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
Voltage surges can damage the components in electrical equipment such as
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.