The first hardware-based, anti-collision methodology for frequency doubling transceivers for RFID and wireless sensing applications

Presented herein is the first ever hardware based methodology for collision avoidance of multiple, frequency doubling transceivers. Frequency doubling transceivers have many advantages over other passive RFID systems, including their simplicity, size, and read range. The drawback of frequency doubling transceivers is the lack of a method for uniquely identifying a single tag when multiple tags are within read range of an interrogator, i.e. collision avoidance. Therefore, a methodology is developed which allows for the switching on and off of individual tags while maintaining a relatively simple and small structure. Measurement demonstrates a switching mechanism which requires -10 dBm of power in a control signal for over 30 dBm of attenuation in the transceivers doubled return power. Different modes of operation are demonstrated which allow for easier signal interrogation. Wireless measurements demonstrate the viability of the transceiver as part of an RFID system. Read range, and number of uniquely identifiable tags are covered in the conclusion.