三种耦合方式下放大电路交流负载线的特性

通过对常见的阻容耦合、变压器耦合及直接耦合方式下共发射极放大电路交流负载线特性的研究,给出了三种耦合方式下放大电路交流负载线的共同形式,以及常见三种耦合方式下共发射极放大电路交流负载线的具体形式,阐述了这三种耦合方式下放大电路交流负载线的相同和不同之处,以及三种耦合方式直流负载线方程与交流负载线方程的关系。     

基于Agrawal模型的双绞线受扰机理与场线配置

电磁环境日益复杂,电磁兼容性问题涌现,各类干扰对传输线信号传输造成的影响不容忽视。基于经典场线耦合Agrawal模型,结合时域有限差分法(FDTD)对双绞线(TWP)各场线参数的电磁耦合效应进行定量计算,为减少受扰的场线配置提出指导性意见。总结了各参数对双绞线电磁耦合效应的具体影响：线长会影响端接负载处的选频特性;节距影响较小,较小的节距会减小耦合;距地高度会显著影响电磁耦合,且高度越高耦合越强;决定入射方式的入射角、方位角和极化角对电磁耦合效应均有不同程度的影响,通过电场切向分量切片图可知,对某一角的分析需要考虑到其余两角的影响。双绞线传输线的电磁耦合效应与场线参数密切相关,各参数均有不同程度的影响,借助本文模型的计算与对结果的分析,可获得有效的低受扰双绞线传输线配置。     

耦合腔慢波线互作用阻抗测试的研究

一 引言 耦合腔慢波线是由许多大功率行波管中的关键性部件,在科学技术突飞猛进的发展中,这此大功率微波器件始终显示着强大的生命力。对耦合腔慢波线的色散和互作用阻抗特性的研究和测量被广泛地作为研制这些大功率微波器件中的重要一环。 在J.slater谐振腔微扰理论〔1〕〔2〕〔3〕基础上发展起来了漫波线互作用阻抗测试法——微扰法。即在慢波线镜象对称     

高速数字电路PCB中串扰问题的研究与仿真

针对高速数字电路PCB中传输线间串扰的严重性,从精确分析PCB中串扰噪声的角度出发,在传统的双线耦合模型的基础上,采用了一种三线串扰耦合模型。该模型由两条攻击线和一条受害线组成,两条攻击线位于受害线的两侧,线间采取平行耦合的方式。利用信号完整性仿真软件Hyperlynx对受害线上的近端串扰噪声和远端串扰噪声进行了仿真。仿真结果表明,不同的传输模式和传输线类型、信号层与地平面的距离、耦合长度、传输线间距和信号上升/下降沿等因素会对受害线上的近端串扰和远端串扰产生较大的影响。在分析仿真结果的基础上,总结出了高速PCB设计中抑制串扰的有效措施,对高速数字电路设计有一定的指导意义。     

机载线缆间的串扰耦合分析

串扰是机载设备间互联线缆干扰耦合的重要因素。以混合模S参数为基础,建立单线-双绞线模型以模拟机载设备之间的动力线缆对信号线产生的串扰耦合。在此模型基础上提出串扰耦合测试方案,搭建串扰耦合测试系统,并根据测试获得的耦合系数评估单线-双绞线线间串扰耦合强弱。通过测试比较,对影响因素进行分析,结果表明,距地高度对线间串扰影响不大,线间距对线间串扰耦合影响显著,因此在条件允许下尽可能增加设备间互联线缆的间距可有效抑制串扰耦合。     

母线型OFLAN传输线的递进耦合

以母线型光纤LAN传输线的光路耦合分析为基础,导出了传输线的最佳耦合状态——递进耦合。并指出构成这种最佳耦合状态的光路耦合器的耦合系数遵循双曲线分布。这一理论结果对OFLAN传输线的设计和光路耦合器的研制、生产有重要意义。     

任意镜像阻抗平行耦合线滤波器的设计

任意镜像阻抗平行耦合线滤波器与传统的平行耦合线滤波器相比,通过选择合理的镜像阻抗,可以得到合适的耦合线的宽度与缝隙,因而使滤波器更容易加工。首先从理论上推导了任意镜像阻抗平行耦合线滤波器的设计公式。根据此理论,设计了80Ω的任意镜像阻抗平行耦合线滤波器。通过EM仿真验证了设计公式的正确性与准确性。     

带状螺旋慢波结构耦合阻抗的研究

本文运用螺旋坐标系计算了带状螺旋慢波线结构的耦合阻抗,本文给出了螺肇带缝隙内的电磁场解,因而明确地计算了螺旋带缝隙内的传输功率,分析这一部分功率对耦合阻抗的影响,结果发现螺肇带缝隙传输功率对耦合阻抗的影响较大,包括这一部分功率后,理论与实验符合得很好。     

微带巴伦设计

根据微带耦合线的准TEM模参数 ,推导出相同耦合线Marchand巴伦须满足的导纳方程 ,讨论了改善巴伦性能的方法———电容补偿法。ADS仿真结果表明 :采用最佳条件选取的耦合线 ,巴伦的反射系数接近最小 ,传递系数接近最大 ;采取电容补偿后 ,可进一步改善巴伦的性能。最后给出宽边耦合线巴伦的实验结果。结果表明 :可用上述导纳方程设计巴伦耦合线的参数。     

小型化三耦合线Marchand巴伦的等效模型分析与验证

为了实现三耦合线Marchand巴伦的快速设计,缩小巴伦的尺寸,提出了一种简化的三耦合线Marchand 巴伦等效模型及小型化设计方法。该等效模型将复杂的三耦合线的S参数散射矩阵的计算问题简化为对两个并联的平行耦合线的S参数散射矩阵的计算。为了验证该模型和设计方法的有效性,采用0.1 μm 砷化镓pHEMT (pseudomorphic High Electron Mobility Transistor)工艺制作了一款75~110 GHz的单平衡混频芯片,最终应用于单平衡混频器的巴伦耦合线长度被缩减为中心频率1/4波长的44%。良好的混频器性能和紧凑的芯片面积证明了所提三耦合线巴伦的等效模型和设计方法能够为单片集成微波电路芯片的设计提供指导作用。     

定位/通信双天线深腔共口径实验研究

该文对载体平台上双天线共口径的可行性进行了研究,口径为带介质罩的深腔.定位天线采用四绕螺旋天线(QHA);通信天线采用以腔壁为地的水平单极振子.对QHA天线在腔内的应用提出了利用腔底与末端水平支节进行调谐的改进.通过理论分析和实验考察了腔体对天线及两副天线之间的影响.结果表明这种方案中的两副天线能够同时在腔内很好地工作,相互的耦合还展宽了水平振子的工作带宽.     

Decoupling antenna elements of PIFA arrays on handheld devices

A novel approach for reducing the electromagnetic coupling between planar inverted-F antennas (PIFAs), built on a common ground plane and forming antenna arrays on handheld devices, is presented. The proposed technique is based on the insertion of two coupled quarter-wavelength slits on the ground plane between the antennas. By optimising the distance between the coupled slits, a magnetic resonance can be established within the operating bandwidth of the PIFAs. This resonance inserts a transmission zero in the coupling path between the closely spaced PIFAs, enabling the reduction of the coupling between them to very lowlevelswithout significantly disturbing their operating bandwidth.     

Mollow谱线与电磁诱导透明和吸收的叠加

对双耦合场作用下的Λ型三能级系统的透明和吸收特性进行了理论研究。在二能级系统中,强耦合场和探测场同时作用于激发态能级和基态能级之间,探测吸收曲线上出现Mollow谱线。在激发态能级和基态的另一精细结构能级之间引入另一个耦合场,构成Λ型三能级系统。在这个双耦合Λ型三能级系统中,出现了一些新的量子相干现象。结果表明,探测吸收谱线中不仅有Mollow现象,还出现了电磁诱导透明(EIT)和电磁诱导吸收(EIA)。分析了EIT和EIA的位置随双耦合场参数的变化规律,并用缀饰态理论做出了解释。     

Directional coupler for gigahertz frequencies, based on the coupling properties of two planar comb transmission lines

The principles of operation are given for a directional coupler based on the coupling properties of two interleaved planar comb transmission lines. It is shown that this arrangement leads to a departure from a contradirectional coupling mechanism. Results are given for an X band ?3 dB coupler, and the performance and manufacturing methods are compared with those of other high-frequency coupler designs.     

Analytical and experimental studies of coupling between antennas over a two-dimensional ground surface of known contour

A numerical procedure is presented for computing the transfer impedance between two antennas located above a two-dimensional ground surface of known contour. The antennas are either both horizontally or both vertically polarized, and may have arbitrary radiation patterns in the vertical plane. The antennas are assumed to be high enough above the ground so that surface wave coupling is negligible but close enough so that a significant portion of the received power arrives via ground scattering. For purposes of computation, the ground is divided into a series of connected (infinite) planar strips of identical projected width. The net scattered field is computed using Green's theorem applied to each strip individually but neglecting edge effects and multiple scattering. The practical utility of this technique has been tested in a limited way by measuring the variation in coupling between two identical horizontally polarized horn-aperture antennas over a single ground contour. Provided the baseline profile is surveyed carefully at the time the coupling measurements are made, the numerical predictions are seen to be in reasonable agreement with the test data.     

Mutual coupling reduction of low-profile monopole antennas onhigh-impedance ground plane

The mutual coupling effects of flush-mounted (horizontal) monopole antennas on high-impedance ground planes (HIP) have been measured. Experiments of horizontal monopoles on HIP with a bandgap centred at 4.7 GHz show that the interference between two adjacent elements is stronger compared to those on a regular metal ground plane due to special properties of HIP. A technique using a combination of HIP and thin metal strip is proven to reduce the mutual coupling by ~6 dB. Similar results have been obtained for the horizontal monopoles on HIP with a bandgap centre at 17 GHz     

Coupling between microstrip lines with finite width ground plane embedded in thin-film circuits

Three-dimensional (3-D) interconnects built upon multiple layers of polyimide are required for constructing 3-D circuits on CMOS (low resistivity) Si wafers, GaAs, and ceramic substrates. Thin-film microstrip lines (TFMS) with finite-width ground planes embedded in the polyimide are often used. However, the closely spaced TFMS fines are susceptible to high levels of coupling, which degrades the circuit performance. In this paper, finite-difference time domain (FDTD) analysis and experimental measurements are used to demonstrate that the ground planes must be connected by via holes to reduce coupling in both the forward and backward directions. Furthermore, it is shown that coupled microstrip lines establish a slotline type mode between the two ground planes and a dielectric waveguide type mode, and that the connected via holes recommended here eliminate these two modes.     

Coupling mechanism of a loop‐type ground radiation antenna

The coupling mechanism of a loop‐type ground radiation antenna is investigated in this paper. We use the equivalent circuit model of the antenna and a full‐wave simulation to explain the coupling mechanism of the antenna. We analyze the effects of various antenna parameters on the coupling between the antenna element and the ground plane to examine the conditions for enhancing the coupling. Based on simulations with the equivalent circuit model, full‐wave simulations, and measurements, we propose optimal design considerations for the antenna. The findings of this study will aid the design and understanding of loop‐type ground radiation antennas for mobile devices.     

Analysis of processes in the antenna-matching circuit with extended passband of a radio transmitting unit for ULF range

This paper presents a model developed for the output circuit of ULF range radio transmitting unit working on a system of two parallel-connected antennas connected to the switching generator through a matching transformer. The model proposed, in addition to magnetic coupling of two antennas, takes into account galvanic coupling of their grounding electrodes resulting in emergence of a balancing ground current. The band pass of the two-antenna system and additional power losses caused by the balancing current were also determined.     

自旋对晶体内强耦合磁极化子基态能量和有效质量的影响

本文采用线性组合算符法研究极性晶体内强耦合磁极化子的特性,讨论了电子自旋对极性晶体内强耦合极化子基态能量和有效质量的影响。对ＣｓＩ晶体所作的数值计算结果表明,电子自旋取不同方向时,强耦有化子的基态能量随磁场的增加而增加或减少,电子自旋对强耦合磁极化子基态能量的影响随磁场的增加而增大。