In this paper the effect of Zr4+ substitution on the dielectric properties of CaLa4Ti5O17 ceramics at microwave frequency by the conventional solid-state method has been studied for application in mobile communication The diffraction peaks of CaLa4Ti5-xZrxO17 ceramics shifted to lower angle as x increasing from 0 to 0 05 and nearly unchanged with x increasing from 0.05 to 0.07 A maximum relative density of 97.5% TD can be obtained for CaLa4Ti4.95Zr0.05O17 ceramic sintered at 1500 degrees C for 4 h A maximum dielectric constant and quality factor (Q x f) of CaLa4Ti4.95Zr0.05O17 ceramic sintered at 1500 degrees C for 4 h are 55 9 and 15,600 GHz. respectively. A temperature coefficient of resonant frequency (tau(f)) of 4.6 ppm degrees C-1 can be obtained for CaLa4Ti4.95Zr0.05O17 ceramic sintered at 1500 degrees C for 4 h. (C) 2009 Elsevier B.V. All rights reserved