Metamaterial based broadband RF absorber at X-band

Metamaterial based electromagnetic wave absorbers may provide perfect absorption over significant range of electromagnetic spectrum. With perfect and broadband absorption, metamaterial absorbers play an important role in stealth technology. In this paper, design, simulation and measurements of a novel X-band (8–12 GHz) metamaterial broadband absorber are presented. An absorber operating in the middle of the microwave X-band is obtained by selecting differently sized unit cells and placing their resonant frequencies close to each other. The paper presents two absorbers which consist of different number of unit cells. The first absorber has 12 unit cells (KOH12) while the other has 16 unit cells (KOH16). It is observed that the simulation results are in good agreement with the measurements. Measurement bandwidth for an absorption level of 80% is 2.73 GHz for KOH12 and 2.55 GHz for KOH16. These are the highest absorption levels for planar metamaterial absorbers at X-band. The absorption mechanism of broadband metamaterial absorber is also investigated by using electric and magnetic field distribution. Results of this study are promising for the stealth applications as absorbing elements against X-band radars.