Tham khảo tài liệu 'current trends and challenges in rfid part 17', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 470 Current Trends and Challenges in RFID Ữ Fig. 12. WSN antenna radiation pattern at 1 meter 2 meters and 3 meters distance away of the gateway a Rohde Schwarz - ESU 26 EMI Test Receiver calibrated antennas and cables. The turntable and the antenna mast were operated by using an in-house made software program. The international standard specifying the emissions level for SRD-RFID Third Generation Active RFID from the Locating Applications Perspective 471 equipments is EN 55022 CISPR 22 - Information technology equipment - Radio disturbance characteristics - Limits and methods of measurements while EN 300-220 - Electromagnetic compatibility and Radio spectrum Matters ERM Short Range Devices SRD is used for the operating performances and functional characteristics evaluation. A standard configuration was used for the tests as the equipment to be measured EUT -Equipment Under Test was positioned on a turn table at meter above the ground and at 3 meters distance from the antenna tip. The gateway was positioned behind the receiving antenna system at meter height. During the measurements the antenna moved from 1 m to 4 m height and the EUT rotated 360 degrees to find out the maximum emission level in the 30 to 3000 MHz band more than the 1000 MHz limit specified in the standards in the final scan procedure the operating frequencies being excluded from the measurement interval . In accord to the standards mentioned above the readings were made continuously one measure per second using quasi-peak and peak detectors for the pre-scan and the final scan measurements respectively. Even the standards do not specify a limit for the radiated emissions for frequencies over 1000 MHz we recorded those levels. The maximum power level recorded for one measured node was around -30 dBm with a minimum of -55 dBm in the working frequency band no other emissions being detected. If there are multiple nodes in the same indoor environment the field strength increases but due to .
