Standard linear antennas, 30 to 1000 MHz

It is demonstrated that the insertion loss between pairs of thin, linear antennas may be calculated using fairly simple equations that are generally considered to be good engineering approximations. Although the insertion loss calculation does not involve antenna gain directly (some measurements are actually made in the near-field where gain is not defined), the result is precisely the quantity obtained using the antenna gains in Friis's transmission formula, assuming the mismatch losses are zero. Therefore, the antenna gain product is implicit in the more general insertion loss equations. The particular measurement of insertion loss used here yields a quantity called site attenuation by electromagnetic compatibility engineers. A close agreement between measured and calculated data provides confidence in the site attenuation calculations when the site is essentially perfect, and provides confidence in the gain product of the antenna pair calculated using basically the same equations as those used for insertion loss. It is assumed that one-half of the mean value of the difference between the calculated and measured data is a good estimate of individual antenna performance. For the antennas described here, this measure of performance is typicallylE0.05dB and on the outside,iE0.42dB.     

A time-domain method for characterizing the reflection coefficientof absorbing materials from 30 to 1000 MHz

A wideband time-domain reflectometer is used to evaluate the reflection characteristics of RF/microwave absorbers. The reflectometer uses an array of two identical broadband antennas (both transmitting and receiving). The two antennas are used in a difference mode to remove the undesired signals and enhance the small reflections being measured. Using this technique, one can separate the target surface reflection from those generated outside the target area. The bandwidth of the pulses is 30 to 1000 MHz, and the reflection coefficient is measured over this range. The method has been used to characterize the reflectivity of three different types of absorber placed in an anechoic chamber. The results are reported together with a discussion of the main sources of errors     

30MHz～1000MHz电场辐射干扰测试中测量不确定度的评估方法

文章以CISPR 16-4:2002为依据,讨论了在标准3m法电波暗室中进行30MHz-1000MHz电场辐射干扰测试时测量不确定度的评估方法.     

Technique for measurement of powerline impedances in the frequencyrange from 500 kHz to 500 MHz

A method for measuring power line impedances using two current probes is examined. This method is characterized by good isolation of the measurement equipment from the power line voltage and by the capability of measuring power line impedances between any pair of power-plug terminals. The use of this two-current probe method with the model described is effective in measuring power line impedances from 0.5 MHz to 100 MHz. Using purely resistive loads for calibration, the error is less than 5% for frequencies below 100 MHz, and less than 20% for frequencies between 100 MHz and 500 MHz. The error in an impedance measurement increases with the magnitude of the load impedance     

用于30MHz～1GHiz电磁辐射骚扰测量的全电波暗室场地校验方法

详细介绍了最新国际标准CISPR 16-1-4:2004第5.8条给出的两种评估方法-场地参考法(site reference method)和归一化场地衰减法NSA.为评估全电波暗室的性能提供重要技术依据.     

用于30MHz～1GHz电磁辐射骚扰测量的全电波暗室场地校验方法

详细介绍了最新国际标准CISPR16-1-4∶2004第5.8条给出的两种评估方法—场地参考法(sitereferencemethod)和归一化场地衰减法NSA。为评估全电波暗室的性能提供重要技术依据。     

The electric field induced in the human body when exposed toelectromagnetic fields at 1-30 MHz on shipboard

The electric field induced in the body of a man standing on the metal deck of a ship near a vertical antenna is determined analytically. Typical antennas for radio communication in the 1-30 MHz band are described and their near fields are calculated. The current induced in the man is determined by solving the relevant integral equation. Explicit formulas are obtained for the total axial current and the associated current densities and electric fields.     

解析25～1000MHz短距离设备电磁兼容欧洲标准

介绍短距离设备欧洲标准ETSI EN 300 220-1 V2.3.1的测试模型选取和测试条件;详尽分析频率误差、平均传导功率、有效辐射功率、扩频调制、瞬态功率、临近信道功率、调制带宽、杂散发射、频率稳定性和占空比等发射机参数,以及灵敏度、LBT阈值、临近信道选择性、阻塞性能、杂散抑制和接收机杂散等接收机参数;并对全电波暗室、半电波暗室和开阔场的试验场地、试验布置和测试方法进行分析说明。     

International comparison GT/RF 86-1 electric field strengths: 27MHz to 10 GHz

This paper describes the international comparison of electric field strength measurements at frequencies between 27 MHz and 10 GHz (GT/RF 86-1). The participating laboratories were NIST, Pilot Laboratory, USA, National Physical Laboratory, U.K., NMi Van Swinden Laboratorium, the Netherlands, Institute Elettrotecnico National, Italy, Laboratoire Central des Industries Electriques, France, Electrotechnical Laboratory, Japan, Korea Research Institute of Standards and Science, Korea, and Technical University of Wroclaw, Poland     

Development and characterisation of tissue equivalent materials for frequency range 30-300MHz

Two formulations for tissue equivalent liquids are presented and characterised in terms of dielectric properties in the frequency range 30-300 MHz. The purpose is to provide viable options for consideration by the standardisation bodies dealing with the assessment of exposure to electromagnetic sources in that frequency range     

A comparison of prediction methods for 800 MHz mobile radio propagation

The design and installation of a mobile radio system involves the evaluation or prediction of the propagation characteristics associated with the geographical area of interest. A wide variety of prediction techniques has been developed for different mobile environments, so that the task of selecting an appropriate propagation prediction method can be difficult and complex. This is especially true for systems operating in the upper-UHF band of 800-950 MHz, where mobile radio services are rapidly growing. A practical comparison is given of current prediction techniques available in the literature (for slow lognormal fading rather than multipath Rayleigh fading), with an emphasis on three essential criteria to consider in the selection process: the type of terrain or geography covered by each method, the form of prediction provided (e.g., transmission loss estimates, field strength contour maps, etc.), and the implementation difficulty and degree of sophistication.     

30～512MHz,100W线性功率放大器极间匹配设计

设计了一种独特的极间匹配网络,使驱动放大器的输出阻抗直接匹配到末级放大器的输入阻抗,而不通过极间50Ω匹配转换。应用这种极间匹配网络,提高了30～512 MHz,100 W功率放大器的线性输出功率和效率,同时简化了匹配网络,减少了匹配元件,缩小了功率放大器的体积。这种极间匹配网络是通过集中L、C匹配网络与宽带同轴传输线变压器相结合实现的。应用ADS软件模拟以及计算集中L、C元件的值和同轴电缆的长度,使设计的极间匹配网络在近十个倍频程的频带内获得最佳性能。     

二重结构30 MSPS采样/保持电路的研究与探讨

通过理论分析和实验仿真，对同相型采样／保持器（S／H）进行扩展改进，提出了三种高速的二重结构S／H电路，采样速率高达30 MSPS。实验表明，在维持采样高速率的前提下，这三种电路在一定程度上解决了截止开关电流泄漏的问题，从而降低了保持电容上的电压跌落率。     

Diffraction by a rectangular building: comparison of three field-strength prediction techniques

A comparison is made between three methods to calculate the electromagnetic field diffracted by a perfectly conducting block-shaped obstacle. The models, that are first briefly described, include a ray-based model (uniform theory of diffraction) and two wave-based models (Fresnel surface integral and parabolic equation method). A test case is analysed with all methods resulting in good agreement between the predicted results for both linear orthogonal polarisations.<>     

30～2 600 MHz超宽带GaN功率放大器的设计与实现

基于第三代半导体GaN的高电子迁移率晶体管技术,利用Cree CGH40010管芯大信号模型并结合ADS2009U1软件,结合商用GaN管芯的自身特性,采用微带-电阻-微带-电容-微带的负反馈回路和整体负载牵引方法及宽带匹配网络,成功设计并实现了30～2 600 MHz超过6个倍频程的超宽带功率放大器.测试结果表明,该功率放大器的带内线性增益大于11.8 dB,线性增益平坦度小于±0.95 dB,输入回波小于-10.2 dB,1 dB压缩点输出功率大于36.5 dBm,功率附加效率大于22％,饱和时输出功率大于39.1 dBm,功率附加效率大于28％.该功率放大器在很宽的频带内有着平坦的增益,适用于对平坦度要求较高的超宽带系统中.     

30MHz以下电动汽车的辐射发射抑制

介绍电动车辆30 MHz以下电场辐射发射和磁场辐射发射的测量方法。以某电动洒水车的实际测量为例,分析其电场和磁场辐射发射严重超标的原因,找到了主要骚扰源—逆变器,并提出对被测车辆加装遮挡和覆盖件等整改措施。整改后,电场辐射发射减少10 dB、磁场辐射发射减少20 dB,为电动汽车的电磁兼容性能优化提供了实践经验。     

一种30 MHz～3 GHz宽带高增益功率放大器

基于0.25 μm GaAs PHEMT 工艺,设计了一种可应用于甚高频和超高频的宽带高增益功率放大器。该功率放大器采用两级级联结构来克服功率增益的不足,采用堆栈结构来实现平坦的增益和输出功率。仿真结果表明,该功率放大器的工作带宽为30 MHz~3 GHz,小信号增益为(38.2±1.6)dB,输入输出回路损耗在-10 dB以下。在连续波测量模式下,输出1 dB压缩点为(35.3±1.0)dBm,功率附加效率为16.8%~11.0%。     

An eighth-order CMOS low-pass filter with 30-120 MHz tuning rangeand programmable boost

A CMOS low-pass filter with programmable boost is presented. The architecture is a G_m/C type with the G_m value controlled through a resistor servo approach. The transfer function has been optimized in order to reduce the sensitivity to component parameter variations. The 1:4 tuning range is achieved by exploiting a dual-loop control over a degenerated differential pair. At the nominal output voltage swing of 200 mV_pp differential, a THD better than 40 dB is guaranteed. The high-frequency boost is programmable between 6 and 14 dB. This filter, realized as a cascade of biquad and first-order cells, is implemented in a 0.25-μm 2.5-V CMOS technology. It dissipates 120 mW with f_c=120 MHz and has a die area of 0.23 mm²     

Muscle-equivalent phantom materials for 10-100 MHz

New tissue-simulating materials that are aqueous solutions are described. Glycine is used to obtain the large permittivity of muscle at frequencies below 100 MHz. The lack of suspended solids simplifies preparation, and ensures the dielectric properties are homogeneous, stable, and reproducible. The solutions are transparent, facilitating placement of probes for measuring temperature or electric field. The optical clarity of the phantom mixture may also be desirable in a quick assessment of RF applicators by the use of liquid crystalline display sheets