Elementary antenna of the polarization agile type and of the cavity antenna type, array antenna comprising a plurality of such elementary antennas
This elementary antenna includes a cavity delimited by front and rear faces and side walls, the front face being provided with first and second slots arranged in a cross, so that, when the cavity operates in a TE210 mode, a wave polarized perpendicularly to the first slot is emitted and when the cavity operates in a TE120 mode, a wave polarized perpendicularly to the second slot is emitted. This elementary antenna is characterized in that the rear face is brought to a reference electric potential, and in that the elementary antenna includes an excitation device, such as a metallized via, capable of exciting the front face through the cavity, the excitation device exciting the front face at a plurality of excitation points, distributed over the front face and presenting a common predefined impedance.
1. An elementary antenna of a polarization agile type and of a cavity antenna type, including a cavity delimited axially by a front face and a rear face and laterally by side walls, the front face, which constitutes a radiating plane of the elementary antenna, being provided with a first straight slot and a second straight slot, the first straight slot and the second straight slot being arranged so as to form together a cross which is centered on a geometric center of the front face and which defines four quadrants on the front face, the elementary antenna being configured such that, when the cavity is placed in a TE210 mode, a wave polarized perpendicularly to the first straight slot is emitted and when the cavity is placed in a TE120 mode, a wave polarized perpendicularly to the second straight slot is emitted, wherein the rear face is brought to a reference electrical potential, and the elementary antenna includes an excitation device, positioned on a rear of the rear face of the cavity and capable of exciting the front face through the cavity, the excitation device exciting the front face at a plurality of excitation points which present a common predefined impedance, each quadrant of the front face carrying at least one excitation point, wherein the excitation device includes a power supply layer and a plurality of metallized vias, electrically connecting the power supply layer, located at the rear of the rear face, and the front face, the power supply layer including a plurality of power supply lines, each power supply line of the plurality of power supply lines being related to a metallized via of the plurality of metallized vias, each metallized via of the plurality of metallized vias opening, onto the front face, at an excitation point of the plurality of excitation points, and wherein each metallized via of the plurality of metallized vias is insulated from the rear face as it passes through said rear face.
2. The elementary antenna according to claim 1 , wherein the front face and the rear face are square and the first straight slot and the second straight slot are arranged parallel to edges of the front face.
3. The elementary antenna according to claim 1 , wherein the common predefined impedance of each excitation point of the plurality of excitation points is 50 Ohms.
4. The elementary antenna according to claim 1 , wherein the rear face acts as an electrical mirror plane between the power supply layer of the excitation device, the power supply layer being located on one side of the rear face while the front face is located on another side of the rear face.
5. The elementary antenna according to claim 1 , wherein two excitation points of the plurality of excitation points that are symmetrically arranged relative to the first straight slot or relative to the second straight slot are excited by signals in phase opposition.
6. The elementary antenna according to claim 1 , wherein the excitation device includes a plurality of slots provided in the rear face and the power supply layer located at the rear of the rear face and including the plurality of power supply lines, each power supply line of the plurality of power supply lines being related to a slot of the plurality of slots, and straddling the related slot of the plurality of slots such that a point of intersection of a power supply line of the plurality of power supply lines and the related slot of the plurality of slots is located in line with a related excitation point of the plurality of excitation points of the front face.
7. The elementary antenna according to claim 6 , wherein the plurality of slots form circular openings.
8. The elementary antenna according to claim 6 , wherein the plurality of slots form straight openings, the plurality of slots forming a cross, a square parallel to edges of the elementary antenna, or a square parallel to diagonals of the elementary antenna.
9. An array antenna including a plurality of elementary antennas, wherein each elementary antenna of the plurality of elementary antennas is the elementary antenna according to claim 1 .
10. The elementary antenna according to claim 1 , comprising eight assemblies, each assembly of the eight assemblies associating one power supply line of the plurality of power supply lines with one metallized via of the plurality of metallized vias and with one excitation point of the plurality of excitation points.