| Abstrakt: |
Dielectric resonator oscillators (DRO) have been used in the systems of telecommunication, radar, missile and other electronics devices operating at microwave frequencies, both for commercial and military applications. The oscillator itself serves as the basic energy source in all microwave systems. MgTiO3−based dielectric ceramics have been recognized as one of the electronic component materials for telecommunication applications in microwaves. In our previous work, characteristics of various compositions of MgTiO3−based dielectric ceramics with addition of Bi2O3, i.e. (Mg0.8Zn0.2)TiO3 + 4wt.%Bi2O3, (Mg1.0Zn0.0)TiO3 + 4wt.%Bi2O3, (Mg0.9Zn0.1)TiO3 + 2wt.%Bi2O3 and (Mg0.6Zn0.4)TiO3+2wt.%Bi2O3 as resonator materials in the microwave DRO circuit have been reported. For all the test materials, the resonant frequencies were recorded between 4.699 to 5.207 GHz with the output powers close to zero, which means that all components in the materials have contributed and resonated at the same frequency. In this present work, we extent the test samples, i.e. a new composition of (Mg0.5Zn0.5)(Ti0.98Sn0.02)O3+10 wt.% polyethylene glycol (PEG) and sintered the ceramics at 1100 °C for 6, 8 and 10 h. Sintering for 6 and 8 h provided single-phase MgTiO3 ceramics, while that for 10 h gave rise to an extra (0.82 ± 0.04) wt.% MgTi2O5 phase in the ceramic system. The PEG addition has induced the formation of grains with spherical or polygonal morphology and inter-grain boundaries, and hence improved the bulk density, as expected. The average grain size is 1-3 µm. Dielectric resonant frequencies of the ceramics were measured at 5.074 GHz (for 6 h), 5.080 GHz (for 8 h) and 5.083 GHz (for 10 h), each with the output power at -2.074, -2.016 and -2.078 dBm. This resonant frequency performance was also supported by the relative permittivity (εr) and quality factor (Qf) data of 17.10 - 17.30 and 5301 - 5340 GHz measured at 3.7 GHz. Having such performance, the test ceramics are good candidates for microwave dielectric resonator materials. [ABSTRACT FROM AUTHOR] |
