| 摘要 |
PURPOSE:To facilitate the installation and to absorb a radio wave over a wide TV frequency band by forming the wall with cement and magnetic particles, providing a specific shape and selecting the length of the wall in the magnetic field direction of the TV radio wave to be a required absorbing wavelength or over. CONSTITUTION:A groove 12 whose depth is (d2-d1) is provided to the wall in the electric field direction of a TV radio wave, a thickness d1 of a recessed part of a forming and a thickness d2 of a projection of a forming are selected to be 0<d1<=50mm and d2<d2<=50mm and 0.2<=(d2-d1)/d2<=1.0. Then the wall is made of major components as 5-20% of cement and 80-95% of magnetic particles in the dry weight ratio, and the length of the wall in the magnetic field direction of the TV radio wave is selected to be the required absorbing wave or over. In this case a cement called generally a cement such as hydraulic cement, air setting cement, and special cement is enough for the purpose. Furthermore, the magnetic particles are oxide magnetic particles and metallic magnetic particles. Then a gap being a groove 12 is provided in the direction of the electric field and a substance with a low dielectric constant is used inbetween, then the substantial induction rate is reduced and the absorbing performance is improved. |
