共查询到20条相似文献,搜索用时 62 毫秒
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本文提出一种用于组成无线能量传输(Wireless Power Transmission,WPT)系统的微带天线结构,并采用基于有限元法的电磁仿真软件(HFSS)对微带天线进行3D建模.在二端口网络分析法的基础上,建立磁耦合共振无线能量传输等效电路模型,求解出系统发生频率分叉现象产生的条件以及最大效率时的频率表达式.基于以上方法,研究本文设计的微带天线传输特性,包括:系统的最优传输效率与耦合距离的关系,工作频率与耦合距离的关系,得出在能量传输距离在50cm左右时,天线的谐振频率为12.5MHz,效率可达63%.微带天线具有很大的结构优势,如与集成电路兼容,成本低,体积相对较小,且工艺相当成熟,易大规模批量生产等优势.因此该设计的平面微带天线可用于无线能量传输系统. 相似文献
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介质损耗对频率选择表面传输特性的影响 总被引:5,自引:0,他引:5
应用模匹配技术,研究了Y形缝隙平面周期阵列夹嵌于均匀有耗介质中心的夹心频率选择表面(FSS)结构对平面波的传输特性。讨论了介质层对结构中心谐振频率、传输带度、以及传输损耗的影响规律。相同介电常数的介质材料在有耗和无耗情况下的模拟分析结果清楚表明介质本身的损耗是影响FSS结构损耗特性的主要因素。 相似文献
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在印制电路板(PCB)上,如果有高速信号进行长距离传输,其传输会因损耗、反射、串扰等方式引起信号完整性(SI)问题,很大概率会造成信号失真,在各个接收端无法完全复原驱动端信号.伴随着当今互联网数据量的快速增加,路由器和交换机等高速率通信设备的研究和设计非常重要,其中的关键传输通道——高速串行链路成为主要技术实现难点.基... 相似文献
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当今 ,光通信在CATV领域得到迅猛发展 ,全国光纤大联网的格局已定。虽然光传输已是众人皆知 ,但是光传输系统的重要载体———光纤 ,许多工程技术人员对它的认识仅停留在表面。下面通过对光纤特性的论述 ,使读者对光纤有一个整体的认识。1 光纤的物理特性(1)光纤是光导纤维的简称。它是用石英玻璃或特制塑料拉成的柔软细丝 ,直径在几 μm(约为可见光波长的 10倍 )到 12 0 μm。在实际应用中 ,石英玻璃光纤因传输损耗小而得到广泛应用。塑料光纤的损耗较大 ,可达到每公里几十分贝以上 ,但塑料比玻璃易于弯曲 ,可以做成粗光纤用于可见… 相似文献
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为了研究三种不同散射相函数下紫外光大气传输特性,文章采用非直视紫外光通信的单次散射简化模型,对系统接收机接收到的能量及紫外光传输路径损耗随传输距离和散射角的变化情况进行分析.结果表明:三种相函数下,都表现为随传输距离的增大,接收能量减小,路径损耗增大,但三者之间存在一定的差异,对于紫外光通信系统,其传输性能的影响以前向散射为主,后向散射作用很小;随着散射角增大,后向散射作用相对明显;三种散射相函数下,紫外光通信链路的最佳散射角不同,但均随发射仰角的增大或接收仰角的增大最佳散射角增大,而接收能量减小. 相似文献
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It is important to characterise the indoor radio propagation channel to ensure satisfactory performance of a wireless communication system. Site measurements can be costly; propagation models have been developed as a suitable low-cost alternative. The existing models can be classified into two major classes: statistical models and site-specific propagation models. Statistical models rely on measurement data; site-specific propagation models are based on electromagnetic wave propagation theory. The ray-tracing technique is very useful in site-specific propagation modelling. This paper gives an overview of indoor propagation modelling and concentrates on a discussion of the ray-tracing modelling technique because of its practical appeal and its applicability to any environment 相似文献
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Propagation prediction models for wireless communication systems 总被引:3,自引:0,他引:3
A comprehensive review of the propagation prediction models for terrestrial wireless communication systems is presented in this paper. The classic empirical models are briefly described and the focus is placed on the application of ray-tracing techniques to the development of deterministic propagation models. Schemes to increase the computational efficiency and accuracy are discussed. Traditional statistical models are also briefly reviewed for completeness. New challenges to the propagation prediction are described and some new approaches for meeting these challenges are presented 相似文献
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《AEUE-International Journal of Electronics and Communications》2014,68(12):1247-1252
The cooperative communication in wireless multi-hop networks is a reliable energy efficient mechanism that mitigates the effects of channel fading and improves the performance and throughput of the systems. In this paper, green cooperative multi-hop scheme is proposed by employing signal space diversity (SSD). The proposed scheme offers a significant improvement in performance of the regenerative multi-hop networks without the requirement of extra bandwidth or power. The expressions for the average end to end bit error probability of the multi-hop networks employing the SSD scheme is derived. The optimal relay location for a better performance and the total energy consumption of the scheme is also probed. The simulation results show that the proposed scheme provides better quality of service and is more energy efficient compared to the conventional decode and forward scheme in single-hop as well as multi-hop situations. 相似文献
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在无线视频通信中,无线信道环境的好坏将直接影响到通信质量,信号传输中的带宽.波动、高误码率和接收的异种性为视频通信系统的设计带来了极大的困难。讨论了无线信道电波传播的特性,给出了无线时变衰落信道的模型并分析了视频传输的信道失真,为复杂无线环境下的视频通信系统的设计提供了理论依据。 相似文献
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This paper discusses stochastic characteristics of hierarchical multi‐hop wireless networks. It is assumed that terminals
and base stations are distributed according to specific distributions, respectively. It is also assumed that a multi‐hop wireless
network is logically divided into clusters by a clustering algorithm. In this paper, the Lowest ID Cluster algorithm and another
simple clustering algorithm are considered. Using theoretical techniques based on the stochastic geometry, this paper analyzes
fundamental characteristics of the multi‐hop wireless networks with the clustering algorithms.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
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设计并演示一个可实现视音频信号同步无线传输的自由空间光通信系统。该系统包括信号发生、调制和接收模块。对由信号发生模块输出的视音频信号进行时分复用(TDM),复用信号以电信号形式作用于声光调制器(AOM)并将其加载于入射到AOM的激光束上,AOM输出调制光信号,最后接收模块还原出视音频信号。整个通信系统带宽为6.7 MHz,通过电-光-电转换过程,将时分复用和声光调制相结合实现了视音频信号同步无线传输。本系统针对具体工作环境,自建核心电路:时分复用/解复用电路和输出光端机电路,采用单片机调控输出信号质量。实验证明该系统具备成本低廉、实用性强和灵活性高等优点,为监控系统、应急通信等应用场合提供一种简易有效的视音频信号同步无线传输方案。 相似文献
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The second part of Spread Spectrum Techniques in Wireless Communication focuses on wireless transmission issues and implementation of a water quality assessment wireless system. I present concepts of electromagnetic propagation, some important issues in open space electromagnetic transmission particularly when a transmission link is over a conductive surface, and a simplified analysis of common occurrences that impair the transmission's quality or can even block the communication between network nodes. I introduce the primary techniques that are used to mitigate open space propagation problems, giving particular attention to solutions that can be used to mitigate fading effects in spread spectrum communication systems. Then, I present experimental results of a wireless transmission system used in water quality assessment. 相似文献