The Research Of Microwave Nondestructive Imaging Algorithm

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. Shining with the microwave field of the low power at first, the scattering field is measured and the image can be reconstructed with the data. Different from the traditional nondestructive testing technique such as the ultrasonic, X-ray, etc., it is not according to the density of the material but electromagnetism properties. It has strong penetrating ability. At microwave frequency bands, the 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 of this paper is the research of microwave imaging algorithm. The algorithm of microwave imaging plays an essential role in MNDT. The electromagnetic scattering is a foundation of the algorithm of microwave imaging, and also one of the important contents of the electromagnetic theoretical research. The research approach of the electromagnetic scattering having introduced at first in the article, and the main introductions are several kinds of numerical computing technologies, which are used widely. Microwave imaging which reconstruct the inner structure of target can get relevant information that people are interested without keeping in touch and destroying the scattering body, and has extremely rich practical value, so the masses of microwave workers keep being devoted to the research of the high-efficient, accurate reconstruction algorithm. Many algorithms of microwave imaging have been developed and have been utilized already. In this paper I introduced several more extensive andrepresentative imaging algorithms, and compared the virtues and applicability of each algorithm. Finally, on the basis of introduced algorithms, we proposed the iterative algorithm that based on LSF and FEM. The algorithm can imaging targets with high contrast and large size, and the result of imaging is not changed by the influence of initial value. Still utilize this algorithm to the artificial data and the real data to imaging in the article; the result verifies the validity of the method.