Reflectarray antenna with two-dimensional beam scanning
Examples disclosed herein relate to a reflectarray antenna system with two-dimensional beam scanning that includes a first reflectarray having a polarizing grid that operates as a reflective surface in a first polarization and operates as a transparent surface in a second polarization. The reflectarray antenna system includes a second reflectarray comprising an array of reflectarray cells and arranged parallel to the first reflectarray. The second reflectarray includes a first set of feed elements arranged along a first axis and a second set of feed elements arranged along a second axis orthogonal to the first axis to scan a field of view along the first and second axes. The second reflectarray can radiate radio frequency (RE) beams in the first polarization with the first and second sets of feed elements for reflection at the polarizing grid and radiate reflected RE beams in the second polarization for transmission through the polarizing grid.
1. An antenna system having a plurality of layers, comprising:
a radio frequency integrated circuit (RFIC) layer;
an antenna layer comprising a plurality of radiating elements creating paths for transmission and receipt of RF signals, wherein the plurality of radiating elements comprises a first set of feed elements arranged along a first axis in one row laterally across an entire surface of the antenna layer to scan a field of view along the first axis and a second set of feed elements arranged along a second axis in one row laterally across an entire surface of the antenna layer, wherein the second axis is orthogonal to the first axis and the second set of feed elements is configured to scan the field of view along the second axis; and
a polarizing layer positioned approximately parallel to the antenna layer.
2. The antenna system as in claim 1 , further comprising a signal plane layer and a ground plane layer.
3. The antenna system as in claim 1 , wherein the polarizing layer is a reflectarray structure having a grid structure forming a reflective surface.
4. The antenna system as in claim 3 , wherein the grid structure includes an array of cells with at least one reflector element.
5. The antenna system as in claim 4 , wherein the array of cells comprises:
a first cell positioned at a first angular position with respect to the antenna layer; and
a second cell positioned at a second angular position with respect to the antenna layer, wherein the first and second angular positions are different.
6. The antenna system as in claim 4 , wherein an axis of the array of cells is tilted with respect to an incident electric field and the array of cells are configured to superimpose reflected beams and modify polarization.
7. The antenna system as in claim 1 , positioned within a vehicle radar system.
8. The antenna system as in claim 1 , positioned within a traffic infrastructure system.
9. A reflectarray antenna system, comprising:
a first reflectarray comprising a polarizing grid configured to operate as a reflective surface in a first polarization and operate as a transparent surface in a second polarization different from the first polarization; and
a second reflectarray comprising an array of reflectarray cells and arranged substantially parallel to the first reflectarray, the second reflectarray comprising a first set of feed elements arranged along a first axis in one row laterally across an entire surface of the antenna layer to scan a field of view along the first axis and a second set of feed elements arranged along a second axis in one row laterally across an entire surface of the antenna layer, wherein the second axis is orthogonal to the first axis and the second set of feed elements is configured to scan the field of view along the second axis, the second reflectarray configured to radiate radio frequency (RF) beams in the first polarization with one or more of the first set of feed elements and the second set of feed elements for reflection at the polarizing grid and to radiate reflected RF beams in the second polarization for transmission through the polarizing grid.
10. The reflectarray antenna system of claim 9 , wherein the first set of feed elements and the second set of feed elements comprise patch elements.
11. The reflectarray antenna system of claim 9 , wherein the array of reflectarray cells in the second reflectarray apply a phase shift to the RF beams in the first polarization to produce the reflected RF beams in the second polarization.
12. The reflectarray antenna system of claim 9 , wherein the first reflectarray and the second reflectarray are separated by a predetermined distance.
13. The reflectarray antenna system of claim 9 , wherein feed elements in the first set of feed elements or the second set of feed elements radiate RF beams concurrently toward a common location on the second reflectarray such that superposition of the RF beams produces a combined beam with a predetermined gain at that location.
14. The reflectarray antenna system of claim 9 , wherein feed elements in the first set of feed elements or the second set of feed elements are switched sequentially.
15. The reflectarray antenna system of claim 9 , wherein the first reflectarray applies a phase shift to the RF beams in the first polarization to modify its polarization by a predetermined amount.
16. The reflectarray antenna system of claim 9 , wherein the first reflectarray has a first phase distribution and the second reflectarray has a second phase distribution that is mapped to the first phase distribution to cause RF beams originating from feed illumination to be reflected from the second reflectarray to a target reflector element in the first reflectarray.
17. The reflectarray antenna system of claim 9 , wherein each of the first set of feed elements and the second set of feed elements includes a subarray of feed elements arranged along both axes such that cells are patterned on a surface of the second reflectarray between each of the first set of feed elements and the second set of feed elements and a periphery of the second reflectarray.
18. The reflectarray antenna system of claim 9 , wherein the second reflectarray comprises an RF Integrated Circuit (RFIC) layer and an antenna layer disposed on the RFIC layer, wherein the antenna layer comprises the array of reflectarray cells and the RFIC layer comprises a plurality of RFIC components configured to apply a gain to the RF beams originating from feed illumination.
19. The reflectarray antenna system of claim 18 , wherein each feed element in the first set of feed elements and the second set of feed elements is coupled to respective ones of the plurality of RFIC components in the RFIC layer.