Design And Research On UWB Antennas Applied To Medical Microwave Imaging System

With the development of microwave imaging technology,its applications are getting wider and wider.Today,people pay more attention to the health,and the safety of medical testing equipment has caused much attention.The microwave imaging technology obtains the target's shape information according to its external scattering.It is a non-destructive physical imaging method,and the microwave signal has minimal harm to the human body.Therefore,microwave imaging technology has attracted great interest as a medical detection method.As one of the most critical factor in the microwave imaging system,the antenna directly affects the imaging performance.These antennas have the characteristics of ultra-wideband,high gain,small size,directional radiation,and good time-domain characteristics to obtain accurate imaging information.In view of the above requirements,a resistance-loaded Vivaldi antenna is proposed in this thesis.Vivaldi antenna is an ultra-wideband antenna with directional radiation characteristics.In this thesis,the exponential slots were placed and the resistances were loaded on the radiating patch of Vivaldi antenna to achieve the purpose of expanding the antenna's low-frequency width,improving the antenna radiation pattern,and miniaturizing the size of antenna.The antenna designed in this thesis was simulated on the CST simulation software platform.The size of the antenna is 75 mm×95 mm,and the working bandwidth is 1.6GHz-15 GHz and the gain is between 4 d Bi and 10 d Bi.The radiation pattern of the antenna has a low sidelobe and can achieve good directional radiation.Physical processing and testing of the antenna are performed.The test results are basically consistent with the simulation results.This thesis establishes a simulation model of cerebral stroke detection system on the CST simulation platform.According to the distribution of the dielectric constant of different tissues in the human head,a head simulation model is established.Use the antenna designed in this thesis as the transceiver antenna of the system,according to the antenna S11 parameters and S21 parameters for data processing,confocal imaging algorithm imaging the head's simulation model.The simulation results can accurately find the abnormal tissue in the head model,and prove that the antenna can be applied in the microwave imaging system theoretically.In order to further verify the feasibility of the antenna designed in this thesis,a simple brain stroke detection experiment system was established in this thesis.The antenna designed was used as the receiving antenna and transmitting antenna of the system,and the vector network analyzer stores the antenna S-parameters.Using the confocal imaging algorithm used in simulation to image the measured data.The imaging results can find the abnormal tissue accurately,which proves that the Vivaldi antenna proposed by this paper can be applied to the microwave imaging system for medical detection.