BISMUTH NIOBATE-BASED GLASS-CERAMICS FOR DIELECTRICALLY LOADED MICROWAVE ANTENNAS

A castable, low melting temperature glass-ceramic system (30% Bi2O3, 30% Nb2O5, 30% B2O3 and 10% SiO2, in mol%) suitable for microwave applications is fabricated and characterized. Depending on heat treatment temperature, the glass ceramic exhibits permittivity, 15 <= epsilon r <= 41, temperature coefficient of resonant frequency of -160 <= tau(f) <= + 100 MK-1 and microwave quality factor of 300 GHz <= Qf <= 15000 GHz. The highest Qf occurs at 960 degrees C heat treatment with epsilon(r) = 15, tau(f) = -80 MK-1 and Qf = 15000 GHz. Applications are envisaged such as castable dielectrically-loaded antenna pucks, removing the need for complex ceramic processing.