꼭지절단 원추형 페라이트 배열 전파흡수체의 최적 설계 및 제작에 관한 연구

Abstract

According to the development of the electronics and the radio communications technologies, the human life has been abundant. Due to the extended use of electromagnetic wave, however, it has become important to work out a countermeasure for EMI/EMS. Thus, the international organazations, for example, ANSI, FCC, CISPR, etc. have studied and established the regulations or the rules for EMI/EMC.

The absorbing ability of 20 dB have required for the electromagnetic wave absorbers used in an anechoic chamber for EMI/EMS measurement in the bandwidth through 30 MHz to 1,000 MHz. From November of 1998, however, the frequency band for EMI measurement from 1 GHz to 18 GHz accepted as CISPR11 in addition to the conventional one. The actually and broadly used wave absorber for an anechoic chamber was a type of tile or grid, which has the bandwidth from 30 MHz to 400 MHz or up to 870 MHz. Therefore, it is required to expand the frequency band of wave absorption.

In this thesis, for this reason, the top-cut corn array type was proposed and the broadband design was carried out using the equivalent material constants method. Moreover, the computer simulation and experiment were performed. The results are as follows :

(1) As a simulation result, the designed absorber has the wide band characteristics from 30 MHz to 50 GHz, the thickness of which is very thin just as 34.7 mm.

(2) It was confirmed experimentally that the fabricated wave absorber has the absorbing ability of 20 dB in the frequency band from 30 MHz to 1.08 GHz .

Thus, it was clearly shown that the available room can be effectively obtained in an anechoic chamber by using the designed thin absorber.

As a further work, the experiments in high frequency band above 1 GHz is made progress.