The Study And Application On The Interaction Of The Microwave With The Lossy Material

The microwave is the electromagnetic wave with high frequency, short wave length, and strong penetrability. It can propagate freely in space and interacts with various mediums. Today it has been widely used in industry, agriculture, medical field, radar, communications, research and other fields.In this paper, firstly, a comprehensive introduction is given to show the theoretical foundation, research methods and development status of the interaction between the microwave and the lossy medium. The research work referred in this paper is divided into two parts. One part is about the interaction of microwave with the human's tissue. In this part, a theoretical model of the interaction is built based on the theory of electromagnetic field. The reflection coefficient, the transmission coefficient, and the penetration depth as functions of the dielectric constant and conductance of human's tissue are deduced. Substituted the values of those electric parameters concerning different microwave frequency to those formulas, a contrast table of the reflection coefficient, the transmission coefficient, and the penetration depth varying with the microwave frequency is built through a detailed calculation; An important conclusion is draw that the key to improve the efficiency of microwave hyperthermia is the reuse of reflected microwave. Another part of this paper is referred to the interaction of microwave with the fly ash containing unburnt carbon. Based on the study of the propagation of microwave in lossy medium, it is found that both the microwave amplitude attenuation and microwave phase shift have certain relation with the carbon content. An innovative method was proposed to measure the unburnt carbon content in fly ash. The theoretical analysis of this method, the design of system architecture and the circuit design are introduced in detail. A new virtual instrument interface designed by means of LABVIEW is used to control the real-time measurement system. On this interface, the functions of input parameters, real-time data display, acquired data saving and deleting are realized. By using this tool, the substantive data dealing ability and the measurement accuracy are enhanced. A lot of experiments for testing this system have been done in laboratory. The results are consistent well with the theoretical expectation. We believe that this method will be sure widely used in coal-fired power plants to monitor the coal-burning status in boiler and make an important contribution to enhance the coal-burning efficiency.