Anechoic chamber having multi-layer electromagnetic wave absorbers of sintered ferrite and ferrite composite membrane

The structure of the multi-layer electromagnetic wave absorber composed of sintered ferrite and ferrite composite membrane is proposed to improve radiowave absorbing characteristics. The absorption characteristics of the multi-layer absorber can be largely extended compared with the single sintered ferrite layer. Moreover, it is shown that the site attenuation characteristics satisfy the FCC standard for 3 m and 10 m transmission distance (3 m method and 10 m method) in the anechoic chambers in which the novel absorbers are fitted. The wall thickness of the novel anechoic chamber can be made thinner of less than 90 mm. Consequently, the anechoic chamber for the 3 m method can reduce its installation area to about 60% of the conventional one