Systems and methods for long-range wireless power transfer

Abstract

To provide a long-distance wireless power transmission system for efficiently transmitting power by using an electromagnetic beam.SOLUTION: The system 100 includes a delivery antenna 110 that receives power from a power source, converts the input power into electromagnetic energy, and radiates the electromagnetic energy into free space as a directional beam that is a collimated or substantially collimated beam. The rectifying antenna 130 is positioned or configured to be positioned at a distance from the delivery antenna 110. The rectifying antenna 130 is configured to receive the directional beam and convert the electromagnetic energy into electricity. The system 100 utilizes one or more phase correction apparatuses 120, 122 to maintain the directional beam as a collimated beam and to increase the extent to which the directional beam is maintained as a collimated or substantially collimated beam.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a system and method for long-distance wireless power transmission. [Background technology]

[0002] The use of transmission wires to transmit electricity is well known. However, transmitting power using transmission lines / cables has several disadvantages. Laying power cables can be expensive, requiring substantial labor, equipment, and land area. Furthermore, installing and maintaining power cables can be costly. Also, transmission lines are not easily implemented in all geographic locations. Overhead transmission lines are aesthetically unpleasing and can be damaged, for example, in severe weather conditions. While underground power cables can solve some of these problems, they also have several disadvantages, such as difficulty in detecting faults, and are difficult and expensive to upgrade.

[0003] One of the problems with transmitting power wirelessly using electromagnetic beams over long distances is the ability to transmit power efficiently, since much of the energy is lost in free space as electromagnetic waves can easily diverge in other directions during the delivery of energy from the sending end to the receiving end. This means that the energy received at the receiving end may be insufficient to provide power, or may not be economically feasible, compared to physical line-based alternatives.

[0004] It is an object of the present invention to provide a system and / or method for long-distance wireless power transmission that overcomes or at least partially ameliorates the above-mentioned problems and discussions of current line-based solutions, or at least provides a useful option for the civilian population. Summary of the Invention

[0005] In a first aspect, the present invention provides a long-distance wireless power transfer system, comprising: a delivery antenna that is a phased array antenna having an array of antenna elements that are radiating elements, the delivery antenna configured to receive power as an input from a power source, convert the input power into electromagnetic energy, and radiate the electromagnetic energy into free space as a directional beam that is a collimated or substantially collimated beam, the collimated or substantially collimated beam being generated by controlling the phase and amplitude of each of the antenna elements; at least one phase correction device positioned or configured to be positioned at a first distance from the delivery antenna, the at least one phase correction device being a multi-layer structure having at least three layers with a central dielectric core sandwiched between at least two layers of two opposite portions of the dielectric core, at least one of the layers being a dielectric skin made of at least one dielectric material, the at least one phase correction device corresponding to the device comprising: receiving the directional beam emitted from the transmitting antenna; performing a phase correction operation on the directional beam, the phase correction operation maintaining the directional beam as the collimated or substantially collimated beam and increasing the extent to which the directional beam is maintained as the collimated or substantially collimated beam; and delivering the phase-corrected directional beam into free space. The system includes: the at least one phase correction device positioned or configured to be positioned between a delivery antenna and a rectifying antenna; and the rectifying antenna positioned or configured to be positioned at a second distance from the delivery antenna, the rectifying antenna configured to receive the directional beam from the at least one phase correction device and convert the electromagnetic energy into electricity.

[0006] In a second aspect, the present invention provides a long-distance wireless power transfer system, comprising: a delivery antenna configured to receive power as an input from a power source, convert the input power into electromagnetic energy, and radiate the electromagnetic energy into free space in a directional beam, the beam being a collimated or substantially collimated beam; at least one phase correction device positioned or configured to be positioned at a first distance from the delivery antenna, the at least one phase correction device comprising: receiving the directional beam emitted from the transmitting antenna; maintaining the directional beam as the collimated or substantially collimated beam and performing a phase correction operation on the directional beam to increase the extent to which the directional beam is maintained as the collimated or substantially collimated beam; and delivering the phase-corrected directional beam into free space. The system includes: the at least one phase correction device positioned or configured to be positioned between a delivery antenna and a rectifying antenna; and the rectifying antenna positioned or configured to be positioned at a second distance from the delivery antenna, the rectifying antenna configured to receive the directional beam from the at least one phase correction device and convert the electromagnetic energy into electricity.

[0007] One or more of the following statements may apply to the invention defined in the first and / or second aspects above.

[0008] In one embodiment, the electromagnetic energy is microwave energy.

[0009] In one embodiment, the delivery antenna is a phased array antenna having an array of antenna elements that are radiating elements, and the collimated or substantially collimated beam is generated by controlling the phase and amplitude of each of the antenna elements.

[0010] In one embodiment, each antenna element has an electronically controlled phase shifter that facilitates electronic steering of the directional beam.

[0011] In one embodiment, each antenna element is a patch antenna element.

[0012] In one embodiment, each antenna element is made from a metal segment etched onto a substrate.

[0013] In one embodiment, each antenna element includes at least one low-loss dielectric element made from a low-loss dielectric material.

[0014] In one embodiment, each antenna element is a radome element formed as a hemispherical or approximately hemispherical shell.

[0015] In one embodiment, the radome element has thin radome element walls with wall thicknesses of less than or equal to one-quarter of the wavelength of the material from which the radome element walls are made.

[0016] In one embodiment, the wavelength of electromagnetic energy in the form of an electromagnetic wave in the material from which the radome element walls are made is given by: JPEG2026009907000002.jpg2234In formula, λ d is the wavelength of the electromagnetic wave in the radome wall material, λ is the free space wavelength, and n d is the refractive index of the radome wall material.

[0017] In one embodiment, the radome element is larger than the antenna element so as to cover the antenna element.

[0018] In one embodiment, the at least one phase corrector is an electromagnetic wave transmitting phase corrector.

[0019] In one embodiment, the at least one phase corrector is a straight-through phase corrector that causes the incident directional beam to travel in a straight direction without diverging into directional beams in other directions.

[0020] In one embodiment, the straight-through phase correction device is a composite multi-layer structure in which the dielectric core comprises at least three layers sandwiched between at least two dielectric skins on two opposite sides of the dielectric core.

[0021] In one embodiment, the dielectric skin comprises a metasurface that simultaneously provides a phase shift while minimizing power loss and maintaining an impedance matching structure.

[0022] In one embodiment, the metasurface is embedded on the dielectric skin.

[0023] In one embodiment, the thickness of the dielectric skin at each portion of the dielectric core is less than one tenth of the wavelength of an electromagnetic wave passing through the material from which the dielectric skin is made.

[0024] In one embodiment, the dielectric core is made from a low-loss dielectric material.

[0025] In one embodiment, the dielectric core is at least three layers with at least one metamaterial layer sandwiched between two dielectric support layers.

[0026] In one embodiment, the at least one metamaterial layer is a metasurface.

[0027] In one embodiment, the thickness of the dielectric core is between 1 / 10 and 1 full wavelength of an electromagnetic wave passing through the dielectric material from which it is made.

[0028] In one embodiment, the dielectric core has a refractive index between 1 and 3.

[0029] In one embodiment, the at least one phase correction device is a reflective phase correction device that reflects the directional beam incident on the reflective phase correction device in another direction, thereby diverging the directional beam in the other direction at a certain angle.

[0030] In one embodiment, the angle is between 60 degrees and 120 degrees, and preferably is at or about 90 degrees.

[0031] In one embodiment, the reflective phase correction device is a composite multi-layer structure having a dielectric core with at least three layers sandwiched between a dielectric skin of a first portion of the dielectric core and a reflective ground plane of a second portion of the dielectric core, the second portion being opposite the first portion.

[0032] In one embodiment, in the reflective phase correction device, the dielectric core is sandwiched between the at least two layers on two opposite sides of the dielectric core, at least one of the layers being the dielectric skin and the other layer being a reflective ground plane.

[0033] In one embodiment, the dielectric skin comprises a metasurface that simultaneously provides a phase shift to the incoming wavefront and completes the reflection with minimal power loss.

[0034] In one embodiment, the delivery antenna has a delivery antenna aperture.

[0035] In one embodiment, the delivery antenna aperture has a dimension D and an aperture efficiency ε, and at least one of the following inequalities applies for the wavelength λ and the distance R between the delivery antenna and the down-range phase correction device or rectenna: JPEG2026009907000003.jpg1447 JPEG2026009907000004.jpg1447

[0036] In one embodiment, D 2 ≧4λR / ε applies to a circular aperture of diameter D.

[0037] In one embodiment, D 2 ≧πλR / ε applies to a square aperture of dimension D.

[0038] In one embodiment, the size of the rectifying antenna is the same as or approximately the same as the size of the delivery antenna aperture.

[0039] In one embodiment, the rectifying antenna is part of a rectifying antenna structure that includes a solid state rectifying component, the rectifying antenna comprising an array of receive antenna elements electrically connected to the solid state rectifying component.

[0040] In one embodiment, the solid state rectifying component is a Schottky diode.

[0041] In one embodiment, the rectifying antenna is part of a rectifying antenna structure, the rectifying antenna structure comprising: a central core having opposed first and second portions and made of at least one dielectric material; a dielectric skin comprising a metasurface disposed on a first portion of the central core, the rectifying antenna being positioned on the second portion of the central core; a rectifier circuit electrically connected to the rectifying antenna for rectifying the incoming electromagnetic energy and producing a direct current (DC) output that is then delivered to a required load.

[0042] In one embodiment, the rectifying antenna is formed as a rectifying antenna array having a plurality of rectifying antenna elements.

[0043] In one embodiment, the central core is made of a low-loss dielectric material.

[0044] In one embodiment, the thickness of the central core is between one tenth and one full wavelength of an electromagnetic wave passing through the dielectric material from which it is made.

[0045] In one embodiment, the central core has a refractive index between 1 and 3.

[0046] In one embodiment, the thickness and refractive index of the central core vary over the surface of the rectifying antenna to achieve a desired impedance match.

[0047] In one embodiment, the system is a terrestrial-based system.

[0048] In one embodiment, the system is configured to wirelessly transmit power up to and beyond a 100 meter range.

[0049] In one embodiment, the delivery antenna is configured to operate within a radiating near-field region in which the electromagnetic field is substantially confined to said collimated or substantially collimated beam.

[0050] In one embodiment, the delivery antenna is configured to operate within a radiating near-field region in which the electromagnetic field is substantially confined to said collimated or substantially collimated beam by imparting a spherical phase distribution across the aperture plane of said delivery antenna to achieve a degree of beam focusing in the radiating near-field region.

[0051] In one embodiment, in the radial near-field region, the maximum on-axis electric field strength exceeds the maximum on-axis electric field strength of the antenna aperture due to constructive interference, and is within a range R max where, when the antenna array elements are excited in phase, R max The value of is given by: JPEG2026009907000005.jpg2047 where λ is the wavelength of the radiation, JPEG2026009907000006.jpg6170 is the effective area of ​​the delivery antenna aperture.

[0052] In a third aspect, the present invention provides a long-distance wireless power transfer system, comprising: a delivery antenna that is a phased array antenna having an array of antenna elements that are radiating elements, the phased array antenna configured to receive power as an input from a power source, convert the input power into electromagnetic energy, and radiate the electromagnetic energy into free space as a directional beam that is a collimated or substantially collimated beam, the collimated or substantially collimated beam being generated by controlling the phase and amplitude of each of the antenna elements; at least one phase correction device positioned or configured to be positioned at a first distance from the delivery antenna, the at least one phase correction device comprising: receiving the directional beam emitted from the transmitting antenna; maintaining the directional beam as the collimated or substantially collimated beam and performing a phase correction operation on the directional beam to increase the extent to which the directional beam is maintained as the collimated or substantially collimated beam; and delivering the phase-corrected directional beam into free space. the at least one phase correction device is positioned, or configured to be positioned, between a delivery antenna and a rectifying antenna, and the rectifying antenna is positioned, or configured to be positioned, at a second distance from the delivery antenna, the rectifying antenna being configured to receive the directional beam from the at least one phase correction device and convert the electromagnetic energy into electricity; The at least one phase correction device is in a system that utilizes at least one metasurface to provide a phase shift while minimizing power loss and maintaining an impedance matching structure.

[0053] In a fourth aspect, the present invention provides a long-distance wireless power transfer system, comprising: a delivery antenna configured to receive power as an input from a power source, convert the input power into electromagnetic energy, and radiate the electromagnetic energy into free space in a directional beam, the beam being a collimated or substantially collimated beam; at least one phase correction device positioned or configured to be positioned at a first distance from the delivery antenna, the at least one phase correction device comprising: receiving the directional beam emitted from the transmitting antenna; maintaining the directional beam as the collimated or substantially collimated beam and performing a phase correction operation on the directional beam to increase the extent to which the directional beam is maintained as the collimated or substantially collimated beam; and delivering the phase-corrected directional beam into free space. the at least one phase correction device is positioned, or configured to be positioned, between a delivery antenna and a rectifying antenna, and the rectifying antenna is positioned, or configured to be positioned, at a second distance from the delivery antenna, the rectifying antenna being configured to receive the directional beam from the at least one phase correction device and convert the electromagnetic energy into electricity; The at least one phase correction device is in a system that utilizes at least one metasurface to provide a phase shift while minimizing power loss and maintaining an impedance matching structure.

[0054] One or more of the following statements may apply to the present invention as defined above in the third and fourth aspects.

[0055] In one embodiment, the electromagnetic energy is microwave energy.

[0056] In one embodiment, the at least one phase correction device utilizes at least two metasurfaces to provide a phase shift while minimizing power loss and maintaining an impedance matching structure.

[0057] In one embodiment, the at least one phase correction device utilizes at least three metasurfaces to provide a phase shift while minimizing power loss and maintaining an impedance matching structure.

[0058] In one embodiment, the at least one phase corrector is a multi-layer structure having at least three layers with a central dielectric core sandwiched between at least two layers of two opposite portions of the dielectric core, at least one of which is a dielectric skin made of at least one dielectric material. In one embodiment, the dielectric skin comprises a metasurface that simultaneously provides a phase shift while minimizing power loss and maintaining an impedance matching structure.

[0059] In one embodiment, the metasurface is embedded on the dielectric skin.

[0060] In one embodiment, the thickness of the dielectric skin at each portion of the dielectric core is less than one tenth of the wavelength of an electromagnetic wave passing through the material from which the dielectric skin is made.

[0061] In one embodiment, the dielectric core is made from a low-loss dielectric material.

[0062] In one embodiment, the dielectric core is at least three layers with at least one metamaterial layer sandwiched between two dielectric support layers.

[0063] In one embodiment, the at least one metamaterial layer is a metasurface.

[0064] In one embodiment, the system is as defined in any one of the preceding and following statements. One or more statements relating to any one of the first and second aspects defined above may equally apply to the present invention as defined in the third and fourth aspects.

[0065] In a fifth aspect, the present invention resides in a long-range wireless power transfer system that utilizes at least one metasurface to provide a phase shift while minimizing power loss and maintaining an impedance-matching structure.

[0066] In one embodiment, a long-range wireless power transfer system utilizes at least two metasurfaces to provide a phase shift while minimizing power loss and maintaining an impedance-matching structure.

[0067] In one embodiment, a long-range wireless power transfer system utilizes at least three metasurfaces to provide a phase shift while minimizing power loss and maintaining an impedance-matching structure.

[0068] In one embodiment, the system is as defined by one or more of the above and below remarks. One or more remarks of any one of the first to fourth aspects defined above may equally apply to the present invention as defined in the fifth aspect.

[0069] In a sixth aspect, the present invention resides in the use of at least one metasurface (preferably at least two metasurfaces) in a long-range wireless power transfer system to provide a phase shift while minimizing power losses and maintaining an impedance matching structure.

[0070] In one embodiment, the system is as defined by one or more of the above and below remarks. One or more remarks relating to any one of the first to fifth aspects defined above may equally apply to the present invention as defined in the sixth aspect.

[0071] In a seventh aspect, the present invention provides a delivery antenna for use in a long-range wireless power transmission system, comprising: The transmitting antenna is a phased array antenna having an array of antenna elements which are radiating elements.

[0072] In one embodiment, each antenna element includes at least one low-loss dielectric element made from a low-loss dielectric material.

[0073] In one embodiment, each antenna element is a radome element formed as a hemispherical or approximately hemispherical shell.

[0074] In one embodiment, each antenna element is a radome element formed as a hemispherical or approximately hemispherical shell.

[0075] In one embodiment, the radome element has thin radome element walls with a wall thickness of less than or equal to one-quarter of the wavelength of the electromagnetic waves passing through the material from which the radome element is made.

[0076] In one embodiment, the radome element is larger than each of the antenna elements so as to cover the antenna elements.

[0077] In one embodiment, each antenna element has an electronically controlled phase shifter that facilitates electronic steering of the directional beam.

[0078] In one embodiment, each antenna element is a patch antenna element.

[0079] In one embodiment, each antenna element is made from a metal segment etched onto a substrate.

[0080] In one embodiment, the delivery antenna is configured to receive power as an input from a power source, convert the input power into electromagnetic energy, and radiate the electromagnetic energy into free space as a directional beam that is a collimated or substantially collimated beam.

[0081] In one embodiment, the delivery antenna has a delivery antenna aperture.

[0082] In one embodiment, the delivery antenna aperture has a dimension D and an aperture efficiency ε, and at least one of the following inequalities applies for the wavelength λ and the distance R between the delivery antenna and the down-range phase correction device or rectenna: JPEG2026009907000007.jpg1447 JPEG2026009907000008.jpg1447

[0083] In one embodiment, D 2 ≧4λR / ε applies to a circular aperture of diameter D.

[0084] In one embodiment, D 2 ≧πλR / ε applies to a square aperture of dimension D.

[0085] In one embodiment, the system is as defined by one or more of the above and below remarks. One or more remarks of any one of the first to sixth aspects defined above may equally apply to the present invention as defined in the seventh aspect.

[0086] In an eighth aspect, the present invention is a phase correction device for use in a long-distance wireless power transmission system, the phase correction device being a multi-layer structure having at least three layers with a central dielectric core sandwiched between at least two layers of two opposite portions of the dielectric core, at least one of the layers being a dielectric skin made of at least one dielectric material.

[0087] In one embodiment, the dielectric skin comprises a metasurface that provides a phase shift while maintaining the impedance matching structure with minimized power loss.

[0088] In one embodiment, the metasurface is embedded on the dielectric skin.

[0089] In one embodiment, the phase corrector is an electromagnetic wave transmission phase corrector.

[0090] In one embodiment, the thickness of the dielectric skin is less than one tenth of the wavelength of the electromagnetic wave passing through the at least one dielectric material from which the dielectric skin is made.

[0091] In one embodiment, the dielectric core is made from a low-loss dielectric material.

[0092] In one embodiment, the thickness of the dielectric core is between 1 / 10 and 1 full wavelength of an electromagnetic wave passing through the dielectric material from which it is made.

[0093] In one embodiment, the dielectric core has a refractive index between 1 and 3.

[0094] In one embodiment, the phase corrector is a straight-through phase corrector that causes the incident directional beam to travel in a straight direction without diverging into directional beams in other directions.

[0095] In one embodiment, the central dielectric core is sandwiched between the dielectric skins on both opposing portions of the dielectric core.

[0096] In one embodiment, the phase correction device is a reflective phase correction device that reflects the directional beam incident on the reflective phase correction device in another direction, thereby diverging the directional beam in the other direction at a certain angle.

[0097] In one embodiment, the angle is between 60 degrees and 120 degrees, and preferably is at or about 90 degrees.

[0098] In one embodiment, the central dielectric core is sandwiched between the dielectric skin of the first portion of the dielectric core and a reflective ground plane of the second portion of the dielectric core.

[0099] In one embodiment, the dielectric skin comprises a metasurface that simultaneously provides a phase shift to the incoming wavefront and completes the reflection with minimal power loss.

[0100] In one embodiment, the phase correction device comprises: receiving a directional beam emitted from a delivery structure; maintaining the directional beam as the collimated or substantially collimated beam and performing a phase correction operation on the directional beam to increase the extent to which the directional beam is maintained as the collimated or substantially collimated beam; and transmitting the phase-corrected directional beam into free space.

[0101] In one embodiment, the central dielectric core is at least three layers, with at least one metamaterial layer sandwiched between two dielectric support layers.

[0102] In one embodiment, the at least one metamaterial layer is a metasurface.

[0103] In one embodiment, the system is as defined by one or more of the above and below remarks. One or more remarks relating to any one of the first to seventh aspects defined above may equally apply to the present invention as defined in the eighth aspect.

[0104] In a ninth aspect, the present invention provides a rectifying antenna for use in a long-range wireless power transfer system, the rectifying antenna being part of a rectifying antenna structure including a solid-state rectifying component, the rectifying antenna comprising an array of receiving antenna elements electrically connected to the solid-state rectifying component.

[0105] In one embodiment, the solid state rectifying component is a Schottky diode.

[0106] In one embodiment, the system is as defined by one or more of the above and below remarks. One or more remarks relating to any one of the first to eighth aspects defined above may equally apply to the present invention as defined in the ninth aspect.

[0107] In a tenth aspect, the present invention provides a rectifying antenna structure for use in a long-range wireless power transfer system, comprising: a central core having opposed first and second portions and made of at least one dielectric material; a dielectric skin having a metasurface disposed on a first portion of the central core; a rectifying antenna positioned on the second portion of the central core; a rectifying circuit electrically connected to the rectifying antenna for rectifying the incoming electromagnetic energy and generating a direct current (DC) output.

[0108] In one embodiment, the rectifying antenna is formed as a rectifying antenna array having a plurality of rectifying antenna elements.

[0109] In one embodiment, the central core is made of a low-loss dielectric material.

[0110] In one embodiment, the thickness of the central core is between 1 / 10 and 1 full wavelength of the electromagnetic wave passing through the dielectric medium of the central core.

[0111] In one embodiment, the central core has a refractive index between 1 and 3.

[0112] In one embodiment, the thickness and refractive index of the central core vary over the surface of the rectifying antenna to achieve a desired impedance match.

[0113] In one embodiment, the system is as defined by one or more of the above and below remarks. One or more remarks relating to any one of the first to ninth aspects defined above may equally apply to the present invention as defined in the tenth aspect.

[0114] In an eleventh aspect, the present invention provides a long-distance wireless power transmission method, comprising at least: providing a long-range wireless power transmission system comprising a delivery antenna, at least one phase correction device, and a rectifying antenna operatively connected to one another; using a delivery antenna configured to receive power from a power source as an input, convert the input power into electromagnetic energy, and radiate the electromagnetic energy into free space in a directional beam, the beam being a collimated or substantially collimated beam; using the at least one phase correction device to receive the directional beam emitted from the delivery antenna, maintain the directional beam as the collimated or substantially collimated beam, perform a phase correction operation on the directional beam to increase the extent to which the directional beam is maintained as the collimated or substantially collimated beam, and deliver the phase-corrected directional beam into free space; and using a rectifying antenna to receive the directional beam from the at least one phase correction device and convert the electromagnetic energy into electricity.

[0115] In one embodiment, the method further comprises positioning the at least one phase correction device positioned between the delivery antenna and the rectifying antenna.

[0116] In one embodiment, the method further comprises positioning the at least one phase correction device at or near a distance from the delivery antenna where the directional beam begins to diverge.

[0117] In one embodiment, the system is a terrestrial-based system.

[0118] In one embodiment, the system is configured to wirelessly transmit power up to and beyond 100 meters.

[0119] In an embodiment, said delivery antenna is as defined in any one of the preceding paragraphs.

[0120] In an embodiment, said at least one phase correction device is as defined in any one of the preceding paragraphs.

[0121] In an embodiment, the rectifying antenna is as defined in any one of the preceding paragraphs.

[0122] In one embodiment, the system is as defined in any one of the preceding claims. One or more of the claims of any one of the first to tenth aspects defined above may equally apply to the present invention as defined in the eleventh aspect.

[0123] In a twelfth aspect, the present invention provides a long-distance wireless power transmission system, comprising: a delivery antenna that is a phased array antenna having an array of antenna elements that are radiating elements, the delivery antenna configured to receive power as an input from a power source, convert the input power into electromagnetic energy, and radiate the electromagnetic energy into free space as a directional beam that is a collimated or substantially collimated beam, the collimated or substantially collimated beam being generated by controlling the phase and amplitude of each of the antenna elements; a rectifying antenna positioned or configured to be positioned a distance from the delivering antenna, the rectifying antenna configured to receive the directional beam and convert the electromagnetic energy into electricity; Each antenna element can be described as comprising a long-range wireless power transmission system that includes a radome element formed as a hemispherical or nearly hemispherical shell.

[0124] In a thirteenth aspect, the present invention provides a long-distance wireless power transmission system, comprising: a delivery antenna configured to receive power as an input from a power source, convert the input power into electromagnetic energy, and radiate the electromagnetic energy into free space in a directional beam, the beam being a collimated or substantially collimated beam; a rectifying antenna positioned or configured to be positioned a distance from the delivering antenna, the rectifying antenna configured to receive the directional beam and convert the electromagnetic energy into electricity; The delivery antenna can be described as a phased array antenna having an array of antenna elements that are radiating elements, each of which comprises a long-range wireless power transmission system having a radome element formed as a hemispherical shell or a nearly hemispherical shell.

[0125] As defined above in the twelfth and thirteenth aspects, one or more of the following statements may apply to the present invention.

[0126] In one embodiment, the electromagnetic energy is microwave energy.

[0127] In one embodiment, a collimated or substantially collimated beam is generated by controlling the phase and amplitude of each antenna element.

[0128] In one embodiment, each antenna element has an electronically controlled phase shifter that facilitates electronic steering of the directional beam.

[0129] In one embodiment, each antenna element includes at least one low-loss dielectric element made from a low-loss dielectric material.

[0130] In one embodiment, each antenna element is a patch antenna element.

[0131] In one embodiment, each antenna element is made from a metal segment etched onto a substrate.

[0132] In one embodiment, the radome element has thin radome element walls with a wall thickness of less than or equal to one-quarter of the wavelength of the electromagnetic wave passing through the material from which the radome element walls are made.

[0133] In one embodiment, the wavelength of electromagnetic energy in the form of an electromagnetic wave in the material from which the radome element walls are made is given by: JPEG2026009907000009.jpg2234In formula, λ d is the wavelength of the electromagnetic wave in the radome wall material, λ is the free space wavelength, and n d is the refractive index of the radome wall material.

[0134] In one embodiment, the radome element is larger than each of the antenna elements so as to cover the antenna elements.

[0135] In one embodiment, the delivery antenna has a delivery antenna aperture.

[0136] In one embodiment, the delivery antenna aperture has a dimension D and an aperture efficiency ε, and at least one of the following inequalities applies for the wavelength λ and the distance R between the delivery antenna and the down-range phase correction device or rectenna: JPEG2026009907000010.jpg1547 JPEG2026009907000011.jpg1547

[0137] In one embodiment, D 2 ≧4λR / ε applies to a circular aperture of diameter D.

[0138] In one embodiment, D 2 ≧πλR / ε applies to a square aperture of dimension D.

[0139] In one embodiment, the size of the rectifying antenna is the same as or approximately the same as the size of the delivery antenna aperture.

[0140] In one embodiment, the rectifying antenna is part of a rectifying antenna structure that includes a solid state rectifying component, the rectifying antenna comprising an array of receive antenna elements electrically connected to the solid state rectifying component.

[0141] In one embodiment, the solid state rectifying component is a Schottky diode.

[0142] In one embodiment, the rectifying antenna is part of a rectifying antenna structure, the rectifying antenna structure comprising: a central core having opposed first and second portions and made of at least one dielectric material; a dielectric skin comprising a metasurface disposed on a first portion of the central core, the rectifying antenna being positioned on the second portion of the central core; a rectifying circuit electrically connected to the rectifying antenna for rectifying the incoming electromagnetic energy and generating a direct current (DC) output.

[0143] In one embodiment, the rectifying antenna is formed as a rectifying antenna array having a plurality of rectifying antenna elements.

[0144] In one embodiment, the central core is made of a low-loss dielectric material.

[0145] In one embodiment, the thickness of the central core is between one tenth and one full wavelength of an electromagnetic wave passing through the dielectric material from which it is made.

[0146] In one embodiment, the central core has a refractive index between 1 and 3.

[0147] In one embodiment, the thickness and refractive index of the central core vary over the surface of the rectifying antenna to achieve a desired impedance match.

[0148] In one embodiment, the system further comprises at least one phase correction device positioned or configured to be positioned between the delivery antenna and the rectifying antenna, the at least one phase correction device comprising: receiving the directional beam emitted from the transmitting antenna; maintaining the directional beam as the collimated or substantially collimated beam and performing a phase correction operation on the directional beam to increase the extent to which the directional beam is maintained as the collimated or substantially collimated beam; and transmitting the phase-corrected directional beam into free space.

[0149] In one embodiment, the at least one phase corrector is an electromagnetic wave transmitting phase corrector.

[0150] In one embodiment, the at least one phase corrector is a straight-through phase corrector that causes the incident directional beam to travel in a straight direction without diverging into directional beams in other directions.

[0151] In one embodiment, the straight-through phase corrector is a composite multi-layer structure comprising a central dielectric core with at least three layers sandwiched between at least two dielectric skins on two opposite sides of the dielectric core.

[0152] In one embodiment, the central dielectric core is at least three layers, with at least one metamaterial layer sandwiched between two dielectric support layers.

[0153] In one embodiment, the at least one metamaterial layer is a metasurface.

[0154] In one embodiment, the dielectric skin comprises a metasurface that simultaneously provides a phase shift while minimizing power loss and maintaining an impedance matching structure.

[0155] In one embodiment, the metasurface is embedded on the dielectric skin.

[0156] In one embodiment, the thickness of the dielectric skin at each portion of the dielectric core is less than one tenth of the wavelength of an electromagnetic wave passing through the material from which the dielectric skin is made.

[0157] In one embodiment, the dielectric core is made from a low-loss dielectric material.

[0158] In one embodiment, the thickness of the dielectric core is between 1 / 10 and 1 full wavelength of an electromagnetic wave passing through the dielectric material from which it is made.

[0159] In one embodiment, the dielectric core has a refractive index between 1 and 3.

[0160] In one embodiment, the at least one phase correction device is a reflective phase correction device that reflects the directional beam incident on the reflective phase correction device in another direction, thereby diverging the directional beam in the other direction at a certain angle.

[0161] In one embodiment, the angle is between 60 degrees and 120 degrees, and preferably is at or about 90 degrees.

[0162] In one embodiment, the reflective phase correction device is a composite multi-layer structure having at least three layers in which a central dielectric core is sandwiched between a dielectric skin of a first portion of the dielectric core and a reflective ground plane of a second portion of the dielectric core, the second portion being opposite the first portion.

[0163] In one embodiment, the dielectric skin comprises a metasurface that simultaneously provides a phase shift to the incoming wavefront and completes the reflection with minimal power loss.

[0164] In one embodiment, the metasurface is embedded on the dielectric skin.

[0165] In one embodiment, the system is a terrestrial-based system.

[0166] In one embodiment, the system is configured to wirelessly transmit power up to and beyond 100 meters.

[0167] In a fourteenth aspect, the present invention provides a long-distance wireless power transmission method, comprising at least: providing a long-range wireless power transmission system comprising a delivery antenna and a rectifying antenna operatively connected to each other, the delivery antenna being a phased array antenna having an array of antenna elements, the antenna elements being radiating elements; using a delivery antenna configured to receive power as an input from a power source, convert the input power into electromagnetic energy, and radiate the electromagnetic energy into free space as a directional beam, the directional beam being a collimated or substantially collimated beam, the collimated or substantially collimated beam being generated by controlling the phase and amplitude of each of the antenna elements; and using the rectifying antenna to receive the directional beam and convert the electromagnetic energy into electricity.

[0168] In a fifteenth aspect, the present invention provides a long-distance wireless power transmission method, comprising at least: providing a long-range wireless power transmission system comprising a delivery antenna and a rectifying antenna operatively connected to one another; using a delivery antenna configured to receive power from a power source as an input, convert the input power into electromagnetic energy, and radiate the electromagnetic energy into free space in a directional beam, the beam being a collimated or substantially collimated beam; and using the rectifying antenna to receive the directional beam and convert the electromagnetic energy into electricity.

[0169] As defined above in the fourteenth and fifteenth aspects, one or more of the following statements may apply to the present invention.

[0170] In one embodiment, the method comprises: The method further comprises positioning the phase correction device between the delivery antenna and the rectifying antenna.

[0171] In one embodiment, the method comprises: The method further comprises using the phase correction device to receive the directional beam emitted from the delivery antenna, maintain the directional beam as the collimated or substantially collimated beam, perform a phase correction operation on the directional beam to increase the range over which the directional beam is maintained as the collimated or substantially collimated beam, and deliver the phase-corrected directional beam into free space to be received by the rectifying antenna.

[0172] In one embodiment, the method further comprises positioning a phase correction device at or near a distance from the delivery antenna where the directional beam begins to diverge.

[0173] In one embodiment, the system is a terrestrial-based system.

[0174] In one embodiment, the system is configured to transmit power up to and beyond 100 meters.

[0175] In one embodiment, the long-distance wireless power transmission method is configured to transmit power up to and beyond 100 meters.

[0176] In an embodiment, the system is as defined in one or more of the twelfth or thirteenth aspects.

[0177] Other aspects of the invention will become apparent from the following description, given by way of example only and with reference to the accompanying drawings, in which:

[0178] Where reference is made herein to patent specifications, other external documents, or other sources of information, it is generally for the purpose of providing a context for discussing features of the present invention. Unless otherwise specified, the reference to such external documents should not be construed as an acknowledgement that such documents or such sources are prior art or form part of the general common general knowledge in any jurisdiction.

[0179] For purposes of the following description, terms such as "upper," "lower," "right," "left," "vertical," "horizontal," "top," "bottom," "lateral," "longitudinal," and derivatives thereof, shall refer to the present invention as directed in the drawings. However, it should be understood that the present invention may contemplate various alternative variations, unless expressly stated to the contrary. It should also be understood that the specific devices illustrated in the accompanying drawings and described in the following description are merely example embodiments of the present invention. Accordingly, specific dimensions and other physical characteristics related to the embodiments disclosed herein should not be considered limiting.

[0180] It is recognized that the term "comprises" can be characterized in various jurisdictions as either exclusive or inclusive. For purposes of this specification, unless otherwise indicated, the term "comprises" shall have an inclusive meaning and may encompass not only the listed components or elements but also other unspecified components or elements. Terms such as "comprises" or "comprised" or "comprising" have similar meanings when used in the context of a system or one or more steps in a method or process.

[0181] The term "and / or" as used above and below means either or both of "and" or "or".

[0182] As used above and below, "(s)" following a noun refers to the plural and / or singular of that noun.

[0183] When used in the claims, unless otherwise indicated, the word "for" shall be construed solely to mean "suitable for," and not, for example, as specifically "adapted for" or "configured for" a stated purpose.

[0184] Unless otherwise specified, a phase correction device may be any suitable device that provides phase correction to collimate or substantially collimate a directional beam. Some non-limiting examples of phase correction devices include a phase plate, a phase corrector, an aberration corrector, a waveplate, a wavefront corrector, a phase correction relay, a collimator, or a combination thereof.

[0185] Unless otherwise specified, the term "Earth-based" shall be interpreted as based entirely within planet Earth and / or its atmosphere, and excludes any systems and components of such systems located outside the Earth's stratosphere.

[0186] Unless otherwise specified, a system that is "Earth-based" should be construed to exclude any such system and components of such systems that are satellite-based.

[0187] Unless otherwise specified, the term "free space" does not refer to outer space. Rather, it refers to space without physical obstacles that may impede the propagation of a signal or beam. In the context of this specification, the term "physical obstacles" refers to trees, buildings, hills, mountains, and other significant material objects, but does not refer to atoms, molecules, or other particulate matter normally present in the atmosphere. The term "physical obstacles" also does not refer to weather conditions such as evaporating water, rain, snow, sleet, or hail.

[0188] It is recognized that the word "substantially" can be used to broaden the meaning of a term in some cases. When the word "substantially" is used in conjunction with a term to define a distinctive feature herein, it should be noted that all the advantages of using the word "substantially" (i.e., the advantages of broadening the meaning) are obtained, and the scope also includes the exact characteristics that the term (without broadening the meaning) describes. For example, if a feature is described / defined herein as "substantially collimated," the scope includes the feature being "close to" collimated (in that regard, "substantially" is considered to broaden the meaning of the word "substantially"), and also includes the feature being "exactly" collimated.

[0189] A preferred embodiment of the present invention will now be described, by way of example only, with reference to the drawings, in which: [Brief explanation of the drawings]

[0190] [Figure 1] FIG. 1 is a schematic diagram of a preferred example of a long-distance wireless power transmission system according to the present invention. [Figure 2] FIG. 2 shows a configuration for increasing the gain of a delivery antenna using a radome element. [Figure 3A] FIG. 3A shows an example of the measured radiation pattern of the delivery antenna with the radome element of FIG. 2 in place. [Figure 3B] FIG. 3B shows an example of the measured radiation pattern of the delivery antenna without the radome element of FIG. 2 in place. [Figure 4] 4 is a schematic diagram illustrating the structure of a straight-through phase correction device according to one embodiment of the present invention, and also illustrates the flow direction of a directional electromagnetic beam when the straight-through phase correction device is used as part of the system of FIG. [Figure 5]5 is a schematic diagram illustrating the structure of a reflective phase correction device according to one embodiment of the present invention, and also illustrates the flow direction of a directional electromagnetic beam when the reflective phase correction device is used as part of the system of FIG. [Figure 6] 6 is a schematic diagram showing a preferred example of a phase correction device according to the present invention. FIGS. 7 to 12 relate to the schematic diagram of FIG. [Figure 7] FIG. 7 shows the normalized shunt susceptance b1 versus phase delay through the device of FIG. 6 for various phase factors. [Figure 8] FIG. 8 shows the normalized shunt susceptance b2 versus phase delay through the device of FIG. 6 for various phase factors. [Figure 9] FIG. 9 shows the behavior of b1 and b2 versus phase delay through the device of FIG. 6 for dielectric thicknesses equivalent to 90 degrees. [Figure 10A] FIG. 10A shows an example of an array of circular patches on a diamond grid. [Figure 10B] FIG. 10B shows an example of an array of square patches on a square grid. [Figure 10C] FIG. 10C shows an example of an array of crosses on a square grid. [Figure 11] Figure 11 shows the typical behavior of patch and aperture FSS layers (metasurfaces) as a function of frequency. [Figure 12] FIG. 12 is a schematic diagram illustrating the application of the phase correction device of FIG. [Figure 13] 13 is a schematic diagram showing a rectifying antenna structure according to an embodiment of the present invention, and also showing the flow direction of a directional electromagnetic beam when the rectifying antenna structure is used as part of the system of FIG. [Figure 14]Figure 14 is a schematic diagram showing a schematic representation of a phased array delivery antenna used to deliver electromagnetic energy in the form of a collimated or substantially collimated beam with little angular divergence to a rectifying antenna. Figures 15, 16A, 16B, 17, 18A, 18B, 19A, 19B, 20A, and 20B relate to the schematic diagram of Figure 14. [Figure 15] FIG. 15 shows the magnitude of the electric field strength calculated along the range axis for a square antenna of width D operating at a single wavelength λ. [Figure 16A] FIG. 16A shows the phase distribution of the electric field on the horizontal axis over a range of 20.8 m in the unfocused case. [Figure 16B] FIG. 16B shows the horizontal electric field amplitude at a range of 20.8 m for the unfocused case. [Figure 17] FIG. 17 is a schematic diagram showing an antenna with a spherical phase distribution applied across the aperture plane. [Figure 18A] FIG. 18A shows the phase plot for the focused case over a range of 17.2 m. [Figure 18B] FIG. 18B shows the amplitude plot at a range of 17.2 m for the focused case. [Figure 19A] FIG. 19A shows the phase distribution of the electric field across the aperture plane. [Figure 19B] FIG. 19B shows the phase distribution of the electric field across the aperture plane. [Figure 20A] FIG. 20A is a contour plot showing the spatial distribution of the electric field strength for the unfocused and focused cases. [Figure 20B] FIG. 20B is a contour plot showing the spatial distribution of the electric field strength for the unfocused and focused cases. DETAILED DESCRIPTION OF THE INVENTION

[0191] It can be difficult to transmit power wirelessly using electromagnetic waves (such as, but not limited to, microwaves) over long distances efficiently, primarily because the electromagnetic waves or beams can easily diverge in other directions during energy delivery, meaning that the energy received at the receiving end may not be sufficient to provide power.

[0192] It would therefore be desirable to have a system and method for efficiently transmitting power over reasonably long distances with very minimal waste and loss of energy during delivery. It would also be desirable to have a system and method for efficiently transmitting power that is not overly complex and cost-effective to implement and maintain.

[0193] The present invention relates to a long-range wireless power transmission system and a method for facilitating long-range wireless power transmission using beam guiding. The range of the wireless power transmission system may be up to and greater than 100 meters. The present invention uses gain-enhancing radiating elements and metasurfaces to facilitate a down-range impedance-matched, collimated, or substantially collimated electromagnetic beam for efficient wireless power transmission. The present invention may also use phase correction devices, such as straight-through phase correction devices and / or reflective phase correction devices, to extend the useful range of the collimated or substantially collimated electromagnetic beam.

[0194] 1, an example of a long-range wireless power transfer system 100 in accordance with the present invention is shown. As shown, the system 100 includes a delivery antenna 110, at least one phase correction device 120, 122, and a rectifying antenna 130.

[0195] The delivery antenna 110 is configured to receive power from a power source (AC source) as an input, convert the input power into electromagnetic energy (e.g., microwave energy), and radiate the electromagnetic energy as a directional beam into free space. For example, the delivery antenna 110 may include a receiver for receiving power from the power source as an input and a converter for converting the input power into electromagnetic energy such that the delivery antenna 110 can radiate / transmit the electromagnetic energy into free space as a directional beam 102. In FIG. 1 , arrow 101 indicates the direction of the directional beam 102. The directional beam 102 may include multiple rays.

[0196] In FIG. 1 , two phase correction devices 120, 122 are shown. Phase correction device 120 is a straight-through phase correction device, and phase correction device 122 is a reflective phase correction device, which are described in further detail later in this specification. Any number of phase correction devices may be used as desired or required. For example, system 100 may use only straight-through phase correction device 120. Alternatively, system 100 may use only reflective phase correction device 122. Similarly, system 100 may use more than one straight-through phase correction device 120 and / or more than one reflective phase correction device 122.

[0197] As shown in FIGS. 1, 4, and 5, the phase correctors 120, 122 are configured to receive the directional beam 102 emitted from the delivery antenna 124 in the direction indicated by the arrow 101. Upon receiving the directional beam 102, the phase correctors 120, 122 are configured to perform phase correction operations on the directional beam. Such phase correction operations cause the phase correctors 120, 122 to maintain the directional beam as a collimated or substantially collimated beam. Additionally, correcting the phase of the directional beam using the phase correctors 120, 122 can increase the extent to which the directional beam 102 remains a collimated or substantially collimated beam, as will be described in more detail below. After performing any desired phase correction operations, the phase correctors 122, 124 deliver the phase-corrected directional beam into free space.

[0198] The rectifying antenna 130 (rectenna) is configured to receive the directional beam from the phase corrector (in this example, from the phase corrector 122) and convert the electromagnetic energy into electricity (DC electricity). For example, the rectifying antenna 130 may include a receiver for receiving the directional beam from the phase corrector 122 as an input and a converter for converting the input power into electromagnetic energy.

[0199] 1, the phase correction devices 120, 122 and the rectifying antenna 130 are positioned at different distances from the delivery antenna, with the phase correction structure devices 120, 122 positioned between / midway between the delivery antenna 110 and the rectifying antenna 130. Each of the three distances, shown as R in FIG. 1, need not be the same.

[0200] It can be appreciated that the directional beam delivered from the delivery antenna 110 can maintain collimation or substantial collimation up to a certain range before the directional beam begins to diverge, resulting in a loss of energy transmission. Such energy loss is undesirable for efficient power transfer. Therefore, by having at least one phase correction device 120, 122 at a suitable distance (preferably at or near the distance at which the directional beam begins to diverge), the collimation or substantial collimation of the directional beam can be maintained / restored. As a result, the range over which the directional beam 102 remains collimated or substantially collimated can be increased, thereby enabling the system 100 to provide efficient wireless power transfer over long distances.

[0201] System 100 is most preferably Earth-based, and advantageously, none of the components of system 100 need be satellite or space-based.

[0202] The delivery antenna 110, phase correction devices 122, 124, and rectifying antenna 130 according to embodiments of the present invention will now be described in more detail.

[0203] Delivery antenna As described above, the delivery antenna 110 is configured to convert input power into electromagnetic energy (e.g., microwave energy) that is then radiated into free space to produce a collimated (preferably highly, i.e., substantially collimated) directional beam 102.

[0204] The delivery antenna 110 may be a phased array antenna having an array of antenna elements that are radiating elements, and a collimated or substantially collimated beam may be generated by controlling the phase and amplitude of each antenna element. Figure 2 shows a single antenna element 112 of the array of antenna elements of the delivery antenna 110. Each antenna element 112 may have an electronically controlled phase shifter to facilitate electronic beam steering, i.e., to facilitate steering of the directional beam 102.

[0205] Each antenna element 112 may be a patch antenna element, and each antenna element 112 may be made from a metal segment etched into a substrate. In other words, each radiating element may consist of a patch antenna configuration made from a metal segment etched onto a substrate.

[0206] 2, the antenna element 112 may include a radome element 114, which may be a low-loss dielectric element. The radome element 114 may be a hemispherical, near-hemispherical, or similar dome-shaped element to allow for increased antenna gain. The radome element 114 may be a thin-walled radome element. Preferably, the wall thickness of the radome element is less than or equal to one-quarter of the wavelength thickness of the material from which the radome walls are made. λ d The wavelength of the electromagnetic wave in the radome wall material, denoted as JPEG2026009907000012.jpg21170In the above formula, λ is the free space wavelength, and n d is the refractive index of the radome wall material.

[0207] As shown, the radome element 114 is larger than the antenna element 112 because it covers the antenna element 112 .

[0208] As mentioned above, wireless power transmission is efficient only if the energy is confined to a collimated or substantially collimated directional beam 102, preferably a highly or substantially collimated beam. Due to diffraction, the collimation or substantial collimation of the directional beam cannot be maintained over arbitrarily long distances in front of the delivery antenna 110. For example, for a circular antenna aperture of size D radiating at wavelength λ, the maximum distance R over which a collimated or substantially collimated beam exists is given by: JPEG2026009907000013.jpg24170In the above equation (2), ε is the aperture efficiency of the electric field distribution extending across the antenna plane.

[0209] As an example, for an antenna with aperture size D=25 m, radiation with a uniform aperture distribution (ε=1) at a wavelength of 0.050 m gives a useful collimated or substantially collimated beam out to a range of about 3,000 m (3 km).

[0210] This range can be expanded if each radiating element, i.e., antenna element 112 of the delivery array, i.e., delivery antenna 110, can be modified to increase its far-field directivity. This can be achieved by adding a structure placed in front of the antenna elements, preferably patch antenna elements. As shown in Figure 2, one way to achieve this is by covering each antenna element 112 with a thin-walled radome (shell) element 114 that is larger (preferably slightly larger) in diameter than the antenna element 112. The radome element 114 may be a low-loss dielectric element that includes at least a dielectric material.

[0211] Such radome elements 114 can radiate scattered waves that can constructively interfere with the primary radiation pattern of the delivering antenna 110, and more particularly with the radiation pattern of each delivering antenna element, to produce improved directivity in the forward direction, thereby effectively increasing the electrical size of the antenna aperture beyond its actual physical size, and thus improving the collimated or substantially collimated extent of the directional beam 102, as per equation (2).

[0212] Figure 3a shows an example of the measured radiation pattern of a delivery antenna element 112 with a radome element 114 in place, and Figure 3b shows an example of the measured radiation pattern of a delivery antenna 110 without such a radome element 114 in place. As shown in Figure 3a, there is a boresight gain improvement of +2.5dB compared to the bare antenna of Figure 3b, normalized to 0db at boresight.

[0213] To show this in more detail, the far-field gain G of any square antenna of dimension D and aperture efficiency ε is given by: JPEG2026009907000014.jpg23170

[0214] Therefore, the distance / range over which useful or substantial collimation of the directional beam 102 can be maintained is directly proportional to the far-field gain. Therefore, improving the gain of an individual antenna element 112 improves the range of the directional beam 102 by the same factor. It can therefore be seen that the use of gain-enhancing structures, such as radome elements 112, on the antenna elements 112 increases the range of wireless power transmission.

[0215] phase correction device As mentioned above, in addition to or instead of using gain-enhancing radiating elements in the delivery antenna 110, i.e., the antenna element 112 and the radome element 114 (the radome shell, which may be a dielectric radome shell), another way to increase the extent of collimation or substantial collimation of the directional beam 102 is to use one or more phase correction structures / phase correction devices 120 in the path of the directional beam 102. As described above and shown in FIG. 1 , the system 100 may include two phase correction devices: a straight-through phase correction device 120 and a reflective phase correction device 122. Also as mentioned above, any number of phase correction devices may be used as desired or needed. In certain embodiments, only one phase correction device 120 or 122 may be used.

[0216] In one example, the system 100 according to the present invention may include enhanced radiating elements in the delivery antenna 110, i.e., the antenna element 112 and the radome element 114 (a radome shell, which may be a dielectric radome shell), as described above, and may not include a phase correction device.

[0217] The straight-through phase corrector 120 causes the incoming directional beam to travel in a straight direction through the device 120 without diverging the directional beam in other directions. The straight-through phase corrector 120 can deliver a high percentage of the incoming power to change the phase of the wavefront of the directional beam 102 in a desired manner. On the other hand, the reflective phase corrector 122 reflects the directional beam 102 incident on the reflective phase corrector in other directions, thereby diverging the directional beam 102 in other directions at a certain angle.

[0218] The reflective phase correction device 122 reflects all of the power incident on its surface with the goal of directing the incoming wave / incoming directional beam at an angle, preferably but not limited to 90 degrees as shown schematically in Figure 1, but capable of changing the phase of the wavefront of the directional beam 102 in a desired manner. This angle may be any angle between 60 degrees and 120 degrees.

[0219] 1, the straight-through phase correction device 120 is preferably mounted or configured to be mounted at a distance R from the delivery antenna 110. Preferably, the distance R is measured from the aperture of the delivery antenna 110. The straight-through phase correction device 120 is designed to perform a phase correction operation on the directional beam 102 (the wavefront of the directional beam 102) emanating from the delivery antenna 110.

[0220] The straight-through phase corrector 120 may introduce a phase delay distribution over the range of the incident directional beam 102 such that any diverging beam behavior caused by a non-planar incident wavefront of the directional beam 102 is corrected in a lens-like manner. The emergent wavefront of the directional beam 102 from the straight-through phase corrector 120 will then be similar to that produced at the aperture face of the delivery antenna 110 and will therefore largely replicate the propagation characteristics of the delivery antenna 110 over a range from zero to R for a similar distance in front of the straight-through phase corrector 120 or the face of the straight-through phase corrector 120. It can therefore be appreciated that this will extend the useful range over which collimation, or substantial collimation, of the directional beam 102 is maintained. Multiple straight-through phase correctors may be chained together to further increase the useful range of a collimated or substantially collimated beam.

[0221] It may also be important to design the phase corrector so that the wavefront of the directional beam 102 incident on the phase corrector minimizes reflection losses, i.e., so that the phase corrector is impedance matched to the incident directional beam / wave, thereby maximizing the amount of power delivered through such a phase corrector, which may be an important aspect in efficient wireless power transfer.

[0222] Therefore, one aspect of the present invention is the design of the phase corrector as a straight-through phase corrector 120 that utilizes at least two metasurfaces to simultaneously provide any desired phase shift while maintaining an impedance matching structure that minimizes losses.

[0223] A straight-through phase corrector 120 such as that shown in FIG. 4 is preferably electromagnetically transparent.

[0224] The straight-through phase correction device 120 may be a composite multi-layer structure, which in this example is a three-layer structure in which a central dielectric core 152 is sandwiched between outer layers, which are dielectric skins 151, 153 on two opposite portions of the dielectric core 153. The multi-layer structure may include more than three layers. In certain embodiments, the dielectric core may be at least three layers with at least one metamaterial layer sandwiched between two dielectric support layers. The metamaterial layer may be a metasurface. Examples of such embodiments are described below with reference to FIGS. 6-11.

[0225] The dielectric skins 151, 153 include / incorporate metasurfaces that simultaneously provide a phase shift while maintaining an impedance matching structure that minimizes power loss. The dielectric skins 151, 153 are preferably thin such that the thickness of each skin is one-tenth of a wavelength or less in the dielectric medium of the skin. The dielectric medium of the skin is the dielectric material from which the skin is fabricated.

[0226] The dielectric core 152 is preferably made from a low-loss dielectric material, such as foam. The thickness of the dielectric material is preferably between 1 / 10 and 1 full wavelength of the electromagnetic wave passing through the dielectric core medium. The dielectric core medium is the material from which the dielectric core is made. The dielectric core preferably has a refractive index between 1 and 3. The thickness and refractive index can be varied across the surface of the device 120 to achieve the desired phase shift.

[0227] 4, directional beam 102a entering device 120 is shown as a diverging wavefront, and directional beam 102b delivered from device 120 is shown as a phase-corrected and collimated or substantially collimated wavefront. Each directional beam 102a, 102b may include multiple rays.

[0228] The phase and amplitude of the waves transmitted and reflected from the device 120 may be determined using standard equivalent transmission line methods, including the so-called "ABCD matrix approach."

[0229] A 2x2 matrix containing elements A, B, C, and D can be defined for each layer with the global system matrix found by matrix multiplication of all three individual matrices as follows: JPEG2026009907000015.jpg19170

[0230] In the above matrices, matrix elements with the subscript "1" refer to metasurfaces that are considered identical in design for both outer layers, the dielectric skins 151, 153 on two opposite sides of the dielectric core 153. This provides the symmetric structure required for impedance matching purposes. The metasurfaces can be on fiberglass or plastic substrates (considered electrically thin), but are assumed to have negligible thickness.

[0231] Similarly, in the above matrices, the matrix elements with the subscript "2" refer to the central dielectric core 152. For the intended application, a directional beam 102 incident on the device 120 may impinge on the device 120 at or near normal incidence. Under these conditions, the matrix elements can be defined in terms of the thicknesses and refractive indices of various materials as follows:

[0232] Regarding (thin) metasurfaces / dielectric skins 151, 153, JPEG2026009907000016.jpg1345 JPEG2026009907000017.jpg1428 JPEG2026009907000018.jpg1228In the formula, b is the normalized shunt susceptance of the metasurface and

[0233] Regarding the dielectric core 152, JPEG2026009907000019.jpg1351 JPEG2026009907000020.jpg2042 JPEG2026009907000021.jpg1239 JPEG2026009907000022.jpg1332 JPEG2026009907000023.jpg2128λ is the free space wavelength, n is the refractive index of the core material, and d is the thickness.

[0234] Inserting the above expressions for the matrix elements into equation (3) and performing the necessary matrix multiplications gives the following for the system matrix elements: JPEG2026009907000024.jpg59170

[0235] The transmission coefficient T and the reflection coefficient Γ are each defined in terms of the ABCD matrix elements as follows: JPEG2026009907000025.jpg45170

[0236] Inspection of the expression in equation (6) for the reflection coefficient Γ shows that a perfectly matched structure gives a reflection coefficient of zero, which requires both A=D and B=C.

[0237] The condition A=D is automatically satisfied due to the symmetry of the structure. Imposing other conditions, B=C gives the following equation, using the formula for the matrix elements in equation (5): JPEG2026009907000026.jpg1269

[0238] The two solutions to this quadratic equation are: JPEG2026009907000027.jpg17170

[0239] Equation (7) is the key equation for specifying the desired metasurface properties via the normalized shunt susceptance b in terms of the refractive index n and electrical thickness θ of the central dielectric core 152.

[0240] In what follows, we use equation (5) to evaluate the transmission coefficient T, but if the condition of a perfectly matched structure is also imposed, ie, A=D and B=C, we obtain: JPEG2026009907000028.jpg2488In the formula, the subscript "0" is used for the transmission coefficient to indicate that it applies when the reflection coefficient is zero.

[0241] Now, using the solution for b given by equation (6), we get: JPEG2026009907000029.jpg2067

[0242] This gives the following: JPEG2026009907000030.jpg25170In the formula, χ = sinθ / n.

[0243] The expression for T0 in equation (8) can be rewritten in polar form as a coefficient and phase, i.e., T0 = |T0|exp(jφ0), where φ0 is the phase function (in radians) of the matching structure. From equation (8), Evaluating the coefficients of JPEG2026009907000031.jpg760, this confirms the expected result for an impedance-matched structure with a reflection coefficient of zero, i.e., 100% transmission (neglecting any dissipative losses). Also, from (8), the phase of T is given by: JPEG2026009907000032.jpg17170

[0244] We can use the results of equations (7) and (9) to find the normalized shunt susceptance required for the metasurface for a matched impedance condition for a given phase shift introduced by the structure of phase c. The resulting equation is: JPEG2026009907000033.jpg20170

[0245] Equations (9) and (10) guide the design procedure for impedance matching device 120. For a given phase shift φ required at a given location on the surface of device 120 to phase correct the incoming wavefront, the required core design (thickness and refractive index) is defined in equation (8) by the parameter χ.

[0246] The metasurface properties (determined by b) are then given by the expression in equation (10) for the core design generated from equation (9).

[0247] Thus, impedance matching can be obtained for device 120 of any specified phase shift by adjusting the metasurface design at each desired location on the surface of device 120. This optimizes power transfer through device 120 while producing a phase-corrected wavefront that extends the useful range of electromagnetic directional beam 102.

[0248] The reflective phase correction device 122 used to diverge a directional beam at an angle, typically but not limited to, perpendicular to the incident directional beam, is similar in configuration to the straight-through phase correction device 120 described above, except that one of the metasurface-incorporating dielectric skins may be replaced with a metallic ground plane, which is a reflective ground plane. This is shown in FIG. 5, in which a central dielectric core 162 is sandwiched between a metasurface-incorporating dielectric skin 161 on one portion (front surface) of the central core 163 and a metallic ground plane 163 on the opposite portion (rear surface) of the dielectric core 163. This arrangement ensures that the directional beam 102 incident on the reflective phase correction device 122 is completely reflected. The incident radiation / directional beam impinging on the single metasurface layer of the device 122 (i.e., the metasurface-incorporating dielectric skin 162) can have its phase front modified by the metasurface. This design can result in a recollimated or substantially recollimated reflected directional beam. 5, the diverging wavefront of directional beam 102 incident on device 122 is designated by reference numeral 102c, and directional beam 102 delivered from device 122 is designated by reference numeral 102c. As shown, directional beam 102c is a diverging beam, and directional beam 102b is a phase-corrected and collimated or substantially collimated beam.

[0249] Other embodiments of phase correctors in accordance with the present invention, in the form of impedance-matching multilayer structures or metalenses, will now be described with reference to Figures 6-11. The phase correctors described with reference to Figures 6-11 may be used in addition to or as an alternative to phase correctors 120 and 122 in system 100 as described above.

[0250] The phase correction device according to 120a in Figure 6 is a passive planar structure incorporating multiple metasurface layers in a composite sandwich configuration. The metasurface in this case is typically an array of metallic patches or apertures in a metal screen etched from a thin metal-coated substrate. The electromagnetic properties of the metallic metasurface are controlled by the size, shape, and periodicity of the array elements.

[0251] The use of phase correction device 120a (i.e., a metalens) can provide a means to impose a given phase advance or phase delay on incident plane waves impinging on a structure at normal incidence or nearby, while filtering out any reflected waves from the front surface of the structure. This latter property is equivalent to matching the input wave impedance of the structure to free space.

[0252] In certain embodiments, the invention resides in the construction of planar lenses (metalenses) to focus or steer an incident beam of electromagnetic radiation while maximizing the electromagnetic energy transmitted through the lens. The impedance-matching properties of the lens structure and the use of low-loss dielectric materials, such as low-density foams and thin dielectric polymer substrates, ensure that energy lost to surface reflections and dissipation is minimized.

[0253] One aspect of lens design is to select suitable electromagnetic properties for the metasurface so that the desired phase advance or delay can be achieved while simultaneously eliminating reflections.

[0254] Another advantageous aspect of this design is the ability to use a constant overall panel thickness. This is achieved by using three metasurface layers, each separated from one another by a fixed thickness of low-density dielectric foam, i.e., dielectric support layer 152a and dielectric support layer 152b. There is enough flexibility in the design process to allow a constant panel thickness to be used to obtain all of the desired phase shifts while simultaneously achieving impedance matching. This greatly simplifies the design and fabrication of the lens (metalens) structure.

[0255] The focusing or beam deflection properties are achieved by constructing a large planar sandwich structure that is divided into many individual zones, each with its own defined phase shift. Each zone panel has a specific metasurface design to achieve the required phase property.

[0256] For each phase zone, one metasurface may be positioned at the center of the multilayer sandwich, while the other two metasurfaces may be positioned on the outermost surfaces of the sandwich. In general, the outer layers may have identical properties, while the central metasurface may have different properties. This results in a sandwich structure with mirror symmetry about its central plane.

[0257] Selecting the properties of the metasurface can also be important. There are mathematical relationships between the properties of the outer metasurfaces or metasurface layers 151 a, 153 a and the central metasurface or metasurface layer 155 a that may need to be satisfied to achieve a given phase shift while maintaining an impedance matching surface. Thus, the metasurface properties are not independent of each other for the phase correction device 120 a to operate in a desired manner.

[0258] As mentioned above, the phase corrector 120a in FIG. 6 is in the form of an impedance-matching planar metalens structure using three metasurfaces 151a, 153a, and 155a and two dielectric cores 152a and 152b. Therefore, the phase corrector may also be referred to as a metalens or a lens. In FIG. 2, the dielectric core 152 includes at least two dielectric layers (i.e., dielectric support layers) 152a and 152b and at least one metasurface layer 155a sandwiched between these dielectric support layers 152a and 152b.

[0259] The design shown in Figure 6 can minimize the amplitude of any reflected wavefront, i.e., directional beam 102b, by imposing a given phase shift on the incoming wavefront of a directional beam, i.e., 102a, impinging on the lens at or near normal incidence, while simultaneously maintaining an impedance match to free space. In Figure 6, directional beam 102b may be a collimated or substantially collimated beam.

[0260] The key elements in achieving these properties are three metasurfaces 151a, 153a, 155a incorporated into the outermost and central surfaces of the overall structure of phase corrector 120a, which are intended to be used as key building blocks of a fixed-thickness planar lens in which the properties of the metasurfaces are locally modified to minimize reflections from the metalens (phase corrector 102a) and impart a given phase shift to specific portions of the incoming wavefront, i.e., directional beam 102a, while maintaining a constant physical thickness without having to modify the dielectric properties of any of the layers.

[0261] The metasurfaces 151a, 153a, 155a themselves can be considered to have negligible thickness and typically consist of an array of printed metal elements or apertures in a conductive plane etched from a thin metal-coated dielectric substrate in a manner similar to that used in printed circuit board fabrication.

[0262] To create an impedance match for the incoming plane wave, i.e., directional beam 102a (i.e., to maximize the delivery of energy through the structure, excluding the reflected wave, i.e., directional beam 102b), one of the necessary requirements is to have a structure that is symmetric about the centerline. In FIG. 7, this is achieved by having identical dielectric support layers of thickness d and refractive index n. Furthermore, a central metasurface 155a is sandwiched between these dielectric layers. Finally, to further achieve the required symmetry, the outermost metasurfaces 151a, 153a, while identical in design, will typically have different properties relative to the central metasurface 155a.

[0263] When designing a lens to produce a desired phase delay / advance on a given portion of the lens surface while maintaining impedance matching conditions, the properties of the two metasurface designs are tailored to a given dielectric layer thickness and refractive index.

[0264] A mathematical analysis of the metalens, i.e., phase corrector 120a, of FIG. 6 is now provided.

[0265] To understand the required metasurface properties, we analyze the multilayer structure in Fig. 6 using the following well-established continuous “ABCD” matrix method. JPEG2026009907000034.jpg18170

[0266] In equation (11), each 2x2 matrix on the right represents the properties of five individual layers in the structure in terms of the equivalent transmission line.

[0267] The outermost metasurfaces 151a, 153a are represented by a normalized shunt susceptance b1, where the normalization factor is the admittance of free space (= 1 / 376.73 Ω -1 )

[0268] Similarly, for the central metasurface 155a, the normalized shunt susceptance is denoted by b2.

[0269] In equation (11), we also It also has JPEG2026009907000035.jpg723. The dielectric support layers 152a, 152b are formed by the other matrix The thickness d and refractive index n are the same for each dielectric support layer 152a, 152b. The propagation phase is JPEG2026009907000037.jpg1424, where λ is the free-space wavelength.

[0270] This set of matrix elements in equation (11) corresponds to the case of normal incidence plane-waves, which is assumed to adequately describe the incident electromagnetic field. This will be sufficient for large diameter lenses, which are assumed to be illuminated from sources at distances much longer than the lens diameter. Based on this assumption of small angles of incidence, the lens properties are nearly independent of the plane of incidence and polarization of the incident wave.

[0271] The left hand side of equation (11) is the resulting 2x2 matrix resulting from matrix generation of all five layers, with matrix elements A, B, C, and D. The transmission and reflection coefficients of the multilayer structure, denoted T and Γ, respectively, are then found from the following equations: JPEG2026009907000038.jpg38170

[0272] Performing the matrix multiplication in equation (11), the matrix elements are: JPEG2026009907000039.jpg51170

[0273] In equation (14), the matrix elements A and D are purely real quantities and are numerically equal to each other following from the symmetry of the multilayer structure about the central plane.

[0274] Equations (15) and (16) show that the matrix elements B and C are purely imaginary quantities and are also a consequence of the symmetry of the structure.

[0275] Inspection of equation (13) for the reflection coefficient of the multilayer structure shows that for the impedance matching condition (Γ=0), the following is required: JPEG2026009907000040.jpg12170

[0276] Since equation (14) automatically satisfies A=D, the condition for impedance matching in equation (16) reduces to a requirement that B=C. Therefore, using the expressions in (15) and (16) gives the following expression for impedance matching: JPEG2026009907000041.jpg13170

[0277] For the impedance matching condition of equation (17), the transmission coefficient defined in equation (12) reduces to the following given form: A=D and B=C. JPEG2026009907000042.jpg19170

[0278] In equation (19), the impedance matching condition is matched is unity in magnitude, eliminating any dissipative losses. If low-loss materials are used for the dielectric layers in the multilayer structure of phase corrector 120a, these dissipative losses can be assumed to be negligible, and the refractive index n is taken to be a purely real number. Thus, equation (19) represents the pure phase shift imposed on the incident wavefront.

[0279] An examination of equations (14) and (15) shows that A is purely real and B is purely imaginary. Hence, equation (19) can be written in the following form: JPEG2026009907000043.jpg30170In equation (20), α = A and β = -jB.

[0280] From equation (20), it is clear that the phase delay θ (in radians) is given by: JPEG2026009907000044.jpg17170

[0281] Rearranging equation (21) gives: JPEG2026009907000045.jpg15170

[0282] Equation (20) can be rewritten using the results of equations (21) and (22) to give: JPEG2026009907000046.jpg17170

[0283] Under impedance-matching conditions, (for an assumed lossless medium) T matched Since the magnitude of is unity, equation (23) requires that JPEG2026009907000047.jpg12170

[0284] Using equation (15) in equation (24) to represent β, for a given phase delay θ and electrical thickness for the dielectric layer φ, we obtain the expression for the normalized shunt susceptance of the central metasurface b2 as follows: JPEG2026009907000048.jpg14170

[0285] An expression for the normalized shunt susceptance of the outermost metasurface b1 can be found by using this expression for α in equation (22) and equating it with the expression for A given by equation (14). JPEG2026009907000049.jpg13170

[0286] Using equation (24) for β and equation (25) for b2 gives, after some algebraic manipulation, JPEG2026009907000050.jpg16170

[0287] Equations (25) and (27) are key equations to guide the design of metalens. For a given phase retardation θ, dielectric phase factor φ, and refractive index n, the required value of the normalized shunt susceptance of the metasurface providing the impedance-matching structure (b1 and b2) can be easily found from equations (25) and (27).

[0288] Design and realization of metasurfaces Graphs / plots of b1 and b2 are shown in Figures 7 and 8, respectively, as a function of phase retardation through the lens structure for various values ​​of the electrical thickness of the dielectric layer φ. In the graphs shown in Figures 7 and 8, the refractive index of the dielectric is set to 1.095, which is typical of the low-density, low-loss foam material assumed in the physical embodiment of the lens. Such a material has a dielectric constant of 1.2, the square root of which gives a refractive index of 1.095.

[0289] There are several important observations regarding the graphs shown in FIGS. Phase delay is allowed to have negative and positive values, i.e., spanning the full range of -180 to +180 degrees. A negative phase delay is equivalent to a positive phase advance. For negative values ​​of the normalized shunt susceptance, the metasurface has inductive properties, which are actually realized by a periodic array of apertures in a thin conducting sheet. For positive values ​​of the normalized shunt susceptance, the metasurface has capacitive properties that are actually realized by an array of conductive patches isolated from each other. A metasurface resonates when the normalized shunt susceptance is either zero or ±infinity. Zero susceptance corresponds to a perfectly transmitting metasurface, and an infinite value corresponds to a perfectly reflective one. For an impedance-matched lens that is ideally non-reflective to the incoming wave, it is clear that reflective resonances (infinite susceptance values) must be avoided. Transmission resonance (zero susceptance) does not fundamentally present a problem in realizing practical implementations of matching lenses. However, the lateral dimensions of the resonating elements are typically between one-quarter and one-half the size of a wavelength, and they also exhibit the largest dissipative losses at the resonant frequency. Therefore, it is preferable to use smaller non-resonating elements in the lens design.

[0290] 7 and 8 for values ​​of b1 and b2 shows that for positive phase retardation (the right half of the horizontal axis of the plot), b1 is mostly negative (inductive), but can pass through zero (transmission resonance) and become positive (capacitive) depending on the particular combination of dielectric thickness and phase retardation. The same is seen for b2.

[0291] For values ​​of b1 and b2 that correspond to negative phase retardation (shown on the left half of the horizontal axis in Figures 7 and 8), b1 is almost always positive (capacitive), but can pass through zero (transmission resonance) and become negative (inductive) for some combinations of dielectric thickness and phase retardation. The same is observed for b2.

[0292] To facilitate the lens design, i.e., the design of the phase corrector 120a, a negative phase delay (phase advance) is preferred because a wide range of phase values ​​can be achieved using only non-resonant capacitive metasurface elements, i.e., periodic arrays of conductive patches that can be made small, with array periodicity small compared to the wavelength. This latter condition, however, reduces the dependence of the metasurface properties on the plane and angle of incidence, which is assumed in this analysis.

[0293] A specific example of a shunt susceptance value that maintains capacitive properties for both b1 and b2 over a wide range of phase advances is shown in Figure 1, where the dielectric layer is JPEG2026009907000051.jpg1012 (90 degrees) is shown in Figure 9. This thickness corresponds to one-quarter of the wavelength of the electromagnetic wave passing through the dielectric medium, which in this example is chosen to have a dielectric constant of 1.2, i.e., a refractive index of 1.095.

[0294] Figure 9 shows the behavior of b1 and b2 versus phase delay through a lens (phase corrector 120a) for a dielectric thickness equal to 90 degrees. The refractive index is 1.095. For the particular case shown in Figure 9, the shunt susceptance equations (25) and (27) are somewhat simplified. JPEG2026009907000052.jpg30170

[0295] Since the phase delay θ in Figure 9, which corresponds to a phase advance, is negative, the above equations (28) and (29) give positive shunt susceptance values. Phase advance values ​​between 20 and 180 degrees can be easily achieved using the design approach shown in Figure 9 for a quarter-wave dielectric layer.

[0296] Physical realization of the required normalized shunt susceptance value for a given phase advance can be achieved using the known properties of periodic arrays of metallic patches, often referred to as frequency selective surfaces (FSS), a form of metasurface. Some typical array element designs and lattices are shown in Figures 10A, 10B, and 10C. Figure 10A shows an example of an array of circular patches on a diamond lattice. Figure 10B is an example of an array of square patches on a square lattice. Figure 10C is an example of an array of crosses on a square lattice.

[0297] In Figures 10A, 10B, and 10C, the shaded areas indicate the metallic regions on the surface. For frequencies below resonance, this type of metasurface generates a positive shunt susceptance, i.e., a capacitive one. These metasurfaces can be easily fabricated using conventional etching techniques applied to thin metal-coated dielectric substrates or by inkjet printing techniques using highly conductive inks.

[0298] Although this may not be useful for the lens design of the present invention, negative shunt susceptance values ​​can be generated in a similar manner, giving inductive metasurfaces. The main difference between this type of metasurface and its capacitive counterpart is that the shaded regions shown in Figures 10A, 10B, and 10C represent aperture areas etched from a continuous metal surface.

[0299] Figure 11 shows the typical behavior of patch and aperture-type frequency-selective surface (FSS) layers (metasurfaces) as a function of frequency. Figure 11 shows the typical normalized shunt susceptance behavior for patch and aperture-type metasurfaces versus normalized frequency. Resonance occurs at a normalized frequency of 1. The desired shunt susceptance value at a given frequency can be obtained by adjusting the size of the patch / aperture elements along with the periodicity and type of the array grating.

[0300] It is customary to assume a large number of array elements in a given metasurface design, so that a detailed electromagnetic analysis of the array properties can be approached by assuming an infinite periodic array, which, in conjunction with periodic boundary conditions that invoke Floquet theory for such periodic structures, forces the analysis to be performed on only a single unit cell within the lattice.

[0301] Computational electromagnetic techniques such as the method of moments (MoM), finite element (FE), and finite difference time domain (FDTD) methods are all well established and exist as commercially available packages that allow the design and analysis of the metasurfaces described above to be easily implemented.

[0302] With regard to the macrostructure of the metalens itself, one approach is to divide the aperture of the lens into multiple zones where different phase advances are achieved to result in a desired wavefront (e.g., converging, diverging, collimated, or substantially collimated).

[0303] The array periodicity and grating type may be the same across the entire lens surface (i.e., across all zones), but each zone tile will contain a subarray of elements sized to achieve the shunt susceptance value required for the desired phase advance across that particular zone.

[0304] Alternatively, one could implement a smooth, gradual transition in element size across the lens surface and still keep the periodicity and grating type the same across the aperture, however this would be more difficult to design and more challenging to manufacture.

[0305] Referring now to FIG. 12, one application of the phase corrector 120a in the form of an impedance matching multilayer structure or metalens, as described above, will be described.

[0306] The range over which power can be transmitted by a delivered electromagnetic energy beam while remaining collimated or substantially collimated is dictated by the antenna aperture size and the wavelength of operation. In particular, the usable range is proportional to the area of ​​the delivery antenna and inversely proportional to the wavelength. Planar phased array antennas are envisioned as radiating structures for the delivery device or delivery antenna that facilitate control over the phase and amplitude of the array elements as a means of providing control over the wavefront of the emerging beam.

[0307] With antenna aperture sizes determined in this manner, long-range performance can result in multiple, expensive phased array components. However, one way to decouple a large exit aperture (to achieve the desired range) from the high cost of the phased array components is to use a passive phase-correcting metalens to achieve the large exit aperture.

[0308] This lens can then be illuminated by another phased array antenna positioned behind the lens. This antenna has a smaller aperture size than the exit aperture of the metalens, thereby requiring fewer components and therefore lowering the cost of the delivery antenna. This is similar to a parabolic reflector dish illuminated by a much smaller feed antenna near its focal point.

[0309] The metalens concept differs in that the lens is transparent to the incoming electromagnetic wave but imposes a phase shift across the wavefront. It has the same physical thickness across the entire aperture and is highly transparent. The particular metalens structure envisioned creates the required phase advance or phase delay across the exit aperture to impedance match the incoming electromagnetic wave and produce the desired phase-corrected delivered wavefront. The emerging wavefront can be a converging or diverging plane wavefront, as desired.

[0310] The desired phase shift can be varied across the surface of the lens, which can be achieved by using different metasurface properties at different locations across the lens aperture. The three-layer metalens design methodology described above allows the various phase shifts to be realized in the form of tiles that are assembled to form the complete metalens structure.

[0311] The amplitude and phase of each phased array delivery antenna element is adjusted to provide a desired illumination field on the metalens. Having electronic control of the phased array antenna elements allows modifications and real-time corrections to be made to the illumination field.

[0312] Returning now to FIG. 12, which is a conceptual schematic of metalens 120a, as discussed above, a planar three-layer metalens 120a may be used to provide phase correction to an illumination field to produce a desired output wavefront across an aperture larger than the delivery antenna 110. FIG. 12 shows the case of an emerging plane wave. A converging wavefront (resulting in focusing) can be achieved by reconfiguring the metalens properties to give the required phase distribution across the exit aperture.

[0313] 12, directional beams 102, 102a refer to the illumination wavefront emitted by a delivery antenna of aperture size D, and directional beams 102, 102b refer to the emerging phase-corrected wavefront. The exit aperture size D is also shown.

[0314] The self-identifying configuration described above with reference to FIG. 12 for the transmitter portion of a long-range wireless power transmission system is equally applicable to the receiver portion or rectifying antenna 130, with the energy flow direction reversed.

[0315] For receiver or rectifying antenna 130, the metalens (i.e., phase corrector 120a) now focuses the incoming electromagnetic waves from the delivery antenna 110 onto the rectifying antenna 130, which is placed behind the metalens. Thus, the size of rectifying antenna 130 can be reduced in the same manner as delivery antenna 110, thereby reducing component cost and weight.

[0316] Rectifying antenna (rectenna) The rectifying antenna 130 of the long-range wireless power transfer system 100 is a structure that terminates to receive the directional beam 102 delivered by the rest of the system and converts the incident electromagnetic energy back into electricity. In other words, the rectifying antenna is configured to receive the directional beam from the phase correction devices 120, 122 and convert the electromagnetic energy back into electricity. This rectifying antenna can be referred to as a "rectenna."

[0317] The rectifying antenna 130 may be similar in size to the aperture of the delivery antenna 110. The rectifying antenna 130 may in turn consist of an array of antenna elements that may be electrically connected to solid-state rectifying components, such as Schottky diodes. Such rectifying components and their associated circuitry can rectify incoming electromagnetic energy to produce a direct current (DC) output that is then transmitted to a required load.

[0318] For efficient electromagnetic-to-DC conversion, the antenna elements (patched elements) of the rectifying antenna may incorporate an impedance matching layer at their boundary with free space. Such an impedance matching layer may incorporate a metasurface. The metasurface may be designed and tuned to reject any reflected waves from the front face of the rectenna, maximizing energy transfer to the rectifying element.

[0319] 13 is a schematic diagram illustrating a rectifying antenna concept using a front-mounted metasurface for impedance matching. The rectifying antenna concept described with reference to FIG. 13 may be applied to rectenna 130, as discussed above.

[0320] As shown in FIG. 13, the rectifying antenna structure 200 may include a central core 203. The central core 203 is preferably made from a low-loss dielectric material such as foam. The thickness of the central core 203 is preferably between 1 / 10 and 1 full wavelength of the electromagnetic wave passing through the dielectric material of the core. The central core 203 preferably has a refractive index between 1 and 3. The thickness and refractive index may be varied over the surface of the rectifying antenna to achieve a desired impedance match.

[0321] The central core 203 may comprise a first portion 201, which is a front surface, and a second portion 202, which is a rear surface opposite the first portion 201. The first portion 201 may comprise a dielectric skin 206. The dielectric skin 206 may comprise / incorporate a metasurface for impedance matching to the directional beam 102e (incident wavefront / electromagnetic energy) incident on the rectifying antenna structure 200. The dielectric skin 206 is preferably thin such that the thickness of the skin is less than one-tenth of the wavelength of the electromagnetic wave passing through the dielectric medium of the skin. The dielectric medium of the skin is the dielectric material from which the skin is fabricated.

[0322] A rectifying antenna array 205 (receiving antenna array) may be positioned in the second portion 202 of the central core 203. A rectifying circuit 208 (solid state rectifying components such as Schottky diodes) may be electrically connected to the rectifying antenna array 205 to generate a DC output 210 that is then delivered to a required load.

[0323] The rectifying antenna array 205 may comprise multiple antenna elements (solid-state rectifying components such as Schottky diodes) electrically connected to a rectifying circuit to generate a DC output that is then delivered to a required load.

[0324] A rectifying antenna structure 200 as described above, including an impedance matching layer incorporating a metasurface, enables efficient electromagnetic-to-DC conversion. The metasurface may be designed and tuned to reject any reflected waves from the front face of the rectenna, thereby maximizing energy transfer to the rectifying element.

[0325] Similar to the transmitting antennas described above, the rectifying antenna array 205 may optionally comprise multiple antenna elements, whereby each antenna element is covered by a small electrical radome shell designed to increase the antenna gain of each receiving antenna element compared to the absence of the radome shell. In other words, each antenna element may include a radome element, which may be a low-loss dielectric element. The radome element may be a hemispherical, approximately hemispherical, or similar dome-shaped element to enable increased gain of the rectifying antenna array 205. The radome element may be a thin-walled radome element. Preferably, the wall thickness of the radome element is equal to or less than one-quarter of the wavelength thickness of the material from which the radome wall is made. λ d The wavelength of the electromagnetic wave in the radome wall material, denoted as JPEG2026009907000053.jpg18170 In the above formula, λ is the free space wavelength, and n d is the refractive index of the radome wall material.

[0326] The radome elements may be larger than the antenna elements of the rectifying antenna array 205 so as to cover the antenna elements of the rectifying antenna array.

[0327] Focusing in the Radiation Near-Field Region as a Means to Increase the Range of Wireless Power Transmission Using Electromagnetic Beams In the present invention, the transmitting antenna 110 may operate in a radiating near-field region where the electromagnetic field is substantially confined to a collimated or substantially collimated beam, which is ideally suited for directional power transfer to a similarly sized receiving antenna or rectenna 130.

[0328] Described herein is a method for increasing the range over which an electromagnetic beam can propagate by using focusing to minimize beam divergence. A primary application of the invention is the efficient long-distance wireless power transfer using electromagnetic radiation or beams, such as microwave beams.

[0329] A key principle of the system proposed here is to operate the delivery antenna in the near-field radiation region rather than the far-field radiation zone, the latter characterized by a diverging beam with an angular distribution that does not vary with distance and an inverse square law of power density as a function of range.

[0330] In contrast, the radiating near-field region (which occurs closer to the antenna aperture than the distance at which far-field conditions begin) maintains a beam range that is limited to a cylinder of size comparable to the antenna aperture. This beam exhibits only modest beam divergence with power density levels comparable to those at the antenna aperture plane. There is no inverse-square law attenuation of power density in the radiating near-field, making it very attractive for the purpose of long-distance wireless power transfer. Placing a similarly sized receiving antenna at the maximum range where the radiating near-field conditions are maintained results in very efficient power transfer with little beam loss.

[0331] The range over which the radiating near-field extends is proportional to the aperture area of ​​the transmitting antenna and inversely proportional to the wavelength. Therefore, for a given range of operation at a particular wavelength, the antenna size must be selected to be large enough to achieve the required radiating near-field condition. To achieve this, any means that can increase the useful range of such a system without increasing the size of the antenna would be advantageous.

[0332] In the present invention, such range extension may be achieved by applying a spherical phase distribution across the aperture of the delivery antenna so as to achieve a degree of beam focusing in the radial near field.

[0333] This results in a converging wavefront emanating from the delivery antenna that partially offsets the natural beam divergence caused by diffraction. This results in a narrowing of the beam waist as one moves away from the antenna. The beam waist eventually reaches a minimum size, and the phase front becomes nearly planar before diverging again as one moves with increasing distance. At a certain range, this diverging wavefront causes the amplitude distribution of the electromagnetic field to expand to mimic the amplitude distribution at the antenna aperture, imposing a phase front on the aperture field that is the conjugate of the spherical distribution. This image of the aperture field essentially reproduces the antenna plane distribution at this distance from the antenna (eliminating phase conjugation). The distance from the antenna aperture at which this image occurs is greater than without focusing, and this is how the increased range of the described system is achieved.

[0334] FIG. 14 shows a schematic representation of a phased array delivery antenna used to deliver electromagnetic energy in the form of a collimated or substantially collimated beam with little angular divergence to a receiving / rectifying antenna 130 (rectenna), as described above. In FIG. 14, the delivery antenna 110 and the receiving or rectifying antenna 130 operate in the radiating near-field. The delivery antenna 110 is a planar phased array delivery antenna with electronically controllable electric field amplitude and phase distribution across the aperture, and the rectifying antenna can be a planar receiving antenna. The delivery antenna 110 and the rectifying antenna 130 may be as described above. If the distance R between the delivery antenna 110 and the receiving antenna is confined within the radiating near-field region, the beam divergence is minimized. The range R is given by the following equation: JPEG2026009907000054.jpg20170 In the above formula, JPEG2026009907000055.jpg6170 is the effective area of ​​the delivery antenna aperture having a physical aperture area A, ε is the aperture efficiency (dictated by the amplitude taper across the antenna), and λ is the free space wavelength.

[0335] Figure 15 shows the magnitude of the electric field strength calculated along the range axis for a square antenna of width D operating at a single wavelength λ. The range R is given by 2 Extending the radiating near-field region, the Fraunhofer limit describing the onset of πλ / πλ must be reached. The electric field strength is normalized to its maximum value at the aperture plane. Figure 15 shows the normalized axial electric field strength versus range for aperture efficiency = 0.85, D = 1.92 m, and frequency = 5.8 GHz.

[0336] In the example of Figure 15, the frequency used is 5.8 GHz, and the antenna consists of an array of patch antenna elements with a 30 mm pitch. For a square array of 64 x 64 patches, the antenna width is 1.92 m. A Gaussian amplitude taper is applied across both major axes in the antenna aperture plane (extent = 0), such that the electric field at the antenna edge is a factor of 1 / e at the maximum level in the aperture. This amplitude tapering results in a smoother near-field beam distribution with lower sidelobes than that from a uniform aperture field. In the example of Figure 15, all elements are excited in phase, i.e., no focusing is applied.

[0337] As the electric field plot in Figure 15 shows, in the radial near-field region, the on-axis electric field strength does not decay with increasing range R according to a reciprocity law (corresponding to the inverse square law for power) as in the radial far-field, but oscillates around the aperture intensity before decaying smoothly.

[0338] In the radiating near-field region, the maximum on-axis electric field strength exceeds that of the antenna aperture due to constructive interference, within the range R max When the antenna array elements are excited in phase, R max The value of is given by the following formula: JPEG2026009907000056.jpg16170 where λ is the wavelength of the radiation; JPEG2026009907000057.jpg6170 is the effective area of ​​the delivery antenna aperture. The effective area is defined as the physical area multiplied by the aperture efficiency. In the example shown in Figure 15, for the Gaussian taper used, the aperture efficiency is 0.85. R max The resulting value for is 20.8 m.

[0339] The phase front profile across the beam in this range (where the maximum electric field strength occurs) is essentially that of a plane wave across much of the antenna aperture width. This phase distribution is shown in Figure 16A. Figure 16A shows the phase distribution across the range = R max = 20.8 m, which shows the phase distribution of the electric field across the horizontal axis for the unfocused case. The corresponding electric field amplitude is shown in Figure 16B. Figure 16B shows the phase distribution of the electric field across the horizontal axis for the unfocused case with a range = R max = 20.8 m.

[0340] 16A and 16B show the R max For ranges up to 1000 GHz, there is little beam divergence, indicating that efficient radiative power transfer to the rectifying antenna 130 is favorable. Thus, an important property of the radiative near-field approach to power transfer is the direct proportionality of useful range to the aperture area of ​​the delivery antenna 110, and the reciprocal dependence on wavelength.

[0341] At first glance, R max may appear to be the maximum range over which an electromagnetic beam (such as a microwave beam) can be transmitted to a rectifying antenna 130 without substantial loss of power due to the diverging beam characteristics introduced by diffraction. However, the useful range of power transmission can be extended by exploiting another property of the radiating near-field region: the possibility of focusing the delivered beam. This can be achieved with a phased array antenna by applying a suitable (and programmable) phase distribution across the radiating elements.

[0342] Figure 17 shows the axial electric field distribution for the same antenna as above, but with a spherical phase distribution across the aperture plane. This phase distribution may be determined by placing a point on the range axis at a distance f from the antenna aperture (focal length), and then applying a phase correction to each of the array elements of the delivering antenna so that the radiation from all elements arrives in phase at point f. Figure 17 shows the normalized axial electric field intensity for the range focusing case of f=50 m, aperture efficiency=0.85, D=1.92 m, and frequency=5.8 GHz.

[0343] It is important to note that when this type of focusing is applied to the antenna aperture elements, the maximum electric field strength along the range axis does not occur at the focal point f, but is shifted closer to the antenna aperture than in the unfocused case. In the example above, after the focal point was set at a range of 50 m, the maximum electric field strength is located at a range of R'max = 17.2 m. As shown in Figure 17, the amplitude of the focusing increases the maximum electric field strength.

[0344] As in the unfocused case, the phase distribution across the beam in the range where the maximum electric field strength occurs is substantially flat. However, the electric field amplitude in this range has a narrower beam waist with focusing. Plots of the phase and amplitude at a range of 17.2 m for this focused case are shown in Figures 18A and 18B, respectively, to illustrate this point. Figures 18A and 18B show the electric field phase distribution across a beam with a range of 17.2 m for the focusing case with f=50 m.

[0345] Since the maximum electric field strength and plane wavefront in the focused case occurs at a shorter range than in the unfocused case, it may seem counterintuitive as to how focusing helps extend the range useful for power transfer.

[0346] However, once a minimum is reached at R'max, the beam waist widens once again as this range increases to the point where the original aperture field distribution is well reproduced. The range where this occurs can be seen by examining Figure 17. The axial field strength reaches its original value for convergence (maximum at the aperture plane) at a range of 39.6 m in the focused case.

[0347] In comparison, for the unfocused case, Figure 15 shows that the on-axis electric field strength reaches the initial aperture field value of the bundle over a range of 32.4 m, which is only 82% of the range of the same electric field strength using focusing.

[0348] For comparison, the phase and amplitude distributions across the beam for the focused and unfocused cases, along with the distribution at the aperture of the delivery antenna, are shown in Figures 19A and 19B, respectively. Figures 19A and 19B show the phase distribution of the electric field across the aperture across the horizontal axis, over a range of 39.6 m for the focused case and 32.4 m for the unfocused case. In Figure 19A, D = 1.92 m, frequency = 5.8 GHz, and f = 50 m. In Figure 19A, reference numerals 1901, 1902, and 1903 correspond to the phase at 39.6 m (focused), the phase at the aperture, and the phase at 32.4 m (unfocused), respectively. Similarly, in FIG. 19B, reference numerals 1901, 1902, and 1903 correspond to the electric field at a range of 39.6 m (focused), the electric field at the aperture plane, and the electric field at 32.4 m (unfocused), respectively.

[0349] From Figure 19B, it can be seen that the amplitude of the focused electric field over the 39.6 m range of the beam closely resembles the amplitude of the aperture field and is more tightly confined over the cross section than the unfocused case over the 32.4 m range.

[0350] The focusing profile in Figure 19B can be thought of as an image of the aperture-plane electric field distribution. The phase of this field in this region, shown in Figure 19A, is the same as that of the aperture (to which the focusing phase taper applies), except that it has the opposite meaning. That is, the convex phase front of the aperture is its phase conjugate, a concave phase front of similar curvature at a 39.6 m extension.

[0351] The phase front curvature for the unfocused case of FIG. 19A at a range of 32.4 m is significantly different from the focused electric field and aperture.

[0352] Thus, the useful range of power transmission using microwave beams in the radial near-field can be increased by focusing the Gaussian distribution in the manner described above.

[0353] In the example shown, a rectenna of similar size aperture to the delivery antenna can be placed over a range of 39.6 m using the focused technique, compared to 32.4 m for the unfocused case, a 22% increase in this example. Furthermore, the electric field amplitude distribution across the beam in the focused case more closely replicates and replicates the electric field amplitude distribution of the aperture field, and is more tightly confined than that of the unfocused example with the same peak amplitude.

[0354] Equally important from a practical standpoint, for a given range between transmitter and receiver, this focusing technique can be used as a way of reducing the aperture area of ​​the antenna by this same factor.

[0355] To illustrate the spatial distribution of the electric field strength for the unfocused and focused cases, Figures 20A and 20B on the following pages show contour plots in the horizontal plane for the system described above. Figure 20A shows the relative electric field strength contours for the horizontal plane omnidirectional beam. Figure 20B shows the relative electric field strength contours for the horizontal plane omnidirectional beam. Figure 20B is for the focused case where f is 50 m.

[0356] Where reference is made in the foregoing description to elements or integers known to be equivalent, such equivalents are encompassed as if individually set forth.

[0357] It will be appreciated that the foregoing description has been made as an illustrative example of the present invention, and that modifications and variations thereof which become apparent to those skilled in the art are considered to be within the broad scope and various aspects of the invention as hereinbefore described and / or as defined in the claims.

Claims

1. A long-distance wireless power transmission system, a delivery antenna configured to operate in a radiating near-field region, the delivery antenna being a phased array antenna having an array of antenna elements that are radiating elements, the phased array antenna being configured to receive power as an input from a power source, convert the input power into electromagnetic energy, and radiate the electromagnetic energy into free space as a directional beam that is a collimated or substantially collimated beam, the collimated or substantially collimated beam being generated by controlling the phase and amplitude of each of the antenna elements; at least one phase correction device positioned or configured to be positioned at a first distance from the delivery antenna, the at least one phase correction device being a multi-layer structure having at least three layers with a central dielectric core sandwiched between at least two layers of two opposite portions of the dielectric core, at least one of the layers being a dielectric skin made of at least one dielectric material, the at least one phase correction device corresponding to the device comprising: receiving the directional beam emitted from the transmitting antenna; performing a phase correction operation on the directional beam, the phase correction operation being to maintain the directional beam as the collimated beam and to increase the extent to which the directional beam is maintained as the collimated or substantially collimated beam; and delivering the phase-corrected directional beam into free space. a rectifying antenna, the rectifying antenna being positioned or configured to be positioned between a delivery antenna and a rectifying antenna, the rectifying antenna being positioned or configured to be positioned at a second distance from the delivery antenna, the rectifying antenna being configured to receive the directional beam from the at least one phase correction device and convert the electromagnetic energy into electricity;

2. The system of claim 1 , wherein the electromagnetic energy is microwave energy.

3. 3. The system of claim 1 or 2, wherein each antenna element has an electronically controlled phase shifter to facilitate electronic steering of the directional beam.

4. 5. A system according to claim 3 or 4, wherein each antenna element is a patch antenna element.

5. A system according to any one of claims 3 to 5, wherein each antenna element is made from a metal segment etched onto a substrate.

6. 8. The system of claim 7, wherein each antenna element is a radome element formed as a hemispherical or approximately hemispherical shell.

7. 10. The system of any one of the preceding claims, wherein the at least one phase correction device is an electromagnetic wave transmission phase correction device.

8. 10. The system of claim 9, wherein the at least one phase correction device is a straight-through phase correction device that causes the incident directional beam to travel in a straight direction without diverging into directional beams in other directions.

9. 9. The system of claim 1, wherein the at least one dielectric skin comprises a metasurface that simultaneously provides a phase shift while maintaining an impedance matching structure with minimal power loss.

10. 10. The system of claim 9, wherein the metasurface is embedded on the dielectric skin.

11. The system of any one of claims 1 to 10, wherein the dielectric core is made from a low-loss dielectric material.

12. 12. The system of any one of claims 1 to 11, wherein the central dielectric core is at least three layers in which at least one metamaterial layer or metasurface is sandwiched between two dielectric support layers.

13. The system of any one of claims 1 to 12, wherein the at least one phase correction device is a reflective phase correction device that reflects the directional beam incident on the reflective phase correction device in another direction, thereby diverging the directional beam in the other direction at a certain angle.

14. 14. The system of claim 13, wherein in the reflective phase correction device, the dielectric core is sandwiched between the at least two layers in two opposite portions of the dielectric core, at least one of the layers being the dielectric skin and the other being a reflective ground plane.

15. 10. The system of claim 9, wherein the rectifying antenna is part of a rectifying antenna structure including a solid state rectifying component, the rectifying antenna comprising an array of receive antenna elements electrically connected to the solid state rectifying component.

16. 16. The system of claim 15, wherein the solid-state rectifying component is a Schottky diode.

17. The rectifying antenna is part of a rectifying antenna structure, and the rectifying antenna structure comprises: a central core having opposed first and second portions and constructed of at least one dielectric material; a dielectric skin comprising a metasurface disposed on a first portion of the central core, the rectifying antenna being positioned on the second portion of the central core; and a rectifier circuit electrically connected to the rectifying antenna to rectify the incoming electromagnetic e-energy and generate a direct current (DC) output that is then delivered to a required load.

18. 20. The system of claim 17, wherein the rectifying antenna is formed as a rectifying antenna array having a plurality of rectifying antenna elements.

19. 19. The system of claim 17 or 18, wherein the central core is made of a low-loss dielectric material.

20. A long-distance wireless power transmission system, a delivery antenna configured to operate in a radiating near-field region, the delivery antenna being a phased array antenna having an array of antenna elements that are radiating elements, the phased array antenna being configured to receive power as an input from a power source, convert the input power into electromagnetic energy, and radiate the electromagnetic energy into free space as a directional beam that is a collimated or substantially collimated beam, the collimated or substantially collimated beam being generated by controlling the phase and amplitude of each of the antenna elements; at least one phase correction device positioned or configured to be positioned at a first distance from the delivery antenna, the at least one phase correction device comprising: receiving the directional beam emitted from the transmitting antenna; maintaining the directional beam as the collimated or substantially collimated beam and performing a phase correction operation on the directional beam to increase the extent to which the directional beam is maintained as the collimated or substantially collimated beam; and delivering the phase-corrected directional beam into free space. the at least one phase correction device is positioned, or configured to be positioned, between a delivery antenna and a rectifying antenna, the rectifying antenna being positioned, or configured to be positioned, at a second distance from the delivery antenna, the rectifying antenna being configured to receive the directional beam from the at least one phase correction device and convert the electromagnetic energy into electricity; The system wherein the at least one phase correction device utilizes at least one metasurface to provide a phase shift while maintaining an impedance matching structure that minimizes power loss.

21. 23. The system of claim 21 or 22, wherein the at least one phase correction device utilizes at least two metasurfaces that provide a phase shift while maintaining the power loss-minimized impedance matching structure.

22. A long-distance wireless power transmission system, a delivery antenna configured to operate in a radiating near-field region, the delivery antenna being a phased array antenna having an array of antenna elements that are radiating elements, the delivery antenna being configured to receive power as an input from a power source, convert the input power into electromagnetic energy, and radiate the electromagnetic energy into free space as a directional beam that is a collimated or substantially collimated beam, the collimated or substantially collimated beam being generated by controlling the phase and amplitude of each of the antenna elements; a rectifying antenna positioned or configured to be positioned a distance from the delivering antenna, the rectifying antenna configured to receive the directional beam and convert the electromagnetic energy into electricity; A system in which each antenna element comprises a radome element formed as a hemispherical or nearly hemispherical shell.

23. 23. The system of claim 22, wherein the electromagnetic energy is microwave energy.

24. 24. A system according to claim 22 or 23, wherein each antenna element has an electronically controlled phase shifter to facilitate electronic steering of the directional beam.

25. The system according to any one of claims 22 to 24, wherein the radome element is larger than the antenna element so as to cover the antenna element.

26. The delivery antenna comprises:

26. The system of any one of claims 22 to 25, having a delivery antenna aperture with a dimension D, wherein at least one of the following inequalities applies to the wavelength λ and the distance R between the delivery antenna and the down-range phase correction device or rectenna:

27. 27. The system of claim 26, wherein the size of the rectifying antenna is the same as or approximately the same as the size of the delivery antenna aperture.

28. 28. The system of any one of claims 22 to 27, wherein the rectifying antenna is part of a rectifying antenna structure including a solid state rectifying component, the rectifying antenna comprising an array of receive antenna elements electrically connected to the solid state rectifying component.

29. 30. The system of claim 28, wherein the solid-state rectifying component is a Schottky diode.

30. The rectifying antenna is part of a rectifying antenna structure, and the rectifying antenna structure comprises: a central core having opposed first and second portions and constructed of at least one dielectric material; a dielectric skin comprising a metasurface disposed on a first portion of the central core, the rectifying antenna being positioned on the second portion of the central core; 30. The system of claim 28 or 29, comprising: a rectifier circuit electrically connected to the rectifying antenna to rectify the incoming electromagnetic e-energy and generate a direct current (DC) output.

31. 31. The system of claim 30, wherein the rectifying antenna is formed as a rectifying antenna array having a plurality of rectifying antenna elements.

32. 32. The system of claim 30 or 31, wherein the central core is made of a low-loss dielectric material.

33. A system according to any one of claims 30 to 32, wherein the thickness of the central core is between 1 / 10 and 1 full wavelength of the dielectric material from which it is made.

34. 34. The system of any one of claims 30 to 33, wherein the central core has a refractive index between 1 and 3.

35. 35. The system of claim 34, wherein the thickness and refractive index of the central core vary over the surface of the rectifying antenna to achieve a desired impedance match.

36. The system further comprises at least one phase correction device positioned or configured to be positioned between the delivery antenna and the rectifying antenna, the at least one phase correction device comprising: receiving the directional beam emitted from the transmitting antenna; maintaining the directional beam as the collimated or substantially collimated beam and performing a phase correction operation on the directional beam to increase the extent to which the directional beam is maintained as the collimated or substantially collimated beam; 36. The system of claim 35, configured to: and deliver the phase-corrected directional beam into free space.

37. 37. The system of claim 36, wherein the at least one phase corrector is an electromagnetic wave transmission phase corrector.

38. 38. The system of claim 36 or 37, wherein the at least one phase correction device is a multi-layer structure having at least three layers with a central dielectric core sandwiched between at least two layers of two opposite portions of the dielectric core, at least one of the layers being a dielectric skin made of at least one dielectric material.

39. The system of any one of claims 36 to 38, wherein the at least one phase correction device is a straight-through phase correction device that causes the incident directional beam to travel in a straight direction without diverging into directional beams in other directions.

40. The system of any one of claims 36 to 38, wherein the at least one phase correction device is a reflective phase correction device that reflects the directional beam incident on the reflective phase correction device in another direction, thereby diverging the directional beam in the other direction at a certain angle.

41. 10. The use of at least one metasurface to provide a phase shift while maintaining an impedance matching structure that minimizes power losses in a long-range wireless power transfer system according to any one of the preceding claims.

42. 41. A delivery antenna for a long-range wireless power transmission system according to any one of claims 1 to 40, wherein the delivery antenna is a phased array antenna having an array of antenna elements that are radiating elements, each antenna element comprising a low-loss dielectric element made from a low-loss dielectric material.

43. 22. A phase correction device for a long-distance wireless power transmission system as described in any one of claims 1 to 21, wherein the phase correction device is a multi-layer structure having at least three layers in which a central dielectric core is sandwiched between at least two layers of two opposite portions of the dielectric core, at least one of these layers being a dielectric skin made of at least one dielectric material.

44. 44. The phase corrector of claim 43, wherein the dielectric skin comprises a metasurface that provides a phase shift while maintaining the power loss-minimized impedance matching structure.

45. 45. The phase correction device of claim 44, wherein the metasurface is embedded on the dielectric skin.

46. The phase corrector according to any one of claims 43 to 45, wherein the phase corrector is an electromagnetic wave transmission phase corrector.

47. A phase correction device according to any one of claims 43 to 46, wherein the thickness of the dielectric skin is less than one tenth of a wavelength of the at least one dielectric material from which the dielectric skin is made.

48. The phase correction device according to any one of claims 43 to 47, wherein the dielectric core is made from a low-loss dielectric material.

49. A phase correction device according to any one of claims 43 to 48, wherein the thickness of the dielectric core is between 1 / 10 and 1 full wavelength of the dielectric material from which it is made.

50. 50. The phase correction device according to any one of claims 43 to 49, wherein the dielectric core has a refractive index between 1 and 3.

51. The phase correction device is a straight-through phase correction device that causes the incident directional beam to travel in a straight direction without diverging into directional beams in other directions. A phase correction device according to any one of claims 43 to 50.

52. 52. The phase correction device of claim 51, wherein the dielectric core is sandwiched between the dielectric skins on both opposing portions of the dielectric core.

53. 53. The phase correction device according to claim 51, wherein the phase correction device is a reflective phase correction device that reflects the directional beam incident on the reflective phase correction device in another direction, thereby diverging the directional beam in the other direction at a certain angle.

54. 54. The phase correction device of claim 53, wherein the angle is at or about 90 degrees.

55. 55. A phase correction device according to claim 53 or 54, wherein the dielectric core is sandwiched between the dielectric skin of the first portion of the dielectric core and a reflective ground plane of the second portion of the dielectric core.

56. 56. A phase correction device according to any one of claims 53 to 55, wherein the dielectric skin comprises a metasurface that simultaneously provides a phase shift to an incoming wavefront and completes the reflection with minimal power loss.

57. 57. The phase correction device of any one of claims 43 to 56, wherein the dielectric core is at least three layers including at least one metamaterial layer or metasurface sandwiched between two dielectric support layers.

58. 10. A rectifying antenna for a long-range wireless power transmission system according to any one of the preceding claims, wherein the rectifying antenna is part of a rectifying antenna structure including a solid-state rectifying component, the rectifying antenna comprising an array of receiving antenna elements electrically connected to the solid-state rectifying component.

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