An On-Body UHF RFID Tag with DDRR Antenna for Healthcare Data Streaming Applications

This paper describes the development of a Direct Driven Resonant Radiator (DDRR) antenna for an ultra-low power UHF RFID tag system, integrating an accelerometer for movement tracking using a passive backscattering communications link. An outline of a system intended for healthcare applications involving wireless movement detection, such as therapeutic recovery exercises is described. The tag comprises of a UHF RFID transponder connected to a 4 cm (0.115λ) diameter, 1 mm thick (0.0028λ) skin-mounted antenna. Off-body read ranges of 3.6 m with 1 kB/s data communication are achieved. The DDRR radiation pattern is a limiting factor in movement tracking, offering only limited angles of detection, which could be improved with spatial diversity in the reader antennas