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DF: Fachverband Dielektrische Festkörper
DF 18: Applications of dielectric solids
DF 18.4: Talk
Thursday, March 17, 2011, 17:00–17:20, MÜL Elch
Glass-ceramics with paraelectric phases for mobile applications in the GHz-range — •Hubertus Braun1,2, Martin Letz1, and Gerhard Jakob2 — 1Schott AG, Hattenbergstraße 10 Mainz — 2Johannes Gutenberg-Universität Mainz
In the last years, handheld devices such as global positioning systems (GPS), satellite phones and radios have required antennas that communicate directly with the satellite. The most attractive technology for this purpose is based on dielectrically loaded antennas (DLA) which utilise microwave ceramics. The advantage of the dielectric antenna technology lies mainly in the miniaturisation by 1/√εr and in the resistance to detuning ("Body Loading") by nearby objects, as for example human tissue. Selective parameters for the needed ceramics are high quality factor Qf > 5000 GHz, near zero temperature coefficient of resonance frequency |τf| ≤ 20 ppm/K and permittivity εr > 20. A possible alternative to usual ceramic fabrication techniques is the use of glass-ceramic technology in which the antenna cores can be cast to net shape followed by crystallisation to achieve intrinsic pore free materials with the desired microwave properties. In the current work, promising low melting temperature dielectric glass-ceramics in the La-Ti-Si System are analysed concerning suitability for DLA applications and lower cost fabrication techniques.