The microwave dielectric properties of (1-x)(Al1/2Ta1/2)O-2-x(Mg1/3Ta2/3)O-2 (AMT) (0 < x < 1.0) ceramics and design of small coplanar waveguide fed antenna (CPWFA) have been investigated. As (Mg1/3Ta2/3)02 concentration increased, dielectric constant(er) and quality factor (Q) significantly increased and the temperature coefficient of resonant frequency (tau(f)) changed from negative to positive value. The tau(f) of 0 ppm degreesC(-1) was realized at x = 0.65 and the Qf(0) value and e(r) for this composition were 112 470 GHz and 26.1, respectively. A newly developed 0.35(Al1/2Ta1/2)O-2-0.65(Mg1/3Ta2/3)O-2 dielectric materials were used for 1.5 GHz band CPWFA design and fabrication. The size of the CPWFA can be reduced by using AMT ceramics with high dielectric constant, insetting slits into patch, and fabricating CPW feed line in the ground plane. The slits play roles in not only lowering a center frequency but also fine-tuning for the proposed CPWFA together with open stub of CPW feed line. The CPWFA with slits has the lower center frequency than the conventional CPWFA, which suggests that an antenna size can reduce as large as 16.3%. Experimental results of the fabricated device were in good agreement with the simulation. (C) 2002 Elsevier Science B.V. All rights reserved.