Bismuth niobate glass-ceramics for dielectrically-loaded microwave antenna applications

2008 17th IEEE International Symposium on the Applications of Ferroelectrics Pub Date : 2008-12-02 DOI:10.1109/ISAF.2008.4693751

M. Mirsaneh, B. Zalinska, O. Leisten, I. Reaney

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引用次数: 1

Abstract

Dielectrically-loaded quadrifillar-helix (D-LQH) antennas are used in applications such as global positioning systems and satellite radio where high gain is required for direct communication with satellites. The current generation of D-LQH antenna are made from hollow cylinders of medium permittivity (15Ç,ßå¿rÇß80), high quality factor (Qf), temperature stable ceramics coated with a helical Cu metallisation. To reduce the processing costs of the ceramic core, a castable bismuth niobate glass-ceramics (30% Bi2O3, 30% Nb2O5, 30% B2O3 and 10% SiO2, in mol%) has been developed. On crystallisation at 600°C, a nano-dendritic, pyrochlore-structured phase evolves with å¿r = 41 and Qf = 226. This phase is unstable at >700°C and is initially replaced by triclinic-BiNbO4 (BN) (700 Ç¿Ï 900°C) and then by orthorhombic BN (>900°C). Optimum properties for antenna core applications occur at 920°C heat treatment with å¿r = 15, Qf = 8000 GHz at which point the temperature ! coefficient of resonant frequency is ¿60 MK-1.

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介电负载微波天线用铌酸铋微晶玻璃

介质负载的四轴螺旋(D-LQH)天线用于全球定位系统和卫星无线电等需要高增益与卫星直接通信的应用中。当前一代的D-LQH天线由中空圆柱体制成，具有中等介电常数(15Ç，ß ¿rÇß80)，高质量因子(Qf)，温度稳定的陶瓷，并涂有螺旋Cu金属化。为了降低陶瓷芯的加工成本，研制了一种可浇注的铌酸铋微晶玻璃(30% Bi2O3, 30% Nb2O5, 30% B2O3, 10% SiO2, mol%)。在600℃结晶时，形成一种纳米枝晶、焦绿结构的相，其¿r = 41, Qf = 226。该相在>700°C时不稳定，最初由三斜型binbo4 (BN) (700 Ç¿Ï 900°C)取代，然后由正交BN(>900°C)取代。天线核心应用的最佳性能发生在920°C的热处理，¿r = 15, Qf = 8000 GHz，此时的温度为:谐振频率系数为¿60 MK-1。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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2008 17th IEEE International Symposium on the Applications of Ferroelectrics

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