Reviewing the RF safety issue in cellular telephones

Sources of RF radiation in the human environment continue to proliferate. New applications of RF energy in telecommunications are being developed at an astonishing rate. As for other RF-emitting devices, concerns have been raised as to the safety of cellular telephones. Cellular telephone base station emissions have been measured and found to be below exposure standards developed by the NCRP and the ANSI. In some cases, handheld and portable units may generate dose rates which approach the NCRP and ANSI standards for localized SARs. RF radiation standard development has been ongoing for over 50 years and substantial information has accumulated regarding RF energy absorption in man. This growing knowledge is reflected in the recent revision to the ANSI RF radiation exposure standard, which emphasizes the dynamic nature of such standards. Continued research on RF health hazards are being led by federal agencies and industry. Thus far, no supportable evidence has been brought forth to show that exposure to non-ionizing radiation from cellular telephones causes adverse health effects     

Risk of human exposure to cellular mobile communication radiation

Most of our knowledge concerning the biological effects of radio frequency (RF) radiation from wireless communication devices has come out of investigations conducted using experimental animals, such as rats, mice, etc. When it comes to the impact of RF radiation on human health and safety, epidemiology can play a pivotal role because it is a study of the distribution of disease and its determinants in human populations. To examine if exposure to wireless communication radiation is involved in cancer induction and promotion, it is necessary to collect data from people with similar backgrounds, other than RF exposure     

Health effects: scientific research and mobile phone testing

A decade ago, a major research initiative, with orchestrated monetary and programmatic support from both industry and the government, was launched to investigate the biological effects and health implications of radio frequency (RF) radiation emitted from cellular mobile telephones. The subject remains a focus of public concern and shows no sign of relenting. There is a lack of scientific consensus on experimental studies that provide clear evidence either refuting or supporting the cancer induction or promotion potential of RF and microwave radiation from cell phones. The uncertainties persist, in part, because of the limited number and scope of studies that have been undertaken.     

Human EEG and microwave radiation from cell phones

The effects of exposure to microwave radiation from cellular mobile telephones on human brain wave potentials or electroencephalograms have been studied. In particular, a large number of small, metallic electrodes typically are placed upon a subject's scalp, with electrically conducting paste or a glue-like substance to hold them in place. Low voltage signals (< 500 /spl mu/V) are amplified by the electronics in the EEG recording system. The resulting polygraphic display is then read by unaided visual inspection, followed by spectral analysis.     

Health effects - effects of cell-phone radiation on lymphoma-prone mice

Discusses the incidence of lymphomas in mice following long-term exposure to pulse-modulated microwave fields similar to those used in digital cellular mobile telephones. The mice are predisposed to developing lymphomas spontaneously.     

Bloelectromagnetics Research Activities in Europe [Health Effects]

A recent report issued by EMF-NET offers a lengthy list of European projects on the biological effects of power line and wireless communication electromagnetic fields. The list also includes projects on potential risks related to exposure in the working environment. The EMF-NET project is an initiative of the EC and is titled "Effects of the exposure to electromagnetic fields: from science to public health and safer workplace." This four-year project, which is to conclude in 2008, is one of the most ambitious and all-encompassing programs funded by the EC to date. It targets exposures from a wide range of nonionizing electromagnetic-energy-emitting devices, sources, and systems - including power lines, cellular mobile phones, base stations, broadcasting antennas, and household electrical appliances such as mixers and induction ovens (IH hobs) - as well as various electromagnetic equipment found in industry environments and health care facilities     

Siliconization of 60 GHz

Silicon-based RF and microwave technology has had a dramatic impact on the world of wireless technology. We can now access voice/data and entertainment in virtually every corner of the globe--with everything from short range Bluetooth and WiFi networks to cellular and satellite networks--to meet different range and throughput requirements. A laptop computer without wireless capability is unthinkable today, whereas, ten years ago, these technologies were in their infancy.What do the next ten years hold? What gaps in wireless technology exist even today? Perhaps the most obvious missing link is between the various devices that we carry with us, such as cellular phones or personal digital assistants (or smart phones if you prefer), digital cameras, music and video players (such as the ubiquitous iPod), laptops, and peripherals such as external hard drives and monitors. The case of the mobile smart phone is particularly important since the existing wireless connectivity is either too slow and power hungry (Bluetooth) or designed and optimized for longer ranges (WiFi). What is missing is a wireless universal connectivity that can support high data rates demanded by large data rate multimedia applications. Wireless technology has been conspicuously absent from MP3 music players (such as Apple's iPod), which are ideal candidates for downloading music and video. While ultrawideband (UWB) technology using the 3--10 GHz band promised to fulfill these needs, it fell short in many ways, and, today, most of the start-up companies pursuing UWB have folded.     

Risks to children from cellular telephone radiation

Are children more vulnerable to the microwave radiation from cellular mobile telephones? It is an open question. The paucity of laboratory results should make anyone hesitate in making definitive remarks on the health and safety of mobile-phone radiation on children. On the other hand, there have been plenty of computational studies on deposition of mobile-phone radiation or the specific absorption rate (SAR) in head models of youngsters and adults.     

In-vehicle WLAN radio-frequency communication characterization

Recently, new standards have emerged in the telecommunication industry, which provide an open global specification that enables mobile devices to access and interact with information and services instantly. These mobile devices are, for example, laptops and personal digital assistants. These emerging standards, generically called wireless "x" area networks (WxAN), will in the future be frequently operated from inside vehicles as part of the deployment of mobile offices and to support advanced intelligent transportation system services. These wireless networks currently operate between 1-6 GHz, although 60 GHz could be used when the technology will be economically viable. These mobile devices are frequently put to use in vehicles. To be ensure that portable equipment left in a jacket pocket somewhere in the trunk can interact with other car equipment or portable objects elsewhere in the car needs some investigation. Thus, this paper characterizes radio-frequency propagation inside vehicle bodies, with passengers, in order to evaluate the effectiveness of such a WxAN in vehicle environments.     

High temp superconductor RF devices

Recently, considerable interest has been expressed for superconducting radio frequency (RF) devices for commercial and government applications. One very interesting example is the application of superconducting RF filters for cellular base stations. The reason is quite clear: RF filters based on superconductor materials are fundamentally more efficient than normal-metal filters. They allow a system to use more of its allocated RF spectrum by reducing “guard bands”, and they allow cellular base stations to cover more ground. Many cellular base station systems engineers are beginning to seriously consider using this technology. Companies, such as Motorola, AT&T and others, have teamed up with R&D labs to investigate the idea. This article gives the reader a brief introduction to the technology and its potential impact on wireless communications systems     

Health effects: hearing microwaves: the microwave auditoryphenomenon

The possible health risk associated with mobile telecommunication devices, used close to the human head and, in particular, effects on the inner ear and hearing of users have been recommended for further investigation by several groups. Recently, a number of projects have been initiated to investigate the structures and functions of the middle and inner ear following exposure to wireless communication radiation. The microwave auditory phenomenon, or microwave hearing effect, pertains to the hearing of short pulses of modulated microwave radiation at high peak power by humans and laboratory animals. Research into this effect is examined     

Microwave exposure and safety associated with personal wireless telecommunication base stations

There are considerable public concerns regarding the biological effects and safety of microwave exposure from wireless base stations. There have been repeated calls for measures and tools that would reduce the exposure to microwave radiation from cellular mobile telephone operations. The radiated power from a base station antenna can vary from less than 1 to as high as 500 W per channel (or transmitter), depending on the location and type of the antenna used for a cellular communication system. The level of public exposure to microwave energy from any base station varies depending on antenna type, location, and distance from the base station. The microwave exposure a person receives from a base station thus depends on both the distances from the antenna, and the angle below the direction of the main beam.     

Cell phone microwaves and cognitive function in children

Are cell phones so harmful that a cautious approach of risk management especially in relation to children should be taken? Are the brains of children more susceptible to the radio frequency (RF) fields emitted by cell phones than those of adults? Some fear any disturbance to brain activity in children could lead to impaired learning ability or behavioral problems. Moreover, any lasting biochemical effects could have important consequences, especially in the young who still have years of development ahead of them. This paper report the results of test conducted to young users of cellular mobile telephones.     

High-efficiency, multi-mode, multi-band terminal power amplifiers

Ubiquitous coverage, the ability of a mobile device to wirelessly communicate as intended from any location in the world, is not a reality today. Multiple wide-area and local-area wireless systems are now deployed in various places around the world. These mobile systems include cellular, local area networks, personal area networks, and specialized networks. Characteristics of these systems span a broad combination of constant-envelope and envelope-varying signals, time-division (half duplex) and code-division (full duplex) multiplexing, and high (several watts) to very low (microwatts) transmitter output powers. As a result, demands on the RF power amplifier (PA) in a multi-mode application are daunting. Linear RF techniques are unlikely to meet all requirements for near-future mobile terminals - particularly the need to simultaneously realize long mobile-battery life while also providing multi-mode operation using bandwidth-efficient signals. Initial results show that newer polar techniques meet many of the objectives for multi-mode and multi-band mobile terminals, including those for battery life. This is information on the cutting edge of RF progress. This article compares and contrasts advanced architectures and presents encouraging preliminary direct polar modulation results.     

Bioelectromagnetics researches in Japan for human protection from electromagnetic field exposures

Research works on bioelectromagnetics in Japan are reviewed with a focus on the efforts devoted to the issue of human protection from electromagnetic field (EMF) exposures. History of this issue in Japan is briefly reviewed first for all EMF spectra. Then research works on radiofrequency (RF) EMF are summarized in more detail. The RF studies reviewed are mainly conducted in the framework of research program by the Ministry of Internal Affairs and Communications (MIC) started in 1997. Because of this program, collaborations between biology/medicine and engineering have been promoted. The results consistently show no evidence against the safety of RF‐EMF within the exposure levels of internationally accepted guidelines. © 2016 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

RF CMOS come of age

Radio-frequency integrated circuits (RFICs) in complementary metal-oxide semiconductors (CMOS) are developing a strong presence in the commercial world. They are dominant for applications such as wireless LAN and Bluetooth and are making inroads into areas such as global system for mobile communications (GSM) cellular transceivers and global positioning system (GPS) receivers. This article offers a brief retrospective on how RF circuits and systems in CMOS have evolved to their current state of the art, followed by perspective of what the future might hold for RF systems on a chip (SOC) in CMOS. It seems appropriate today, roughly ten years after the first publications reporting RF circuits in CMOS, to document the key developments and first reports of the circuit techniques and architectural innovations that are now in widespread use for the development of a new generation of RFICs.     

Development of a mobile spreadsheet-based PID control simulation system

The use of the electronic spreadsheet as a modeling and simulation tool in the engineering fields is increasingly popular with an increasing number of tertiary institutions, including spreadsheet as a teaching resource in the core curriculum of these fields. Concurrently, the dramatic improvement in Internet speed allows certain course material to be delivered online, facilitating electronic-learning (E-learning). E-learning frees students from the restriction of time, although they are still largely constrained by space to the nearest wired computer. However, the boundary of computing has expanded with the advance in wireless communication; now numerous handheld mobile devices (e.g., personal digital assistants (PDAs) and cellular phones) are available that will allow computing to be accomplished on the move. In turn, this wireless trend has contributed to move E-learning toward mobile learning (M-learning). Based on the previously mentioned trends, this paper presents the development, implementation, and evaluation of a mobile spreadsheet-based Proportional, Integral, Derivative (PID) control simulation system that aims to enhance the learning of the student in the field of control engineering. The system has been used in an industrial control system course at the National University of Singapore (NUS), Singapore. The mobile spreadsheet system developed is able to work with most handheld mobile devices, including the cellular phone. The methods and difficulties (e.g., limited storage space and small screen display of a cellular phone) involved in the development of the system will be duly discussed. Feedback from students that is used to assess the usefulness of the system will be released to share the benefits of such an M-learning system.     

EGPRS 中的冗余递增

EGPRS中采用冗余递增技术,通过空中接口（RF）实现最大效率。通过采用冗余递增技术,只有在收到的数据带有误码时,系统才会发送纠错数据（冗余）,从而大大提高了空中式,以提供最大的数据吞吐量。接口的效率。本文介绍了冗余递增的工作方式,讨论了怎样使用这种技术调节链路,在必要时改变编码和穿孔格采用冗余递增技术的无线器件设计人员面临着许多问题,如内存问题,从复杂算法的故障侦测,到器件的正常工作状态等及一般操作。本文阐述了测试冗余递增和无线器件接收机性能可采用的方法。通过这些方法,用户/开发人员可以检查运行情况,准确地查看器件在不同的空中接口条件下的性能、运行状态、数据吞吐量和存储器状态。     

无线测控定位系统移动终端射频子系统的设计

本文主要讨论用于某无线测控定位系统的移动终端射频子系统的主要构成电路及芯片选择,并且对芯片要求及电路的设计做相关的讨论。该无线测控网定位系统上行通信为835～837MHz的直接序列扩频通信,实现传输无线定位信号功能;下行通信为280MHz窄带寻呼通信,实现传输命令数据功能。本文通过对该无线测控网定位系统的分析,介绍满足系统要求的射频收发子系统构成及具体芯片,并为系统设计提供必要的分析和计算。