Component for a continuous antenna tuning unit

The presented project proposal deals with the analysis and development of a novel component for continuous antenna tuning circuits. The "CD-Laboratory for Automotive Measurement Research" located at the EMT TU-Graz has been concerned with the analysis and design of single antenna RFID systems in the 13.56 MHz range. These systems work based on inductive (magnetic) coupling between reader (antenna) and transponder (tag), i.e. in the near-field of the antenna. They basically represent a weakly coupled air-transformer. Passive tags draw their operating power from the RF-magnetic field of the antenna. The read/write range, the r/w volume, of a single antenna is limited by several factors, e.g. power transmission efficiency and EMC regulations, modulation and noise, detuning of the resonant antenna by environmental conditions and even the RFID-tag itself(!), etc. To reliably operate RFID systems with maximised r/w-range under varying environmental conditions, exact tuning and impedance matching of the antenna is required. Antenna array systems can help to extend the limited r/w-range and even allow to localise different RFID tags in the field space. The r/w range/volume could be multiplied by the used number of antennas. To reliably operate RFID systems with multiple antennas, however, advanced control strategies to quickly synchronise the single antennas, which are mutually influencing eachother are required. The key component for these antenna circuits is an automatically and continuously operating antenna tuning unit (ATU) for a resonant antenna transformer. A simple prototype for a novel magnetic component of the ATU has been used for first experiments, and has shown the principle functionality. A thorough theoretical and experimental investigation of possible designs, the choice of materials to optimise this component is the goal of this proposal. Besides the skills and experience of EMT in measurement technology and RFID-system design, the expertise for modelling and simulation of ferromagnetic and ferrimagnetic materials and devices has been found at the AEM- group of the "Institute of Sensor and Actuator Systems" at the TU-Vienna. The novel tuning transformer for resonant loop antennas utilises a modified transductor setup. The behaviour and performance of this component will be studied by modelling the materials properties of the involved ferromagnetic and ferrimagnetic materials, by integration into Finite Element Models, and last but not least, by careful experimental investigation.