Study On The Antenna Applications Of Borate-based Microwave Dielectric Ceramics

In recent years,there has been an increasing demand for Internet of Things（Io T）and satellite communications,which has placed higher requirements on communication devices.The trends in this development include miniaturization,high stability,and low loss.Microwave dielectric ceramics have found wide applications in modern communication fields,and low-temperature co-fired microwave dielectric ceramics enable the realization of multi-band antennas.Microwave dielectric ceramic antennas play a crucial role in communication systems.Magnesium and boron have been extensively utilized in industries and daily life,benefiting from mature industrial systems and relatively low production costs.By using boron-magnesium compounds,microwave dielectric antennas with excellent performance can be fabricated,holding broad prospects for commercial applications and contributing positively to environmental protection.The present study focuses on the investigation of the low dielectric Mg₂B₂O₅ material system.The research aims to explore the effects of the two-phase composite method on the microwave dielectric properties,sintering temperature,and microstructure of Mg₂B₂O₅ with the addition of Ba₃（VO₄）₂.Considering the favorable microwave performance adjustment of Ba₃（VO₄）₂ in Mg₃B₂O₆,it is expected that Ba₃（VO₄）₂ may also exhibit good tuning effects on the performance of Mg₂B₂O₅.Experimental results demonstrate that Ba₃（VO₄）₂ exhibits excellent optimization functionality for Mg₂B₂O₅（ε_r=10.0,Q×f=48,050 GHz,τ_f=-3 ppm/℃）.The raw material V₂O₅ used for the synthesis of Ba₃（VO₄）₂ is a costly and toxic chemical.To achieve environmental and cost-effective goals,the present study explores the use of Ba₃（PO-₄）₂,which has a similar chemical structure and properties to Ba₃（VO₄）₂,as a substitute.The composite of Ba₃（PO₄）₂ and Mg₂B₂O₅ demonstrates excellent microwave dielectric performance,with Ba₃（PO₄）₂-Mg₂B₂O₅（τf=-1.9 ppm/℃,Q×f=61250 GHz,ε_r=10.7）effectively improving the microwave dielectric properties of Mg₂B₂O₅ and reducing its sintering temperature from 1100℃to 920℃,making it possible for use in LTCC antennas.Based on the performance tuning results,0.8Ba₃（PO₄）₂-0.2Mg₂B₂O₅ with its environmentally friendly,low-cost,and high-performance properties is more suitable for designing antenna applications.Using the electromagnetic simulation software CST,a cylindrical RF patch antenna with a center frequency around 5.5GHz was designed for Wi Fi Dynamic Frequency Selection（DFS）,which corresponds to a frequency range of 5.49GHz-5.67GHz.Simulation results show that the cylindrical RF antenna（0.8Ba₃（PO₄）₂-0.2Mg₂B₂O₅）achieves good impedance matching within a frequency range of 5.346GHz to 5.7GHz with an effective bandwidth of 354MHz,a maximum gain of 5.95d B,and a radiation efficiency of 97%within the effective bandwidth.The voltage standing wave ratio（VSWR）can reach 1.02 at the operating frequency.The simulation results also show that as the thickness（height）of the 0.8Ba₃（PO₄）₂-0.2Mg₂B₂O₅ dielectric increases,the resonant frequency of the 0.8Ba₃（PO₄）₂-0.2Mg₂B₂O₅microwave antenna will move to higher frequencies,and the bandwidth will increase,with minimal impact on VSWR and radiation efficiency.The actual antenna was fabricated and tested,and the center frequency was found to be 5.52GHz,with a starting frequency of 5.38GHz,a cutoff frequency of 5.68GHz,and an overall bandwidth that was slightly smaller but still within an acceptable error range.The VSWR was always controlled below 2,the efficiency was above 80%,and the gain was above 4.3d B.The final physical antenna achieved complete coverage within the expected design frequency range and high gain and efficiency within the operating frequency range.