Wideband Function Reconfigurable Metamaterial for RCS Reduction

A wideband function reconfigurable metamaterial (FRM) with a miniaturized periodic unit that is capable of switching between cancellation and absorption responses is proposed for radar cross section (RCS) reduction. The proposed FRM unit is a 3-D structure comprising metal ground and two pairwise orthogonally arranged circuit substrates. By regulating the p-i-n diodes (ON and OFF states), the responses of the proposed FRM unit can switch between two modes. In one mode, wideband absorption is realized for the TE and TM polarized waves. In the other mode, the TE and TM waves are completely reflected with a nearly 180° reflection phase difference. Equivalent circuit models (ECMs) are constructed to provide physical insight into the working mechanism of the switchable structure. Furthermore, a chessboard-like FRM is designed based on the proposed FRM unit to satisfy the phase cancellation principle. The measured results indicate that the proposed FRM can achieve a 10 dB RCS reduction from 2.84 to 7.30 GHz in absorption function and a 10 dB RCS reduction in the range of 2.50-7.44 GHz in cancellation function. The operating frequency bands of these two functions almost overlap. Good agreements between the measured and simulated results are obtained.