This article presents a procedure for electromagnetic field and polarization control with antennas. The concept previously introduced by the authors for spatially distributed three-dimensional electromagnetic polariza...This article presents a procedure for electromagnetic field and polarization control with antennas. The concept previously introduced by the authors for spatially distributed three-dimensional electromagnetic polarization (as time varies) is discussed and extended also to include non-ideal antennas and the control of electromagnetic field distributions (at a given instant of time). These polarizations and fields are herein referred to as “3D”, although time is also inherent to them. Even that the main objective is to introduce a mathematically/numerically consistent synthesis technique for controlling the 3D electromagnetic fields and polarizations, an effort is made to present and discuss possible applications, including but not limited to torus-knotted distributions and spatial multiplexing for transmission of information in wireless digital communication systems.展开更多
近场通信(Near Field Communication,NFC)系统通信频率为13.56 MHz,采用近场磁耦合方式进行信号传输,具有通信距离近、安全度高等特点,广泛应用在银联、公交、门禁等领域.随着NFC技术的发展,越来越多的智能终端设备中配备了NFC系统.由于...近场通信(Near Field Communication,NFC)系统通信频率为13.56 MHz,采用近场磁耦合方式进行信号传输,具有通信距离近、安全度高等特点,广泛应用在银联、公交、门禁等领域.随着NFC技术的发展,越来越多的智能终端设备中配备了NFC系统.由于NFC系统工作频率低,NFC天线面积较大,天线尺寸通常为30 mm×40 mm,而且配置磁性基板用于金属环境使用,这使NFC天线制造成本较高,不利于NFC系统应用.本文通过空间磁场分布理论计算,采用分布式磁性基板设计,大幅降低磁性基板使用面积,并通过NFC天线结构设计,提高天线磁场辐射性能.仿真与实验证明,该设计方法使NFC天线磁性基板使用面积下降约40%,且天线辐射能力增强.在提升天线性能的同时,有效降低天线成本.展开更多
针对现有的13.56 MHz NFC(Near Field Communication)天线因结构而引起回波损耗偏高的问题,设计了一种工作在13.56 MHz的近场通信天线,通过优化天线结构,有效降低了天线的回波损耗。使用Ansoft HFSS(High Frequency Structure Simulator...针对现有的13.56 MHz NFC(Near Field Communication)天线因结构而引起回波损耗偏高的问题,设计了一种工作在13.56 MHz的近场通信天线,通过优化天线结构,有效降低了天线的回波损耗。使用Ansoft HFSS(High Frequency Structure Simulator)进行天线模型的设计以及仿真分析,对NFC天线的3大结构参数(天线边长L_x、线间距S和线径W)进行了仿真分析探究,最后得到以13.56 MHz为中心频率的最优天线结构参数,即L_x=40 mm,S=1 mm和W=0.5 mm。在上述天线结构参数下,优于已有的NFC天线(回波损耗为-22.2 d B),其回波损耗降低至-28.8 d B,-10 d B以下的带宽为0.8 MHz。展开更多
Radio Frequency IDentification(RFID)and related technologies such as Near Field Communication(NFC)are becoming essential in industrial contexts thanks to their ability to perform contactless data exchange,either devic...Radio Frequency IDentification(RFID)and related technologies such as Near Field Communication(NFC)are becoming essential in industrial contexts thanks to their ability to perform contactless data exchange,either device-to-device or tag-to-device.One of the three main operation modes of NFC,called read/write mode,makes use of the latter type of interaction.It is extensively used in business information systems that make use of NFC tags to provide the end-user with augmented information in one of several available NFC data exchange formats,such as plain text,simple URLs or enriched URLs.Using a wide variety of physical form factors,NFC-compatible tags(wireless transponders)are currently available in many locations with applications going from smart posters,contactless tokens,tap-and-go payments or transport ticketing to automated device configuration,patient identification at hospitals or inventory management within supply chains.Most of these applications handle sensitive processes or data.This paper proposes a complete security threat model for the read/write operation mode of NFC used in Next Generation Industrial IoT(Nx-IIoT)contexts.This model,based on a wellknown methodology,STRIDE,allows developers and users to identify NFC applications vulnerabilities or weaknesses,analyze potential threats,propose risk management strategies,and design mitigation mechanisms to mention only some significant examples.展开更多
Public transport plays an important role in the daily lives of hundreds of millions of people. The limited national and local finances starve the public transport networks of funding, although greater usage would impl...Public transport plays an important role in the daily lives of hundreds of millions of people. The limited national and local finances starve the public transport networks of funding, although greater usage would imply important environmental and financial benefits. The recent advances in mobile technologies and services could be harnessed to increase the attractiveness and efficiency of various public transport systems. Increasingly flexible electronic ticketing, smart cards and real-time information feeds via smartphones are making transportation networks faster, cheaper and more efficient for both the passengers and operators. In this paper, we present our approach in designing and implementing an M-ticketing system for urban transport based on NFC technology. We make initial design decisions based on a study of two similar systems Oyster and U-Go. We make use of Microsoft technologies for the prototype implementation and we propose a test suite to validate the system. We conclude on presenting the experience gained from this project and propose a set of further developments in order for the prototype to become more realistic.展开更多
针对目前Web站点的身份认证安全问题,提出了一种基于手机令牌和近距离无线通信(NFC,near field communication)技术的身份认证方法,并在Android平台上实现了该系统.该系统利用手机使用手机令牌实现了USBKey的主要功能,当用户访问站点进...针对目前Web站点的身份认证安全问题,提出了一种基于手机令牌和近距离无线通信(NFC,near field communication)技术的身份认证方法,并在Android平台上实现了该系统.该系统利用手机使用手机令牌实现了USBKey的主要功能,当用户访问站点进行注册时,将获得惟一的手机令牌并存于带有加解密功能的手机中.在下次访问站点进行身份认证时,用户可通过手机直接在Web站点进行身份认证,也可通过NFC技术将手机令牌传于PC机,使得用户可在PC机上利用手机进行身份认证.该系统将手机作为类USBKey设备,在增强Web站点身份认证安全的同时,省去了为用户颁发USBKey的流程和成本,具有较强的实用价值.展开更多
文摘This article presents a procedure for electromagnetic field and polarization control with antennas. The concept previously introduced by the authors for spatially distributed three-dimensional electromagnetic polarization (as time varies) is discussed and extended also to include non-ideal antennas and the control of electromagnetic field distributions (at a given instant of time). These polarizations and fields are herein referred to as “3D”, although time is also inherent to them. Even that the main objective is to introduce a mathematically/numerically consistent synthesis technique for controlling the 3D electromagnetic fields and polarizations, an effort is made to present and discuss possible applications, including but not limited to torus-knotted distributions and spatial multiplexing for transmission of information in wireless digital communication systems.
文摘针对现有的13.56 MHz NFC(Near Field Communication)天线因结构而引起回波损耗偏高的问题,设计了一种工作在13.56 MHz的近场通信天线,通过优化天线结构,有效降低了天线的回波损耗。使用Ansoft HFSS(High Frequency Structure Simulator)进行天线模型的设计以及仿真分析,对NFC天线的3大结构参数(天线边长L_x、线间距S和线径W)进行了仿真分析探究,最后得到以13.56 MHz为中心频率的最优天线结构参数,即L_x=40 mm,S=1 mm和W=0.5 mm。在上述天线结构参数下,优于已有的NFC天线(回波损耗为-22.2 d B),其回波损耗降低至-28.8 d B,-10 d B以下的带宽为0.8 MHz。
文摘Radio Frequency IDentification(RFID)and related technologies such as Near Field Communication(NFC)are becoming essential in industrial contexts thanks to their ability to perform contactless data exchange,either device-to-device or tag-to-device.One of the three main operation modes of NFC,called read/write mode,makes use of the latter type of interaction.It is extensively used in business information systems that make use of NFC tags to provide the end-user with augmented information in one of several available NFC data exchange formats,such as plain text,simple URLs or enriched URLs.Using a wide variety of physical form factors,NFC-compatible tags(wireless transponders)are currently available in many locations with applications going from smart posters,contactless tokens,tap-and-go payments or transport ticketing to automated device configuration,patient identification at hospitals or inventory management within supply chains.Most of these applications handle sensitive processes or data.This paper proposes a complete security threat model for the read/write operation mode of NFC used in Next Generation Industrial IoT(Nx-IIoT)contexts.This model,based on a wellknown methodology,STRIDE,allows developers and users to identify NFC applications vulnerabilities or weaknesses,analyze potential threats,propose risk management strategies,and design mitigation mechanisms to mention only some significant examples.
文摘Public transport plays an important role in the daily lives of hundreds of millions of people. The limited national and local finances starve the public transport networks of funding, although greater usage would imply important environmental and financial benefits. The recent advances in mobile technologies and services could be harnessed to increase the attractiveness and efficiency of various public transport systems. Increasingly flexible electronic ticketing, smart cards and real-time information feeds via smartphones are making transportation networks faster, cheaper and more efficient for both the passengers and operators. In this paper, we present our approach in designing and implementing an M-ticketing system for urban transport based on NFC technology. We make initial design decisions based on a study of two similar systems Oyster and U-Go. We make use of Microsoft technologies for the prototype implementation and we propose a test suite to validate the system. We conclude on presenting the experience gained from this project and propose a set of further developments in order for the prototype to become more realistic.
文摘针对目前Web站点的身份认证安全问题,提出了一种基于手机令牌和近距离无线通信(NFC,near field communication)技术的身份认证方法,并在Android平台上实现了该系统.该系统利用手机使用手机令牌实现了USBKey的主要功能,当用户访问站点进行注册时,将获得惟一的手机令牌并存于带有加解密功能的手机中.在下次访问站点进行身份认证时,用户可通过手机直接在Web站点进行身份认证,也可通过NFC技术将手机令牌传于PC机,使得用户可在PC机上利用手机进行身份认证.该系统将手机作为类USBKey设备,在增强Web站点身份认证安全的同时,省去了为用户颁发USBKey的流程和成本,具有较强的实用价值.
