Research On Electromagnetic Model Of Metal Tag Identification

Nowadays，the society has been moving towards the era of the internet ofthings gradually. Generally speaking, IOT is composed of many local sensornetworks and the function of these networks is realizing the identification of itemsinformation automatically. Up to now, the information automatic recognitiontechnology is consists of bar code, magnetic stripe and RFID, etc. The commondefect of these technologies is that they are all difficult to adapt to the harshenvironment, so its widely application is limited. This project presents a newtechnology of automatic identification of information—metal tag. The shortcomingof the current automatic identification technology can be overcome by thistechnology. In this paper, based on the innovative application of electromagneticnondestructive detection technology, the electromagnetic model has been built bythe research of the characteristics of space electromagnetic information generated bymetal tag. The recognition of metal tag has been realized theoretically.The prototype of metal tag technology is electromagnetic nondestructivetesting. Eddy current testing (ECT) and the alternating current field measurem enttechnique (ACFM) are important methods realizing NDT. A mature theoreticalsystem of NDT has been established. Therefore, the mathematical model of ECT andACFM has been studied deeply. Through comparison and analysis, it has been foundthat the impedance analysis method of ECT is suitable for detecting the surfacedefects which has large size. And the method of field component analysis of ACFMis more sensitive for small size defects. Integrated these characteristics and theactual situation in this subject of meal tag which has very small scalar, the methodof field component analysis of ACFM has been selected as the core theory of thisproject to establish the mathematical model of metal tag. The main content ofmathematical modeling includes the determination of boundary conditions and theestablishment of wave equation. In this paper, the wave equation was derived byMaxwell’s equations and the boundary conditions of metal tag were determined bythe general boundary conditions of electromagnetic field and the actual situation ofthis project. This is the first step of model building. The second step is to solve thewave equation. After the study of the general method for solving wave equation, theFourier transform was selected to solve the mathematical model. The analyticalexpressions of the electromagnetic field were got finally. At the last, the simulationof the established mathematical model has been conducted for two kinds ofconductor--copper and mild steel.