This paper describes the design of a battery-assisted Ultra-High Frequency (UHF) Radio-Fre- quency IDentification (RFID) tag suitable for embedding in concrete materials and its measurement in a mortar slab. The devic...This paper describes the design of a battery-assisted Ultra-High Frequency (UHF) Radio-Fre- quency IDentification (RFID) tag suitable for embedding in concrete materials and its measurement in a mortar slab. The device is built to communicate wirelessly not only the ID number of the RFID chip but also the digitalized output of a strain gauge sensor. Design optimizations of the RFID antenna is based on published permittivity and conductivity values of concrete. Experimental read ranges are measured from 800 to 1000 MHz with the help of commercial test equipment. Reading is possible up to 50 cm from the surface of a mortar block for a tag embedded 5 cm below the surface. This result is the first published one for RFID tags embedded in concrete or mortar.展开更多
已有的针对海上VHF/UHF(Very High Frequency/Vltra High Frquency)频段信道环境的研究,在电波传播特性和底噪特性方面缺少试验数据支撑.本文在VHF/UHF频段上做了一系列海上通信试验,基于试验数据,分析了传统电波传播模型对海上视距、...已有的针对海上VHF/UHF(Very High Frequency/Vltra High Frquency)频段信道环境的研究,在电波传播特性和底噪特性方面缺少试验数据支撑.本文在VHF/UHF频段上做了一系列海上通信试验,基于试验数据,分析了传统电波传播模型对海上视距、超视距、视距超视距临界等传播路径的适用性.同时本文提出了空时二维海上频率选择性信道分析方法,从空间、时间二维视角下定量描述了海上无线信道演变现象,对空时频率迁移和空时频率衰变的概念做了定义.结论可用于海上电波传播建模和异常现象分析.展开更多
通过分析HEMT器件低温特性以及低温低噪声放大器的应用特点,重点阐述了器件选择、电路拓扑结构对电路稳定性的影响,以及稳定性设计对于电路匹配设计的重要性,并提出了VHF/UHF频段宽带低温LNA的设计思路。以设计实例为基础,给出了改善电...通过分析HEMT器件低温特性以及低温低噪声放大器的应用特点,重点阐述了器件选择、电路拓扑结构对电路稳定性的影响,以及稳定性设计对于电路匹配设计的重要性,并提出了VHF/UHF频段宽带低温LNA的设计思路。以设计实例为基础,给出了改善电路稳定性、有利于驻波、噪声匹配的设计方法,低温LNA的测试结果(相对带宽≥90%、噪声系数≤0.3 d B@77 K、反射损耗≤-18 d B)和应用效果表明,文中的技术能够有效地指导设计与研制,具有较大的参考意义。展开更多
文摘This paper describes the design of a battery-assisted Ultra-High Frequency (UHF) Radio-Fre- quency IDentification (RFID) tag suitable for embedding in concrete materials and its measurement in a mortar slab. The device is built to communicate wirelessly not only the ID number of the RFID chip but also the digitalized output of a strain gauge sensor. Design optimizations of the RFID antenna is based on published permittivity and conductivity values of concrete. Experimental read ranges are measured from 800 to 1000 MHz with the help of commercial test equipment. Reading is possible up to 50 cm from the surface of a mortar block for a tag embedded 5 cm below the surface. This result is the first published one for RFID tags embedded in concrete or mortar.
文摘已有的针对海上VHF/UHF(Very High Frequency/Vltra High Frquency)频段信道环境的研究,在电波传播特性和底噪特性方面缺少试验数据支撑.本文在VHF/UHF频段上做了一系列海上通信试验,基于试验数据,分析了传统电波传播模型对海上视距、超视距、视距超视距临界等传播路径的适用性.同时本文提出了空时二维海上频率选择性信道分析方法,从空间、时间二维视角下定量描述了海上无线信道演变现象,对空时频率迁移和空时频率衰变的概念做了定义.结论可用于海上电波传播建模和异常现象分析.
文摘通过分析HEMT器件低温特性以及低温低噪声放大器的应用特点,重点阐述了器件选择、电路拓扑结构对电路稳定性的影响,以及稳定性设计对于电路匹配设计的重要性,并提出了VHF/UHF频段宽带低温LNA的设计思路。以设计实例为基础,给出了改善电路稳定性、有利于驻波、噪声匹配的设计方法,低温LNA的测试结果(相对带宽≥90%、噪声系数≤0.3 d B@77 K、反射损耗≤-18 d B)和应用效果表明,文中的技术能够有效地指导设计与研制,具有较大的参考意义。
