Tham khảo tài liệu 'development and implementation of rfid technology part 4', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | UHF RFID of People 81 Fig. 23 shows the simulated reader input power PrREADER values with respect to the reader sensitivity PrREADERmin. Use of the standard meander dipole antenna leads to unacceptably low PrREADER values especially off-axis. Employment of the RFID patch optimized for operation on a human body can guarantee high enough power even in this return TAGreader link. Fig. 23. Simulated reader input power PrREADER on the TAG-reader trace Pt dBm h1 3 m h2 m 30 4. Testing of RFID systems According to f it is always necessary to perform practical testing of the optimized RFID system. As examples testing of two RFID systems optimized for different applications are presented. The first system was optimized for identification of sportsmen see Section . The second system was tuned for identification of employees in buildings and factory areas. Both arrangements employ the same reader and TAG chips. Description of the RFID reader and chips For the identification tests a commercial RFID system Trolleyscan Ltd 2006 operating in the 869 MHz band was used. The main parameters of the system can be seen in Table 3. System components Parameter Values Operating frequency Europe - MHz Reader Transmitted power dBm - dBm Receiver sensitivity -64 dBm 200 pW Identification rate 70 s-1 Chip Sensitivity dBm 200 pW Impedance measured value 76 - j340 Q Conversion loss approx. 20 dB Table 3. Standard UHF RFID system parameters from Trolleyscan Ltd 2006 82 Development and Implementation of RFID Technology Identification of sportsmen In order to verify identification reliability of the optimized system tests simulating real RFID system applications were performed. A group of racers moved on an asphalt surface in several different formations see Fig. 24. In the first formation 7 racers moved in a row in the second formation 7 racers formed a kind of a matrix. Each formation moved with 3 different speeds simulating a walk approx. 4 km
