Beam pattern projection for metamaterial antennas

Patent metadata

Field	Value
Publication number	US-10050345-B2
Application number	US-201514954732-A
Country	US
Kind code	B2
Filing date	Nov 30, 2015
Priority date	Nov 30, 2015
Publication date	Aug 14, 2018
Grant date	Aug 14, 2018

Abstract

A determined far-field beam pattern can be approximately formed by applying a modulation pattern to metamaterial elements receiving RF energy from a feed network. For example, a desired beam profile projected onto a two-dimensional plane of a far-field of an antenna is desired to be produced by an antenna. A computing system can calculate a modulation pattern to apply to metamaterial elements receiving RF energy to a feed network that will result in an approximation of desired beam profile.

First claim

What is claimed is:

1. An antenna system comprising:
an aperture coupled to a feed network and approximated by an aperture taper function, the aperture comprising:
a set of radiating aperture elements having an element modulation range and configured to selectively transfer energy from a reference wave, the set of radiating aperture elements configured to radiate a beam pattern based on energy received from the reference wave; and
a control system comprising a processor configured to:
define a desired beam profile projected onto a two-dimensional plane located in a far-field of an antenna;
convert the desired beam profile from a spatial domain far-field pattern into a frequency domain field description;
construct a transfer function of free space;
back-propagate the frequency domain field description in the far-field back to an antenna plane using the transfer function of free space to form an antenna plane frequency domain field description;
convert the antenna plane frequency domain field description into a spatial domain to form an object wave;
compute a modulation function to apply to radiating elements of the antenna to form the object wave by discarding a phase portion of an ideal modulation pattern to form a magnitude modulation pattern used to compute the modulation function; and
apply the modulation function created by discarding the phase portion of ideal modulation pattern to the set of radiating aperture elements of the antenna to form an approximation of the desired beam profile using the energy received from the reference wave.

2. The system of claim 1 , wherein to compute the modulation function to apply to the radiating elements of the antenna to form the object wave further comprises:
determine the ideal modulation pattern based at least in part on the reference wave multiplied by the object wave, wherein the feed network comprising a feed input port is configured to provide the reference wave to the set of radiating aperture elements;
discard the phase portion of the ideal modulation pattern to form the magnitude modulation pattern;
form a tapered modulation pattern by multiplying the aperture taper function with elements of the magnitude modulation pattern;
normalize the tapered modulation pattern based at least in part on an upper bound and lower bound of the element modulation range of the aperture to form an aperture modulation pattern; and
apply the modulation function to the aperture to approximate the desired beam profile based at least in part on the aperture modulation pattern and the reference wave.

3. The system of claim 2 , wherein the reference wave further comprises a set of fields in the feed network.

4. The system of claim 3 , wherein each field in the set of fields in the feed network is associated with a radiating aperture element from the set of radiating aperture elements.

5. The system of claim 1 , wherein the processor is further configured to cause the set of radiating aperture elements to emit the beam pattern based on the desired beam profile.

6. The system of claim 5 , wherein the beam pattern approximates the desired beam profile.

7. The system of claim 1 , wherein the reference wave is a plane wave.

8. The system of claim 1 , wherein the antenna system further comprises metamaterial surface antenna technology (MSA-T).

9. The system of claim 8 , wherein the set of radiating aperture elements further comprises metamaterial elements.

10. A device for beam shaping, the system comprising:
storage configured for storing an aperture taper function and an element modulation range of an aperture of an antenna;
circuitry configured to interface with the antenna and provide a modulation function to apply to radiating elements of the aperture; and
a processor configured to:
receive a two-dimensional beam profile projection located in a far-field of the antenna;
back-propagate a representation of the two-dimensional beam profile projection to an antenna plane to form an object wave;
compute the modulation function to form the object wave by discarding a phase portion of an ideal modulation pattern to form a magnitude modulation pattern used to compute the modulation function; and
transmit the modulation function created using the magnitude modulation pattern formed by discarding the phase portion of the ideal modulation pattern to the antenna for application to the radiating elements of the antenna to radiate an approximation of the object wave which results in an approximation of the two-dimensional beam profile projection.

11. The device of claim 10 , wherein to compute the modulation function to form the object wave further comprises:
determine the ideal modulation pattern based at least in part on a reference wave from a feed network of the antenna multiplied by the object wave;
discard the phase portion of the ideal modulation pattern to form the magnitude modulation pattern; and
form the modulation function based at least in part on an aperture taper function, magnitude modulation pattern, a lower bound of the element modulation range of the aperture and an upper bound of the element modulation range of the aperture.

12. The device of claim 11 , wherein the reference wave is a plane wave.

13. The device of claim 11 , wherein the reference wave is propagating through a transmission line such as a parallel-plate waveguide, a rectangular waveguide or a microstrip line.

14. The device of claim 11 , wherein the reference wave further comprises a set of fields in the feed network.

15. The device of claim 11 , wherein to form the modulation function further comprises:
form a product pattern by scaling and multiplying elements of the aperture taper function with elements of the magnitude modulation pattern; and
normalize the product pattern based at least in part on the upper bound and the lower bound of the element modulation range of the aperture to form the modulation function.

16. The device of claim 10 , wherein to back-propagate the representation of the two-dimensional beam profile projection to the antenna plane to form the object wave further comprises converting the two-dimensional beam profile projection from a spatial domain into a frequency domain to form a k-space field description.

17. The device of claim 10 , wherein to back-propagate the representation of the two-dimensional beam profile projection to the antenna plane further comprises constructing the transfer function of free space between the two-dimensional beam profile projection and an aperture plane of the antenna.

18. The device of claim 10 , wherein to receive the two-dimensional beam profile projection located in the far-field of the antenna further comprises defining a far-field pattern based on the two-dimensional beam profile projection on a two-dimensional planar grid located in the far-field of the antenna, the grid corresponding to a set of radiating element locations at an aperture plane.

19. The device of claim 18 , wherein the two-dimensional planar grid corresponds to the set of radiating element locations at the aperture plane.

20. The device of claim 10 , wherein to transmit the modulation function to the antenna for application to the radiating elements of the antenna further comprises to apply the modulation function to an antenna system aperture.

21. The device of claim 20 , further comprising an antenna system that includes the aperture.

22. The device of claim 10 , wherein the processor is configured to control an antenn

Assignees

• Elwha Llc

Inventors

• Black Eric J
• Deutsch Brian Mark
• Katko Alexander Remley
• Machado Melroy
• Mccandless Jay Howard
• Urzhumov Yaroslav A

Classifications

• H01Q15/006

  Selective devices having photonic band gap materials or materials of which the material properties are frequency dependent, e.g. perforated substrates, high-impedance surfaces · CPC title

• H01Q3/46 Primary

  Active lenses or reflecting arrays · CPC title