Abstract: The low thermal expansion coefficient and the moderate permittivity of Li₂O-Al₂O₃-SiO₂ glass-ceramicmake it possible to be used as an impedance transfer layer of radar wave absorbing materials to increase the microwave absorbing efficiency and expand absorbing bands. But a series of accurate permittivities of impedance transfer are needed to meet the impedance matching design. Therefore, the relationship between permittivity of the glassceramic and sintering conditions was studied. The results showed that the real and imaginary parts of permittivity ofthe glass-ceramic increase with the sintering densities, and no frequency dependency of permittivity was found. Thereflectivity-frequency curves illustrate that the attachment of the glass-ceramic to the microwave absorbing materialsgreatly reduces the materials’reflectivity to microwave and a little change of permittivity of the glass-ceramic can also exert a remarkable influence on microwave absorbing materials. So an expected permittivity of the glass-ceramic isneeded and can be obtained by varying sintering conditions of the glass-ceramic.

Key words: Li₂O-Al₂O₃-SiO₂ glass-ceramic, impedance, permittivity, microwave absorbing material