| Radio frequency identification (RFID) is a rapidly emerging technology that enables automatic remote identification of objects. Passive and semi-passive RFID systems can be distinguished from other forms of wireless systems, because the RFID tags (transponders) communicate by way of backscatter. In addition, passive tags derive their energy from the RF energy emitted by the reader. RFID technology can provide a fully automated data capture and analysis system.;This thesis develops a prototype of a semi-passive UHF RFID tag that is compatible with the leading UHF RFID standard EPCglobal Gen 2 Class 1. I alsot has the flexible I2C and analog digital converter(ADC) interface, which allows the additional of external analog and digital sensors. The sensor data can be read by microcontroller and stored at memory. Standard reader can get sensor data by sending QUERY and READ command to tag.;Test results of our open platform semi-passive UHF RFID tag demonstrated that it can achieve a read rate above 50% when an open platform semi-passive UHF RFID tag is placed four meters from the reader antenna and the reader output power is set to 21 dBm. In addition, the proposed semi-passive open platform RFID tag consumes very little power (4.9 mA in 2V with system frequency set to 8MHz).;Compared to a passive RFID system, an open platform semi-passive UHF RFID tag can provide identification, security, low-power (compared to a wireless sensor net- work(WSN)), medium range and medium processing speed. However, the field of semi- passive RFID is still under development, and has yet there are no open development platforms available. |
