Wideband frequency tunable metamaterial absorber by splicing multiple tuning ranges

A band-splicing strategy is proposed to greatly extend the tunable bandwidth of metamaterial absorbers (MMAs) based on circular split-rings (CSRs) containing varactors. In this strategy, the CSRs are split into multiple segments with the absorption frequency continuously tunable in a pre-set frequency range by adjusting varactors that are bridged by PIN diodes, enabling the splicing of the separately tunable frequency bands with the PIN diodes On/Off. By optimizing the parameters of the PIN diodes and varactors following a circuit model, the designed MMA experimentally demonstrated a significantly extended tunable frequency band of 2.8-4.95 GHz, which is spliced by the two tuning bands of 2.8-3.9 GHz (at PIN On) and 3.9-4.95 GHz (at PIN Off). To further show the expandability of this strategy, we also present another tunable MMA which in simulation performs a much wider bandwidth of 2.9-8.12 GHz.

Automated summary

The band-splicing strategy proposed in this study greatly extends the tunable bandwidth of MMAs based on CSRs with varactors. By splitting the CSRs into multiple segments and adjusting varactors bridged by PIN diodes, the absorption frequency can be continuously tuned in a pre-set range, demonstrating expandability. Additionally, simulation results show a much wider bandwidth can be achieved using this strategy.