调频天线驻波比过大故障分析与维护

天津调频天线采用6层4面双偶极板天线,承载功率120kW.本文针对机房开关板上反应的驻波变大现象进行逐级排查、分析,并对判断步骤、维修方法进行阐述,给出天线振子由于进水导致驻波变大的解决方法.     

业余电台的天线

天线是无线电收发信机的窗口，窗口开小了，电波进出受阻，收、发效果均会不佳。对于业余电台来讲，天线的好坏更是通信距离远近的关键。业余电台的电波频率与传播方式业余电台经常使用的频率分布在1．9～28MHz及144～146MHz之间。由于频率不同，电波的传播方式也不同，对天线的要求也不同。电波传播的方式有地波、天波、空间波等几种：①地波就是沿着大地表面传播的电波。一般用于低频率、近距离的通信，如1．9～3．5MHz。②天波是利用高空大气层中的电离层进行反射的原理来传播电波，见图1。天波可用于越洋远距离全球通信，使用频率为3…     

短波天线与通信效果

笔者曾多次参加部队野战演习、通信台站的报务考核及友邻部队通信演练的技术保障工作。在对短波电台进行检查过程中，发现相当一部分单位存在着在传统的短波通信中往往只注重发射机的输出功率(或接收机的灵敏度)和频率选择，而忽视天线的作用；随着短波自适应通信电台的应用，又过分依赖设备，而忽视天线的作用的现象。而且在天线架设、使用和管理方面存在着一些问题，有必要尽快加以改进，以使短波电台更好地发挥它应有的作用。     

浅析CATV系统接收天线

讨论了CATV系统接收天线的工作原理、主要技术指标以及VHF频段（或部分频道）天线有源（或无源）振子大小、间距与频道的关系，并给出了常用的3单元、5单元和7单元引向天线的一系列参考数据。     

2016主流业余无线电台新设备一览

在2016年中,业余无线电台设备又有很多新品与魏们见面,业余电台设备主力厂家YAESU和ICOM都发布了新品,更新了产品线,使得HAM有更多的新款电台设备玩,通信界的很多新技术新应用都在新款业余电台设备上得以应用,使喜欢玩通信设备的HAM紧随时代的科技步伐。     

浅析智能天线在电磁环境监测中的应用

1 引言 随着信息技术的迅速发展,无线通信设备的种类和数量迅速增加,呈现出大功率、高频率、宽频段、智能化的用频特点,电磁环境变得日益复杂,频谱资源管理面临新的挑战。电磁环境监测是频谱资源管理的有效手段和必要基础。目前,我国已经形成了以固定监测站为主,可搬移监测站（含车载）、便携式监测设备为辅的无线电监测网体系。     

巧用拉杆天线——浅谈可调谐频率的J型天线

这段时间我制作了几种UHF频段的手持电台天线，有Moxon天线、J型天线和J型折合天线。这几种天线都有谐振频率，尤其是J型折合天线，做好的几个天线可以将驻波比调到1．1左右，但装入PPR塑料管后驻波会有很大变化，给封装天线带来困难。为了达到预定的频点，还得精调振子的尺寸。往往天线很快做好，但调试需要花费很多时间，很考验制作者的耐心。     

户外通联进阶（上）

金秋十月，秋高气爽，让我们放飞心情，扑向大自然的怀抱吧！     

推动业余无线电台事业健康有序发展初探

山东省东营市虽然是一个石油新兴城市,但业余无线电活动自1983年建市之初就开始出现了。随着经济社会的高速发展,业余无线电爱好者以及业余电台数量与日俱增。多年来,东营市无线电管理办公室(以下简称"东营无管办")本着积极扶持、正确引导、加强监管的方针,推动全市业余无线电事业健康有序发展。     

Axial ratio of balanced helical antenna and ellipticity measurement of incident wave

The axial ratio of a balanced helical antenna shows a wavelike change with increase in the number of helical turns The ellipticity measurement of an incident wave is carried out using the balanced helical antenna with excellent axial ratio regarded as being entirely circular polarisation.     

对测绘无线电台的检测

近年来,江苏省无线电管理部门加强了对辖区内频率资源使用情况的监测识别。扬州市无线电监测站在排查不明信号过程中,发现某土地测绘单位使用了UHF频段信号传送数据,属于违规发射。     

Smart antennas in software radio base stations

The application of adaptive antenna techniques to fixed-architecture base stations has been shown to offer wide-ranging benefits, including interference rejection capabilities or increased coverage and spectral efficiency. Unfortunately, the actual implementation of these techniques to mobile communication scenarios has traditionally been set back by two fundamental reasons. On one hand, the lack of flexibility of current transceiver architectures does not allow for the introduction of advanced add-on functionalities. On the other hand, the often oversimplified models for the spatiotemporal characteristics of the radio communications channel generally give rise to performance predictions that are, in practice, too optimistic. The advent of software radio architectures represents a big step toward the introduction of advanced receive/transmit capabilities. Thanks to their inherent flexibility and robustness, software radio architectures are the appropriate enabling technology for the implementation of array processing techniques. Moreover, given the exponential progression of communication standards in coexistence and their constant evolution, software reconfigurability will probably soon become the only cost-efficient alternative for the transceiver upgrade. This article analyzes the requirements for the introduction of software radio techniques and array processing architectures in multistandard scenarios. It basically summarizes the conclusions and results obtained within the ACTS project SUNBEAM, proposing algorithms and analyzing the feasibility of implementation of innovative and software-reconfigurable array processing architectures in multistandard settings     

Software radio issues in cellular base stations

The use of the “software radio” concept in cellular applications is a topic of widespread interest. Two key issues in the implementation of software radios are the development of optimal receivers that require the minimum number of bits in the wide-band analog-to-digital converter (ADC) and efficient channelizers that extract individual channels from the digitized wide-band signal. In this paper, both of these issues are studied in detail for cellular base stations. A computationally efficient wide-band channelizer is presented. This channelizer is closely related to the discrete Fourier transform filter bank used in transmultiplexers. It is shown that the complexity of the proposed channelizer is significantly less (2-50×) than the complexity of conventional channelizers. An optimal receiver that explicitly takes into account the effect of the quantization noise of the wide-band ADC is also derived. The analysis of the ADC noise provides guidelines for specifying wide-band ADC for use in cellular applications. The development of the channelizer and the optimal receiver yield important insights into the implementation of cellular software radios. All of the key results of this paper are applied to a detailed example based on the Digital Advanced Mobile Phone System (D-AMPS, IS-54/IS-136) cellular standard. The bit-error rate (BER) performance simulations of a D-AMPS wide band receiver is presented as a part of this example     

GPRS实时无线电台站管理监控系统方案初探

当前，现代通信技术发展迅猛，备类无线电台站的设置和使用数量迅速增加，这给各级无线电管理机构带来了很大压力。为了能够对无线电台站特别是固定类型无线电台站实施及时、有效的管理，本文提出了利用中国移动公司的GPRS通信系统进行实时管理的方法。     

用于认知无线电的自适应可重构天线研究

针对未来无线电系统如软件无线电、认知无线电给天线设计特别是可重构天线设计提出的新挑战,提出了一种基于全波/网络混合的可重构天线仿真分析方法.该方法将可重构天线看作多载天线,采用全波仿真分析无加载的天线阵列,将网络分析法与遗传算法相结合分析任意加载可重构天线的网络特性和辐射方向图,并利用该方法对一种矩形环形可重构天线的频率和方向图可重构能力进行了仿真分析.仿真结果表明,矩形环形可重构天线具有频率可重构和方向图可重构的功能,该特性可以使其应用于未来的认知无线电、智能天线等系统中.     

准确定位村庄内的非法电台

2007年9月17日,河北省无线电管理局接到上报:保定市某县发现非法广播信号,发射频率为99.6MHz。接到申告后,省监测站技术人员立即冒雨驱车赶往事发地点。次日上午监测到信号再次出现,我们出动两辆监测车从外围确定了发射源所在的村庄。技术人员携带便携设备确定了发射源所在的具体区域后返回村外,一切准备就绪后会同当地公安干警到达预定区域,迅速定位找到该非法台站。     

Plasma travelling wave antenna

The possibility of using plasma column as linear travelling wave antenna is studied. It is shown that surface current waves propagating in plasma column of finite length are a source of paraxial electromagnetic radiation of decimeter band. Influence of dielectric waveguide, which surrounds cold isotropic plasma, on dispersion properties of plasma column is investigated. The corresponding dispersion equation for eigenwaves of circular dielectric waveguide filled with plasma is derived and solved numerically. Plasma and waveguide parameters are determined under which the surface wave slowing-down is close to unity leading to antenna’s radiation primarily in axial direction. It is shown that in case of plasma density around 10¹²−10¹³ cm⁻³ dispersion of the considered wave is close to dispersion of waves propagating in metal travelling wave antenna.     

空中无线电监测载体的比较及注意事项

空中监测作为一种新颖的监测方式在现代化立体化监测网中发挥着重要作用,本文首先就空中监测介绍了其应用场景,之后针对空中监测载体的特点进行了分析和比较,提出了各种监测载体的适应性以及在监测活动中应注意的一些问题,最后给出了各种场景下空中无线电监测载体的建议类型。     

High performance antenna systems for new VOA stations

Advancements in curtain-type high-frequency (HF) broadcast antennas are reviewed. Novel high-performance antennas for the Voice of America (VOA) are described, including vertical and horizontal beam selections, performance measurements, effects of finite ground and hills, radiation hazard zones, and transmission lines. Specifications for antennas to be installed at four new VOA stations are examined. The designs provide substantial flexibility in radiation-beam characteristics with four vertical beam modes and seven horizontal beam angles. it is believed that the technique of selecting the optimum radiation beam for ionospheric propagation to VOA target areas will provide a substantial improvement in the performance