Flat antenna for satellite communication

Abstract

A flat antenna for satellite communication includes a radiating board. The radiating board includes at least one radiating line, and an adapter configured to modify the delay of the fields transmitted or received by the radiating line. The adapter includes a horn mobile in rotation between the two metal plates, and a multilayer power supply circuit. The first layer of the multilayer power supply circuit is formed at least one metal plate containing an array of slot sensors and the last layer of the multilayer power supply circuit is provided with at least one coupling slot connected to the radiating line. The first layer and the last layer is linked by at least one transmission line. The length of the transmission line is suitable for introducing a delay required to focus the wave radiated by the radiating line.

Claims

1. A flat antenna for satellite telecommunication, comprising: a radiating board comprising at least one radiating line; and an adapter configured to modify a delay of fields emitted or received by said at least one radiating line, the adapter comprises: a horn movable in rotation between two metallic plates; a multilayer power feed circuit, a first layer of which is formed by at least one metallic plate comprising an array of sensors of a slot type and a last layer of which is provided with at least one coupling slot connected to said at least one radiating line; at least one transmission line links the first layer and the last layer; a length of said at least one transmission line is configured to introduce a delay required to focus a wave radiated by said at least one radiating line.

2. The flat antenna as claimed in claim 1, wherein the horn transmits the wave between the two metallic plates, an electric field of the wave is perpendicular to the metallic plates.

3. The flat antenna as claimed in claim 2, wherein the length of said at least one transmission line is configured to introduce an additional delay to obtain an initial fixed pointing such that a total pointing varies from 0 to 60 for a symmetric displacement of the horn of 30.

4. The flat antenna as claimed in claim 1, wherein the length of said at least one transmission line is configured to introduce an additional delay to obtain an initial fixed pointing such that a total pointing varies from 0 to 60 for a symmetric displacement of the horn of 30.

5. The flat antenna as claimed in claim 1, wherein the multilayer power feed circuit comprises five metallic circuit layers separated by four dielectric layers.

6. The flat antenna as claimed in claim 1, wherein two layers of the multilayer power feed circuit are linked by at least one metallized hole passing through a conducting layer contactlessly through a non-metallized wafer.

7. The flat antenna as claimed in claim 1, wherein the multilayer power feed circuit is assembled adhesively.

8. The flat antenna as claimed in claim 1, wherein the two metallic plates comprises the array of sensors of the slot type, the two metallic plates are fixed on a plane parallel to a plane of the radiating board.

9. The flat antenna as claimed in claim 1, wherein the radiating board comprises a plurality of radiating lines spaced apart by a half of a wavelength.

10. The flat antenna as claimed in claim 1, wherein the radiating board comprises a plurality of radiating lines comprising an alignment of radiating elements.

11. The flat antenna as claimed in claim 10, wherein the radiating elements are dipoles, patches or slots.

12. The flat antenna as claimed in claim 10, wherein each radiating line comprises a distributor with one input and a plurality of outputs corresponding to a number of the radiating elements of said each radiating line.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention will be better understood with the aid of the description, given hereinafter purely by way of explanation, of the embodiments of the invention, with reference to the figures in which:

(2) FIG. 1 illustrates a flat and movable satellite telecommunications antenna according to the prior art;

(3) FIG. 2 illustrates a flat satellite telecommunications antenna partially represented according to an embodiment of the invention;

(4) FIG. 3 illustrates the movable horn of the antenna of FIG. 2;

(5) FIG. 4 illustrates the multilayer power feed circuit of the antenna of FIG. 2;

(6) FIG. 5 illustrates a pathway of the multilayer power feed circuit according to an embodiment in a perspective view;

(7) FIG. 6 illustrates the pathway of FIG. 5 in a sectional view;

(8) FIG. 7 illustrates the first layer of transmission lines of the multilayer power feed circuit for an exemplary antenna comprising 49 radiating lines;

(9) FIG. 8 illustrates the second layer of transmission lines of the multilayer power feed circuit for the example of FIG. 7; and

(10) FIG. 9 illustrates the first and the second layer of transmission lines of the multilayer power feed circuit for the example of FIG. 7.

DETAILED DESCRIPTION OF THE EMBODIMENTS OF THE INVENTION

(11) FIG. 2 reveals a flat satellite telecommunications antenna 10 consisting of a radiating board 16 linked to an adaptation means 11 able to modify the delays of the fields emitted or received by the radiating board 16.

(12) The radiating board 16 extends in a plane xy and comprises several radiating lines 17 disposed along the axis y at a spacing of about half a wavelength along the axis x. Each radiating line 17 consists of an alignment of N radiating elements (not represented), for example dipoles, patches or slots disposed at a spacing of less than a wavelength along the y axis and fed by a distributor comprising one input and N outputs.

(13) The adaptation means 11 consists of a horn 12 movable in rotation between two metallic plates 13a and 13b parallel to the radiating board 16. The horn 12, represented in FIG. 3, is movable in rotation about the axis z (parallel to or coincident with the axis z) extending in a direction normal to the plane xy. The mobility of the horn 12 is ensured by a numerically controlled guide 20.

(14) The horn 12 radiates between the two metallic plates 13a, 13b a TEM (for transverse electric-magnetic) wave whose electric field is perpendicular to the metallic plates 13a, 13b. The adaptation means 11 also comprises a multilayer power feed circuit 14, represented in FIG. 4, linking the horn 12 to the radiating board 16. This power feed circuit 14 consists of five layers of copper circuit 13a, 20-23, separated by four dielectric layers. The assembly is bonded together adhesively. The first layer 13a is formed by the upper metallic plate 13a. A coupling slot 27 made in this layer 13a gives one of the sensors of the array of sensors.

(15) The layers 13a, 20 and 21 form a transmission line of triplate type whose conducting line is situated on the layer 20 and whose ground planes are situated on the layers 13a and 21.

(16) The layers 21, 22 and 23 form a second transmission line of triplate type whose conducting line is situated on the layer 22 and whose ground planes are situated on the layers 21 and 23

(17) A through passage 28 making it possible to connect the lines 25 of the layers 20 and 22 is made by means of a metallized hole passing through the conducting layer 21 contactlessly through a non-metallized resist or wafer. The layer 23 is furnished with a coupling slot 26 making it possible to feed a line 17 of the radiating board 16.

(18) This structure makes it possible to obtain a coefficient of transmission between the coupling slot 27 and the radiating board 16 with a modulus substantially equal to one and with a delay that can be easily controlled by tailoring the length of the lines 25 of the layers 20 and 22. These lines also induce an additional delay making it possible to obtain an initial fixed pointing in such a way that the total pointing varies from 0 to 60 for a symmetric displacement of the horn 12 of about 30.

(19) FIGS. 5 and 6 represent an exemplary embodiment of the adaptation means 11 for a pathway. The adaptation means 11 consists of the metallic plates 13a, 13b disposed around the horn 12 (not represented). The propagation of the waves emitted and received by the horn 12 are transmitted to the multilayer power feed circuit 14 by a coupling slot 27. The propagation is closed between the metallic plates 13a and 13b at the rear of the slot 27 by a metallic piece 30 whose profile allows adaptation of the transmission.

(20) The power feed circuit 14 consists of four printed-circuit layers assembled adhesively. The material used may be for example Rogers RT/duroid 5880 with a thickness of 0.508 mm.

(21) The layers 13a and 21 are connected in the vicinity of the slot 27 by metallized holes making it possible to avoid the propagation of undesirable modes in the circuit. The energy tapped off by the slot 27 travels down the line 25a and then down the line 25b after a change of layer effected by means of the through passage 28. The layers 13a, 21 and 23 are connected in the vicinity of the through passage by metallized holes making it possible to avoid the propagation of undesirable modes in the circuit. The through passage is embodied as a metallized hole linking the layers 20 and 22. It passes through the layer 21 contactlessly through a non-metallized wafer.

(22) The coupling at the input of a line of the radiating board 16 is effected by the slot 26. The layers 21 and 23 are connected in the vicinity of the slot 26 by metallized holes making it possible to avoid the propagation of undesirable modes in the circuit.

(23) The input of the line of the radiating board 16 is also effected by triplate technology between the radiating line 17 and the ground planes 36 and 37. It is embedded in a metallic piece 40 ensuring precise positioning and low impedances between the various metallic layers 23, 36 and 37. The coupling between the radiating line 17 and the line 25b is obtained by virtue of the slot 26 and of the connection of the radiating line 17 to the ground plane 37 through the metallized hole 41. The layers 36 and 37 are connected by metallized holes 42 making it possible to avoid the propagation of undesirable modes in the circuit.

(24) FIGS. 7, 8 and 9 depict the complete circuit for an exemplary antenna comprising 49 radiating lines. The slots for coupling with the radiating lines 26 are aligned at a spacing of about half a wavelength (5 mm at 30 GHz). The slots 27 in connection with the horn 12 are disposed on the exit curve (nearly a circular arc) at a spacing of likewise about half a wavelength. The length of the lines 25a, 25b, which is tailored by means of the position of the through passages 28, gives the delay necessary for the focusing and for the initial pointing of the beam toward 30 (horn in central position).

(25) This embodiment makes it possible to limit the bulkiness of the power feed circuit 14 for linking the horn 12 to the radiating lines 17.

(26) The invention also makes it possible to point in all the directions contained in the cone of half-angle 60 centered on the axis z by rotating the horn 12 by around 30 about the axis z and by rotating the antenna assembly by 360 about the axis z. This antenna structure operates in a very broad band of frequencies since the movable horn 12 makes it possible to obtain frequency-independent pointing.