Characterization of TixZn(1-x)Al2O4 thin films by sol-gel method for GPS patch antennae

The need for miniaturization and weight reduction of a GPS patch antennae has forced scientists to search for new microwave dielectric materials. The sol-gel method was used to prepare TixZn(1-x)Al2O4-based microwave dielectric ceramic thin films (x = 0.00, 0.10, 0.20 and 0.30) and to fabricate a GPS patch antennae. The phases of ZnAl2O4 and TiO2 co-exist with each other and form a two-phase system, which is confirmed by the X-ray diffraction (XRD) patterns and the Fourier-transform infrared (FTIR) spectra analysis. The addition of titanium dioxide (TiO2) increased the crystallite size, grain size, surface roughness and apparent density. A material with a higher density tends to increase the dielectric constant (εr), which is suitable for miniaturization of a GPS patch antenna. As the TiO2 content increased, the εr values increased linearly. Finally, GPS patch antennae were successfully fabricated using the ZnAl2O4 and Ti0.30Zn0.70Al2O4 material. The performances and the operating frequencies of the GPS patch antennae were measured using a PNA series network analyzer. The result showed that both patch antennae resonated at frequency of 1.570 GHz and gave a return loss less than -10 dB. The optimal performance of the GPS patch antennae was obtained from the specimen using Ti0.30Zn0.70Al2O4 (εr ~ 14.57, wide bandwidth of 240 MHz and low return loss of -34.5 dB), which meets the requirements of GPS applications.