抄録
Recently, electromagnetic environmental problems have become more serious. With rapid development in the field of information technology, there has been increased interest in electromagnetic shielding in the radio frequency (RF) region. The present paper has examined bincho-charcoal, a high quality charcoal found in Japan, for use as RF magnetic shielding. This is advantageous since the relative permittivity of bincho-charcoals has a very large value (10^7 – 10^2) in RF region of 1 MHz - 3 GHz. In the frequency region from 1 MHz to 100 MHz, however, the RF magnetic shielding degree (SDH) for bincho-charcoal plate is not sufficient to shield electromagnetic waves. The present paper has improved the frequency characteristics of SDH for a bincho-charcoal plate by the superposition of ferrite and Bi-Pb-Sr-Ca-Cu-O (BPSCCO) plates on the bincho-charcoal plate, under conditions of room temperature (300 K) and is termed the compound plate. Experimental results revealed several characteristics of the compound plate that included, among others, the dependence of SDH on radio frequency, and the dependence of SDH on the value of RF output power.
