手机电磁辐射评估

介绍目前国内外对手机电磁辐射评估研究的进展,以及国际上对手机电磁辐射限值(SAR)的要求,并简要分析了SAR评估方法.     

Low SAR Ferrite Handset Antenna Design

The benefits resulting from the inclusion of ferrite in material loaded antennas are investigated, initially through the use of a spherical analytic model and then through a transmission line matrix simulation tool applied to a rectangular slab geometry. It is observed that a material with equality of relative permittivity and permeability in combination with specific positioning of the antenna in relation to the head, can result in the definitive small-size, high efficiency and bandwidth, low specific absorption rate (SAR) antenna. The accuracy of the simulations is validated both through efficiency and SAR measurements of three material coated monopole samples. Further research into optimizing the above attributes and translating them into a handset antenna leads to a multiband antenna design covering the GSM 1800, 1900, UMTS and Bluetooth bands, with a SAR value reduced by 88% compared to conventional phones and an efficiency of 38% at 1.8 GHz. A tri-band antenna design is also presented, utilizing currently available lossy ferrite material and it is considered as the first step towards the feasibility of the ultimate low SAR multiband ferrite handset antenna, until further material development specifically for antenna applications takes place     

多发射手机的FCC SAR测试技术要求

从工作频率、发射功率、天线间的距离、SAR分布等方面,阐述FCC对集成了多个同时发射的射频模块和天线的手机SAR测试技术要求,内容包括仅需进行单发射机模式SAR评估的条件、多发射模式的SAR测试判定原则和执行程序,以及头部模型的紧凑部位的替代测量方法等。     

Effects of Ear Shape and Head Size on Simulated Head Exposure to a Cellular Phone

The dependence of the specific absorption rate (SAR) on ear shape and head size have been investigated using human-head and cellular-phone models. Cubical and realistic head models were used. Various ear shapes were used with the cubical head model whereas a low-loss thin ear or a lossy realistic ear was used with the realistic head models. The SAR distribution depends significantly on the shape of the ear, regardless of the head model. The effects of the head size have been investigated using a 90th-percentile head model and a Japanese-average head model. The head size has considerably less effect than the ear shape. The measurement results have been validated by numerical calculation, and support the use of the specific anthropomorphic mannequin (SAM) standard head model.     

Reduction of the Peak SAR in the Human Head With Metamaterials

The electromagnetic interaction between the antenna and the human head is reduced with metamaterials. Preliminary study of SAR reduction with metamaterials is performed by the finite-difference time-domain method with lossy Drude model. It is found that the specific absorption rate (SAR) in the head can be reduced by placing the metamaterials between the antenna and the head. The antenna performances and radiation pattern with metamaterials are analyzed. A comparative study with other SAR reduction techniques is also provided. The metamaterials can be obtained by arranging split ring resonators (SRRs) periodically. In this research, we design the SRRs operated at 900 and 1800 MHz bands. The design procedure will be described. Numerical results of the SAR values in a muscle cube with the presence of SRRs are shown to validate the effect of SAR reduction. These results can provide helpful information in designing the mobile communication equipments for safety compliance     

利用FDTD方法比较手提电话天线的方向图,输入阻抗及人头部的比吸收率(SAR)(英文)

本文给出了利用FDTD电磁模拟方法对常用的五种个人通信手提电话的天线和人头部组织相互作用的比较研究。在研究中考虑的蜂窝通信手提电话常用的天线种类为单极子、偶极子和倒F型（IFA）天线。不均匀的实际人头模型被用于预测天线特性（包括输入阻抗，方向图和辐射效率等）和对操作作者耦合的电磁效应。天线在人头部的潜在危险影响是用1W辐射功率在人组织产生的比吸收率（SAR）来评估。     

电子元器件技术化解手机开发"瓶颈"

一直以来,手机开发就被业界公认为3G发展的“瓶颈”,要解决这个难题,需要技术进步、运营商推广及3G市场初步形成的规模经济效益等因素的推动,3G终端的最终完善也非常重要,这恰恰需要依赖于上游电子元器件技术的不断创新。可以说,未来手机的技术支点就是先进的电子元器件及其应用软件。从在天津举行的国际制造业(手机)配套采购洽谈会上可以发现,     

头部尺寸对头相关传输函数的影响

对不同尺寸大小的椭球简化头模进行HRTF仿真计算与实际测量,分析了头部尺寸对HRTF的影响.结果表明头部尺寸对HRTF幅度谱的影响,表现为不同尺寸头模对应的HRTF幅度值与谷点尖锐度会有一定的差异,而谷点位置基本不变.声源位于不同方位时,头部尺寸对HRTF幅度谱的影响大小不同.相比于耳朵同侧,声源位于耳朵异侧时差异更大...     

手机近场辐射的人体效应

手机的辐射对人脑的影响一直是人们关注的话题。首先建立手机辐射的电磁模型和人体头部电磁模型,利用FDTD法在900 MHz工作频率下模拟计算了人体与天线手机系统的辐射,并分析手机辐射对人体的影响。研究发现:在靠近人体模型一侧,人体模型内部,电场的减小速度较磁场明显;手机约有40.4%的幅射能量被人体模型吸收,其中头部吸收的电磁能量占总吸收能量的54.4%。     

手机广告业务初探

近年来,各类新型的移动增值业务如雨后春笋,层出不穷。其中,向手机、PDA等移动终端发送广告信息的手机广告业务正成为部分运营商和ISP关注的焦点,     

移动通信手机电池的工作原理及电气性能

简述了目前常用的移动电话手机电池的工作原理，介绍了手机电池的电气性能和检验方法。     

如何选择适合手机应用的开关

智能手机中通常都集成一个收音机、MP3播放器和照相机。这种多媒体应用的增长已经引起对高性能模拟开关传输高质量音频信号和铃声需求的增加。为了适应这些复杂的应用,手机的设计必须最大限度地减少元器件数量、减小封装尺寸、降低功耗和成本。本文将介绍如何利用几个专门设计的开关来解决上述问题。     

CSD在GSM-R手持终端的实现

介绍GSM-R手持终端实现CSD功能的方法.应用GSM模块MC55实现编组站调车指令500ms内端到端收发功能.     

基于NSCT-Gabor特征和脉冲耦合神经网络的SAR图像分割

针对SAR图像目标的精确分割问题,利用非下采样轮廓波变换(NSCT)和Gabor滤波器分别提取图像特征,然后采用脉冲耦合神经网络(PCNN)对目标区域进行增强,提出了一种分割算法。分别对图像进行NSCT分解和Gabor滤波,对NSCT域的高、低频子带系数构造一个特征图,对Gabor滤波的不同尺度构造对应的特征图,对所获取的各个特征图用PCNN进行目标增强,最后对增强的特征图进行合理合并与分割。利用MSTAR SAR数据库中各种干扰强度下的图像进行了实验,结果表明,相比于模糊C均值、马尔可夫随机场等常见的分割算法,所提出的算法分割结果更为准确,同时受噪声干扰更小。     

人体对移动通信手机天线辐射特性的影响

本文用时域有限差分法成功地模拟了移动通信中常用的单极天线手机的辐射特性，并考虑了实际使用条件下天线与人体的作用，计算得到了受人体影响时的天线辐射方向图的辐射效率。     

手机与人体系统近场的研究综述

文章探讨有关手机辐射与人体相互作用的主要研究热点、分析方法和模型特征,并展望了今后的发展趋势 和研究走向。     

Modified Sierpinski Fractal Monopole for ISM-Bands Handset Applications

Antenna design is a mature field of research; it is therefore rare that a new approach arises in view of the traditional methods. In the past antennas had simple form based on Euclidean geometry. Fractal antennas do not follow this design. Their complex structure is built up through replication of a base shape. The purpose of this research is to explore fractal element antennas, through simulation and design experimentation. This research revealed unexpected results, which provided additional insight into these unique structures. Results of MoM and FDTD simulation methods as well as measurements of physical models of the circuit- and field-antenna parameters are presented and discussed. Measurements well confirmed simulation.     

GPRS手机芯片中增强型通用定时器的设计

介绍了一种增强型通用计数器。它除了具有通用定时器的功能以外，还可以实现输出中断和信号控制，以及选择确定输入信号出现的时间。对于频繁的定时输出，更是可以用模锁存器控制产生定时中断输出。该设计已用于2．5代手机基带芯片中(芯片采用0．18μm工艺)。     

StarCore DSP结构--一种可扩展的手持设备设计方案

充分利用各种DSP应用上现有的软件对加速产品上市至为重要。这一点在支持最新标准的产品上体现得尤为明显。例如第三代移动通信对各种形式无线手持设备的需要在迅速增长,其中包括以声音、数据及媒体为主的平台等。     

智能机对移动分组域的影响

Smartphone的普及对移动核心网带来了信令及数据增长的挑战,运营商不仅需要通过构建新一代移动分组网应对信令及流量挑战,还需要依托移动分组网实施精细化流量经营,提供个性化数据业务,同时通过盘活网络资产,构建能力开放平台实现与OTT合作互赢。