Passive Radiative Cooling Film for Antennas

Patent metadata

Field	Value
Publication number	US-2025118882-A1
Application number	US-202318850179-A
Country	US
Kind code	A1
Filing date	Apr 18, 2023
Priority date	Apr 21, 2022
Publication date	Apr 10, 2025
Grant date	—

Abstract

A cooling film for use in passively cooling an antenna includes an antisoiling layer secured to a first major surface of a reflective microporous layer. The reflective microporous layer comprises a first fluoropolymer and is diffusely reflective of electromagnetic radiation over a majority of wavelengths in the range of 400 to 2500 nanometers. The film can also include an infrared-absorptive layer secured to a second major surface of the film opposite the first major surface, and the infrared-absorptive layer is optionally metallized. The film is shaped into a self-supporting three-dimensional structure, such as fins, and a thermally conductive material is inside the structure and secured to a portion of the antenna, either the front side of the antenna for the non-metallized film or the back side of the antenna for the metallized film.

First claim

1 . A cooling film, comprising:
an antisoiling layer secured to a first major surface of a reflective microporous layer, wherein the reflective microporous layer comprises a first fluoropolymer and is diffusely reflective of electromagnetic radiation over a majority of wavelengths in the range of 400 to 2500 nanometers, the antisoiling layer has an outwardly facing antisoiling surface opposite the reflective microporous layer, the film is shaped into a self-supporting three-dimensional structure, and the film is transmissive to radio frequency wavelengths.

2 . The cooling film of claim 1 , further comprising a thermally conductive material inside the self-supporting three-dimensional structure.

3 . The cooling film of claim 1 , wherein the self-supporting three-dimensional structure comprises fins.

4 . The cooling film of claim 1 , wherein the reflective microporous layer has an average absorbance of at least 50 percent over a wavelength range of 8 microns to 13 microns.

5 . The cooling film of claim 1 , further comprising an infrared-absorptive layer secured to a second major surface of the film opposite the first major surface, wherein the infrared-absorptive layer has an average absorbance of at least 50 percent over the wavelength range of 4 to 20 microns.

6 . The cooling film of claim 5 , wherein the infrared-absorptive layer is secured to the reflective microporous layer opposite the antisoiling layer.

7 . The cooling film of claim 1 , further comprising an auxiliary reflective microporous layer secured to the reflective microporous layer opposite the antisoiling layer.

8 . The cooling film of claim 1 , wherein the reflective microporous layer comprises a first fluoropolymer and is diffusely reflective of electromagnetic radiation over a majority of wavelengths in the range of 300 to 3000 nanometers.

9 . The cooling film of claim 1 , wherein the outwardly facing antisoiling surface comprises a nano-structured surface superimposed on a micro-structured surface.

10 . The cooling film of claim 1 , wherein the antisoiling layer comprises a second fluoropolymer.

11 . The cooling film of claim 1 , wherein the reflective microporous layer comprises a micro-voided polymer film.

12 . The cooling film of claim 11 , wherein the micro-voided polymer film further comprises polymer particles.

13 - 20 . (canceled)

21 . An antenna having a cooling film of claim 1 secured to a front side or a back side of the antenna.

22 . An antenna having a cooling film of claim 1 secured to a front side or a back side of the antenna with pressure sensitive adhesive.

23 . An antenna having a cooling film of claim 1 secured to a front side of the antenna with a fluoropolymer hot melt adhesive having a melting point of less than 150° C.

24 - 25 . (canceled)

26 . The cooling film of claim 1 , wherein the film is transmissive to radio frequency wavelengths in a range from 1.1 to 33.6 GHz.

27 . The cooling film of claim 26 , wherein the film transmits at least 96% of power over a range from 22 to 33 GHz.

Assignees

• 3M Innovative Properties Company

Inventors

• Hebrink Timothy J
• Broddner Pontus S B
• Baetzold John P
• Dehn Derek J
• Hill Charles A

Classifications

• B32B2307/584

  Scratch resistance · CPC title

• B32B2307/518

  bi-axially · CPC title

• B32B2307/416

  Reflective · CPC title

• B32B2270/00

  Resin or rubber layer containing a blend of at least two different polymers · CPC title

• B32B2255/26

  Polymeric coating · CPC title