Microwave Materials with High Q and Low Dielectric Constant for Wireless Communications.

Abstract

ABSTRACTMicrowave dielectrics with high Q and low εr are expected for millimeterwave applications. In this paper the preparation and properties of some candidates for microwave dielectrics such as forsterite, willemite, alumina, corundum-type compounds, green phase of Y2BaCuO5 are presented. High purity forsterite has low εr of 7.0 high Q·f of 270000 GHz and τf of -65ppm/°C. Willemite also has low εr of 6.5, and high Q·f of 160000 GHz. Alumina has ultra high Q·f of 680000GHz with εr of 10.05, and τf of -60 ppm/°C. Mg4(Nb2-x Tax)O9 which belongs to corundum group has εr of 11.5, Q·f of 350000 GHz, and τf of -70ppm/°C. Y2Ba(Cu1/4Zn3/4)O5 which belongs to green phase group has εr of 15.4, Q·f of 220000 GHz. The τf’s of these materials, which are an important property for millimeterwave applications, have been adjusted to zero ppm/°C by the addition of rutile, or adjustment of solid solution composition.