A backbone highway communications system using coaxial cable

The problem of providing the communication link for modern highway management and control is analyzed. A 100- mile span of highway is analyzed for typical voice and control function requirements plus closed circuit television monitoring capability. Based on this analysis, the number of channels and hence the bandwidth required to meet typical requirements is developed. It is proposed that a coaxial cable system can best provide the bandwidth and access flexibility that will be necessary for the many links required for effective highway management. A coaxial cable system as a transmission path is shown to be two dimensional in that it involves absolute signal levels as well as spectrum considerations. An analysis of distortion characteristics of state of the art coaxial cable systems is included to arrive at signal to noise plus distortion ratios versus cable length and amplifier gains. Typical cable costs, burial and tunneling labor costs are discussed to show economic practicality. Finally, two high-capacity cable systems are discussed to illustrate the communications capacity of coaxial cable systems.     

Thru characteristics of a coaxial gap (FDTD model and measurements)

Thru characteristics of a coaxial cable interrupted by a small gap are modeled and measured. Finite-difference time-domain (FDTD) modeling is applied in cylindrical coordinates to semirigid coaxial cable and to the intervening gap material. Both dispersive and nondispersive gap materials are investigated. Gap loss and phase shift are accurately predicted by this two-dimensional model which accounts for TEM and TM modes in the gap and coaxial apertures. An application of the model is to establish reference data for thin sample permittivity or moisture measurements     

On the electromagnetic field of a dielectric coated coaxial cable with an interrupted shield

A boundary value treatment is used to derive field expressions for a dielectric coated coaxial cable with a gap in the shield. Specific results are given for an incident TEM mode in the interior coaxial region. For example, it is shown that, for the VHF region, as much as 18 percent of the incident power is radiated into the external region via a single circumferential gap in the shield. Comparable amounts of power are transferred to a reflected TEM mode in the cable and into surface waves in the dielectric jacket.     

Rigorous Analysis of Rectangular Dielectric Resonator Antenna With a Finite Ground Plane

A probe-fed rectangular dielectric resonator antenna (RDRA) placed on a finite ground plane is numerically investigated using method of moments (MoM). The whole structure of the antenna is exactly modeled in our simulation. The feed probe, coaxial cable and ground plane are modeled as surface electric currents, while the dielectric resonator (DR) and the internal dielectric of coaxial cable is modeled as volume polarization currents. Each of the objects is treated as a set of combined field integral equations. The associated couplings are then formulated with sets of integral equations. The coupled integral equations are solved using MoM in spatial domain. The effects of ground plane size, air gap between dielectric resonator and ground plane, probe length, and position on the radiation performance of the antenna including resonant frequency, input impedance, radiation patterns, and bandwidth are investigated. The results obtained for the antenna parameters based on the MoM investigation shows that there is a close agreement with those obtained by measurement. Moreover it is shown that the MoM results are more accurate than other simulation results using software package such as High Frequency Structure Simulator (HFSS).      

同轴线斜置缝隙振子的阻抗和辐射特性

同轴线斜置缝隙天线以其独特的辐射特性与阻抗特性，在通信和广播中得到广泛应用。文中对同轴线斜置缝隙振子的阻抗特性和辐射特性进行了全面分析，推导了等效阻抗与辐射场数学表达式，给出了例算结果。     

Magnetic Field Pickup by Flexible Braid Coaxial Cables

Cabling systems have long been known to be a source of unwanted pickup of radio-frequency interference. A typical source of pickup occurs when the outer sheath of a coaxial cable system forms part of a ground return for potentially interfering electromagnetic energy. Another source of penetration arises from a magnetic field which is perpendicular to the axis of the coaxial cable. A previous study demonstrated that the field emanating from a coaxial cable could be characterized as an equivalent open-wire pair. This particular effect is caused by the eccentricity between the centers of the outer and the inner conductors or because of other asymmetrical characteristics. The susceptibility of a coaxial cabling system to perpendicular magnetic fields can also be characterized in terms of an equivalent open-wire pair for short runs. The purpose of this investigation was to measure the shielding effectiveness of a typical flexible braid coaxial cable to magnetic fields perpendicular to its axis and to demonstrate that a coaxial cable may be considered as an equivalent open-wire pair in a cylindrical shield. A test setup employed a parallel plane transmission line to generate a uniform magnetic field perpendicular to the axis of the coaxial cable. The shielding effectiveness of the braid was measured for several classes of braid conditions. Then, using the same braid, a coaxial cable with an experimentally induced known eccentricity was employed and the overall pickup measured. The results confirmed the objectives of the investigation.     

一种新型双侧漏泄同轴电缆辐射特性分析

为了解决室内5G 信号覆盖盲区的问题,对单侧漏泄同轴电缆进行了改进,设计了一种新型的双侧漏泄同轴电缆。根据周期结构的槽孔天线阵列理论,以电磁仿真软件Ansoft HFSS作为分析工具,建立双侧开槽的漏缆仿真模型,得到了电场分布、耦合损耗、方向图和S参数的特性;对不同节距和槽长进行仿真,获得了不同辐射模式下,漏缆耦合损耗随节距、槽长变化的曲线。研究结果表明:双侧漏缆比单侧漏缆的电场强度更均匀,方向图更加对称,通信质量更高,为5G信号在室内覆盖提供解决方案。     

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.     

圆形隧道中泄漏同轴电缆辐射场的FDTD 分析

随着泄漏同轴电缆在各种闭域空间中的应用越来越广泛,其精确的辐射特性数值解也引起人们的关注。在圆柱坐标系下,根据泄漏同轴电缆的辐射理论,分析了圆形隧道中电磁波的传播途径,用时域有限差分（FDTD）方法求解了泄漏同轴电缆在圆形隧道中的辐射场。该方法相比于解析法,简化了计算程序,提高了结果的精确度,并且易于实现。 仿真结果表明在圆形隧道中,泄漏同轴电缆不存在传统天线所具有的通信盲区的缺点,可以实现与外部空间的全方位双工通信。     

Analysis of linear coaxial antennas

Two types of linear coaxial antennas, coaxial-colinear antennas, and slotted coaxial antennas are studied to check the possibility of using them as the base-station antenna in personal communication systems. The slot voltages and input impedance of linear coaxial antennas are obtained by using a transmission-line analysis where the radiation effect is accounted by a shunt and a serial admittance, respectively. The current distribution is obtained by solving an integral equation using the method of moments. The radiation pattern and directivity are then obtained from the current distribution and the reflection coefficient inside the coaxial cable. Factors analyzed include frequency, coaxial filling permittivity and segment number     

3GHz宽带“八”字槽漏泄同轴电缆的设计及性能

3GHz宽带漏泄同轴电缆的设计要求是在3GHz宽带频率范围内所有使用频段都具有有效的传输距离（衰减）及良好的辐射特性（足够的耦合损耗及均匀的全向辐射场强图）。通过外导体“八”字槽孔结构参数的设计调整,研制出在3GHz所有的通信频率中均能使用,并具有优良性能的辐射型漏泄同轴电缆。     

A Study on the EM Leakage Arising from Braided Shielding Cable

1 Introduction For its good shielding and flexibility properties ,braided shielding cable is widely used in modern com-munications[1 ~2]. Because there are diamond shapedholes onthe shield,the magnetic fieldthat generated bythe current onthe shield goesintothe cable throughtheholes. On the other hand,the magnetic filed that gen-erated by the inner conductor current penetrates theholesinto the outer space . The electromagnetic leakagewill occur due tothe diffusionthroughthe metal andthefield pe…     

Underground use of a coaxial cable with leaky sections

The optimum efficiency of a leaky cable as a support for radio communications in tunnels involves a compromise between high leakage fields and a low increase of the coaxial mode attenuation. The latter is an important disadvantage of continuous leaky feeders. To obviate this, short leaky sections can be inserted in an otherwise well-shielded coaxial cable. These sections act as mode converters or radiators. A theoretical analysis based on coupled line theory enables us to determine the optimum characteristics of the leaky sections. Numerous experiments were carried out in a tunnel at various frequencies, using different lengths and characteristics of the leaky sections.     

Linear Dummy Loads

The need for linear dummy loads is established. It is indicated that nonlinear dummy loads generate predominantly oddorder harmnonics. A theoretical analysis is presented which demonstrates that an ?infinite? coaxial cable with an infinite load (open circuit)at the output has an input impedance equivalent to the cable's characteristic impedance Z0. An equation is derived relating the voltage standing-wave ratio S, cable length h, and the cable attenuation constant ?. The linearity of a cable load is compared with the linearity of ?typical? commercially available loads and the commercial loads tested are found to generate 20 to 80 dB more third harmonic. Cable selection guidelines for a linear coaxial cable load are presented.     

The Effect of Mutual Inductance and Mutual Capacitance on the Transient Response of Braided-Shield Coaxial Cables

A quantitative comparison is made of the importance of mutual inductance and mutual capacitance in the leakage of transient signals through the braid of a coaxial cable. The difference between mutual inductance and mutual capacitance coupling is vividly exhibited in the transient predictions. Comparisons of predictions to measurements made on a length of RG-214 test cable are also included.     

Open-ended coaxial exposure device for applying RF/microwave fieldsto very small biological preparations

An easily fabricated open-ended coaxial exposure device for applying radiofrequency/microwave energy to very small biological preparations is described. The device utilizes the fringing fields of a coaxial cable opening into a ground plane. Operation of the device is easily integrated into standard laboratory procedures in order to: observe a biological specimen; monitor temperature; regulate temperature, pH, and pO₂; and record cellular membrane potentials. The electromagnetic field configuration of the device leads to elimination of detectable interaction with microelectrodes. Measured patterns of electric field and specific absorption rate are given for a device built with quarter-inch semirigid coaxial cable and operating at 2450 MHz. Comparison is made to previous exposure devices for small biological preparations. The particular advantages of the open-ended coaxial exposure device over previous devices are the easy access to the preparation during exposure and the minimal, if any, coupling RF/microwave fields to microelectrodes used in electrophysiological studies     

Numerical analysis of the propagation characteristics of multianglemultislot coaxial cable using moment method

In this paper, multiangle multislot coaxial cable is analyzed qualitatively and quantitatively. This is the extended result of the previous studies of the single-slot coaxial cable. The properties of this cable have been studied by many authors, especially for the surface-wave type. However, the slotted coaxial cable utilizing leaky waves has not been treated rigorously despite its wide use. In this paper, a numerical analysis of a leaky coaxial cable with a multiangle multislot configuration is performed to obtain many useful results, which are impossible to derive employing the approximate model frequently used in this area. Using the moment method, the propagation constant has been obtained for the leaky coaxial cable as a function of various parameters. Several slot configurations are considered to give insight into the properties of coupling loss and transmission loss complicated by simultaneous existence of leaky and surface waves     

8D—FB型同轴电缆生产工艺的探讨

介绍了8D-FB型同轴电缆的结构及生产工艺。详细分析了温度循环试验后引起8D-FB型同轴电缆内导体突出的主要原因,针对导致电缆内导体突出的主要原因,对生产工艺进行了改进,从根本上解决了该问题,并且经过反复试验验证工艺改进后生产的8D-FB型同轴电缆的衰减性能基本没有改变。     

漏泄同轴电缆耦合损耗特性评定的探讨

除长度耦合损耗(Lc,50、Lc,95)值外,增加Lc,95-Lc,50值、天线三向Lc,95值、Lc,95耦合损耗圆图及其不圆度参量,扩展了IEC标准中的"耦合损耗",全面评定漏泄同轴电缆辐射电场特性。实例分析讨论不同结构漏泄同轴电缆辐射电场特性。     

ESD indirect coupling modeling

Electrostatic discharge (ESD) indirect coupling on electronic equipment is theoretically and experimentally investigated considering the effects for three typical structures: a coaxial cable, a multilayer PCB, and a metallic enclosure. The analytical approach is based on classical electromagnetic theory and is developed in a simple way that is easy to apply and accurate enough to give the designer a reliable estimation of the interference produced by an ESD event