# US 2019/0356247 A1 · System for Converting Electromagnetic Radiation to Electrical Energy Using Metamaterials

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- Number: US 2019/0356247 A1
- Document ID: US20190356247A1
- Status: Published application
- Kind: A1
- Application number: 16/529,976
- Filed: 2019-08-02
- Published: 2019-11-21
- Earliest claimed: 2014-06-20
- Assignees: Redwave Energy, Inc.
- Applicants: Redwave Energy, Inc.
- Inventors: Patrick K. Brady; Dale K. Kotter; Wounjhang Park
- Web page: https://patentgrep.com/patent/US20190356247A1

## CPC

- H02N 11/002: {Generators}
- G02B 1/002: {made of materials engineered to provide properties not available in nature, e.g. metamaterials}
- H01Q 1/248: {provided with an AC/DC converting device, e.g. rectennas}
- H10F 10/00: Individual photovoltaic cells, e.g. solar cells (electrolytic light-sensitive devices, e.g. dye-sensitised solar cells, H01G9/20)
- H10F 77/12: Active materials
- Y02E 10/52: PV systems with concentrators
- H02N: ELECTRIC MACHINES NOT OTHERWISE PROVIDED FOR
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- H01Q: ANTENNAS, i.e. RADIO AERIALS (radiators or antennas for microwave heating H05B6/72)
- H10F: INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
- Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION

## Abstract

Spectral tuning of heat source to emit radiation at a desired frequency or frequency band is accomplished using metamaterials. The metamaterials include a structured geometry having holes with dimensions and spacing chosen such that the resulting surface will emit radiation in the desired spectrum. A collector can be made of a similar metamaterial or antenna array to detect the emitted radiation and transfer it to a converter device that converts the detected radiation to electricity. Embodiments also provide efficient coupling to the converter device for energy harvesting. Cooling of the converter devices can be accomplished using a cooling sink or deep space.

## Claims

### Claim 1

A system for harvesting electricity from electromagnetic radiation, comprising:
a metamaterial that is heated by a heat source and has a surface that is tuned to generate an electric field at a tuned frequency; and
a rectenna, placed over the electric field at a distance to interact with the electric field, that includes:
an antenna element that is configured to resonate at the tuned frequency to generate and electron flow; and
a transfer element that is configured to receive the electron flow and output electricity.

### Claim 2 (depends on 1)

The system recited in claim 1, wherein the surface of the metamaterial has a plurality of holes over each of which an electric field is concentrated when the metamaterial is heated.

### Claim 3 (depends on 2)

The system recited in claim 2, wherein there are one or more rectenna, and each rectenna is placed in the near field over one or more of the plurality of holes.

### Claim 4 (depends on 3)

The system recited in claim 3, wherein the rectenna are placed with 3 μm over one or more of the plurality of holes.

### Claim 5 (depends on 3)

The system recited in claim 3, wherein the rectenna are placed within one half the tuned frequency wavelength over one or more of the plurality of holes.

### Claim 6 (depends on 3)

The system recited in claim 3, wherein the rectenna are tuned to 1 THz.

### Claim 7 (depends on 2)

The system recited in claim 2, wherein each hole is circular has a depth of approximately 40 μm, the spacing between holes is approximately 50 μm, and each hole has a diameter of approximately 10 μm.

### Claim 8 (depends on 2)

The system recited in claim 2, wherein each hole is square has a depth of approximately 40 μm, the spacing between holes is approximately 50 μm, and each side has a length of approximately 10 μm.

### Claim 9 (depends on 1)

The system recited in claim 1, wherein the components of the system are configured to be manufactured using roll-to-roll technology.

### Claim 10 (depends on 2)

The system recited in claim 2, wherein each hole is square with a side length of a, and the tuned frequency ωpl , is determined as:
ω
pl
=
π


c
0
a

ɛ
H

μ
H

### Claim 11 (depends on 2)

The system recited in claim 2, wherein the distribution of plurality of holes is periodic.

### Claim 12 (depends on 1)

The system recited in claim 1, wherein the surface is tuned using a simulation to obtain a reflectance spectrum and tuning the surface to achieve a a dip in the reflectance spectrum at the tuned frequency.

### Claim 13 (depends on 1)

The system recited in claim 1, wherein the surface is tuned using a simulation to obtain a reflectance spectrum and tuning the surface by adjusting the dimensions and spacing of the holes to achieve a dip in the reflectance spectrum at the tuned frequency.

### Claim 14 (depends on 12)

The system recited in claim 12, wherein tuning the surface further comprises minimizing the width of the dip and maximizing the depth of the dip.

### Claim 15 (depends on 13)

The system recited in claim 13, wherein tuning the surface further comprises minimizing the width of the dip and maximizing the depth of the dip.

### Claim 16 (depends on 1)

The system recited in claim 1, wherein the metamaterial is copper.

### Claim 17 (depends on 1)

The system recited in claim 1, wherein the metamaterial has a thickness of 50 μm.

### Claim 18 (depends on 2)

The system recited in claim 2, wherein each hole is filled with a highly insulating material that is transparent to radiation.

### Claim 19 (depends on 1)

The system recited in claim 1, wherein materials on top of the rectenna couple the rectenna to a cold source.

### Claim 20 (depends on 1)

The system recited in claim 1, wherein the surface of the metamaterial has a plurality of posts over each of which an electric field is concentrated when the metamaterial is heated.

### Claim 21 (depends on 20)

The system recited in claim 20, wherein the tuned frequency is in the clear band of the Earth's atmosphere.

### Claim 22 (depends on 20)

The system recited in claim 20, wherein each post is surrounded by a material that is heat insulating and radiation transparent.

### Claim 23 (depends on 20)

The system recited in claim 20, wherein there are one or more rectenna, and each rectenna is placed over a post.

### Claim 24 (depends on 23)

The system recited in claim 23, wherein there is a rectenna placed over each post.

### Claim 25 (depends on 20)

The system recited in claim 20, wherein the rectenna are placed approximately 2 μm over the posts.

### Claim 26 (depends on 20)

The system recited in claim 20, wherein the height of each post is at least one quarter of the tuned frequency wavelength.

### Claim 27 (depends on 20)

The system recited in claim 20, further comprising an environmental overcoat that is heat insulating and radiation transparent in the clear band of the Earth's atmosphere.

### Claim 28 (depends on 23)

The system recited in claim 23, wherein each rectenna is pointed toward that sky.