Outdoor meteorological effects on UHF RFID phase shift: Experimental simulations

The present study investigates meteorological factors that affect the phase of RFID passive tags at 868 MHz, in outdoor conditions. The study identifies the effect of the water on the antennas, the temperature of the cables and tags, the moisture of the tag support, and the atmospheric conditions. These effects could lead to over 8 radians phase drift, over a year in a typical environment. That leads to a possible yearly error of 20 centimeters in a typical outdoor ranging application. The article proposes techniques to correct those effects, in order to increase the accuracy of phase-based outdoor monitoring applications.