Experimental study on a broadband omnidirectional electromagnetic absorber

A broadband omnidirectional electromagnetic absorber is constructed with traditional materials including silicon powder, polyethylene and a mixture of water and ethanol. Variation of the dielectric constant in the radial direction of the device is realized by gradually changing the fraction of silicon powder and polyethylene, and the absorbing core is made by mixing water and ethanol. By placing the device into a parallel metallic board and under electromagnetic illumination, we demonstrate that the trajectories of the incident waves fall into the core at both 9.0 and 10.0 GHz, as predicted by numerical simulation. Since the device is constructed without a resonant element, it can be expected to have a broadband nature.