Evaluation of the Dielectric Properties of CaMoO4-TiO2 Composites for Microwave Applications Under Temperature Variation

This work presents experimental and numerical investigations of the microwave dielectric properties of the ceramic matrix CaMoO4 (CMO) with the addition of 8, 12, and 20 wt% TiO2, obtained through the solid-state reaction method. X-ray diffraction and Rietveld's refinement revealed no evidence of secondary phases, indicating no reaction between the CMO and TiO2 phases. The dielectric properties presented an improvement with the addition of TiO2, with the CMO8 sample presenting epsilon(r)' 12.8, tan delta = 7.8 x 10(-4), and tau(f) = - 6 ppm degrees C-1, demonstrating that this material has thermal stability (tau(f) < 0). The ceramic was tested as a dielectric resonator antenna (DRA) and numerical simulation results showed that the materials have a realized gain of 4.40-4.92 dBi, a bandwidth of 741-1079 MHz, and a radiation efficiency above 86%. The results indicate that CMO-TiO2 systems could be employed in devices operating in the S-band.