Development of incombustible radio frequency (RF) absorber

The paper reports on an incombustible inorganic substance-type RF absorber which the author has succeeded in developing as a material to take the place of conventional flammable organic-type RF absorber material. The material of this new RF absorber is composed of super-light cement mortar as a base, to which carbon fibers and also carbon graphite (if and when necessary), are combined. The material is super-light with a specific gravity of about 0.3, stronger than the conventional material and easier to handle. The material is not only incombustible but also small in dispersion, and has excellent RF absorbing performance. Regarding to the ferrite pyramid composite-type RF absorber (hybrid absorber), which has been trial-manufactured using the present material, it has been confirmed that a wave absorbing performance of about 25 dB can be obtained at a high frequency band of more than 30 MHz