Overview
Closeup |
An RFID tag sends information from a reading device to an IC chip using
electromagnetic induction.
The resonance phenomenon of the coil antenna and capacitor inside an RFID
tag is used to accurately transmit information on specific frequencies.
The inductance of the RFID tag needs to be accurately obtained to produce
the correct resonance on the specified frequency by identifying the capacity
of the external capacitor.
This example presents the use of a magnetic field analysis to obtain the
magnetic field distribution and inductance of an RFID tag with a specific
frequency of 13.56 MHz.
The example analyzes the iron loss of a reactor. |
Magnetic Field Distribution
Closeup |
The magnetic field distribution around the RFID tag is indicated in Fig.
1.
The magnetic field is shielded toward the metal sheet as indicated in Fig.
1. This magnetic field distribution largely affects the inductance. |
Inductance
The inductance of the RFID tag and the capacity of the resonant capacitor
are indicated in Table 1.
The inductance of the RFID tag is obtained from the relationship of the
voltage and current. The inductance of the RFID tag in this analysis is
941 nH. The capacity of the capacitor, calculated from the resonance frequency
and inductance is 146 pF. |
Closeup |
|
