|
| |
When we talk about PASSIVE RFID tags
there are 2 basic types of communication used with the passive RFID tag.
Backscatter
Induction Coupling
as you may have guessed induction coupling is used for induction coiled antenna
type while backstatter is (in general)the communication method for RFID tags
with UHF antenna
Backscatter RFID tags reflect the RFID Readers own RF signal back to the reader,
only now the signal has been modified with the tag data embedded and the RF
signal is modulated . instead of a constant RF wave it's now an On/Off signal
Inductive Coupling is generally used by LF and HF RFID Tags .
How it works :
The RFID Reader/Interrogator uses current to generate a magnetic field .
As the RFID tag enters this magnetic field generated by RFID Reader
the current is transfered and powers the RFID Chip . The RFID tag/Chip switches
the impedance of the RFID tag's antenna , causing modulation of the magnetic
field thereby joining(coupling) the RFID tag and RFID Reader. this modulated
signal is de-modulated by the RFID Reader and the data is extracted or collected
|
