DUAL-POLARIZATION ANTENNA

Abstract

Dual-polarized antenna, including several antenna elements arranged in cell units. Each cell unit includes four antenna elements and two 1-to-4 junctions, a first of the two junctions being associated with a first polarization and a second of the two junctions being associated with a second polarization. The antenna also includes an array of dividers/combiners. The four antenna elements of each cell unit are superposed and several cell units are juxtaposed. Each cell unit includes two antenna elements and two other antenna elements which are offset.

Claims

1. Antenna with dual polarization, comprising: at least one first port for connecting the antenna to an active circuit for transmitting or emitting a signal with a first polarization; at least one second port for connecting the antenna to an or to the active circuit for transmitting or emitting a signal with a second polarization, several dual-polarized antenna elements, the antenna elements being arranged in cell units, each cell unit including four antenna elements and two 1-to-4 junctions, a first of the two junctions being associated with a first polarization and a second of the two junctions being associated with a second polarization, each said junction comprising four branches for connecting it to one of the polarization of each antenna element of the corresponding unit and a common stub, an array of dividers/combiners for connecting the stub of each said 1-to-4 junction of a cell unit associated with the first polarization to the first port and for connecting the stub of each said 1-to-4 junction associated with the second polarization to the second port the four antenna elements of each cell unit being superposed, several cell units being juxtaposed, wherein each cell unit comprises two antenna elements in a first plane and two other antenna elements in a second plane parallel to the first plane, said planes being offset from each other in a direction perpendicular to said planes by a distance smaller than the width of an antenna element.

2. Antenna of claim 1, said array of dividers/combiners comprising a first sub-array of dividers/combiners formed by a stack of juxtaposed blades and arranged to connect together the stubs each said 1-to-4 junction of several superposed cell units associated with the first polarization and to connect together the stubs of each said 1-to-4 junction of several superposed cell units associated with the second polarization.

3. Antenna of claim 2, said first sub-array of dividers/combiners comprising an alternance of first blades associated with the first polarisation and of second blades associated with the second polarisation.

4. Antenna of claim 3, comprising a second sub-array of dividers/combiners arranged to connect said first blades to each other and to the first port and to connect said second blades to each other and to the second port.

5. Antenna of claim 2, each blade extending in a first direction substantially perpendicular to the direction of the signal transmission, and between the two planes defined by the extreme lateral edges of the antenna elements associated with this blade.

6. Antenna of claim 3, a said first blade and a said second blade extending between the two planes defined by the extreme lateral edges of the antenna elements associated with these two blades.

7. Antenna of claim 4, the second sub-array being provided between said blades and said ports and comprising waveguide portions extending in a second direction substantially perpendicular to the direction of the signal transmission.

8. Antenna of claim 1, each blade being associated with four cell units.

9. Antenna of claim 3, comprising 32 said blades.

10. Antenna of claim 1, each antenna element comprising a septum for combining in transmission or separating in reception the two polarizations of a radio frequency signal.

11. Antenna of claim 10, each antenna element being connected to two neighboring blades.

12. Antenna of claim 1, each antenna element having a cross-section perpendicular to the direction of the signal propagation of square shape.

13. Antenna of claim 1, having at least one cylindrical opening in a direction perpendicular to the direction of the signal transmission, and for mounting the antenna on a rod for holding and orienting the antenna.

14. Antenna of claim 1, comprising a core made by 3D printing and a surface layer at least on the inner side of this core.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0048] Examples of embodiments of the invention are shown in the description illustrated by the attached figures in which:

[0049] FIG. 1 shows a perspective view of an antenna comprising four cell units according to the invention.

[0050] FIG. 2 shows an example of a blade for connecting together the first polarization of four superposed cell units.

[0051] FIG. 2 shows an example of the juxtaposition of two blades designed to connect together the first and second polarization of four superposed cell units.

[0052] FIG. 4 illustrates a first array of dividers/combiners made up of 32 juxtaposed blades.

[0053] FIG. 5 shows a 1-to-4 junction comprising four branches to be connected to the first polarization of the elementary antennas of a cell unit, and a stub for the common signal.

[0054] FIG. 6 shows a perspective view of a power combiner/divider in the H-plane.

[0055] FIG. 7 shows a side view of a power combiner/divider in the H-plane.

[0056] FIG. 9 shows a second array of dividers/combiners in the plane E.

[0057] FIG. 10 shows schematically how one of the polarities of the superposed elementary antennas are connected via the associated blade.

[0058] FIG. 11 shows schematically the connections within the second array of combiners/dividers.

EXAMPLE OF EMBODIMENTS OF THE INVENTION

[0059] The present invention relates generally to an antenna array, referred to hereinafter simply as an antenna, and comprising several elementary antennas 3 (radiating elements) arranged in a matrix such that the openings of these elementary antennas are all in the same plane. The direction d of the signal transmission, both in the antenna and at the output of the antenna, is perpendicular to this plane.

[0060] FIG. 1 illustrates an antenna 1 comprising four juxtaposed cell units 8, each cell unit comprising four superposed elementary antennas 3. The antenna 1 of this example thus comprises 16 elementary antennas, numbered by row and column from 3.sub.0;0 to 3.sub.3;3 and forming a matrix with four rows and four columns, each column being formed in this example by a single cell unit. As will be seen later, the number of columns can be increased by juxtaposing additional cell units, and the number of rows can be increased by superposing additional cell units within each column.

[0061] The pitch between two adjacent antenna elements as well as the pitch between two rows is advantageously smaller than the nominal wavelength of the signal to be transmitted, thus reducing undesirable secondary lobes in transmission or in reception sensitivity.

[0062] The successive rows of the antenna are phase shifted; in the example shown, the even rows are phase shifted with respect to the odd rows by a pitch corresponding to half the width of an elementary antenna. This phase shift enables beamforming or spatial filtering of the signals received or transmitted by the antenna elements of the cell unit 8, so that in particular directions the signals interfere constructively while in other directions the interference is destructive.

[0063] The antenna elements 3 each include an aperture forming a radiating element directed towards the ether, and two connection ports to the junction 5 described later. One of the two ports is intended for a first polarization and the second is intended for the second polarization. The antenna includes a polarizer, preferably in the form of a septum 32 for separating the two polarizations LHCP and RHCP of a signal on reception respectively for combining the two polarizations on transmission. In another embodiment, the antenna elements 3 may comprise another type of polarizer, or be linked to a separate polarizer.

[0064] The antenna 1 further comprises a series of 1-to-4 junctions 5. Two junctions 5 are associated with each cell unit, in order on the one hand to divide respectively combine the LHCP first polarization signals of the four elementary antennas of the cell unit, and on the other hand to divide respectively combine the RHCP second polarization signals of the four elementary antennas of the cell unit. In this example, the number of 1-to-4 junctions is thus equal to 8.

[0065] In the case of an antenna comprising several superposed cell units 8, and thus more than 4 rows, the signals at the output of the junctions 5 are combined using a first power divider/combiner in the H-plane, separately for each polarization. A port 7 (FIG. 8) allows each polarization to be connected to an active electronic circuit.

[0066] FIGS. 2 to 4 illustrate an example of a first divider/combiner 4 with the 1-to-4 junctions of the associated cell units, in the case of a dual polarization antenna comprising 16×16 antenna elements 3. The first divider/combiner consists of a number of juxtaposed blades 2, each blade being dedicated to one of the two polarizations LHCP or RHCP. As each antenna element provides two polarizations, the number of blades is therefore equal to twice the number of antenna elements per row, i.e. 32 blades in this example.

[0067] Each blade 2 is intended to be connected to all the antenna elements 3 of a column, i.e. to four cell units 8 superposed in this example. It therefore comprises branches 500.sub.0 to 500.sub.15, each of these branches being directly connected to one of the two output ports of one of the antennas. Two levels of 1-to-2 junctions in the H-plane form a 1-to-4 junction (reference 5) enabling the signals within each cell unit 8 to be combined/divided; the signal common to the stub 501 of the junctions in the blade 2 is combined using two further levels of 1-to-2 junctions in the H-plane, the signal resulting from the addition of the signals in all the branches 500 of a blade 2 thus ending up at the stub 23 of that blade.

[0068] FIG. 2 shows a single blade 2. FIG. 3 shows two juxtaposed blades, one dedicated to a first LHCP polarization of several superposed cell units and the other to the second RHCP polarization of the same cell units. FIG. 4 shows the juxtaposition of 32 blades 2 constituting the first array of dividers/combiners of the antenna.

[0069] FIG. 5 illustrates a 1-to-4 junction 5 present in each cell unit. The junction thus comprises four branches 500 for connection to four ports of the antenna elements 3 of a cell unit 8. The first level comprises two 1-to-2 junctions 51 for combining/dividing in pairs the signals of the same polarization of two superposed antenna elements. The two antennas of each pair being out of phase, the junction is made in the H-plane. A second 1-to-2 junction 50 then combines together the stubs of the two junctions 51, joined in a common stub 501.

[0070] FIGS. 6 and 7 illustrate in more detail an example of a 1-to-2 junction. This example relates to the first power divider/combiner 21 in the first array 4; however, the implementation of the 1-to-2 junctions 50 and 51 in the cell units, and of the second power divider/combiner 22 in the first array 4 may be the same or similar, with only the direction of the junction branches differing. As can be seen in particular in FIG. 7, the height b1 of the stub 201 is less than the height b2 of the portion of the junction in which the signals combine or divide, this height b2 being itself less than the total height b3 of the two branches 200.

[0071] FIG. 8 shows the rear of the antenna 1, i.e. the side opposite the front side from which the antenna elements 3 point. In particular, this figure shows a second array of dividers/combiners 6 in the E-plane, intended to combine/divide the signals from the different blades 2, independently for each polarization. This array 6 comprises a first half-array 6.sub.LHCP for the first polarization LHCP, the branches of which form a first comb intended to be connected to the blades 2 of the first polarization. A second half-array 6.sub.RHCP for the second RHCP polarization comprises branches forming a second comb interposed between the first comb and intended to be connected to the second polarization blades 2. The stub of the first half array forms the first port 7.sub.LHCP of the antenna 1 and the stub of the first half array forms the first port 7.sub.RHCP.

[0072] FIG. 9 illustrates one of the half-arrays, for example the first half-array 6.sub.LHCP. In the illustrated example, it comprises 16 branches 60.sub.0 to 60.sub.15 forming the comb intended to connect to the stub/port of the different blades 2. The number of branches 60 is of course dependent on the number of blades 2. Four levels of 1-to-2 junctions 61,62,63,64 in the E plane allow the signals of these different branches to be combined/divided successively in a common stub 7 forming one of the two ports of the antenna. The output of this stub 7 is angled at 90° to facilitate connection to a waveguide or directly to the electronic circuit.

[0073] FIG. 10 schematically illustrates the junction arborescence within each blade 2, with the blade combining both the first array of dividers/combiners 4 and the 1-to-4 junctions 5 of the cell units 8 associated with that blade.

[0074] FIG. 11 schematically illustrates the junction arborescence within the second array of dividers/combiners 6.

[0075] The antenna is advantageously made monolithically, preferably by 3D printing of a metal or polymer core, then deposition of a conductive layer at least on the inner faces of the antenna waveguides.

[0076] The above example refers to an antenna with 16×16 antenna elements. This number is non-limiting and the number of antenna elements can be any number. However, the number of rows is preferably a multiple of 4 so that the antenna can be designed by stacking cell units with four antenna elements each. This number is also advantageously a power of two so that a first array of dividers/combiners 4 can be constructed with an equal number of junctions between each branch of this array and the stub of the blade, thus more easily guaranteeing paths of isophase length to the different branches.

[0077] The number of antenna elements per branch, and thus of blades 2, can be any number. However, this number is advantageously a power of two, so that a second array of dividers/combiners 6 can be made with an equal number of junctions between each branch of this array and the antenna ports 7, thus more easily guaranteeing isophase length paths to the different branches.

[0078] The antenna may have a mounting hole passing through the array of dividers in a direction perpendicular to the direction of signal transmission, allowing it to be mounted by fitting it around a cylindrical mounting rod. This solution allows the orientation of the antenna to be easily adjusted by pivoting it around the rod.

REFERENCE NUMBERS USED IN FIGURES

[0079] 1 Antenna [0080] 2 Blade [0081] 21 First power divider/combiner in the blade (H plane) [0082] 22 Second power divider/combiner in the blade (H plane) [0083] 200 Branch of a power divider/combiner in the blade [0084] 201 Stub of a power divider/combiner in the blade [0085] 23 Main stub in the blade [0086] 3 Antenna element [0087] 32 Septum [0088] 4 First array of dividers/combiners (H-plane) [0089] 5 1-4 junction of a cell unit [0090] 50 First power divider/combiner in the junction [0091] 51 Second power divider/combiner in the junction [0092] 500 Branch of a 1-4 junction in the cell unit [0093] 501 Stub of a 1-4 junction in the cell unit [0094] 6 Second array of dividers/combiners (plane E) [0095] 60 Connection branch between the second array of dividers and a blade [0096] 61 First power divider/combiner in the plane E [0097] 62 Second power divider/combiner in the plane E [0098] 63 Third power divider/combiner in the plane E [0099] 64 Fourth power divider/combiner in the plane E [0100] 7 Port [0101] 8 Cell unit [0102] LHCP Index for components related to left polarisation [0103] RHCP Index for components related to right polarisation