Metamaterial absorber with active frequency tuning in X-band

This paper presents the design, fabrication, and measurement of an active frequency tunable metamaterial absorber. The unit cell of the metamaterial absorber consists of a metallic strip on the top layer of the fully grounded dielectric substrate, with a varactor loaded at the slit in the middle of the central strip. Simulation and measurement results show that by tuning the bias voltage applied on the varactors, the peak absorption frequency can be tuned about 0.44 GHz with the peak absorption greater than 95%. Field analysis reveals that the unit cell of the absorber works as the microstrip resonator which exhibits matched input resistance to the incident waves.