Antenna Design Of Microwave Nondestructive Testing System And Detection Method Research

Detection research of reinforced concrete and research status, as well as the practical application of research results and an overview of the development of microwave nondestructive testing at home and abroad are introduced. The metal cylinder scattering and electromagnetic lossy dielectric properties are expatiated. Explaining the basis knowledge of antenna and microstrip transmission line theory. Electromagnetic field numerical analysis method is introduced.Microstrip antenna analysis method and the EDA simulation software which is used in microwave, high frequency and electromagnetic fields are introduced. Designing a piece of four cells microstrip antenna array. Dielectric permittivity of 2.6, thickness 2.8mm polystyrene material is selected as substrate of antenna, and the top and bottom of substrate are sticked with copper. The S-parameters , the radiation characteristics and feed network are simulated with HFSS and ADS software .From the result of simulation ,the design is satisfied requirement ,and the antenna is produced manually finally.The directional and the size of antenna sidelobe level are tested To determine whether the result is accord with the requirements of the follow-up experiment. The attenuation factor and refractive index of concrete are measured using microstrip antenna array, the value of attenuation factor and the refractive index is gained, and complex permittivity of the concrete is figured out using these two terms. Concrete attenuation factor is measured using antenna which is radiated concrete planar, and power value is measured both metal plate is placed behind concrete and metal plate is not placed. By calculating the margin and bring it into formula, attenuation factor is gained. Refractive index is measured by that the microstrip antenna array is used to transmit the microwave to the concrete with a 30°angle inclination to the concrete plane, and the refractive index of concrete is calculated by measuring the size of the refraction angle.The reinforcing steels in concrete are accurately located by means of revising the refractive index. The microstrip antenna array is used to transmit the microwave to the concrete with vertical incidence to and a 30°angle inclination to the concrete plane respectively. The microwave frequency used is 2.4GHz. The horizontal position of reinforcing steel is determined by the vertically incident microwave, and the vertical position of reinforcing steel is found out by the inclined incident wave. The position of reinforcing steel is corrected accurately by refractive index because of the refraction from oblique incidence. The experiment results show a quite accurate location to the reinforcing steels, and the biggest error is not more than 0.6cm.