WIRELESS POWER TRANSFER USING TUNABLE METAMATERIAL SYSTEMS AND METHODS
The present disclosure provides system and methods for optimizing the tuning of impedance elements associate with sub-wavelength antenna elements to attain target radiation and/or field patterns. A scattering matrix (S-Matrix) of field amplitudes for each of a plurality of modeled lumped ports, N, may be determined that includes a plurality of lumped antenna ports, N a , with impedance values corresponding to the impedance values of associated impedance elements and at least one modeled external port, N e , located external to the antenna system at a specified radius vector. Impedance values may be identified through an optimization process, and the impedance elements may be tuned (dynamically or statically) to attain a specific target radiation pattern.
1 . A wireless power transmission system, comprising:
a plurality of sub-wavelength antenna elements configured to scatter received electromagnetic fields;
a plurality of lumped impedance elements in communication with the plurality of sub-wavelength antenna elements;
a plurality of variable impedance control inputs configured to allow for the selection of an impedance value for each of the lumped impedance elements;
a computer-readable medium providing instructions accessible to a processor to cause the processor to perform operations for radiation patterning, comprising:
determining a scattering matrix (S-Matrix) of electromagnetic field amplitudes for each of a plurality of lumped ports, wherein the lumped ports include:
a plurality of lumped antenna ports with impedance values corresponding to the impedance values of each of the plurality of lumped impedance elements;
at least one lumped external port corresponding to a first wireless power receiver located physically external to the wireless power transmitter, and
at least one lumped external port corresponding to a second wireless power receiver located physically external to the wireless power transmitter,
wherein the S-Matrix is expressible in terms of an impedance matrix, Z-Matrix, with impedance values of each of the plurality of lumped ports;
identifying a target electromagnetic radiation pattern of the wireless power transmitter defined in terms of target electromagnetic field amplitudes in the S-Matrix for the at least one lumped external port in each of the first wireless power receiver and the second wireless power receiver; and
determining an optimized port impedance vector {z n } of impedance values for each of the lumped antenna ports that results in an S-Matrix element for the at least one lumped external port that approximates the target electromagnetic field amplitude for an operating frequency.
2 . The wireless power transmission system 2 , wherein the instructions accessible to a processor are further configured to cause the processor to adjust at least one of the plurality of variable impedance control inputs to modify at least one of the impedance values of at least one of the plurality of variable lumped impedance elements based on the determined optimized {z n } of the impedance values for the lumped antenna ports.
3 . A method for antenna radiation patterning, comprising:
determining a scattering matrix (S-Matrix) of field amplitudes for each of a plurality of lumped ports, N, associated with an antenna device, including
a plurality of lumped antenna ports, N a , wherein each lumped antenna port corresponds to an impedance value of a lumped impedance element in communication with at least one sub-wavelength antenna element of an antenna device, and
at least one lumped external port, N e , located physically external to the antenna device,
wherein the S-Matrix is expressible in terms of an impedance matrix, Z-Matrix, with impedance values, z n , of each of the plurality of lumped ports, N;
identifying a target radiation pattern of the antenna device defined in terms of target field amplitudes in the S-Matrix for the at least one lumped external port, N e ; and
determining an optimized port impedance vector, {z n }, of impedance values for each of the lumped antenna ports, N a , that results in an S-Matrix element for the at least one lumped external port, N e , that approximates the target field amplitude for an operating frequency.
4 . The method of claim 3 , wherein the impedance value of each of the lumped impedance elements is variable based on one or more impedance control inputs.
5 . The method of claim 3 , wherein each lumped impedance element is associated with a unique dielectric loading, such that the impedance value of each lumped impedance element is independently selectable.
6 . The method of claim 5 , wherein the dielectric material comprises at least one material printed using a 3D printer and the dielectric value is selected based on a filling fraction of the at least one 3D-printed material.
7 . The method of claim 5 , wherein the dielectric material comprises at least one material printed using a 3D printer and the dielectric value is selected based on a dielectric constant of the at least one 3D-printed material.
8 . The method of claim 5 , wherein the dielectric material comprises a combination of at least two dielectric materials and the impedance value is based at least in part on the ratio of the two dielectric materials.
9 . The method of claim 8 , wherein the at least two dielectric materials are printed using a multi-material 3D printer and the dielectric value is selected based at least in part on a ratio of the at least two 3D-printed materials.
10 . The method of claim 3 , wherein each lumped impedance element is associated with a unique dielectric loading, such that the impedance value of each lumped impedance element is independently selectable.
11 . The method of claim 3 , wherein each of the sub-wavelength antenna elements comprises an antenna element with a maximum dimension that is less than half of a wavelength of the smallest frequency in an operating frequency range.
12 . The method of claim 3 , wherein at least some of the sub-wavelength antenna elements comprise resonating elements.
13 . The method of claim 3 , wherein at least two of the sub-wavelength antenna elements comprise a metamaterial.
14 . The method of claim 3 , wherein each of the plurality of lumped antenna ports, N a , are coupled to a common transmission line (TL).
15 . The method of claim 14 , wherein the common TL is treated as another of the plurality of lumped ports, N, in addition to the plurality of lumped antenna ports, N a , and the at least one lumped external port, N e .
16 . The method of claim 3 , wherein the at least one lumped external port, N e , comprises an external port with an infinitesimal volume located at a particular radius-vector relative to the antenna device.
17 . The method of claim 3 , wherein the at least one lumped external port, N e , is in the far-field of the antenna device.
18 . The method of claim 3 , wherein the at least one lumped external port, N e , is in the near-field of the antenna device.
19 . The method of claim 18 , wherein the near-field is a radiative near-field.
20 . The method of claim 18 , wherein the near-field is a reactive near-field.