Investigation on tunable ultra-thin radar absorber based on active metamaterial

A sort of state-of-the-art metamaterial was introduced to serve as an active ultra-thin RAM. The metamaterial consisted of resistors, varactor diodes and micro-structure array. The effect of resistor, capacitor and electromagnetic polarization on the absorbing properties was investigated in detail. The results indicate that its absorption band can be regulated in 3. 7 times frequency-band by actively changing the external voltage. The total thickness of the metamaterial RAM is only 1/181 of the wavelength. Compared with the traditional absorbing materials, the metamaterial RAM shows excellent ultra thin feature under the same wave absorbing performance. In addition, for TE and TM polarized electromagnetic wave, the metamaterial RAM exhibits the same wave absorbing property, i. e. , its absorbing property is insensitive to the polarization direction of incident wave.