Magneto-dielectrics for antenna applications
Miniaturization of high frequency antennas while maintaining desirable bandwidth, impedance, and loss characteristics has been of continuing interest for many years and has seen greater attention as a result of the rise in demand for portable communication devices. The natural method for miniaturizing an antenna is to increase the index of refraction. Previous attempts in antenna miniaturization have focused on non-magnetic media with very high permittivity, although the bandwidth (~1/ε) and impedance matching characteristics (η=μ/ε) of such antennas tend to suffer. An alternative approach involves utilizing the additional degree of freedom offered by the magnetic part of the index of refraction. The creation of a material with a high and balanced combination of μ and ε would provide a substrate with a sufficiently high index of refraction while optimizing the bandwidth and impedance. However, the choice of viable single-constituent materials with high μ and ε is limited, so a composite approach is an attractive alternative. Composites with both magnetic and dielectric properties greater than unity are created through embedding ferromagnetic inclusions within a low-loss, insulating, polymeric matrix. In an effort to simplify the production of bulk quantities of antenna substrate; this work is centered on the preparation, characterization, and reduction of loss in these meta-materials.