Miniaturization of an Ultra‐Wideband Antenna with Two Spiral Elements

In this letter, novel antennas with two spiral elements are presented for ultra‐wideband application. The original antenna consists of a T‐shaped microstrip feed line, two spiral radiating elements, and a ground plane with two circular slots. It measures 30 mm × 40 mm × 1.6 mm. Spiral elements are used to increase the lower bandwidth limit. To further reduce the size of the antenna, the original antenna is cut in half by using the symmetry of the surface current distributions. The proposed antennas feature omnidirectional radiation patterns and good gain flatness.     

有耗传输线的TLM模型法

本文从传输线理论出发,介绍了一种解决传输线问题的新方法－－TLM法。     

有耗传输线的阻抗圆图

本文针对有耗传输线的特点，，分析了有耗传输线的阻抗圆图，并讨论了利用该圆图计算有耗线阻抗的方法。     

宽带平面螺旋天线的研究与设计

平面螺旋宽带天线具有频带较宽、体积较小、圆极化性能较好等特点,应用范围很广。但是这种天线增益较低,馈电匹配较难实现,尤其是前者,使得其性能大打折扣。通过研究影响平面螺旋宽带天线增益和馈电匹配的主要因素,设计了2~7GHz范围内的宽频带平面螺旋天线。理论分析和仿真实验结果表明,对改善平面螺旋宽带天线的性能有一定的工程参考价值。     

Transmission Line Model for an Edge‐Coupled Patch Antenna

In this paper, a simple transmission line model for an edge‐coupled patch antenna is presented. The coupled section is modeled with a lump network which represents the mutual admittance between patches and from patch to ground. Theoretical analysis of two edge‐coupled patch antenna models are compared by simulation and experiment in antennas designed to operate at the 2 GHz band. The proposed model predicts the return loss of the antenna accurately.     

Impedance Transformation and Matching for Lumped Complex Load with Nonuniform Transmission Line

New nonuniform transmission-linematching networks for a class of lumped complex loads are presented. A parabolic (or reciprocal parabolic) tapered transmission line, whose exact equivalent circuit is represented by a mixed lumped and distributed circuit, can transform the lumped series RC (or parallel RL) loads into different lumped impedances which are more convenient than the original load impedances for ordinary matching network design. Simple design procedures are described and useful design charts are given. Also, numerical examples are shown including experimental verification.     

A Lumped Circuit for Wideband Impedance Matching of a Non-Resonant, Short Dipole or Monopole Antenna

A new technique is proposed for wideband impedance matching of short dipole- or monopole-like antennas in the VHF-UHF bands. Instead of constructing the network topology for every particular antenna, we propose a simple network of one fixed topology. This network is an inductive L-section cascaded with a high-pass T-section. The network includes five discrete components—three inductors and two capacitors. Although the approach is not general, the paper proves that matching with the present network is close to the theoretical limit impedance matching confirmed by Bode-Fano theory. The matching performance also approaches the performance of the Carlin's equalizer for short dipoles and monopoles. The dipoles and monopoles may have different shape and different matching bandwidths. By using the matching circuit of fixed topology we avoid greater difficulties related to the practical realization of the Carlin's equalizer. The key point is to minimize the antenna's matching network complexity (and loss) so that the circuit can be designed and constructed in a straightforward manner.      

基于传输线模分析法的2G Hz矩形微带天线设计

在现代通信系统中,微带天线以其体积小、便于实现线极化或圆极化,并能很好的适用于双频工作的优点,被广泛的应用在2G移动通信通信系统中.本文采用传输线模分析法设计了一种适用于3G移动通信系统的2GHz矩形微带天线,并通过仿真及优化,改进了天线的增益和效率.     

基于传输线模分析法的2G Hz矩形微带天线设计

在现代通信系统中,微带天线以其体积小、便于实现线极化或圆极化,并能很好的适用于双频工作的优点,被广泛的应用在2G移动通信通信系统中。本文采用传输线模分析法设计了一种适用于3G移动通信系统的2GHz矩形微带天线,并通过仿真及优化,改进了天线的增益和效率。     

System Capacity Analysis and Antenna Placement Optimization for Downlink Transmission in Distributed Antenna Systems

System capacity and antenna placement play crucial roles in wireless communication systems, and they are of great value to network planning. In this paper, we are motivated to analyze the system capacity and optimize the antenna placement in distributed antenna systems. This paper establishes a composite channel model which takes path loss, lognormal shadowing and Rayleigh fading into consideration. To reduce the computational complexity, an approximate theoretical expression of system capacity is derived with selective transmission at the transmitter and maximal ratio combining at the receiver. An antenna placement optimization problem is formulated, and then a genetic algorithm (GA) based searching scheme is proposed to solve the proposed optimization problem. The computational complexity analysis indicates that the proposed GA-based searching scheme is computationally efficient in terms of both running time and storage space. Numerical results show that the approximate theoretical expression of system capacity can provide a very good approximation to the simulation results, and the proposed GA-based searching scheme for solving the antenna placement optimization problem can consistently offer a large capacity gain over other existing schemes.     

Kuroda's Identity for Mixed Lumped and Distributed Circuits and Their Application to Nonuniform Transmission Lines

Kuroda's identities, which are used in analysis and synthesis of distributed transmision line circuits, may be applied to mixed lumped and distributed circuits. It is shown that circuits consisting of cascade connections of lumped reactances and uniform transmission lines are equivalent to circuits consisting of a cascade connection of nonuniform transmission lines, lumped reactances, and ideal transformers. Moreover, by using these equivalent transformations, network functions of some nonuniform transmisssion lines can be derived exactly.     

片上螺旋电感集总模型中衬底因子的分析与拟合

石英、高阻SOI、高阻硅等衬底上实现的电感具有比低电阻率衬底的电感更优的高频性能,因而研究基于不同衬底的电感性能,并在高频模型中进行精确的衬底因子表征就显得十分重要.综合考虑高频下的趋肤效应和邻近效应及衬底电磁损耗对电感性能的影响,实现了片上螺旋电感的集总元件模型,并通过与SOI、石英衬底的电感仿真参数及高阻硅衬底的电感测试参数进行了模型验证,结果表明,该模型拟合的S参数及Q值曲线能与仿真及测试结果吻合,同时模型中衬底因子的提取值与衬底性质相符合,因而该模型适用于片上电感的模拟与设计.     

A Simple Model for Weakly Coupled Lossy Transmission Lines of Finite Length

A simple formula for coupling between two parallel lossy wires of finite length above a conducting plane is derived. Weak coupling is assumed. The first wire is driven by a source at one end and terminated with an impedance at the other end. The second wire is terminated with an impedance at each end. The formula is shown to agree well with the results of a previously reported experiment. For low frequencies, the formula reduces to the familiar inductive and capacitive coupling terms plus a term which is contributed by wire losses. For higher frequencies, the lossiness of the wires is shown to be a dominant factor in the coupling mechanism if the undriven wire is terminated by large impedances and the driven wire is terminated by low impedances.     

传输线分布参数模型与物理模型

本文详细分析了传输线的分布参数电路模型与真实的物理电路模型之间的关联,同时对均匀传输线模型给出了明确的适用范围。如此,可以解决＂电磁场＂和＂电磁兼容＂等课程中经常令学生困惑的问题,对正确理解二端口模型的本质,提高理论素养大有裨益。     

Design and Characterization of Wideband Aperture-Coupled Circularly Polarized Antenna for Gigabits Per Second Wireless Communication System

In this paper, design and characterization of an aperture-coupled circularly polarized (CP) rectangular patch antenna suitable for Gigabit per second wireless communications system is presented. The proposed antenna exhibits a large bandwidth of 2.77 GHz at centre frequency \({\text{f}}_{\text{c}}\) = 19.5 GHz (about 15% of fractional bandwidth (FBW)). It also has a gain of about 7.25 dBi at 18 GHz with good stable gain and radiation characteristics in the frequency band of interest. For indoor wireless channel measurements, two developed prototypes are employed as single input single output transmit receive (TX–RX) antennas with a robust and versatile channel modeling system. We demonstrate a measurement campaign to investigate the dynamic range of the system by calculating path loss. The pulse dispersion effect is quantified by pulse fidelity factor (PFF). The measurements are performed in laboratory environment using Gaussian pulse based sounding signal modulated at 19.3 GHz carrier frequency. The design and characterization of compact size antennas with pertinent bandwidth and excellent radiation characteristics is one of our initiatives towards developing a millimeter wave (MMW) test bed system for channel modeling and measurement, since 5G wireless communication is supposed to operate in MMW band.

     

Double-Sided Exponentially Tapered GPR Antenna and Its Transmission Line Feed Structure

A double-sided broadband antenna for applications including ground-penetrating radar for detecting buried target is described. When compared with traditional coplanar-strip antennas, a better performance is achieved with a more practical design for construction. The steps in the design procedure are demonstrated herein. In addition, using incremental segments of current elements, a distributed dipole array model is derived and presented for determining$S_11$in the time domain and for determining the radiation pattern of this antenna. By comparing measured results and HFSS simulations, our straightforward dipole array model of the more complicated antenna structure is justified by the accuracy of the results obtained. Finally, an experimental example is presented to show that this antenna in a GPR system application is effective in detecting even small plastic targets.     

BCB/InP基宽带低损耗共面波导微波传输线

面向高速行波电吸收(EA)调制器的需要,设计并制作了基于苯并环丁烯(BCB)聚合物/InP衬底的宽带(0～40 GHz)、低损耗微波共面波导传输线.对共面波导结构开展仿真设计,分别对BCB材料厚度、InP衬底导电率和信号电极宽度等关键参数进行了优化.结果表明,当设计的BCB膜厚为4 μm、InP衬底导电率小于0.002(Ω·cm)-1和信号线宽度为84μm时,微波传输性能可达最优.在此基础上,采用电阻率为108Ω·cm的半绝缘(SI)InP衬底、涂覆4μm BCB薄膜,制作出0～40 GHz范围内微波损耗小于0.5 dB/mm的共面波导传输线.     

A Parameterization Scheme for Lossy Transmission Line Macromodels With Application to High Speed Interconnects in Mobile Devices

We introduce a novel parameterization scheme based on the generalized method of characteristics (MoC) for macromodels of transmission-line structures having a cross section depending on several free geometrical and material parameters. This situation is common in early design stages, when the physical structures still have to be finalized and optimized under signal integrity and electromagnetic compatibility constraints. The topology of the adopted line macromodels has been demonstrated to guarantee excellent accuracy and efficiency. The key factors are propagation delay extraction and rational approximations, which intrinsically lead to a SPICE-compatible macromodel stamp. We introduce a scheme that parameterizes this stamp as a function of geometrical and material parameters such as conductor-width and separation, dielectric thickness, and permittivity. The parameterization is performed via multidimensional interpolation of the residue matrices in the rational approximation of characteristic admittance and propagation operators. A significant advantage of this approach consists of the possibility of efficiently utilizing the MoC methodology in an optimization scheme and eventually helping the design of interconnects. We apply the proposed scheme to flexible printed interconnects that are typically found in portable devices having moving parts. Several validations demonstrate the effectiveness of the approach     

Oscillatory Transmission Line Pulsing for Characterization of Device Transient Response

An oscillatory transmission line pulse generation system is introduced. This measurement system allows one to observe the response of an electrostatic discharge (ESD) protection device to a large-amplitude radio-frequency damped sinusoid; such waveforms mimic ESD tests. The trigger voltage of silicon-controlled rectifiers used for ESD protection is observed to be dependent on the past state of the device, due to charge storage in the bipolar bases.