峰值功率

㈠额定峰值功率射频电统传输高功率时,如上节所述,在电缆上会承受很高的电压,同时也还有大电流通过,因此电缆上允许传输的功率会受到电压击穿以及电流发热的限制,前者取决于传输的峰值功率,后者取决于传输的平均功率,在一般情况下,只要电缆的平均功率满足不产生过     

大功率同轴射频电缆在广播电视发射中的应用与维护

本文介绍了大功率射频同轴电缆的材料结构、技术参数,对如何合理使用、日常维护大功率射频同轴电缆,提供了一些经验。     

同轴电缆额定平均功率确定方法的讨论

额定平均功率为同轴电缆重要指标,该值取决于电缆衰减、热阻、介质耐温、敷设环境等。实例证明在确定电缆额定平均功率中,工频模拟法可替代高频功率运行试验方法。     

椭圆软波导的理论功率容量

本文介绍了椭圆软波导功率容量的理论计算方法,并以图表形式给出了BT系列椭圆软波导的额定平均功率和峰值功率容量。     

测量电视差转机的功率和互调的一些问题

输出功率和相互调制是电视差转机最重要的指标,它们是相互关联、相互制约的,本文就分别讨论测量其功率和互调的一些问题。一、功率测量中的几个问题 1.测量框图及计算公式电视差转机的额定输出功率定义为同步顶功率,在部颁标准的测量方法中指出,图机的输出功率,是指在同步顶处一个射频周期的平均功率。用全黑电平调制的射频信号测量时,功率计读数与差转机图象输出标称(额定)功率的关系式如下     

一种复用传输射频和基带信号的新方法

介绍了一种在同轴电缆上,射频和基带信号复用传输的新方法。设计了射频信号和基带信号隔离电路,采用C-MBUS标准传输基带信号,在长为1 km、传输射频信号功率为40 d Bm的同轴电缆上,达到了4 800 b/s的数据传送速率,且同时可以为通信从机节点提供10 m A的电流。该方法具有硬件电路简单、成本低廉,容易组网的优点,适用于在射频线路上同时传输低数据速率的附加信息。     

RF同轴电缆传输系统的设计与维护

介绍同轴电缆的结构与传输特性、射频传输干线与分配网络设计技术.     

功率吸收钳法测量射频同轴电缆屏蔽效能

屏蔽效能是表征射频同轴电缆电磁兼容性的重要指标,用功率吸收钳法可以测量射频同轴电缆的屏蔽效能.从射频同轴电缆的屏蔽效能和表面转移阻抗的各种典型测量方法入手,叙述转移阻抗和屏蔽效能的关系,并重点阐述如何用功率吸收钳法测量电缆屏蔽效能以及对测试结果的归一化处理,并给出了相关的测量曲线.     

大功率微波柔软同轴电缆的研制

介绍了大功率微波柔软同轴电缆的设计思路,以及降低电缆衰减和提高电缆传输功率的有效途径。阐述了采用复合型聚四氟乙烯（F4）薄膜绕包绝缘的柔软同轴电缆的结构特性,其可在高传输功率环境下满足耐大功率、柔软性好、低损耗等的综合技术要求,并具有很好的应用前景。     

射频同轴电缆电压驻波比影响因素综合分析

电压驻波比(VSWR)是射频同轴电缆重要的传输特性,采用场-路结合的方法建立了射频同轴电缆的三维有限元分析模型,分析了影响射频同轴电缆VSWR的因素,深入研究了内外导体直径偏差、绝缘层质量、内外导体的偏心度和电导率对射频同轴电缆VSWR因素的影响。     

馈线同轴电缆的全铝化

移动基站及布线用馈线同轴电缆受铜价飞涨的影响而使网络建设费用大幅攀升,以铝代铜的方法来降低产品成本是目前行业的一种基本思想和方法。馈线同轴电缆的全铝化就是受此思想的影响而派生的一种新产品。同规格的这种产品的传输性能与全铜产品相比,主要在传输衰减方面略显增加,这种增加也在用户或系统或以忍受的情况下方能成立。本文提出了电缆用的铝材要求、生产过程的注意事项、产品电气与机械传输参数的变化程度等问题,为全铝化同轴馈线电缆的行业标准制定及商用打下基础。     

射频功率放大器的宽带匹配设计

多倍频程功率放大器具有显著的优点,同轴电缆阻抗变换器能实现射频功率放大器有效的宽带匹配。在给出同轴电缆阻抗变换器方案设计的基础上,详细介绍了其基本原理以及1∶1和1∶4同轴变换器的具体结构及等效电路。针对工程需要,以同轴电缆阻抗变换器为宽带匹配网络的核心,设计了一款超宽带匹配功率放大器,经软件仿真优化及测试验证,阻抗匹配准确,测试结果达到了技术指标要求。     

低阻抗同轴电缆的制备与可调电阻测试法

在射频功放运用中经常会涉及到使用一些低阻抗的同轴电缆的情况,如制作平衡-非平衡轮换的巴伦,以及特定阻抗变换电路? 研究了根据标准同轴电缆的结构,通过改变部分关键结构参数,制备任意非标准的低阻抗同轴电缆技术方法;通过同轴电缆中的电磁传播理论分析和推导,提出准确测试低阻抗同轴电缆的可调电阻测试法?     

Resonance Properties of the Shield of a Coaxial Cable over a Ground Plane

In situations where several high-power transmitters and their antennas are to be used near one another, a certain amount of mutual interference can be expected. An instance of particular interest is that of high-intensity radiation inducing standing waves between the shields of nearby coaxial cables and a metal deck of ground plane. Standing waves induced may cause high potentials and possible breakdown at the ends of the cable, damaging connectors and antennas. There may also be some reduction of the shielding effectiveness of the coaxial cable when high-voltage standing waves are present in the shield. It has been common practice to eliminate such standing waves by periodic grounding of the outer conductor of the coaxial cable. This, however, requires penetration of the insulation material on the cable and formation of metal-to-metal joints on the shield. This is not only an inconvenient method of installation, but is also undesirable around salt water. Copper shielding will corrode, and corrosion at the joint of the dissimilar metal can cause nonlinear interference effects. The standing waves induced in the transmission system formed by the cylindrical shield of a coaxial cable and a conducting plane are examined theoretically and experimentally as a function of the shield-to-ground impedance at the end points only (Z1 and Z2 of Fig. 1). Ordinarily, standing waves are eliminated by terminating a guiding system in its characteristic impedance. In this situation, however, the exciting source (i.e., incident radiation) is distributed along the length of the transmission system.     

毫米波半柔软射频同轴电缆的研制

介绍了一种毫米波半柔软射频同轴电缆的结构设计与制造工艺。该电缆可传输毫米波射频信号,具有传输频率高(40GHz)、插入损耗小、弯曲成型能力强等性能特点。微孔聚四氟乙烯绝缘和导电金属层+镀锡铜线编织+热浸锡整体外导体结构是该电缆的主要创新点。     

50Ω皱纹铝管外导体射频同轴电缆的研制

简述了50Ω皱纹铝管外导体射频同轴电缆的研制,着重介绍了其生产工艺难点。该电缆的实测性能表明,皱纹铝管外导体射频同轴电缆可替代同规格的皱纹铜管外导体射频同轴电缆用于移动通信市场。     

Design of a tunnel relay system with a leaky coaxial cable in an 800-MHz band land mobile telephone system

System design of a tunnel relay system in an 800-MHz band land mobile telephone system is described. Several dozen RF signals from a base station or many different mobile units in the tunnel are directly amplified in the RF stage, without frequency conversion, by a common amplifier in the relay equipment installed near the tunnel entrance, then radiated into the tunnel through a leaky coaxial cable (LCX) or to the base station by a unidirectional antenna. Repeaters are inserted along the LCX to compensate for transmission loss in RF signal power inside the cable. Amplifying a number of RF signals simultaneously, a common amplifier generates intermodulation products and radiates spurious signals. The required amplifier linearity to suppress the spurious signals is discussed in detail. The combination of LCX and service area in the tunnel is determined according to the amplifier performance, the number of radio channels assigned to the base station, and the radio wave propagation characteristics in the tunnel.