# US 8,784,151 B1 · Variable emissivity material

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- Number: US 8,784,151 B1
- Document ID: US8784151B1
- Status: Granted
- Kind: B1
- Application number: 13/188,213
- Filed: 2011-07-21
- Granted: 2014-07-22
- Earliest claimed: 2008-05-09
- Assignees: HRL Laboratories, LLC
- Applicants: Daniel J. Gregoire; Deborah J. Kirby
- Inventors: Daniel J. Gregoire; Deborah J. Kirby
- Web page: https://patentgrep.com/patent/US8784151B1

## CPC

- H01Q 15/0026: {said selective devices having a stacked geometry or having multiple layers}
- H01Q 1/425: {comprising a metallic grid}
- H01Q 17/00: Devices for absorbing waves radiated from an antenna; Combinations of such devices with active antenna elements or systems
- Y10S 428/913: Material designed to be responsive to temperature, light, moisture
- Y10S 428/919: Camouflaged article
- Y10T 428/12361: having aperture or cut
- Y10T 428/24273: including aperture
- Y10T 428/24322: Composite web or sheet
- Y10T 428/24331: including nonapertured component
- Y10T 428/31678: Of metal
- H01Q: ANTENNAS, i.e. RADIO AERIALS (radiators or antennas for microwave heating H05B6/72)
- Y10S: TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION

## Abstract

A material of variable emissivity includes a first metallic layer having a first aperture, a second metallic layer having a second aperture, and a variable dielectric layer interposed between the first metallic layer and the second metallic layer.

## Claims

### Claim 1

A method for manufacturing a variable emissivity material, the method comprising:
providing a first metallic layer having a first aperture;
providing a second metallic layer having a second aperture; and
disposing a variable dielectric layer interposed between the first metallic layer and the second metallic layer;
disposing a first dielectric layer interposed between the first metallic layer and the variable dielectric layer; and
disposing a second dielectric layer interposed between the second metallic layer and the variable dielectric layer;
wherein in an activated state the variable dielectric layer has a high permittivity compared to the first and second dielectric layers.

### Claim 2 (depends on 1)

The method of claim 1 further comprising:
selecting a third dielectric layer;
providing a third metallic layer; and
joining the third dielectric layer to the second metallic layer and joining the third metallic layer to the third dielectric layer.

### Claim 3 (depends on 2)

The method of claim 2 wherein:
the first metallic layer has a first array of periodically spaced apertures, wherein a pitch between the apertures is in the range of about 5 to 20 microns;
the second metallic layer has a second array of periodically spaced apertures, wherein a pitch between the apertures is in the range of about 5 to 20 microns;
the variable dielectric layer comprises vanadium oxide; and
the first, second and third dielectrics have low permittivity in the infrared band.

### Claim 4 (depends on 3)

The method of claim 3 wherein the first and second metallic layers are each about 400 nm thick, the variable dielectric is about 100 nm thick, the first and second dielectric layers are each about 200 nm thick, and the third dielectric layer is about 400 nm thick.

### Claim 5 (depends on 4)

The method of claim 4 wherein:
the first and second apertures are identical; and
the first array of periodic apertures is substantially aligned with the second array of periodic apertures.

### Claim 6 (depends on 1)

The method of claim 1 wherein the first and second apertures are rectangular.

### Claim 7 (depends on 1)

The method of claim 1 wherein the first and second apertures are shaped as crosses.

### Claim 8 (depends on 1)

The method of claim 1 wherein the first and second apertures are shaped as bow tie apertures.

### Claim 9 (depends on 1)

The method of claim 1 wherein the first and second apertures are shaped as crossed bow ties.

### Claim 10 (depends on 1)

The method of claim 1 wherein the variable dielectric layer is a ferroelectric material.

### Claim 11 (depends on 10)

The method of claim 10 wherein the variable dielectric layer is vanadium oxide.

### Claim 12

A method for creating a variable emissivity surface, the method comprising:
selecting a first metallic layer having a first aperture;
selecting a second metallic layer having a second aperture;
disposing a variable dielectric layer interposed between the first metallic layer and the second metallic layer;
disposing a first dielectric layer interposed between the first metallic layer and the variable dielectric layer;
disposing a second dielectric layer interposed between the second metallic layer and the variable dielectric layer; and
applying an electric field between the first metallic layer and the second metallic layer;
wherein in an activated state the variable dielectric layer has a high permittivity compared to the first and second dielectric layers.

### Claim 13 (depends on 12)

The method of claim 12 further comprising:
selecting a third dielectric layer;
selecting a third metallic layer; and
joining the third dielectric layer to the second metallic layer and joining the third metallic layer to the third dielectric layer.

### Claim 14 (depends on 13)

The method of claim 13 further comprising laminating the third metallic layer to a surface.

### Claim 15 (depends on 12)

The method of claim 12 further wherein applying an electric field between the first metallic layer and the second metallic layer comprises applying a voltage in the range of about 5 to 100 volts between the first metallic layer and the second metallic layer.

### Claim 16 (depends on 12)

The method of claim 12 wherein the variable dielectric layer is a ferroelectric material or vanadium oxide.

### Claim 17 (depends on 12)

The method of claim 12 wherein:
the first metallic layer has a first array of periodically spaced apertures, wherein a pitch between the apertures is in the range of about 5 to 20 microns;
the second metallic layer has a second array of periodically spaced apertures, wherein a pitch between the apertures is in the range of about 5 to 20 microns;
the variable dielectric layer is vanadium oxide; and
the first and second dielectric layers have a low permittivity in the infrared band.

### Claim 18 (depends on 12)

The method of claim 12 wherein the first and second metallic layers are each about 400 nm thick, the variable dielectric is about 100 nm thick, and the first and second dielectric layers are each about 200 nm thick.

### Claim 19 (depends on 12)

The method of claim 12 wherein the first and second dielectric layers have a low permittivity in the infrared band.

### Claim 20

A method for creating a variable emissivity material, the method comprising:
selecting a first metallic layer having a first aperture;
selecting a second metallic layer having a second aperture;
disposing a variable dielectric layer interposed between the first metallic layer and the second metallic layer;
disposing a first dielectric layer interposed between the first metallic layer and the variable dielectric layer;
disposing a second dielectric layer interposed between the second metallic layer and the variable dielectric layer; and
providing a temperature change in the range of about 50 to 100 degrees centigrade to the variable dielectric layer;
wherein in an activated state the variable dielectric layer has a high permittivity compared to the first and second dielectric layers.

### Claim 21 (depends on 20)

The method of claim 20 further comprising:
selecting a third dielectric layer;
selecting a third metallic layer; and
joining the third dielectric layer to the second metallic layer and joining the third metallic layer to the third dielectric layer.

### Claim 22 (depends on 21)

The method of claim 21 further comprising laminating the third metallic layer to a surface.

### Claim 23 (depends on 20)

The method of claim 20 wherein the variable dielectric layer is a ferroelectric material or vanadium oxide.

### Claim 24 (depends on 20)

The method of claim 20 wherein:
the first metallic layer has a first array of periodically spaced apertures, wherein a pitch between the apertures is in the range of about 5 to 20 microns;
the second metallic layer has a second array of periodically spaced apertures, wherein a pitch between the apertures is in the range of about 5 to 20 microns;
the variable dielectric layer is vanadium oxide; and
the first and second dielectric layers have a low permittivity in the infrared band.

### Claim 25 (depends on 20)

The method of claim 20 wherein the first and second metallic layers are each about 400 nm thick, the variable dielectric is about 100 nm thick, and the first and second dielectric layers are each about 200 nm thick.

### Claim 26 (depends on 20)

The method of claim 20 wherein the first and second dielectric layers have a low permittivity in the infrared band.