Electroactive PVDF-based composite thin films incorporating metal phosphate fillers as flexible dielectric substrates for dual-band microwave antennas.

Flexible antennas represent key enabling components for emerging Internet-of-Things (IoT) platforms and next-generation wireless communication systems. This work presents a compact dual-band CPW-fed antenna based on electroactive PVDF composite thin films incorporating metal-phosphate fillers (Ni, Ag, and Co) as dielectric substrates. The proposed metamaterial-inspired configuration enables stable operation at 3.5 GHz and 5.8 GHz, covering the sub-6 GHz and ISM frequency bands relevant to modern wireless communication systems. Experimental validation performed on prototypes fabricated using PVDF/3Ni-P and PVDF/3Co-Pn substrates demonstrates good agreement with simulated results, confirming reliable dual-band performance. The antenna achieves measured impedance bandwidths of 3.17-3.50 GHz and 5.62-7.16 GHz, along with peak gains of 1.56 dBi and 5.32 dBi and radiation efficiencies reaching up to 91%. The results highlight that the developed PVDF-based composite substrates offer a favorable combination of mechanical flexibility, tunable dielectric properties, and stable electromagnetic performance under bending conditions. In addition, the SAR analysis confirms compliance with international safety limits, ensuring safe operation in proximity to the human body. Overall, this study demonstrates that electroactive PVDF composites incorporating metal-phosphate fillers can serve as effective multifunctional dielectric platforms for compact microwave antennas. These findings open new perspectives for the development of advanced flexible RF systems in 5G, Internet-of-Things (IoT), and wireless body area network (WBAN) applications.