波导的探针激励研究

本文主要用等效电路法推导了单探针激励矩形波导和圆波导时，探针输入阻抗的表达式。同时，利用反应的概念，探讨了双探针激励波导时，探针间的互阻抗问题，以及在进行多探针激励同一波导时，输入阻抗对功率合成的影响。     

半无限长柱形波导第一类并矢Green函数的镜像法解

本文将无限长矩形波导、圆波导和同轴线的第一类电型并矢Green函数(?)_(e10)统一成一般表达式。并由此出发,用镜像法求出了相应半无限长波导的第一类电型并矢Green函数(?)_(e10)所用方法及得到的结果也适用于具有任意截面形状的柱形波导。此外,还对探针激励半无限长矩形波导内的电场进行了分析和计算。     

NSOM中石英音叉控制探针—样品间距的机制

建立了音叉－探针－样品系统机械振动方程和电子学振荡方程，并得到其振动特性的解析表达式，进一步得到等效电路的电子学特性，进而系统分析了压电石英音叉的控制探针与样品（T－S）间距离的作用机制及其机电特性。为探针－样品间距控制方法提供了依据。     

基于开口圆锥近场探针的太赫兹超分辨成像研究

基于近场探针的太赫兹扫描成像系统能够突破衍射极限探究物质隐藏的细节,但是传统基于微纳加工工艺的近场探针存在工艺复杂、传输损耗较大的缺点。提出了一种基于空心圆波导的渐变开口圆锥形近场探针设计方法,所设计的探针能够通过圆波导实现低损耗传输,同时利用渐变开口圆锥形针尖实现亚波长聚焦。为了验证方法的可行性,采用3D打印技术对所设计的探针进行加工,然后基于高精度三维扫描平台搭建了一套0.1 THz近场扫描成像系统。实验结果表明该探针能够实现亚波长超分辨聚焦,实验结果与仿真结果一致。     

探针式同轴线-矩形波导转换器输入阻抗的计算

本文利用探针上假定电流的自反应,导出了探针式同轴线-矩形波导转换器输入阻抗的表达式。文末还给出了实验结果与理论计算值的比较。     

微波晶体管的噪声性能

本文导出了微波晶体管噪声参数的表达式。其理论基于一个小信号共发射极等效电路,而该等效电路包含有一个新的噪声等效电路和主要的管壳寄生参数。该理论已用 Ge和 Si 的微波晶体管在 L 波段(1～2千兆赫)的频率范围得到实验证明。发现管壳寄生参数对最小噪声系数的影响很小,但在频率高于由寄生参数与管芯参数共同作用产生的谐振频率的一半以上时,管壳寄生参数对等效噪声电阻和最佳源导纳的影响就很大。为快速估计噪声性能,给出了噪声系数与产生最小噪声的最佳电流的近似表达式。     

多模伪单脉冲自跟踪系统的性能限制

给出了大信噪比和小信噪比情况下圆波导TE11和TE21模伪单脉冲系统合成信号的包络表达式。指出在小信噪比情况下将不能从合成信号的包络解调出角误差电压。给出了大信噪比情况下热噪声引入的跟踪误差。     

正脊、背脊和矩形波导锁式铁氧体相移器的一般理论

本文研究了脊波导中心对称加载铁氧体环移相器的差相移、插入损耗和LSE_(20)模的截止波长,理论差相移与实验结果基本一致。此外,还给出了适用于脊波导、背脊波导和矩形波导三种结构移相器的相位常数和LSE_(20)模的截止波长的超越方程,以及插入损耗表达式。计算了三种不同波导移相器的相对插入损耗与频率的关系曲线。     

圆锥波导中电磁场的一种新的等效表达式

本文提出了一种新的等效圆波导半径表达式,改进了计算圆锥波导内电磁场的传播常数,波阻抗和场分量的计算精度,运用数值对比方法,证明新的表达式在高次模和近截止区仍有较好的适用性,最后结合实例讨论了相关的插值方法,以便处理工程设计中常邮的特征值非整数时的计算问题。     

横闩式同轴波导过渡的理论分析

应用辅助势函数,推导了一端具有短路板的矩形直波导中单位电流源的辐射场。当波导只传输主模(TE_(10)模)时,求得从同轴线看去的输入阻抗的实部和虚部表达式。理论计算和实验结果接近。     

On Solving TM0n Modal Excitation in a Ka-Band Overmoded Circular Waveguide by the Conservation of Complex Power Technique

To measure the radiation properties of relativistic diffraction generator (RDG) in Ka-band, a TM0n modal excitation model is established, which consists of an overmoded circular waveguide and a coaxial line feeding probe. Using the transverse E-field mode matching and the conservation of complex power technique (CCPT), we deduce the scattering matrix at coaxial line to coaxial line and coaxial line to circular waveguide junctions. Then using the overall cascaded junction scattering matrix, the numerical results for the reflection coefficient of the coaxial line and the power distribution of TM0n multi-modal are presented. The numerical results are in agreement with HFSS simulation results and experimental results. The analysis shows that by choosing the appropriate position of coaxial line probe, the power proportion of the device operating mode excited in circular waveguide could be the largest.     

On Solving TM0n Modal Excitation in a Ka-Band Overmoded Circular Waveguide by the Conservation of Complex Power Technique

To measure the radiation properties of relativistic diffraction generator (RDG) in Ka-band, a TM0n modal excitation model is established, which consists of an overmoded circular waveguide and a coaxial line feeding probe. Using the transverse E-field mode matching and the conservation of complex power technique (CCPT), we deduce the scattering matrix at coaxial line to coaxial line and coaxial line to circular waveguide junctions. Then using the overall cascaded junction scattering matrix, the numerical results for the reflection coefficient of the coaxial line and the power distribution of TM0n multi-modal are presented. The numerical results are in agreement with HFSS simulation results and experimental results. The analysis shows that by choosing the appropriate position of coaxial line probe, the power proportion of the device operating mode excited in circular waveguide could be the largest.     

Accurate characterization of planar printed antennas usingfinite-difference time-domain method

The finite-difference-time-domain method (FD-TD) is used to characterize complex planar printed antennas with various feed structures, which include coaxial probe feed, microstrip line feed, and aperture coupled feed structures. A coaxial probe model is developed by using a three-dimensional FD-TD technique. This model is shown to be an efficient and accurate tool for modeling coaxial line fed structures. A novel use of a dispersive absorbing boundary condition is presented for a printed antenna with a high dielectric constant. All the numerical results obtained by the FD-TD method are compared with experimental results, and the comparison shows excellent agreement over a wide frequency band     

Input Impedance of Coaxial Line to Circular Waveguide Feed

The expressions for the real, imaginary parts of the input impedance seen by a coaxial line driving a thin cylindrical probe in a dominant TE/sub 11/ mode circular waveguide are derived. The analysis is carried out by assuming that the cylindrical post is replaced by a curvilinear strip having maximum width equal to the diameter of the probe. Theoretical results on input VSWR and input impedance seen by a coaxial line are in close agreement with experimental data.     

同轴线TEM波到圆波导TM0n模的转换

本文用复功率守恒技术对同轴探头在圆波导中激励ＴＭ０ｎ多模问题进行了严格的全波分析，得到了同轴线到圆皮导的总散射矩阵，并从散射矩阵出发求得了同轴线中的反射系数和在圆波导中激励出的各ＴＭ０ｎ传输模的功率分布。反射系数同实验结果作了比较，计算结果表明，当同轴探头在圆波导中激励出ＴＭ０ｎ多模时，圆波导允许传输的最高次模式功率含量大。     

The dependence of the input impedance on feed position of probe andmicrostrip line-fed patch antennas

The impedance of a rectangular patch antenna fed by an inset microstrip transmission line was measured for various feed positions. The dependence found was then compared to theoretical predictions both for this geometry and for the similar case of an inset coaxial probe feed     

电解质溶液复介电常数测量中气泡影响的分析

电解质溶液复介电常数的准确测量对于生物电磁学和微波化学等领域是至关重要的,简单而有效的测量方法就是使用开口同轴线。由于电化学反应,插入溶液的测量探头表面容易产生气泡,对测量结果产生影响。文中针对气泡的不同位置和大小对氯化钠溶液复介电常数测量的影响进行了数值分析,计算结果表明,电解质溶液复介电常数测量值的实部受气泡影响很小,而虚部受气泡的位置、大小和个数的影响。     

Simple transmission line feed model for microstrip antennas in two-sided structure with coaxial probe coupling

A simple transmission line feed model is presented for microstrip antennas in a two-sided structure coupling through a coaxial probe. The parameters of the model are extracted directly from the feed structure. The validity of the feed model combined with the recently developed transmission line model of microstrip antennas is verified by measurement.<>     

弧面电流探头传输阻抗的校准

利用内圆外方同轴传输线理论,提出弧面电流探头传输阻抗的校准方法.详细介绍了校准装置的设计制作、测试及校准应用.     

Wide-Bandwidth Coaxial PWB Transmission Line Probe

The design, fabrication, and test of a wide-bandwidth (3-dB attenuation bandwidth ges 30 GHz), 50 Omega, passive coaxial probe for the electrical characterization of printed wiring board (PWB) transmission lines is described. The probe can make thousands of repeated contacts, using spring-loaded interconnects, without affecting probe performance. The probe contains an internal mechanism for dissipating static charge on the signal line of the PWB transmission line and is long enough (approximately 10 cm) to act as a transfer standard for characteristic impedance testing, as per the time-domain reflectometry test method described in IPC TM 2.5.5.7.