Study On The Characterizations Of Magneto-dielectric Materials And Their Applications In Antennas

With the rapid development of the field of 5G wireless communication,devices for wireless communication are moving in a smaller,lighter and thinner direction,which makes miniaturization of wireless communication devices an important research issue.The size of the antenna occupies a large proportion in the wireless communication equipment.It is an international hot issue to study the substrate material of the antenna and simulate the miniaturized antenna.Realizing the planar integration of the antenna and improving the gain,efficiency and bandwidth of the antenna are the main research contents of this thesis.The use of magneto-dielectric material as the antenna substrate is based on the influence of the electromagnetic parameters of the material on the size of the antenna.Composite ferrite is a type of magnetoelectric material with a relatively large permittivity and permeability.Therefore,this thesis focuses on the M-type barium ferrite material with magneto-dielectric properties,and analyzes its basic performance and dynamic properties as a microstrip antenna substrate material.Firstly,the effect of ion substitution on the magneto-dielectric properties of M-type barium ferrite was investigated.It was found that ion substitution can effectively regulate the magneto-dielectric properties of M-type barium ferrite.The experimental data of the first group of Sm instead of M-type barium ferrite(BaFe_（12-x）Sm_xO₁₉)shows that when the test frequency is 800 MHz and the Sm³⁺ion doping amount is x=0.6,it is the best choice.At this time,the sample has a lower loss value,which is tanδ_ε=0.019,tanδ_μ=0.109,and has a large miniaturization factor of n=9.74.In the second group of Na-Ta substituted M-type barium ferrite(BaFe_（12-2x）（NaTa）_xO₁₉),when the test frequency is also800 MHz,the Na⁺and Ta⁵⁺ion doping amount is x=0.3,The best choice.At this time,the loss value of the sample was tanδ_ε=0.011,tanδ_μ=0.229,and the miniaturization factor n=9.30.In the third group of La-Co substituted M-type barium ferrite(BaFe_（12-5x）（LaCo）_3xO₁₉),when the test frequency is 1 GHz and the La³⁺and Co²⁺ion doping amount is 3x=0.36,it is the most excellent choice.At this time,the loss value of the sample was tanδ_ε=0.0033,tanδ_μ=0.075,and the miniaturization factor n=6.27.Secondly,the influence of the magneto-dielectric parameters on the size and performance of the microstrip antenna is studied.The effects of different types of traditional substrate materials and magneto-dielectric substrate materials with different magneto-dielectric parameters on the size and performance of microstrip antennas were analyzed by HFSS software.The simulation results show that the 2×2 array antenna model is obtained.The simulation results show that the array antenna with the material in the third group is the substrate size of 24.6 mm,the array element spacing is 50 mm,the bandwidth is 70 MHz,and the gain is 1.93 dBi.The array antenna with FR4 as the substrate has a patch size of 71.5 mm,an array element spacing of 150 mm,a bandwidth of 20 MHz,and a gain of 3.97 dBi.Finally,a 2×2 array antenna with the magneto-dielectric material in the third group as the substrate was processed and tested.The test data showed that the center operating frequency of the antenna was slightly deviated from 1 GHz,and the measured gain was1.03 dBi at a frequency of 1 GHz.This result is smaller than the results of the simulation.