The Application Research Of Microwave Imaging Radar In Nondestructive Testing Of Concrete Wall

Nowadays Microwave imaging has become an advanced research field in application electromagnetism. It is a non-contact method in study objects properties by using microwave technique, electronic technique and digital processing technique. Microwave imaging is also a kind of nondestructive testing technique, the research of which is according to the measured scattering data to reconstruct the image of material dielectric constant. Microwave imaging is not according to the density of the material but electromagnetism properties of different materials change more sensitively than other physical properties. This is the superiority by using microwave. Microwave imaging is still at developing stage and its future depends on the improvement of microwave technologies and perfect imaging algorithm.The main work in this paper is designing a radar which is using to microwave imaging in nondestructive testing of concrete Wall. The whole system is consisted of active model which including signal source, power amplifier and power detector;passive model which including power divider, coupler and antenna;and the controlling system that based on MSP430. The four kinds of PLL are used in the design which are at different frequency intervals to get four way signals. The four ways power distributor selects only one way to connect to power amplifier. The input and reflect signals from the antenna is divided by the coupler, and the reflect signal is change to voltage signal by power detector. This voltage signal is collected by A/D and send to computer to imaging. The whole system is controlled by MSP430.The work in this project include passive model , active model and control model. The passive model is designed with the help of simulate software which are ADS in Agilent and HFSS in ansoft. The active system is realized by some RFIC, the match part in the work is base on Smith chart and ADS software. The MCU system's hardware and software are done by myself.Using the radar which designed in this project to detect three kinds of 450mm X 350mm X 300mm concrete model, the scattering data is collected and imaged by co-k algorithm. In the experiment we find out that it is clear to make out one steel bar and two parallel steel bars in the concrete wall. For two vertical steel bars , we can only judge the position of it , but not make out the number of the steels.