Radio-frequency identification systems and advances in tag design

Radio-frequency identification (RFID) is one of the most enabling technologies that continues to be considered in numerous applications. It is basically a wireless system exploiting the principle of communication by reflected waves. This paper reviews the principle of RFID systems, and discusses the main characteristics. Since the tag is the most constrained device in RFID - since it is usually does not have a battery, and is quite versatile and low cost - the paper reviews different tag designs, as well as some advanced results and proposals.