention;

(6) FIG. 5 is a front view of the antenna according to FIG. 2;

(7) FIG. 5A is a detailed view of FIG. 5 showing the connection of one of the pantograph devices to one of the servomotors for translationally moving the transmit-array in a direction;

(8) FIG. 6 is a schematic view showing the dynamic depointing of a beam of a reflector-array antenna obtained according to the invention.

(9) FIG. 1 relating to the prior art has already been discussed in the preamble. Therefore, it is not described hereafter.

(10) For the sake of clarity, the same elements of a transmit-array antenna according to the prior art and a transmit-array antenna according to the invention are denoted using the same reference numerals.

(11) FIGS. 2, 4, 5 show a transmit-array antenna 1 according to the invention.

(12) The antenna 1 firstly comprises a support 4, on which the focal source 2 is fixed on the side opposite the transmit-array 3.

(13) The transmit-array 3 is arranged above the support 4 in a transmission plane parallel to the focal plane of the source 2.

(14) This array 3 comprises a printed circuit 30 and a plurality of basic cells 31 produced in a central zone of the printed circuit 30. As will be seen from FIG. 2, the general shape of the printed circuit 30 is square, whereas the shape of the central zone of the printed circuit is circular. However, the central zone may be square.

(15) According to the invention, a displacement mechanism 5 connected to the printed circuit 30 in its peripheral zone allows the transmit-array 3 to translationally move in the two directions X, Y in the transmission plane.

(16) As will be seen from FIGS. 2, 4 and 5, the arrangement of the displacement movement mechanism 5 does not interfere with the central zone of the printed circuit 30, which therefore supports the basic cells 31. In other words, the central zone 31 remains transparent, and this is the case regardless of the translation movement of the array 3. The movement of the transmit-array 3 in an approximate direction X in the transmission plane is enabled by a servomotor 7 fixed on the support 4 on the side opposite the array 3, whereas the movement in the other approximate direction Y in the transmission plane is enabled by another servomotor 8, which is also fixed on the support 4 on the side opposite the array 3.

(17) To ensure that the translation movement is imposed in the transmission plane, the displacement mechanism 5 comprises four pantograph devices 5.1, 5.2, 5.3, 5.4, which are identical and are arranged by being evenly distributed around the central zone of the printed circuit 30, i.e. at 90 to each other, as will be explained hereafter.

(18) The movement obtained by each pantograph device is not strictly linear, but is in a large diameter circle and therefore at least two devices 5.1, 5.2 allow an approximate movement respectively in direction X and perpendicular direction Y.

(19) Four pantograph devices ensure that the fixing of the transmit-array 3 is robust, without as such increasing the spatial requirement of the antenna.

(20) The production of one 5.1 of these pantograph devices will now be described with reference to FIG. 4.

(21) This device 5.1 is a one-piece part, advantageously made of polypropylene.

(22) It comprises two deformable parallelograms each formed by four articulation segments 50, 51, 52, 53 and 52, 54, 55, 56 connected pairwise by a flexible articulation forming a pivot link. Therefore, the flexible articulations are produced by tapering the material of the part between two adjacent segments.

(23) The segment 52 is common to the two parallelograms.

(24) Thus, each device 5.1, 5.2, 5.3, 5.4 is called pantograph device since, regardless of the angle formed between the segments, the segments 52, 53 and 56 always remain parallel to each other.

(25) Each of the articulation segments is perforated with at least one housing defining a fixing point either on the printed circuit 30 or on the support 4 or on the output shaft of one of the servomotors 7, 8. Each of these fixings or catches may be produced by means of screws, preferably made of plastic, or even by clipping or other means.

(26) More specifically: the segment 53 is fixed on the support 4 by two fixing points 60, 61; the segment 56 is fixed on the printed circuit 30 of the array 3 by two fixing points 62, 63; the common segment 52 is either free or is fixed to the output shaft of one of the servomotors 7, 8 by a single, preferably central, fixing point 64.

(27) Even more specifically, the connection via the point 64 between the common segment 52 of the device 5.1 and the servomotor 7 allows said servomotor to move the common segment 52 and hence move the printed circuit 30 in approximately the direction (X) in the transmission plane.

(28) The connection via the point 64 between the common segment 52 of the device 5.2 and the servomotor 8 allows the servomotor to move the common segment 52 and hence move the printed circuit 30 in approximately the direction (Y) in the transmission plane.

(29) In order to guide the movement of the printed circuit over a predetermined course, the support 4 is perforated with two emerging openings 41, 42 of predetermined length.

(30) The point 64 of each of the devices 5.1 or 5.2 may slide in each of these openings 41 or 42 when it is translationally moved by either one of the servomotors 7 or 8.

(31) FIG. 6 schematically shows the movement operation of the antenna 1 according to the invention, as previously described, which allows dynamic depointing of its beam.

(32) By virtue of the displacement mechanism 5, the transmit-array 3 translationally moves in a transmission plane Pt parallel to the focal plane Pf. The position of the source 2 still remains constrained in the focal plane of the array 3.

(33) Thus, with the movement mechanism 5, the beam of the antenna may be emitted (the solid lines in FIG. 6) by several degrees around the main axis of the antenna by which the nominal beam is emitted (dashed lines in FIG. 6).

(34) Other variations and improvements may be made without necessarily departing from the scope of the invention.

(35) The invention is not limited to the aforementioned embodiments. In particular, features of the illustrated embodiments may be combined together within variations that are not shown.

(36) The term comprising a must be understood to mean comprising at least one, unless otherwise specified.

CITED REFERENCES

(37) [1] L. Di Palma, A. Clemente, L. Dussopt, R. Sauleau, P. Potier, and P. Pouliguen, Circularly-Polarized Reconfigurable Transmitarray in Ka-Band with Beam Scanning and Polarization Switching Capabilities, IEEE Trans. Antennas Propag., vol. 65, no. 2, pp. 529-540, February 2017. [2] A. Moknache et al., A switched-beam linearly-polarized transmit array antenna for V-band backhaul applications, in 2016 10th European Conference on Antennas and Propagation (EuCAP), 2016, pp. 1-5.