Dispersion of LiZnTiBi ferrite particles into PMDS film for miniaturized flexible antenna application

In this work, LiZnTiBi ferrites with high permeability (∼142@1 MHz, ∼13@1 GHz) over a wide frequency range were synthesized at low temperature. Next, the ultrafine ferrite particles were obtained by grinding, centrifugation and ultrasonic method. The flexible PDMS-based film was prepared by dispersing the ferrite particles into PDMS film by a fast curing method. The high frequency magnetic and dielectric properties of the flexible films with various ferrite particles were investigated. Results demonstrated that effect of ferrite particles on permittivity ( ε′ ) can be weakened by residual air bubbles in the flexible film, which leads to measured value lower than calculated value. Due to same permeability ( μ ′= 1) of PDMS and air bubbles, the residual bubbles have a little effect on permeability of flexible film. At last, a flexible PDMS-based film with desirable normalized characteristic impedance (Z/Z 0  = 0.95η 0 ) and miniaturization factor (n = 5.26) at 100 MHz was obtained, which can be applied to miniaturized flexible antenna. Moreover, the strategy that introducing magnetic particles and a small amount of pores into flexible film to adjust magnetic-dielectric properties is also a reference for developing other high-frequency materials for flexible electronics, especially for wearable electronics.