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Shielding Effectiveness of Metal Mesh and Radio Frequency Shielding Film for Optical Applications

In this paper, an investigation was conducted to find materials that are optically transparent and radio frequency (RF) shielding. Materials were first optically tested, followed by a shielding effectiveness test. The optical test evaluated metal mesh sizes 20, 22, 40 and 100, single layer RF film, double layer RF film, and combinations of film and mesh. Size 22 copper mesh and RF film demonstrated desirable optical properties and were then RF tested from 26 MHz to 40 GHz. The test was conducted using a shielded enclosure featuring an aperture in a wall panel to mount the material under test. Reference field strength measurements of the aperture were compared to measurements taken when material samples were placed within the aperture in order to characterize the shielding effectiveness of each shielding material. Test results for size 22 copper mesh, RF shielding film, and a combination of one layer of size 22 copper mesh with one layer of film demonstrate average shielding effectiveness results of 43 dB for the mesh, 46 dB for the film, and 69 dB for the mesh and film together. This information can be used when there is a requirement for a material to provide optically transparent RF shielding.