Reflection and transmission control of electromagnetic wave for concrete walls



With an advance of office automation and intelligent offices, use of various electrical and electronic devices has proliferated. Accordingly, the interference of electromagnetic waves generated by these devices with other equipment, causing malfunction and wave leakage through walls, is of concern. Especially for wireless LANs, the degradation of communication quality due to the reflected waves from walls, floors, and ceilings is a problem. It is necessary to shield and absorb the interference signals by construction materials such as walls. In this paper, the surface shapes of the concrete walls are proposed to be triangular and sinusoidal to shield and absorb these interference waves. Their characteristics are analyzed by the FD-TD method. It is found that the triangle-shaped and sinusoid-shaped walls have larger power loss than conventional concrete walls, so that they can suppress reflection and transmission. Further, the effectiveness of the analysis is confirmed by experiment. © 2000 Scripta Technica, Electron Comm Jpn Pt 2, 83(11): 12–21, 2000