1–2 GHz dielectrics and ferrites: overview and perspectives

Trends in the cellular communications industry are examined with reference to their likely effect on dielectric and magnetic ceramic materials currently used in 1–2 GHz devices. Cost pressures on dielectrics are likely to see the elimination of tantalate and even niobate based materials except for special devices. Titanate based ceramic compositions must compete with metal topologies in near antenna filters in Base Stations. Ceramic dielectric will continue to be used in coaxial form for resonators, filters and delay filters in this frequency range and higher for wireless infrastructure, but less so in high volume handheld products. Low temperature co-fired ceramics (LTCC) will be used increasingly for the latter in microwave multifunctional modules. Magnetic ceramics such as those based on yttrium iron garnets (YIG) will continue to be used in wireless infrastructure and some handheld products, where intermodulation effects (IMD) are the major remaining issue. Hexagonal ferrites have useful permeability close to the microwave region, and also are being used as absorbers at higher frequencies.