Modulation patterns for surface scattering antennas

Patent metadata

Field	Value
Publication number	US-9806414-B2
Application number	US-201615010118-A
Country	US
Kind code	B2
Filing date	Jan 29, 2016
Priority date	Jun 20, 2014
Publication date	Oct 31, 2017
Grant date	Oct 31, 2017

Abstract

Modulation patterns for surface scattering antennas provide desired antenna pattern attributes such as reduced side lobes and reduced grating lobes.

First claim

What is claimed is:

1. A method, comprising:
discretizing a hologram function for a surface scattering antenna that defines an aperture, where the discretizing includes
identifying a discrete plurality of locations on the aperture for a discrete plurality of scattering elements of the surface scattering antenna and
identifying a discrete set of states for each of the scattering elements corresponding to a discrete set of function values at each of the locations of the scattering elements; and

identifying an antenna configuration that reduces artifacts attributable to the discretizing, wherein the identifying of the antenna configuration includes dithering the discretized hologram function.

2. The method of claim 1 , further comprising:
adjusting the surface scattering antenna to the identified antenna configuration.

3. The method of claim 1 , further comprising:
operating the surface scattering antenna in the identified antenna configuration.

4. The method of claim 1 , further comprising:
storing the identified antenna configuration in a storage medium.

5. The method of claim 1 , wherein the dithering of the discretized hologram function includes, for each location in the plurality of locations:
selecting a virtual displacement for the location;
identifying a virtual location corresponding to the location plus the virtual displacement; and
selecting a function value from the discrete set of function values, the selected value being that value in the discrete set of function values that is closest to the hologram function evaluated at the virtual location.

6. The method of claim 5 , wherein the virtual displacements are random virtual displacements.

7. The method of claim 6 , wherein the random virtual displacements have a standard deviation greater than one-fifth of a lattice spacing of the plurality of locations.

8. The method of claim 6 , wherein the random virtual displacements have a standard deviation greater than one-half of a lattice spacing of the plurality of locations.

9. The method of claim 5 , wherein the virtual displacements are non-random virtual displacements that vary gradually across the aperture.

10. The method of claim 5 , wherein the identifying of the antenna configuration includes, for each scattering element in the plurality of scattering elements:
identifying a state for the scattering element selected from the discrete set of states and corresponding to the selected function value for the location of the scattering element.

11. The method of claim 1 , wherein the dithering of the discretized hologram function includes, for each location in the plurality of locations:
selecting a function noise amount corresponding to the location; and
selecting a function value from the discrete set of function values, the selected value being that value in the discrete set of function values that is closest to a sum of the hologram function evaluated at the location and the function noise amount.

12. The method of claim 11 , wherein the function noise amounts have a standard deviation greater than 10% of a difference between a maximum function value of discrete set of function values and a minimum function value of the discrete set of function values.

13. The method of claim 11 , wherein the function noise amounts have a standard deviation greater than 25% of a difference between a maximum function value of discrete set of function values and a minimum function value of the discrete set of function values.

14. The method of claim 11 , wherein the identifying of the antenna configuration includes, for each scattering element in the plurality of scattering elements:
identifying a state for the scattering element selected from the discrete set of states and corresponding to the selected function value for the location of the scattering element.

15. A system, comprising:
a surface scattering antenna with a plurality of adjustable scattering elements that are adjustable between a discrete set of states corresponding to a discrete set of function values at each location in a plurality of locations for the plurality of adjustable scattering elements;
a storage medium on which a set of antenna configurations corresponding to a set of hologram functions is written, each antenna configuration being selected to reduce artifacts attributable to a discretization of the respective hologram function; and
control circuitry operable to read antenna configurations from the storage medium and adjust the plurality of adjustable scattering elements to provide the antenna configurations;
wherein at least one antenna configuration is a dithered discretization of the respective hologram function.

16. The system of claim 15 , wherein the dithered discretization is obtained by an algorithm that includes, for each location in the plurality of locations:
selecting a virtual displacement for the location;
identifying a virtual location corresponding to the location plus the virtual displacement;
selecting a function value from the discrete set of function values, the selected value being that value in the discrete set of function values that is closest to the respective hologram function evaluated at the virtual location; and
identifying a state for the adjustable scattering element at the location, the identified state being selected from the discrete set of states and corresponding to the selected function value for the location.

17. The system of claim 16 , wherein the virtual displacements are random virtual displacements.

18. The system of claim 17 , wherein the random virtual displacements have a standard deviation greater than one-fifth of a lattice spacing of the plurality of locations.

19. The system of claim 17 , wherein the random virtual displacements have a standard deviation greater than one-half of a lattice spacing of the plurality of locations.

20. The system of claim 16 , wherein the surface scattering antenna defines an aperture and the virtual displacements are non-random virtual displacements that vary gradually across the aperture.

21. The system of claim 15 , wherein the dithered discretization is obtained by an algorithm that includes, for each location in the plurality of locations:
selecting a function noise amount corresponding to the location;
selecting a function value from the discrete set of function values, the selected value being that value in the discrete set of function values that is closest to a sum of the respective hologram function evaluated at the location and the function noise amount; and
identifying a state for the adjustable scattering element at the location, the identified state being selected from the discrete set of states and corresponding to the selected function value for the location.

22. The system of claim 21 , wherein the function noise amounts have a standard deviation greater than 10% of a difference between a maximum function value of discrete set of function values and a minimum function value of the discrete set of function values.

23. The system of claim 21 , wherein the function noise amounts have a standard deviation greater than 25% of a difference between a maximum function value of discrete set of function values and a minimum function value of the discrete set of function values.

24. A method of controlling a surface scattering antenna with a plurality of adjustable scattering elements, comprising:
reading an antenna configuration from a storage medium

Assignees

• Searete Llc
• The Invent Science Fund I Llc

Inventors

• Chen Pai-Yen
• Driscoll Tom
• Ebadi Siamak
• Hunt John Desmond
• Landy Nathan Ingle
• Machado Melroy
• Perque Jr Milton
• Smith David R
• Urzhumov Yaroslav A

Classifications

• H01Q3/44 Primary

  varying the electric or magnetic characteristics of reflecting, refracting, or diffracting devices associated with the radiating element · CPC title

• H01Q13/20 Primary

  Non-resonant leaky-waveguide or transmission-line antennas; Equivalent structures causing radiation along the transmission path of a guided wave · CPC title

• H01Q11/02

  Non-resonant antennas, e.g. travelling-wave antenna (Yagi antennas H01Q19/30) · CPC title