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基于射频识别技术原理及Friis传输方程,导出了自由空间下无源超高频射频识别(RFID)系统路径损耗表达式.结合菲涅耳区理论,分析了菲涅耳余隙及阅读器天线至标签间距两因变量条件下第一菲涅耳区受阻隔对RFID系统路径损耗的影响,并提出了双斜率对数距离路径损耗模型.在开阔室内环境下,测试了菲涅耳余隙及阅读器天线至标签间距变化时的系统路径损耗.测试结果表明:菲涅耳余隙大于第一菲涅耳区半径1.5倍时,刃形障碍物对系统路径损耗影响较小;相比传统对数距离路径损耗模型,双斜率模型标准差减小10%.
Based on the principle of radio frequency identification and Friis transmission equation, the expression of path loss of passive UHF radio frequency identification (RFID) system in free space is deduced. Combined with Fresnel zone theory, the influence of Fresnel clearance and reader antenna to The influence of the first Fresnel zone blockage on the path loss of RFID system under the condition of two-variable tag spacing is put forward and the dual-slope logarithmic distance path loss model is proposed.In the open environment, the Fresnel clearance and reading And the system path loss when the space between the antenna and the tag is changed.The test results show that the edge-shaped obstacle has less influence on the system path loss when the Fresnel clearance is greater than 1.5 times the radius of the first Fresnel zone. Compared with the traditional logarithm From the path loss model, the standard deviation of the double slope model is reduced by 10%.