An RFID tag uses electromagnetic induction to communicate information by supplying electrical power to an IC chip from a reading device. In order to relay information in specific frequencies with a good degree of sensitivity, the RFID tag uses resonance between its internal coil antenna and capacitor. The coil antenna's inductance and the capacitor's resonance frequency need to be estimated for resonance to be produced accurately at the specified frequency. When the capacitor is external, the inductance of the coil antenna needs to be obtained accurately and the capacitor's capacity needs to be identified. Some RFID tags have magnetic sheets or metallic films on them. The sheet's magnetic properties and eddy currents generated in the film can affect the inductance. This Application Note performs a magnetic field analysis of an RFID tag that has a metallic film and a magnetic sheet with a resonance frequency of 13.56 MHz, and obtains the magnetic field distribution and the RFID tag's inductance.
Voltage surges can damage the components in electrical equipment such as an inverter. Busbar inductance can be a cause of surges. Therefore, it is important to reduce it to protect the electrical equipment. Using FEM allows for the calculation of inductance based on the magnetic field and current distribution obtained from the magnetic field analysis. This note presents a case study on the current distribution and the frequency versus inductance characteristic of the busbar.