The Application Of BST Microwave Materials (preparation) And Magnetic Dielectric Materials In Implantable Antennas

In the era of big data and the Internet of Things,information and communication technologies are developing at a high speed,which puts higher demands on materials related to communication equipment.Barium strontium titanate(Ba_0.5SrTiO₃,BST)has the advantages of large dielectric constant,low dielectric loss,good dielectric tuning and stable properties,and has a good application prospect in the field of microwave devices.Implantable biomedical devices are evolving rapidly,antennas are important devices for implantable medical devices,and miniaturization of antennas effectively reduces the size of implanted devices.With the combination microwave material and antenna,The high dielectric constant and high magnetic permeability of the materials can effectively reduce the size of the antenna,achieve high performance,and reduce the difficulty of antenna design and fabrication?This provides a good solution for miniaturization of implanted antennas.This paper aims to prepare a suitable BST material,select a suitable magnetic dielectric material,apply it to the implantable antenna,improve the performance of the antenna,and reduce the size of the antenna.The main work of this paper is as follows:?1?The pure phase Ba_0.5Sr_0.5TiO₃ was prepared by solid phase sintering method,and it was doped with magnesium oxide?MgO?.The effect of MgO on the properties of BST ceramics under different doping ratios was investigated.The performance of implantable antenna was tested with the loading of BST/MgO.According to the test results,we prepared BST ceramics doped with 55 wt%MgO.The prepared BST/MgO sample has a relative dielectric constant?_r=120.62 and a dielectric loss tangent tan?_?=204.92×10^-5.From the XRD analysis test,only two phases of BST and MgO were found,and no other doped phases were found.It can be seen from the cross-section and surface SEM spectrum of the sample that the sample structure is dense and evenly distributed.Two new Coplanar Waveguide?CPW?antennas were designed,one of which has a symmetrical structure of 8×9×0.5 mm³,and the antenna is cut in half and has a size of 4×9×0.5mm³.The above two antennas are loaded on the antenna using BST/MgO.The vector network analyzer is used to test the implantable antenna.After loading the BST/MgO sample,the antenna resonance frequency is shifted to the left.The bandwidth of the symmetrical structure antenna is 326.49-774.06 MHz,and the bandwidth of the cut-half antenna is 305-592.41 MHz,both can cover the frequency band of 402 MHz;the antenna has good directivity.This approach provides a new idea for the design of implantable antennas.?2?In this paper,a flexible magnetic dielectric material is selected.The parameters of the material are:relative dielectric constant?_r=13,dielectric loss tangent tan?_?=0.17,relative permeability?_r=20.7,and magnetic loss tangent tan?_?=0.12.The material was loaded into our designed coplanar waveguide type implantable antenna.The size was4×12×0.275 mm³ after loading the material.The performance of the antenna was tested.The tested bandwidth is 810-1062 MHz and can cover the frequency band of 902 MHz.This antenna is an omnidirectional antenna.This technique is helpful for reducing the size of the antenna and reducing the difficulty of the antenna design.