Modeling of Multilabel Scenarios of 13.56 MHz RFID Systems

The continual growing field of applications for contactless smartcards and NFC (nearfield communications) leads also to the occurrence of several close coupled labels in the operating field. This close coupling leads to additional physical effects, as a strong mutual interaction between labels results. It is topic of this work to characterize the physical behavior of such close coupled systems in terms of effected resonance frequency. A mathematical analysis (in particular an eigenvalue decomposition) will be given, allowing to predict the behavior of several cards very well. Based on different coupling factors between cards the resulting resonance frequency will be anticipated and lower limits of physical possible resonance frequencies will be calculated and pointed out.