Passive 5.8-GHz radio-frequency identification tag for monitoring oil drill pipe

This paper reports a new passive 5.8-GHz radio-frequency identification tag proposed for monitoring oil drill pipe (patent pending). The tag is to be inserted into the tool joint of the drill pipe in order to predict the pipe\´s lifetime and to provide inventory control. The tag requires a minimal incident power density of 13.5 mW/cm² to establish a link and transmit 64-bit coded information to the interrogating reader. The tag uses a circular patch etched on a 60-mil Duroid with ε_r=2.33 to receive the interrogating RF power and transmit the identification (ID) information simultaneously. An efficient Schottky diode is used to rectify the RF power to provide the DC power necessary to operate the "on-board" electronics. A p-i-n diode modulates the tag\´s ID code onto the 5.8-GHz carrier frequency. The tag\´s physical size has to be small so that it can be imbedded into the pipe without weakening the structure. It has been designed to withstand large pressures normal to its surface. The system was successfully demonstrated in the laboratory.