Application of absorbing material in higher frequency filtering

In this paper, absorbing ability of eight kinds of fill-in absorbing material is measured through coaxial waveguide in the frequency band from 0.5 GHz to 40 GHz. The test data show that in this frequency band, the average value of insert loss of coaxial waveguide, which is filled with eight kinds of absorbing material respectively, is greater than 80 dB. If they are employed in EMI filter, maybe the filter's highest operating frequency can reach 40 GHz or even higher.