The RFID- Handbook contains all information about RFID, Radio Frequency Identification, Transponder, RFID Tag, RFID Reader, 14443, 15693, 18000, GTAG, EPC, Antenna, ...

Physical background of RFID-systems

This page provides additional information to the physical background provided by the book. All of thediagrams are animated to show the effects by altering one of the parameters.
(This page will be updated temporarily - please come back later).

Dip generated at reader coil by EAS RF-transponder

If an EAS RF-transponder is taken into the field of a reader, the label influences the generated field. Thus the impedance of the generator coil in the reader is influenced. The video clip shows the impedance of a reader-coil, where the frequency is swept from 7 to 9 MHz. An EAS RF-label is slowly taken into the field and then taken out again. At the resonance freyency of the label, a “dip” occures which allows the label to be detected.

download video (2 MB): RF-system_response_reader_coil_Z.avi

 

inductive reader-coil: circle radius vs. fieldstrength

The video-clip shows the relation ship between the circle radius of the reader-antenna and the field strength H  a distance of  0 .. 10 m. At the video-clip the circle radius slowly increases from 1 .. 50 cm,  while the current I is kept constant. It can be seen that while the field strength decreases at zero distance decreases, the distance in large distance increases. That’s the reason, that inductive coupled long range systems (ISO 15693) use large diameter reader antennas, compared to short range systems (ISO 14443) using small diameter reader antennas.

download video (1.3 MB): field_strength_H_as_function_of_R.avi

 

Free sample reader: chapter 3 (Fundamental Operating Principles of RFID-Systems)