Design and Fabrication of Wideband Dielectric Resonator Antenna Using Low Loss Ultra-Low Sintering Temperature Li₆B₄O₉ Microwave Dielectric Ceramic for Wireless Communication Applications

Low dielectric constant (ɛ_r), high quality-factor (Q × f), and temperature stable microwave dielectric ceramics with ultra-low sintering temperature are the preferred choice of researchers for the development of low-cost and high-performance dielectric resonator antenna (DRA), which have wide application prospects for wireless communication technology. In this work, wideband DRAs fabricated using ultra-low sintering temperature, low-loss, and high-quality Li₆B₄O₉ microwave dielectric ceramics are reported. Li₆B₄O₉ ceramic synthesized via solid-state reaction at sintering temperature of 620 °C demonstrates excellent microwave properties with optimum ɛ_r = 5.95, high Q × f = 38,700@12.4 GHz, and thermal coefficient of the resonant frequency (TCF ≈ −68.6ppm/^○C). For the first time, performance comparison of two Li₆B₄O₉-based cylindrical DRAs with different ceramic aspect (radius to height) ratios excited by slot coupled microstrip line is realized. In the first DRA with ceramic aspect ratio of 0.864, DRA HE_11δ mode is excited and bandwidth of 20.01%, 95% radiation efficiency, and 6.3 dBi maximum gain is attained. In the second DRA with ceramic aspect ratio of 2.367, slot and dielectric resonator resonances are merged to attain wide bandwidth of 38.15% over which antenna broadside radiation performance is preserved. The proposed DRAs can be utilized for high-capacity, high-speed wireless communication applications.