Unit cell of a transmitter array

1. A unit cell of a transmitter array for transmitting an incident wave with a phase shift, the unit cell comprising:

a ground plane;

first and second dielectric substrates, arranged on either side of the ground plane, and each having a first surface, oriented toward the ground plane, and a second surface, opposed to the first surface;

first and second planar antennas, extending on the second surfaces of the first and second dielectric substrates, respectively;

a via, arranged to pass through the first and second dielectric substrates so as to electrically connect the first and second planar antennas; the via being electrically isolated from the ground plane; and

a third planar antenna, extending between the ground plane and the first surface of the first dielectric substrate, and electrically connected to the via.

2. The unit cell as claimed in claim 1 , wherein the third planar antenna extends on the first surface of the first dielectric substrate.

3. The unit cell as claimed in claim 1 , wherein the first, second and third planar antennas are configured to operate in a same passhand.

4. The unit cell as claimed in claim 3 , wherein the first and third planar antennas are oriented according to two orthogonal linear polarizations.

5. The unit cell as claimed in claim 3 , wherein the first and third planar antennas are movable in rotation relative to the second planar antenna.

6. The unit cell as claimed in claim 1 , further comprising a fourth planar antenna, extending between the ground plane and the first surface of the second dielectric substrate, and electrically connected to the via; wherein

the first and third planar antennas are configured to operate in different first and second passbands, respectively; and

the second and fourth planar antennas are configured to operate in the first and second passbands respectively, or in the second and first passbands respectively.

7. The unit cell as claimed in claim 6 , wherein the fourth planar antenna extends on the first surface of the second dielectric substrate.

8. The unit cell as claimed in claim 7 , wherein

the third planar antenna extends on the first surface of the first dielectric substrate;

the first planar antenna has separate first and second radiating surfaces; and

the unit cell comprises a first phase-shift circuit comprising:

first and second switches each having a conducting state and a non-conducting state alternately, the conducting and non-conducting states corresponding to a permitted or prevented flow of a current respectively, between the separate first and second radiating surfaces of the first planar antenna, and

first bias lines, arranged to bias the first and second switches of the first phase-shift circuit;

the first and third planar antennas being electrically connected to the first bias lines, and the second and fourth planar antennas being electrically connected to the ground plane.

9. The unit cell as claimed in claim 8 , comprising a third dielectric substrate, extending between the ground plane and the third planar antenna, the first bias lines extending on the third dielectric substrate.

10. The unit cell as claimed in claim 6 , wherein the first and second planar antennas each have separate first and second radiating surfaces; the unit cell comprising:

a first phase-shift circuit, comprising:

first and second switches, each having a conducting state and a non-conducting state alternately, the conducting and non-conducting states corresponding to a permitted or prevented flow of a current respectively, between the separate first and second radiating surfaces of the first planar antenna, and

first bias lines, arranged on the first surface of the first dielectric substrate to bias the first and second switches of the first phase-shift circuit; the first planar antenna being electrically connected to the first bias lines; and

a second phase-shift circuit, comprising:

first and second switches, each having a conducting state and a non-conducting state alternately, the conducting and non-conducting states corresponding to a permitted or prevented flow of a current respectively, between the separate first and second radiating surfaces of the second planar antenna, and

second bias lines, arranged on the first surface of the second dielectric substrate to bias the first and second switches of the second phase-shift circuit; the second planar antenna being electrically connected to the second bias lines;

the second and fourth planar antennas being configured to operate in the second and first passbands, respectively, so that the first and second planar antennas are configured to operate in two different passbands, the third and fourth planar antennas being electrically connected to the ground plane.

11. The unit cell as claimed in claim 10 , comprising:

a third dielectric substrate, extending between the ground plane and the first dielectric substrate, the third planar antenna extending on the third dielectric substrate; and

a fourth dielectric substrate, comprising a first surface on which the ground plane extends, and a second, opposed, surface on which the fourth planar antenna extends.

12. An antenna reconfigurable to an operating frequency, comprising:

a first transmitter array comprising a set of unit cells as claimed in claim 6 ; and

first and second radiating sources, operating, respectively, in first and second passbands, and arranged to illuminate the first transmitter array.