Radio wave absorptive building materials for depressing multipath indoors

For the effective use of wireless data communication systems indoors, a building material of over 6 dB in reflection loss at frequencies of PHS-PIAFS (1.9 GHz) and wireless LAN (2.45 and 19 GHz) was designed based on the distributed constant circuit theory. Two types of building materials were developed, one with excellent absorptive performance and the other having excellent building material characteristics with a thickness of 9.5 mm and a weight of 9 kg/m/sup 2/. In an electromagnetic shielded room having walls covered with these materials, the delay spread was depressed and the rate of the especially low speed position for the file forward of the wireless LAN decreased. The results indicate that these materials are useful for depressing multipath.