Passive radiative cooling film for antennas
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.
1 . A cooling film assembly comprising:
a cooling film shaped into a self-supporting three-dimensional structure comprising a plurality of fins, wherein the cooling film comprises:
a reflective microporous layer having opposed first and second major surfaces, wherein the reflective microporous layer is reflective of electromagnetic radiation over a majority of wavelengths in the range of 400 to 2500 nanometers; and
an antisoiling layer secured to the first major surface of the reflective microporous layer, the antisoiling layer having an outwardly facing antisoiling surface opposite the reflective microporous layer, and
a thermally conductive material disposed inside of the plurality of cavities, wherein the thermally conductive material comprises one or more of: metal, aluminum oxide, boron nitride, graphene particles, metal-coated glass beads, and metal-coated glass fibers.
2 . 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.
3 . The cooling film of claim 2 , wherein the film transmits at least 96% of power over a range from 22 to 33 GHz.
4 . The cooling film of claim 1 , wherein the reflective microporous layer is diffusely reflective of electromagnetic radiation over a majority of wavelengths in the range of 400 to 2500 nanometers.
5 . A cooling film assembly, comprising:
a cooling film comprising
solar reflective multilayer film, wherein the solar reflective multilayer is specularly reflective of electromagnetic radiation over a majority of wavelengths in the range of 400 to 2000 nanometers, and
an antisoiling layer secured to a first major surface of the solar reflective multilayer film, the antisoiling layer having an outwardly facing antisoiling surface opposite the first major surface, and the film is shaped into a self-supporting three dimensional structure, wherein the self-supporting three-dimensional structure comprises a plurality of fins; and
a thermally conductive material disposed inside of the plurality of fins, the thermally conductive material comprising one or more of: metal, aluminum oxide, boron nitride, graphene particles, metal-coated glass beads, and metal-coated glass fibers.
6 . The assembly of claim 5 , further comprising an optional metallized infrared-reflective layer secured to a second major surface of the solar reflective multilayer film.