Re-configurable repeater device including beam-shaping unit
A re-configurable repeater device—such as a large intelligent surface or an amplify-and-forward repeater—includes an array of reflective elements and a beam-shaping unit in front of the array. The beam-shaping unit is configured to increase a beam diameter of an incoming beam. For instance, the divergence of incoming electromagnetic waves can be increased. It would be possible that the beam-shaping unit is im-plemented as a lens, e.g., a Luneberger-type lens.
1. A re-configurable repeater device re-configurable to provide multiple spatial filters, each one of the multiple spatial filters being applied to an incoming beam, to thereby obtain an outgoing beam, wherein the re-configurable repeater device comprises:
an array of re-configurable elements, wherein the re-configurable elements of the array of re-configurable elements are configured to impose a respective phase shift onto outgoing electromagnetic waves of the outgoing beam with respect to incoming electromagnetic waves of the incoming beam, and
a beam-shaping unit arranged at an offset from the array of re-configurable elements upstream along a propagation direction of the incoming beam and configured to increase a beam diameter of the incoming beam.
2. The re-configurable repeater device of claim 1 , wherein the beam-shaping unit is a spreading lens configured to provide beam-shaping at a fixed focal length across its lateral dimension, by increasing a beam divergence of the incoming electromagnetic waves.
3. The re-configurable repeater device of claim 1 , wherein the beam-shaping unit provides beam-shaping at varying focal lengths across its width direction.
4. The re-configurable repeater device of claim 1 , further comprising:
a control unit configured to re-configure each one of the re-configurable elements to provide a selected one of the multiple spatial filters, said re-configuring of each one of the re-configurable elements being based on an incident angle of the incoming beam, an outgoing angle of the outgoing beam, and a predefined beam-shaping coefficient associated with the beam-shaping unit.
5. The re-configurable repeater device of claim 4 , wherein the pre-defined beam-shaping coefficient is implemented using a machine-learned algorithm, the machine-learned algorithm accepting, as an input, at least one of the incident angle or the outgoing angle.
6. The re-configurable repeater device of claim 4 , wherein the control unit is configured to re-configure the re-configurable elements independent of a propagation distance of at least one of the incoming beam or the outgoing beam.
7. The re-configurable repeater device of claim 1 , wherein the offset between the array of re-configurable elements and the beam-shaping unit is dimensioned so that the beam diameter of the incoming beam is widened at least by a factor of 2.
8. The re-configurable repeater device of claim 1 , wherein the array of re-configurable elements is configured to reflect and optionally amplify the outgoing electromagnetic waves of the outgoing beam towards the beam-shaping unit.
9. The re-configurable repeater device of claim 1 , wherein the array of re-configurable elements is configured to reflect and optionally amplify the outgoing electromagnetic waves away from the beam shaping unit.
10. The re-configurable repeater device of claim 1 , wherein an optical aperture of the beam-shaping unit is not larger than 50% of an optical aperture of the array of re-configurable elements.
11. The re-configurable repeater device of claim 1 , wherein the beam-shaping unit comprises a laterally structured dielectric surface, optionally a metamaterial array of multiple beam-shaping elements.
12. The re-configurable repeater device of claim 1 , wherein the beam-shaping unit comprises multiple sheets stacked along the propagation direction of the incoming beam, each sheet comprising one or more beam-elements.
13. The re-configurable repeater device of claim 1 , wherein the re-configurable repeater device is configured to provide the multiple spatial filters for the incoming electromagnetic waves and the outgoing electromagnetic waves having frequencies of not less than 20 GHz or optionally not less than 500 GHz.