Research On Design And Improvement Of Microwave Nondestructive Testing And Imaging System

Domestic and international general situation about researches on microwave nondestructive testing and its practical applications are introduced. Practical project background, the technology progress and develop trend are introduced. The theory of microwave nondestructive test and imaging on reinforce steel bar concrete are introduced, the structure of the microwave nondestructive test and imaging system and aspects need improved are settled according analysis.Basic theory of three dimension high frequency electromagnetic field finite element analysis, the step and key points to realize the analysis are introduced. Finite element models of reinforced concrete block which contrapose aim task are built and simulations are performed. Improvements ofω-k imaging arithmetic and influence effects the system parameters setting on imaging quality are studied and discussed using results of simulation.Antenna scan and control part is designed according to system scan precision and automatic request with stepper motor control it. Select experiments of the stepper motor are presented. The driver circuit is simulated and the real circuit is designed and debugged, realized the high precision antenna scan part.High precision data acquire system is realized according system precision request. Sigma-Delta AD chip, parameters of AD7712 and high precision mixed signal circuit system design are introduced. Real circuit designed and debugged, precision requirement realized combine with software filter technology.Aim nondestructive test and imaging system require the standard microwave source has high precision and wide frequency band wide. Theory and design technique of integrated PLL microwave synthesizer are introduced, design expanded frequency and simulating validate with simulation software ADIsimPLL are performed. Basic theory of Spectrum analyzer and the technique of test microwave source parameters with it are introduced. The parameters of microwave source are test and the test results proved that the parameters match requirement of system.Upward PC software program is developed using virtual instruments development software LabVIEW. Friendly human-machine interface, system automatic control, imaging arithmetic inbed as well as the display and storage of images and measure data are realized.Test and image on real reinforced steel bar concrete test block through using disgned and improved nondestructive test and imaging system proceeded. It is proved the system has definite reliability and practical value. More improvement suggestions are given about system structure and arithmetic.