Flexible tunable compact monopole antenna integrated with flexible zinc-ion batteries

Abstract A flexible and compact tunable monopole antenna based on a polyimide (PI) substrate is proposed. The antenna’s resonant frequency was dynamically tuned through organic electrochemical transistors (OECTs), which were integrated on the PI substrate as RF switches. Additionally, flexible zinc ion batteries (FZIBs) were also integrated on the same substrate to provide DC bias voltage for OECTs. The antenna has a simple structure, consisting of an optimized monopole radiator and a coplanar waveguide feed. When OECTs were switched between ON and OFF states, the antenna’s resonant frequency was tuned from 4.5 GHz to 5.21 GHz. The antenna demonstrated omnidirectional radiation patterns with measured realized gains of 4.72 dB at 4.5 GHz and 4.2 dB at 5.21 GHz. The mechanical flexibility and stability of the antenna were verified through testing under both flat and bent conditions. Test results confirmed that the designed flexible antenna maintains consistent performance characteristics across different mechanical states, making it particularly suitable for 5 G (n46) and sub-6 GHz (n79) frequency bands. This work presents a promising solution for next-generation wireless communication systems requiring conformal and flexible antenna designs.