Biomedical Engineering Reference
In-Depth Information
optimizing the slit dimension and the thickness of the granite and ferrite.
Figure 5.13 is a photo of a Tokyo agency building which conducted this
countermeasure.
5.5.4
Pyramidal Wave Absorber
The pyramidal wave absorber is broadly used for anechoic chambers. This
absorber is composed of material made by mixing carbon powder into forming
urethane, forming styrene, rubber materials, and so on, as mentioned in Section
5.1. The matching characteristics depend on the frequency dispersion charac-
teristic of the complex relative permittivity of the material. This kind of
absorber usually possesses broadband matching characteristics at frequencies
above 30 MHz. It is desirable for the pyramidal wave absorber for an anechoic
FIGURE 5.14
Examples of pyramidal absorber.
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