Effect of porosity and grain size on the microwave dielectric

摘要

The real part of the permittivity (ε') and the tan δ of sin- tered alumina (Al_2O_3) at about 9 GHz have been measured. The dielectric properties have been examined as a function Of purity, pore volume, and sintered grain size. The tan δ is Found to depend very strongly on the pore volume, purity, And grain size. ε' if far less sensitive to impurities and grain Size. The dependence of ε' on porosity can be described by Simple mixture models as expected.