There are many window films (and glass coatings) on the market which contain sputtered or coated metalized layers. These coatings provide a variety of appearances and primarily, solar energy performance and/or low emissivity. Some of these products have begun to be re-branded or marketed as “RF Films”. While any conductive metal coating may inherently provide some amount of RF attenuation, this is typically an accident or unintended side-effect of the coating.
Since these products were built for energy performance and not RF/IR security, they contain many gaps or weaknesses in their frequency coverage. Any film or coatings being used specifically for RF/IR security should have been tested to the ASTM F3057 method to confirm its performance across the proper RF spectrum. This method requires a large window be tested with hundreds or thousands of test points.
Any film or coating only tested to “IEEE-299” will not contain complete data, as only a minimum of 6 data points are required, from a very small sample. In addition, IR performance curves should be verified prior to proceeding with any commercial solar-control coating.