Development of a 5 GHz band realtime wireless sensing system with low power consumption for sensor networks

A novel semi-passive sensor RF-tags using 5 GHz band for a low power consumption and a long reading range are proposed. Multi-subcarrier back scattering communications are employed for the data transmission and the distance measurement of 1 mm resolution over 30 m range. Current requirements of 3 V battery in the distance measurement tag and monitoring tag of sensing data are 30 μA and 600 μA with transmission rates of 30 sps and 40 kbps, respectively, which are much smaller than the conventional active RF-tags.