X-band Cylindrical Dielectric Resonator Based on Lithium-Niobium-Titanium-Oxide Microwave Ceramics

In this study, we report on the performance of the cylindrical dielectric resonator fabricated by lithium-niobium-titanium-oxide (LNTO) ceramics modified with 0 and 5 wt% of ZnO as functional additive. These microwave ceramic materials were prepared by using a combustion-assisted solid-state reaction method and final cylindrical pellets with diameter of 9.5 mm and height of 1.3 mm were sintered at 900°C for 4 h. Using scanning electron microscopy and X-ray diffraction techniques, structural analysis confirmed the densely packed structure of the synthesized M-phase type LNTO ceramics with an average crystallite size in the nano range. The LNTO sample with 5 wt% of ZnO showed a higher temperature stability of dielectric constant and resonant frequency compared to the LNTO sample without ZnO. Further, the fabricated LNTO ceramic-based dielectric resonator possesses the minimum of the return loss at resonant frequency of 9.85 GHz with relative bandwidth of 4.9%.