Millimeter‐wave dielectric characteristics of Sr1−xCaxSmAlO4 ceramics

Abstract

ABSTRACTMillimeter‐wave dielectric characteristrics of Sr1−xCaxSmAlO4 ceramics were investigated together with their structures. The solid solution in the space group I4/mmm was determined in the entire composition range, and the excellent microwave dielectric characteristics were not only obtained in the centimeter‐wave range but also in the millimeter‐wave range. The dielectric constant εr indicated a slight decrease from 19.5, and the significantly improved Q×f value was achieved, while the temperature coefficient of resonant frequency τf became more negative (from −3.4 to −12 ppm/°C) with increasing x. Q×f value showed apparent increase with increasing frequency, and the Q×f value at 28 GHz was improved from 88 000 to 160000 GHz with increasing x. The best combination of millimeter‐wave dielectric characteristics was achieved at x = 0.6: εr = 19, Q×f = 143 300 GHz (at 27.3 GHz), and τf = −9.3 ppm/°C. The present ceramics could be expected as the promising candidates as millimeter‐wave dielectric ceramics.