Research On The Key Technology Of Microwave Detection Applied To Stroke

"Brain science and brain-like research"was once again listed as one of the 7 major"research frontier fields of science and technology"projects in the"14th Five-Year Plan".The exploration of stroke diseases is particularly important in the research of brain science.The detection of cerebral hemorrhage has become a research hotspot in the field.Microwave detection of stroke has the advantages of non-invasiveness,low radiation and portability.The detection and imaging of stroke are mainly carried out by the electromagnetic wave which emitted by the antenna.Therefore,this thesis will study the antenna and confocal algorithm imaging and simulation experiments.The main work is as follows:1.First,a broadband directional antenna loaded three-circle director is designed,which size is 70mm×30mm×30mm.The antenna adopts a three-dimensional dipole structure and loads a three-circle director to improve the radiation characteristics of the antenna in the entire frequency band.The operating frequency band of the antenna with S₁₁<-10 d B is 1.1～3.57GHz,the relative bandwidth is 104.3%,and the maximum gain reaches 7.24d Bi.Secondly,a broadband directional antenna loaded ring resonance-based reflector with a size of108mm×108mm×30mm is designed which is in order to reduce the antenna-air-brain tissue transition loss and thus increase the penetration of the signal.The monopole antenna adopts a flexible dielectric substrate to achieve conformal shape with the head model,and a circular resonant reflector is loaded to enhance the directional radiation performance of the antenna.Flexible directional monopole antenna operating at 1～4.4GHz,the relative bandwidth is125.9%,and the gain of 1～3.2GHz in the operating frequency band is 5d Bi.The test results of the two antennas are in good agreement with the simulation,and the specific absorption rate meets the safety standards for electromagnetic radiation.2.The electromagnetic simulation software was used to simulate the microwave detection of brain white matter tissue hemorrhage.Introducing 3D high-precision models into electromagnetic simulation software Sim4Life.First,importing 3D broadband directional dipole antenna arrays loading directors with 6-element and 12-element,arranging them around the DUKE head model.The bleeding position,the bleeding volume and the number of antenna arrays are used as variables for simulation research respectively,the amplitude information of the scattered signal reflected from the hemorrhagic target is obtained,and the target inversion is performed using the confocal imaging algorithm.Secondly,a 6-element flexible directional monopole antenna array loaded resonant-based reflector is introduced,the antenna circled around the DUKE head model and fit completely.Intracerebral hemorrhage detected by different hemorrhage locations,different hemorrhage amounts and different antenna arrays is simulated,and the target inversion is performed by using the confocal imaging algorithm.The simulation results of the cerebral hemorrhage detection are analyzed,and the simulation data is inverted by microwave confocal imaging algorithm.The research results show that the scattering data obtained by the two antennas used to detect cerebral hemorrhage can invert the location of the hemorrhage target,and the flexible directional monopole antenna array loaded the resonant-based reflector has a better imaging effect on the detection of cerebral hemorrhage.There are fewer artifacts,the energy is focused on the bleeding location,and the image resolution is higher.3.The bionic head model,turntable,designed broadband directional antenna and vector network analyzer are used to build a simulated experimental platform for intracerebral hemorrhage.The 12-element antenna array for detecting stroke is realized by the rotation of the turntable,bleeding location and amount of bleeding were used as experimental variables and experimental studies were conducted.Analyze the scattered signals received in different directions by a 3D broadband directional dipole antenna with a director and a flexible directional monopole antenna with a resonant-based reflector around the head model,and the confocal imaging algorithm is used to perform target inversion on the acquired data.The results show that the reflected signals received by the two antenna arrays can be used for inversion of the hemorrhage position,with less artifacts,and the maximum energy value is focused on the hemorrhage target position.