A Tunable Metamaterial Absorber Based on Liquid Crystal with the Compact Unit cell and the Wideband Absorption

In this paper, a design method for tunable liquid crystal (LC)-based metamaterial absorber (MMA) with the compact unit cell and the wideband absorption is proposed. A compact LC-based MMA unit cell with a dimension of 0.204 λ × 0.204 λ is designed based on the method, and full-wave numerical simulations and experiments are conducted to demonstrate its performance. Results show that the central frequency of the MMA is tuned from 11.04 to 10.21 GHz as the bias voltage increases from null to saturation, and the tuning range reaches up to 7.8%. The designed LC-based MMA exhibits wideband absorption for arbitrary tuning states. Moreover, the bandwidths with an absorptivity of more than 90% are 493 MHz and 458 MHz for no bias state and saturation bias state, which corresponds to the same relative bandwidth of 4.5%.