Abstract
According to the progress of the electronic industy and radio communication technologies, mankind might enjoy its abundant life On the other hand, many social problems such as EMI, and unnecessary electromagnetic wave occur due to the increased use of electromagnetic wave. Therefore, the organiztions such as CISPR, FCC, ANSl,etc. have provided the standard of electromagnetic wave enviroment for the countermeasure of the EMC. It had been required that the absorbing ability of an electromagnetic wave absorber is more than 20 dB, the bandwidth of which is required through 30 MHz to 1,000 MHz for satisfying the international standard about an anechoic chamber for EMI/EMS measurment. From November of 1998, however, the CISPRll has accepted the extended frequency band from 1 GHz to 18 GHz additionally in the bandwidth of EMI measurementent$^{[1]}$ . In this paper, we proposed a new type absorber satisfying the above requirements and carried out broadband design using the equivalent material constants method. Futheremore, the experiments were carried out over the frequency band from 30 MHz to 2 GHz, and hence, the validity of the proposed design theory was confirmed.