Low-profile patch antennas for biomedical and wireless applications

Printed microstrip-fed antennas based on a slotted radiating patch are proposed herein. First, a basic rectangular antenna without any slots was designed, being suitable for wideband applications and showing impedance bandwidth of 2714 MHz for \(S_{11} < -10\) dB. Next, dual-band operation for worldwide interoperability for microwave access (WiMAX, from 3.11 to 3.97 GHz) and wireless local-area network (WLAN, 4.97–5.71 GHz) was obtained by including slots only on the left side of the basic design. Then, using a structure with slots on the right side of the radiating patch, WLAN operation was obtained in the frequency range of 2.865–2.096 GHz. The fourth antenna, with slots on both sides of the patch, was characterized and realized for biomedical applications at 2.45 GHz (\(S_{11} <-10\) dB). The proposed antennas can be realized with small ground plane size and total antenna area of only \(27.5 \times 21\,\hbox {mm}^{2}\). This reduction in total antenna area is achieved by using a truncated patch. All the simulations were carried out using Empire XCcel. The designs were characterized based on their radiation pattern, return loss, voltage standing wave ratio (VSWR), gain, and current distribution. The simulated and measured results show good compatibility.     

Frequency-reconfigurable antennas for multiradio wireless platforms

Looking to increase the functionality of current wireless platforms and to improve their quality of service, we have explored the merits of using frequency-reconfigurable antennas as an alternative for multiband antennas. Our study included an analysis of various reconfigurable and multiband structures such as patches, wires, and combinations. Switches, such as radio-frequency microelectromechanical systems (RFMEMS) and p-i-n diodes, were also studied and directly incorporated onto antenna structures to successfully form frequency-reconfigurable antennas.     

Electromagnetic modeling and analysis of wireless communication antennas

The goal of this article is threefold: to present the basic principles of the application of method of moments (MoM), finite-difference time-domain (FDTD) and finite-element method (FEM) to analysis of antennas; to present examples of antenna simulations that show the capabilities of some modern commercially available simulators; to discuss future trends in modeling and analysis of microwave and millimeter-wave antennas for wireless communications.     

A low-cost wireless platform for first-year interdisciplinary projects

This paper presents a low-cost wireless circuit that is demonstrated to be a simple, yet flexible platform to support a variety of low-level educational activities. The circuit, implemented by many for K-12 outreach activities, is based on a 555-timer and an AM radio transmitter. At the University of Vermont, Burlington, this CricketSat circuit has enabled the development of a wide variety of wireless sensor and actuator projects. In this paper, design specifics, circuit utilization within an interdisciplinary first-year design course, and assessment results are presented. The novelty of the approach is twofold. First, the course and projects pertain to the area of wireless sensor networks. Second, student groups come up with their own project applications and problem statements for which to design a system. The key finding is that this platform has enabled students to take ownership of a concept and bring it to a working reality within the time constraints of a single semester course.     

Duo triangle-shaped rectangular microstrip-fed patch antennas input and output parameters investigation

Conventional rectangular microstrip-fed patch antennas are initially investigated numerically within the frequency band 2.0 to 2.8 GHz for Wi-Fi applications. In order to enhance the input parameters of the underlying antennas, three prototypes are designed. A split is diagonally loaded on a conventional radiating patch to achieve a duo triangle-shaped microstrip-fed patch antenna in the first step. The conducting ground plane of the conventional and the duo triangle-shaped patches is modified to design the microstrip-fed monopole and duo triangle-shaped monopole antennas in the second and third steps, respectively, within the frequency band of 2.0 to 7.0 GHz. Concepts of voltage and current waves as well as classical electrostatics approach solutions are used to, respectively, investigate the return loss bandwidth and the electric field radiation pattern of the proposed antennas. Numerical simulations show some relevant antenna performances such as a triple-band, a −10-dB return loss bandwidth of 29% , a gain of 7.5 dB, and a calculated half power beam width of 120^° in E-plane.     

一种无线光通信中空间分集技术

针对移动无线光通信中,由于平台抖动、大气湍流等原因造成瞄准偏差,从而影响系统误码率的问题,本文提出一种采用双光束发射双发散角的空间分集技术。在系统的发射端中使用光分路器,将一束光分成两束发散角大小不同的光进行传输。经过计算表明,该方案能有效地降低系统的误码率,改善信噪比和提高稳定性。这种设计方案可以成为移动无线光通信传输系统中切实可行的方案。同时表明,双光束系统两束光发散角的最优选择与偏差角度和传输距离密切有关。     

现代测量中的数据融合技术

近年来，作为面向复杂应用的高性能测量和自动控制集成系统正跨入传感、通信与执行为特征的新时代。在多传感器应用领域，数据融合技术能够充分利用不同时间和空间的测量数据信息，并汇集通信和控制于一体，从而大大提高测量系统的性能和效率，扩展测量系统的功能，成为现代测量包括电测与仪表范畴的关键技术之一。     

Theoretical computation of input impedance of gap-coupled circular microstrip patch antennas loaded with shorting post

In this paper, theoretical analysis of the input impedance of the two gap-coupled circular microstrip path antennas loaded with shorting post has been performed. The concept of coupled microstrip lines is applied to the gap-coupled microstrip antennas loaded with shorting post and using circuit theory approach the input impedance of the structure is calculated. The effect of mutual coupling between the radiating apertures has been taken into account. Simulated results are presented for input impedance of the gap-coupled circular microstrip patch antenna loaded with shorting post which supports the theoretical predictions. The simulation work has been performed using the method-of-moment based commercially available simulator IE3D. The comparison shows good agreement between simulated and numerically computed results.     

Equivalent circuits for repeater antennas used in wireless power transfer via magnetic resonance coupling

The demand for wireless power transfer via magnetic resonance coupling is increasing. Magnetic resonance coupling is a new technology that achieves power transfers across a large air gap by using transmitting and receiving antennas. However, repeater antennas can enable power transmission across an even larger distance. These repeater antennas without cross coupling can be expressed as a T‐type equivalent circuit. Equivalent circuits that include cross coupling and mutual inductance, which is related to the antenna position, have not been studied. In this paper, a novel way to represent a repeater antenna by an equivalent circuit and a way to determine the mutual inductance are proposed and veri?ed by performing an electromagnetic ?eld analysis and experiment. © 2013 Wiley Periodicals, Inc. Electr Eng Jpn, 183(1): 51–62, 2013; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/eej.22360     

ZigBee技术在无线抄表中的应用

针对目前抄表系统存在的缺点和问题,提出了一种基于ZigBee无线网络平台的自动抄表系统的设计方案,介绍了整个系统的软硬件平台以及每个节点的功能和实现方法,深入分析了整个系统的工作原理及通信方式。     

采用无线通信技术的避雷器检测器

提出的避雷器在线检测方案能自动测量泄漏电流、记录雷击时间和累计雷击次数。避雷器检测器以微处理器（MPU）为核心,由太阳能电池和唤醒、泄漏电流采集、雷击计数脉冲、无线收／发控制、LCD显示等电路组成。避雷器在线检测系统由避雷器检测器、集中器（每个电力变电站使用1台,1台集中器可用短距离无线通信方式与64台检测器通信）、网络检测系统3部分组成。避雷器在线检测系统现场投运1年来,运行良好。     

无线市话PHS的组网技术

文章详细介绍了我国现有的个人接口系统(PAS，Personal Access System)、基于IP的PAS系统(iPAS，IP—based PAS)、中兴个人通信系统(ZXPCS，Zhong Xing Personal Communication System)三种主要小灵通系统核心网络的组网技术。讨论了它们各自的技术特点优势和演进过程，同时对PHS在电力专网中的无线接入和厂矿企业的区域应用前景进行了简要的分析。     

无线电鉴相定位技术的改进

在目前的定位技术中,能够实现厘米级定位的系统造价高,而造价低的系统精度达不到厘米级。本方案利用无线电鉴相定位技术,对载波信号进行鉴相,可使定位精度达到1cm。其方法是在机车轨道两端各安装一个无线电发射机,机车上安装接收机,当机车在轨道上行驶时,接收到的2列无线电波会产生相位差,利用这个相位差来确定机车的位置。在改进方案中采用了调制技术和倍频技术,并采用温顿天线同时接收2列无线电波,从而使该系统结构简单、成本低、可靠性高。     

Challenges facing technology assessment in modern health care

Clearly, a precise tool does not now exist for making technological assessments. Yet, however imperfect the process might be, technology assessment is a valuable tool for use by doctors, health-care providers, and hospital administrators to control the increasing cost of health care. Technological assessment allows hospitals to evaluate the safety, efficacy, and cost-effectiveness before the commitment to purchase new equipment. As advancements in medical technology continue, the concerns associated with moral and ethical issues related to quality of life become increasingly difficult to assess. Hospitals must place the needs of the community and the quality of patient care ahead of profits and the purchase of new technologies. Stuart Poston, administrator of Murray-Calloway County Hospital, best concludes the authors' discussion with his view on the importance of technology assessment: "If you keep up with technology and buy quality equipment, you can enhance your medical staff and maintain a solid financial base. Then you can afford new equipment"     

浅谈现代信息技术对会计的影响

信息变革以破竹之势冲击着传统行业,由此新生出各式各样的商业模式,如：虚拟工厂、网上银行、网上广告、网上采购、电子商务等等,且都表现出不凡的增长态势和良好的市场前景,正在抢滩传统商业模式的地盘。     

超大型地面天线辐射特性实地测量技术

针对口径超过 10 m 的超大型地面天线由于极高成本难以进行精确测量的难题,提出了基于无人机的平面近场实地测 量方法。 首先对无人机散射、定位精度及测量场区选择等影响天线实地测量结果的主要因素进行了仿真分析,确定了测量区 域。 采用多旋翼无人机和高精度飞控技术,在高性能无人机最好 20 mm 飞控精度、5 mm 测量精度的条件下,进行了天线实地测 量系统的射频链路设计,并给出了两种近远场数据变换方法,可以有效解决在较高频段无人机定位精度差导致测量结果不可信 的问题。 采用实例分析验证了方法的有效性,为超大型地面天线低成本精确测量提供了较好的解决途径。     

Dynamic interconnection component using wireless infrared technology

An efficient dynamic interconnection model using wireless infrared technology and the theory of optical interconnections was constructed to design a dual-channel interconnection component. There were three conditions between the rotating optical field and the stationary optical field: end separation, angle misalignment and lateral misalignment. The calculation formulas were given for these three conditions. A dual-channel optical interconnection component was designed based on the dynamic interconnection model and the data transmission rate of the component was measured. The experimental result showed that the dual-channel optical interconnection component could transmit optical signals across the rotating interface. The maximum transmission rate can reach 2.14 Mb/s. Translated from Journal of Tianjin University, 2006, 39(8): 985–988 [译自: 天津大学学报]     

超宽带无线通信技术及其应用

通过将超宽带（UWB）无线通信技术应用于组建无线个人局域网（PAN）和无线多媒体网络,可实现数据在近距离范围内的高速传输,并有效地解决了信道衰减、成本高和功耗大等难题,同时,UWB技术也可应用于探测、定位、成像等方面.文章通过介绍UWB无线通信技术的基本概念,分析了它的2种调制方式以及性能特点,最后详细介绍了其在无线通信中的应用.     

无线技术在上海电力中的应用

无线应用在上海电力数字化进程的发展中需求越来越强烈,以营销的抄表系统和通信网络应急系统为代表。目前,无线技术呈现多元化发展,如GPRS、CDMA1X等,并已大量商用;而一些基于专网应用或数据应用的还有类似卫星Modem、CDPD、MOB ITEX以及基于IEEE 802.16标准的W iMAX等,都是既可以实现语音也可以实现数据传输的无线网络和技术,给用户提供了多样选择的机会。文章通过对上海电力无线应用现状描述、无线技术发展的比较、无线应用的需求分析,提出了适合上海电力系统的无线应用建议。