A Modified Split⁃Ring Resonator Antenna for Radio Frequency Identification Tag

A compact antenna formed by three concentric split rings for ultra-high frequency(UHF)radio frequency identification(RFID)tag is proposed in this paper.The antenna is composed of two parts,an outer short-circuited ring modified from a traditional split-ring resonator(SRR)antenna and an inner SRR load,so the antenna can be regarded as a short-circuited ring loaded with SRR.According to the transmission line theory,to conjugate match with the capacitive input-impedance of a tag chip,the length of the short-circuited ring isλg/4 shorter than that of an open-circuited dipole of a traditional SRR antenna,whereλg is the wavelengh of the operating frequency.Hence,the size of the proposed antenna is more compact than that of the traditional SRR antenna.Thereafter,the proposed antenna is simulated and optimized by ANSYS high-frequency structure simulator(HFSS).The impedance,efficiency,and mutual coupling of the fabricated antenna are tested in a reverberation chamber(RC).The results show that the size of the presented antenna is 83%smaller than that of the traditional SRR antenna and the proposed antenna can cover the whole UHF RFID operating frequency band worldwide(840—960 MHz).The measured read range of the tag exhibits maximum values of 45 cm in free space and 37 cm under dense tag environment.

机器人手术指南与专家共识的方法学质量评价

目的分析评价机器人手术临床应用相关指南或专家共识的方法学质量。方法计算机检索国内外指南网站及电子数据库中关于机器人手术临床应用的指南或专家共识,检索时限为2000年1月1日—2021年12月29日,按照纳入和排除标准进行筛选。2名评价人员采用AGREEⅡ(Appraisal of Guidelines for Research and EvaluationⅡ)工具对指南和专家共识独立进行评价,对2名研究人员的组内相关系数进行一致性检验,并计算指南和专家共识在AGREEⅡ6个领域的得分。结果共纳入34篇文献,其中指南10篇,专家共识24篇。2名研究人员的一致性较好,组内相关系数>0.75。纳入指南和专家共识在AGREEⅡ6个领域(范围和目的、参与人员、制定的严谨性、表达的清晰性、应用性和编辑的独立性)的平均得分分别为81.0%、43.5%、28.2%、81.5%、12.7%和51.7%。结论目前国内外的机器人手术指南在制定的严谨性、应用性和编辑独立性等方面仍有待提高。随着机器人手术的不断开展,建议制定证据等级更高的循证指南和专家共识,以促进机器人手术的规范化应用。