Layered Al/sub 2/O/sub 3/-TiO/sub 2/ composite dielectric resonators with tuneable temperature coefficient for microwave applications

摘要

Aluminium oxide displays very low dielectric loss factor (tan /spl delta/) at microwave frequencies. However, its temperature coefficient of resonant frequency (/spl tau//sub f/) is approximately -60 ppm/K and is unsatisfactory for certain applications. It is shown that applying a film of titanium oxide with a /spl tau//sub f/ of 450 ppm/K produces a composite in which the /spl tau//sub f/ can be tuned to zero over a wide temperature range. The tan /spl delta/ of the composite at zero /spl tau//sub f/ is 3.3/spl times/10/sup -5/ (Q=30000) at room temperature (300 K) and at 10 GHz.