Harmonic RFID Communication Using Conventional UHF System

In this paper, a harmonic radio frequency identification (hRFID) system is proposed to overcome the challenges that limits the capabilities of a conventional UHF radio frequency identification (RFID) system, such as self-jamming and multipath interference without any extensive modifications to the existing infrastructure. The proposed system exploits the third harmonic generation from the existing RFID chips for communication. The system is realized by designing an additional RF interface layer between the conventional RFID interrogator and an RFID tag. The interface layer transmits the query signal at the fundamental frequency and receives the backscattered harmonic signal from an RFID tag. It down converts the backscattered third harmonic signal to the fundamental frequency, and feeds it back to the conventional UHF interrogator for extracting the information. A dual band antenna design is also shown for improving the radiation efficiency of hRFID tags using a conventional RFID ICs with improved signal to noise ratio (SNR) and increased read range. A path is shown for improving an hRFID system by performing a study that relates the read range, RFID IC's sensitivity, and the noise level with efficiency. The proposed system can be easily adapted to any of the current RFID applications.