| 摘要 |
PURPOSE:To make it possible to access signal without damaging shielding ability by making a cut-off wave guide tube filter composed of a cut-off wave guide tube and an attenuation wave guide tube. CONSTITUTION:As a means of shielding frequency band which does not let out the magnetic flux leaked from an optical fiber 13 which is provide at least at one side of the inside and the outside of a room with a shield wall, a loss type wave absorbing substance is stuck to the inside of a metallic tube so as to provide a attenuation wave guide tube 12 to constitute a cut-off wave guide filter 11. Through the filter is effective to plane waves, in case that the magnetic flux is so applied as to pass the tube the shielding ability lowers. A magnetic shield 16 being a cover made of steel plate is attached so as not to let out the leaked magnetic flux to the outside, and a return path for the magnetic flux is provided so as to prevent the lowering in low-frequency magnetic shielding ability. It is preferable that optical fibers are taken out from below the magnetic shield 16. |
