CHARACTERISTICS OF MICROSTRIP TRANSMISSION LINES

An efficient hybrid field solution to microstrip transmission lines is presented byusing SLE and SLM modes in spectral domain.It by-passes the lengthy process of formulatingthe determinant equation for the unknown propagation constant.Compared with spectral domainadmittance approach,this method is clear in both physical and mathematical senses and may beapplied to a variety of structures.

ANALYSIS OF OPEN MICROSTRIP STRUCTURES BY USING DIAKOPTIC METHOD OF LINES COMBINED WITH PERIODIC BOUNDARY CONDITIONS

This paper presents the analysis of open microstrip structures by using diakoptic method of lines (ML) combined with periodic boundary conditions (PBC). The parameters of microstrip patch are obtained from patch current excited by plane wave. Impedance matrix elements are computed by using fast Fourier transform(FFT), and reduced equation is solved by using diakoptic technique. Consequently, the computing time is reduced significantly. The convergence property of simulating open structure by using PBC and the comparison of the computer time between using PBC and usual absorbing boundary condition (ABC) show the validity of the method proposed in this paper. Finally, the resonant frequency of a microstrip patch is computed. The numerical results obtained are in good agreement with those published.

CMOS Phase and Quadrature Pulsed Differential Oscillators Coupled through Microstrip Delay-Lines

An innovative solution to design phase and quadrature pulsed coupled oscillators systems through electromagnetic waveguides is described in this paper. Each oscillator is constituted by an LC differential resonator refilled through a couple of current pulse generator circuits. The phase and quadrature coupling between the two differential oscillators is achieved using delayed replicas of generated fundamentals from a resonator as driving signal of pulse generator injecting in the other resonator. The delayed replicas are obtained by microstrip-based delay-lines. A 2.4 - 2.5 GHz VCO has been implemented in a 150 nm RF CMOS process. Simulations showed at 1 MHz offset a phase noise of -139.9 dBc/Hz and a FOM of -189.1 dB.

微带交指带通滤波器小型化结构设计

文中提出在终端短路式交指带通滤波器的开路端引入一段微带加载线,使谐振器产生尺寸跳变。通过改变微带加载线的线宽,增加谐振器的等效电感值,从而实现降低该带通滤波器中心频率的目的,并且给出了在设计指标下,随加载线宽变化中心频率变化的经验公式。对X波段的微带交指带通滤波器和微带线尺寸跳变进行了研究,研究数据表明:谐振器越短,中心频率往高频偏移越多;微带线尺寸跳变越大,中心频率往低频偏移越多。通过合理减小谐振器长度和增加微带加载线线宽,滤波器整体长度减小而宽度不变,且改进前后滤波特性不发生改变,达到了滤波器小型化的目的。通过在HFSS中建立滤波器模型并进行仿真,改进后增加了传输零点,回波损耗更加稳定,谐振器长度减小10%,微带加载线线宽增加0.15 mm,整体滤波器尺寸减小10%,验证了所提出结构的可行性。

Nonlinear properties of the lattice network-based nonlinear CRLH transmission lines

The nonlinear properties of lattice network-based（LNB） composite right-/left-handed transmission lines（CRLH TLs）with nonlinear capacitors are experimentally investigated.Harmonic generation,subharmonic generation,and parametric excitation are clearly observed in an unbalanced LNB CRLH TL separately.While the balanced design of the novel nonlinear TL shows that the subharmonic generation and parametric processes can be suppressed,and almost the same power level of the higher harmonics can be achieved over a wide bandwidth range,which are difficult to find in conventional CRLH TLs.

High-gain planar TEM horn antenna fed by balanced microstrip line

A printed TEM horn antenna with high gain fed by balanced microstrip line is proposed. The radia- tion part of the antenna consists of two symmetrical triangular metal slice branches printed on the FR-4 substrate with 1.5 mrn thickness. The two branches are fed by balanced mierostrip line. The antenna is simulated by soft- ware CST MICROWAVE STUDIO and the equivalent adopted dipole model is proposed to describe the radia- tion characteristic of the antenna. The simulation results indicate that the frequency range is from 1.64 GHz to 5 GHz with reflection coefficient less than -6 dB, and the typical gain value is 8 dB in the operating band- width. In order to improve antenna gain without influencing the bandwidth, the length of the dielectric slab should be extended appropriately in the main radiation direction. By extending the length of the dielectric slab appropriately in the main radiation direction, the antenna gain can be improved significantly without the influ- ence on the bandwidth. Besides, a metal disc loaded in the radiation direction makes the gain in band be more stable. The prototype has been fabricated and measured in microwave anechoic chamber which is coincident with the simulation results. This antenna can be widely applied in the UWB field.

Design and Development of a 2 ×1 Array of Slotted Microstrip Line Fed Shorted Patch Antenna for DCS Mobile Communication System

Compact microstrip antennas have recently received much attention due to the increasing demand of small antennas for personal communication equipment. The problem of achieving a wide impedance bandwidth for compact microstrip antennas is becoming an important topic in microstrip antenna design. In this paper the design and development of a 2 × 1 array of a low cost slotted microstrip line fed shorted patch antenna (MFSPA) has been presented. Both the shorted patch and microstrip line feed network have air substrate. The material cost is thus reduced to a minimum. The array consists of two adjacent patches fed, using a simple microstrip T network. The impedance bandwidth of nearly 40%, covering the bandwidth requirement of 1750 MHz band is obtained. Also the antenna exhibits dual band operation. The cross polarization radiation in H-Plane observed with a single element antenna has been reduced considerably with 2 × 1 array. A peak antenna gain of 9.2 dBi is obtained with a small variation of 0.8 dBi. From the results obtained it is clear that the antenna array studied has a low cost fabrication and is suitable for applications in DCS mobile communication base station.

Aperture Coupled Microstrip Antenna for Dual-Band

This paper presents air gap aperture coupled microstrip antenna for dual-band operation over the frequency range of (2.9 to 6.0 GHz). This antenna differs from any other microstrip antenna with their feeding structure of the radiating patch element. Input signal couples to the radiating patch trough the aperture that exists on the ground plane of microstrip feed line. The dual-band achieved by variation of air gap [2 mm to 6 mm] between single patch antenna and aper-ture coupled microstrip antenna. The main advantage of this type antenna is increased the bandwidth of the antenna as compared to a single layered patch antenna. The two resonant frequencies can vary over a wide frequency range and the input impedance is easily matched for both frequencies. The obtain ratios of resonance frequencies are variable from 2.1 GHz to 1.1 GHz with increasing the air gap between single patch and aperture coupled microstrip antenna. The measured return loss [–14 dB] exhibits an impedance bandwidth of 35%. The input impedance and VSWR return loss have been measured with the help of Network analyzer.

Design, Modelling and Characterization of Transmission Lines for mm-Wave Silicon ICs

This article describes the design, modelling and characterization of transmission lines for millimetre wave silicon integrated circuits up to 65 GHz. The simulation results of three different EM （electro-magnetic） simulators for a selected hybrid coplanar layout structure are presented. Two different deembedding methods are investigated and compared with respect to sensitivity to typical measurement errors. Finally both methods are applied to the measurement results of the fabricated test structures in a 250 nm BiCMOS technology showing good agreement to EM simulations and predicted sensitivity to measurement errors.

Study on a W-band modified V-shaped microstrip meander-line traveling-wave tube

The study on a miniaturized, low-voltage, wide-bandwidth, high-efficiency modified V-shaped microstrip meander-line slow-wave structure is presented. This structure is evolved from the original U-shaped microstrip meander-line slow-wave structure, combining the advantages of a traditional microstrip and a rectangular helix. In this paper, simulations of the electromagnetic characteristics and the beam-wave interaction of this structure are carried out. Our study shows that when the design voltage and the current of a sheet electron beam are set to be 4700 V and 100 mA, respectively, this miniature millimeter-wave power amplifier is capable of delivering 160-W output power with a corresponding gain of 37.3 dB and a maximum interaction efficiency of 34% at 97 GHz.

浅埋深中厚煤层预掘回撤通道支护技术研究与应用

为进一步提高综采工作面末采回撤速度、确保设备回撤空间,采用理论计算、现场试验相结合的方法对浅埋深中厚煤层预掘回撤通道支护技术进行初步研究,建立了工作面残余煤柱承载力学模型,理论分析得知残余煤柱宽度对煤柱承载性能的时空演化规律具有重要影响,末采期间残余窄煤柱出现区域性脆性破坏失稳状态是导致超前采动应力、顶板岩层断裂线前移的主要原因。现场试验末采段残余煤柱宽度约5 m时,整条窄煤柱在多重载荷作用下发生屈服,进而呈现大面积失稳破碎状态,巷内支护体承载受力急剧增加,锚索最大受力约为225 kN,最大顶底板移近量出现在通道中部靠工作面侧,约为100 mm,结果表明,采用高预应力强力锚杆(索)联合支护结构配合垛式支架外部支撑,可有效控制末采期间预掘回撤通道顶底板之间的闭合位移,为类似条件下预掘回撤通道支护提供工程借鉴。

面向环境射频能量收集的宽频整流电路

整流电路是射频能量回收系统的核心,能够将射频能量转换为直流。但由于整流电路中使用的二极管具有非线性特性,导致整流效率会随频率变化而降低。为解决这一问题,本文提出一种具有宽频带的整流电路,它通过采用与二极管串联的短路线、与二极管并联的开路线以及多级微带线结构来调整阻抗匹配,实现了在宽频带范围内的高转换效率。设计的整流电路在0 dBm的输入功率下,从1.7~2.7 GHz,均达到50%的整流转换效率,最高整流转换效率为63.3%。该宽带整流电路可以运用在无线能量收集系统中。

基于BIM技术的浅埋隧道无限元法数值研究

近年来,BIM技术在交通运输基础工程领域的应用日益广泛,如地铁、高铁、公路、隧道等项目全生命周期的管理都有BIM技术的参与。本研究通过BIM软件–Revit建立浅埋隧道的信息模型,基于BIM信息模型,导入ABAQUS有限元分析软件,对越秀公园站浅埋暗挖多孔隧道进行有限元与无限元耦合模拟,验证了无限元在隧道数值模拟中的可行性。其次通过设置不同的工况,验证了无限元与有限元耦合模拟的准确性,并且研究了隧道的开挖对不同工况下,地表沉降和衬砌内力的影响,得出最优的开挖工序,为后续浅埋隧道的力学行为的研究提供借鉴。

基于THz-TDR的芯片金属微带线缺陷检测

针对体积小、走线密集、集成度高的封装芯片缺陷检测,目前的主要检测手段存在精度低、周期长等缺点。为弥补传统检测方法的不足,作者结合太赫兹技术与时域反射技术,探究对芯片上金属导线缺陷检测的可行性。首先在不同宽度的金属微带线上加工了不同比例的凸起、凹槽缺陷,模拟集成芯片中金属导线的不完全开/短路等阻抗不匹配情况,利用太赫兹时域反射计采集其时域反射信号。然后根据时域反射脉冲对应的时间分别对不同缺陷程度、不同缺陷类型进行定性分析,并精确计算出了芯片上金属微带线的缺陷位置。最后利用有限元分析法对硅基底上存在缺陷的金属微带线进行仿真分析,与实验结果具有良好的一致性。该研究表明,太赫兹技术与时域反射技术结合能够实现对芯片上金属导线缺陷的诊断检测,为集成芯片的缺陷检测提供了经验参考。

爆破荷载作用下邻近深埋隧道衬砌动力响应数值模拟

为了研究深埋小净距隧道在爆破荷载下的动力响应以及保证隧道的安全和稳定,以三洞分离隧道爆破开挖工程为背景,通过ANSYS/LS-DYNA模拟分析深埋小净距隧道在爆破荷载作用下的衬砌动力响应。分析了隧道同一截面拱顶、拱腰、拱脚不同测点,不同断面的振速和位移。研究结果表明:衬砌内侧(与净空面接触)拱脚首先产生振动,爆破卸载后,衬砌外侧(与岩石接触)振动速度达到峰值。纵断面的振动速度差异较大,水平位移的影响大于垂向位移的影响。最大位移出现在拱顶,其次出现在迎爆侧拱腰处。断面拱脚处测点振动加速度最大,受到的爆轰也最大。

一种波导耦合的AlGaN/GaN HEMT太赫兹探测器

自由空间的太赫兹电磁波与太赫兹天线/探针之间的耦合通常是通过波导或硅透镜来实现的。基于波导的耦合方案可以提供比透镜耦合方案更高的耦合效率,而此前AlGaN/GaN HEMT太赫兹探测器/混频器具有高阻抗的特性,因此一般采用硅透镜耦合。文中仿真设计了一种110 GHz的波导耦合型AlGaN/GaN HEMT太赫兹直接探测器,采用波导-微带过渡结构和微带线阻抗匹配结构使探测器的阻抗降低至275Ω,在降低热噪声电压的同时具有高的响应度。在设计好探测器各部分结构后,对其进行整体全波仿真、数据提取与后处理计算,最后可得到探测器的性能指标即噪声等效功率(NEP)。结果表明:在110 GHz的频率下,太赫兹探测器的NEP可达到22pW/√Hz,与透镜耦合型直接探测器灵敏度相当,其中该探测器中HEMT混频器的栅长和栅宽分别为1μm和150μm。仿真结果还表明通过将栅长从1μm缩减至100 nm,可以进一步降低探测器的NEP,提高探测器的灵敏度。

基于周期性枝节加载的微带线串扰抑制研究

针对当前印刷电路板上相邻微带线之间的串扰抑制问题,提出了一种在超宽带频率范围内利用周期性耦合枝节来抑制微带线远端串扰的电磁兼容设计。在串扰的形成原因分析基础上,该设计将沿传统微带线纵向方向加载的周期性开路枝节进一步与相邻两条微带线之间周期性加载的工字型耦合枝节相结合。微带线上的开路枝节以及线间的耦合枝节主要用于增加微带线等效自感和线间等效互容,并减小线间等效互感,由此显著降低远端串扰强度。同时,线间等效互感的减小能抑制因容性耦合增大而导致的近端串扰上升。全波结果表明,该设计在1~20 GHz范围内可使相邻微带线的远端串扰强度小于-48 dB,且物理结构中不涉及金属化通孔,具有几何结构简单、成本低和可布线空间大等特点。

Q波段微带到带状线垂直过渡结构

层间垂直过渡结构通常被用来实现组件结构的小型化和高密度设计,在毫米波电路布线中起着不可或缺的作用。本文设计了一种可用于Q波段的微带线到带状线的垂直过渡结构,在微带线的末端采用“水滴”匹配结构,以金属通孔连接传输线的形式进行射频信号的垂直传输。运用三维高频电磁仿真软件(HFSS)建立该结构,并与其他类似结构进行性能仿真比对。优化结果表明,这种结构在42~47 GHz频带范围内,反射系数小于-20 dB,带内插入损耗优于0.3 dB,可以满足工程应用的要求。相比同类型的其他垂直过渡结构,本文结构在减小占用面积的同时保持了良好的传输性能。

输电线路短路电流对埋地管道电位抬升及抑制方法研究

针对城市中输电线路与埋地油气金属管道临近问题,通过建立架空导/地线-杆塔-接地网-埋地管道一体化电磁场计算模型,综合考虑导线和避雷线对金属管道的感性耦合影响以及杆塔入地电流对管道的阻性耦合影响。基于此模型研究土壤电阻率、临近距离、管道参数、交叉跨越角度以及不同供流方式对金属管道电位、防腐层耐受电压的影响规律,并开展管道电位抬升的抑制方法研究,可以为输电线路发生接地短路故障时临近燃油(气)管道安全防护提供指导。

反平面线源荷载作用下浅埋圆形非完全粘结隧道动力响应研究

为加深理解波源距离和非完全粘结对地震波散射的影响规律,结合位移不连续模型、波函数展开法、Graf公式和镜像方法推导了反平面线源荷载下浅埋圆形非完全粘结隧道动力响应的级数解,并通过衬砌内外边界条件残余量与级数解截断项数的关系校验了该解的精度。通过对该级数解进行参数分析,系统地探讨了衬砌与围岩的接触刚度、衬砌模量、衬砌厚度、隧道埋深和波源距离等因素对衬砌内表面位移和周向剪应力的影响。结果表明:衬砌与围岩的接触刚度对隧道的动力响应具有显著的影响,尤其在某些较小接触刚度情况下隧道动力响应幅值可能非常大;增大衬砌模量会减小位移,但同时会导致周向剪应力增加;增大衬砌厚度能同时减小位移和周向剪应力;增大隧道埋深会使最大位移和周向剪应力向隧道拱顶附近移动;增大线源与隧道的水平距离会使隧道背波侧相对幅值增大。