Abstract:

Radio Frequency Identification (RFID) is a contact-less data capturing technique based on using radio frequency electromagnetic waves for data transmission.

A typical RFID system is consisted of a RFID transponder (tag) and interrogator (reader). The role of the transponder is to transfer data to the reader and the reader’s role is to receive and process the data and in some examples of RFID systems even send data to the transponders.

The whole idea of RFID systems is to replace the existing bar code in order to automate and improve the way today’s industry manages logistics and supply chain management. In order to do that it is needed to develop a very cheap and cost effective RFID transponder that can compete with the price of a barcode which is a fraction of a cent.

Researchers and engineers around the world are trying to bring down the cost of RFID tags by discarding the use of silicon chips and on-board power supply thus leaving the RFID tag with a simple structure. The simplicity of the tag’s architecture and the disability to have data processing using digital circuitry will make the transponder fairly “dumb” thus influencing the reader’s “intelligence” to go up.

Our idea is to develop a very smart and agile RFID reader unit in order to detect and/or interrogate chipless RFID transponders. The chipless transponders would be based on spectrum signatures achieved by using planar microstrip technology and multiresonating ctructures. The reader would interrogate the transponder using a frequency sweep technique and then process the signals received from the transponders. The detection of a transponder would be determined by the presence or absence of a certain frequencies received by the reader which would indicate the transponders unique ID.

We have investigated several different architectures for the chipless tag RFID reader. The first RFID reader developed is a wired RFID reader which interrogates the multiresonator circuit hardwired to the reader circuit. The second RFID reader was able to detect a single RFID tag using wireless technology. The developed reader was also able to detect semi-passive and passive tags using ASK modulation for data transfer. The prototype semi active transponder was developed as well to ensure testing of the reader. The third proposed reader architecture would be able to detect multiple chipless tags in its interrogation zone by using SDMA, FDMA and TDMA techniques.