| 摘要 |
A screen for blocking high frequency electromagnetic emissions EMI from electromagnetic devices is formed of conductive elements 3 separated by a supporting dielectric substance 4 with high Dielectric Constant and High Dissipation factor. Preferably the loss factor and/or the dissipation factor of the dielectric is above 0.1 at 1 Mhz; the dielectric constant is above 4. The dielectric may be a composite of a ferro-electric polymer, such as PVDF, and a mineral such as Barium titanate (BaTiO3) to give loss factors above 3 and dielectric constants above 15. The Screen may comprise islands 3 on the surface or within the dielectric 4 and may comprise an array of regular hexagonal elements with an edge length of 1mm (see figures 3a, 3b and 5) The screen may also comprise straight or zig-zag strips, granular islands and other shapes (figures 2a, 2b) The screen may be formed as a corrugated sheet E1, or a plane E3 for using in a mobile phone. The screen may also be used in the construction of cables to reduce interference (figures 4a, 4b ) between conductors, such as sets of twisted pairs (7,8). |
