Size reduction of RFID tags by using an on-chip antenna

RFID is a well-established and well used technology for item tracking and anti-theft protection. Further on-going development goals include a size reduction of the transponders. On UHF frequency the transponder antenna is typically the largest element. Thus, a size reduction of the transponder can be achieved by a size reduction of the antenna. There are a lot of well-established techniques for achieving this. However, an external antenna remains typically the largest part of a transponder. A further size reduction can done by using an on-chip antenna. This will also lead to a strong reduction of the production costs since, besides the chip production, no further steps are necessary. Another way to reduce the size of a transponder is to increase its working frequency. Due to the inverse antenna size and frequency relationship, an increased frequency allows a size reduction of the antenna at the same proportion. We have used this principle to design an RFID transponder at 24 GHz using an on-chip antenna. The transponder has a size of 2.5mm x 1.5mm and is using the standard EPC G2 protocol for communication.