Wideband frequency tunable metamaterial absorber by splicing multiple tuning ranges

Abstract 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.