New broadband button-shaped antenna on innovative magneto-dielectric material for wearable applications

The design and characterization of a new broadband small patch antenna, based on an innovative magneto-dielectric material and suitable for wearable applications at 868 MHz, is presented. To reduce antenna dimensions while preserving its radiation and matching performances, a barium-strontium hexaferrite Ba_0.75Sr_0.25Fe₁₂O₁₉ has been synthesized to achieve a magnetic permeability double than vacuum in the band of interest. The material is first experimentally characterized and the dispersive permittivity and permeability behaviors are accounted for during the design of a small patch antenna with a shorting-plate. Very good agreement with measurements is demonstrated for both matching and radiation performances of the antenna.