Transmission Line Structure Research Articles

Shape Memory Alloy-Spring Pendulum for Vibration Suppression of Wind-Induced Transmission Tower-Line Systems

Wind-induced vibration suppression of transmission line structures is critical for structural reliability and serviceability. In this study, a shape memory alloy-spring pendulum (SMA-SP) is proposed for a wind-induced tower-line system to improve the reliability and serviceability of the control unit. A numerical calculation method of the transmission tower line structure coupled with the SMA-SP is established with special emphasis on the solid elements of the damper. Furthermore, the effectiveness and reliability of vibration suppression on wind-induced transmission line structures are evaluated and parametric analyses are conducted; the results reveal the influences of key parameters on the performance of SMA-SP and provide design recommendations for applications. In this study, it is demonstrated that the SMA-SP provides more stable control effects on the wind-induced vibration of transmission line structures than a conventional spring pendulum (SP), and the proposed numerical method effectively demonstrates the nonlinear mechanism of the damper. The parametric analyses show that SMA-SP exhibits low sensitivity levels to variations in the tuning frequency ratio and achieves optimal reduction effects after satisfying the internal resonance condition.

PSO-Algorithm-Assisted Design of Compact SSPP Transmission Line

This letter proposes a compact spoof surface plasmon polariton (SSPP) transmission line (TL) structure. The particle swarm optimization (PSO) algorithm is utilized to numerically optimize the traditional rectangular groove SSPP structure. The SSPP unit cell is pixelated into 23 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times $ </tex-math></inline-formula> 9 pixels with a resolution of 0.2 mm, and the asymptotic frequency is reduced to 5.4 GHz through optimization. The developed SSPP TL exhibits a compact structure, and its electrical dimension is only about <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.842\lambda _{g} \times 0.28\lambda _{g}$ </tex-math></inline-formula> , where <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\lambda _{g}$ </tex-math></inline-formula> is the wavelength of the cutoff frequency. A prototype of the developed SSPP TL is fabricated and tested, and the experimental result agrees well with the simulated one. The proposed optimization approach is applicable to both single- and dual-conductor SSPP structures. The results are of great significance to the miniaturization of components and circuits based on SSPP.

Investigation of signal integrity of fuzz button connectors under different compression states

AbstractFuzz button connectors are extensively used in vertical interconnection for high‐density integrated circuits. This work studied the impact of fuzz buttons under different compression states on high‐frequency signal transmission using theoretical analysis and experimental testing. The resistance values for fuzz buttons with different heights in compression states were measured. The physical dimensions were obtained for sample fuzz buttons subjected to various compression states. The effects of long‐term compression of fuzz button on the resistance values and S parameters of the device under test (DUT) were analyzed. In addition, the high‐frequency parameters were measured for the DUT with fuzz buttons in various compression states. Both a three‐dimensional (3D) electromagnetic field model and an equivalent circuit model for the fuzz buttons under compression states were developed and the results of these two models show good agreement with experimental results. In the circuit model, a fuzz button connector with a three‐wire transmission line structure was modeled as a π impedance network, composed of equivalent inductances and capacitances. It was found that the proposed 3D electromagnetic field model and an equivalent circuit model can accurately predict the effect of fuzz buttons under different compression states on the signal transmission in the affected frequency band. However, the models cannot evaluate the communication performance of the whole system.

An efficient modeling approach of 1D-planar metamaterials in the high-frequency regime

PurposeThe purpose of this paper is to present an alternative modeling approach in terms of the determination of a physically equivalent circuit model for one-dimensional (1D) planar metamaterials in the high-frequency regime, without a postprocessing optimization procedure. Thereby, an efficient implementation of physical relationships is aimed.Design/methodology/approachIn this paper, a method based on quasi-stationary simulations and mathematical conversions to derive the values for a physically equivalent circuit model is proposed. Because the electromagnetic coupling mechanisms are investigated in detail, a simplification for the considered multiconductor transmission line structure is achieved.FindingsThe results show that the proposed modeling approach is an efficient and physically meaningful alternative to classical full-wave simulation techniques for the investigated inhomogeneous transmission line structure in both the time domain as well as in the frequency domain. In the course of this, the effort is reduced while a comparable accuracy is maintained, whereby specific coupling mechanisms are considered in circuit simulations.Originality/valueThe process to obtain information about physically interpretable lumped element values for a given structure or to determine a layout for known ones is simplified with the aid of the proposed approach. An advantageous adaption of the presented procedure to other areas of application is well conceivable.

Leveraging space–time modulation for energy coupling control in electromagnetic coupled transmission lines structures

This article presents a technique for controlling energy coupling in a coupled transmission line system based on the space–time modulation concept. The per-unit-length mutual capacitance and mutual inductance of the structure are modulated in space and time. The main idea is based on the harmonic generation property of space–time modulated media. As the amplitude of harmonics is a function of modulation parameters it is demonstrated that by choosing an appropriate space–time modulation scheme energy of different harmonics can be engineered leading to crosstalk reduction. In the quest for designing an effective space–time modulation scheme, an analytical method is developed for the examination of the space–time modulated coupled transmission line. The proposed method which is based on the state space formulation and benefits from the coupled mode theory is fast and accurate making it feasible for design problems. To validate the proposed analytical method, a full-wave simulation method has been used. The time-varying nature of the problem makes the finite-difference-time-domain the most appropriate choice. The validity of the analytical method is rigorously verified against the developed finite-difference-time-domain technique. The interest in circuit design techniques in an IC-compatible fashion in microwave circuits and the introduction of tunable material such as graphene in the THz regime leads to a positive future for the proposed space–time modulation-based crosstalk reduction method.

Investigation of Electromechanical Reliability and Radio Frequency Performance of a Highly Stretchable Liquid Metal Conductor for Wearable Electronics

Abstract Liquid metal-based gallium conductors exhibit unique physical and electromechanical properties, which make them excellent candidates for the next generation of wearable electronics. In this study, a novel fluid phase-based gallium conductor was stencil printed on thermoplastic polyurethane (TPU) to fabricate a stretchable conductor as well as a stretchable radio frequency (RF) transmission line. The electromechanical reliability of the conductor during high elongation as well as cyclic tension and bend fatigue was evaluated and compared with commercially available stretchable silver-filled polymer paste. The microstructure of the liquid metal conductor and the silver paste was investigated via scanning electron microscopy (SEM) before and after the samples were subjected to high elongation (&amp;gt;100%). Unlike the silver paste, the liquid metal conductor maintained its microstructural integrity while its resistance showed a linear response to changes in length. A cyclic tension fatigue test confirmed the fatigue-free performance of the liquid metal conductor during 8000 stretching cycles at a strain amplitude of 30%. The electromagnetic structure of the RF transmission line was simulated and then compared to the measured data. The measurements for insertion loss showed that U-bending, 90 deg twisting, and 1000 stretching cycles at a strain amplitude of 100% did not have a significant impact on the RF performance. Details of the DC tests and RF measurements, including the microstructural analysis and simulation results, will be discussed in this article.

Area-Efficient 28-GHz Four-Element Phased-Array Transceiver Front-End Achieving 25.2% Tx Efficiency at 15.68-dBm Output Power

An area-efficient 28-GHz four-element phased-array transceiver front-end (TRx FE) is proposed in this article. Transmitter/receiver (T/R) switch, phase shifter (PS), and power combining/splitting network all use customized coupler-based structures to replace area-consuming quarter-wavelength ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\lambda $ </tex-math></inline-formula> /4) transmission line (T-line) structures. In Tx mode, a three-stage power amplifier (PA) is designed by cascading a class-AB predriver amplifier, a deep class-AB driver amplifier, and a class-A output amplifier for high output power. In Rx mode, a two-stage low noise amplifier (LNA) is designed with a 3-bit resistive adjusting load for high dynamic range of input power. A coupler is adopted in the variable gain amplifier (VGA) to achieve constant phase during gain adjustment. The proposed TRx FE is fabricated in a 40-nm CMOS process. Measurement results show that output 1-dB compression point (OP1dB) of 14.99 dBm and saturated output power (OPsat) of 15.68 dBm with 25.2% power efficiency are achieved in each Tx element. In each Rx element, noise figure (NF) of 4.54 dB, input 1-dB compression point (IP1dB) of −10.15 dBm, and maximum gain of 26.3 dB with 56.1-mW power consumption are realized. The gain range of Rx/Tx mode is 9.9–26.3 dB/24.2–44.6 dB with a resolution of 0.3 dB and phase variation less than 2° at 28 GHz. Thanks to the area-efficient coupler-based structures, the phased-array TRx FE occupies an area of 0.42 mm2 for each element and 0.084 mm2 for total area of combiner/splitter, achieving high area efficiency for Ka-band phased-array TRx FEs.

Regional Multihazard Risk-Assessment Method for Overhead Transmission Line Structures Based on Failure Rate and a Bayesian Updating Scheme

In this study, a new method for multihazard risk assessment of an overhead transmission line grid located over a relatively large area is proposed. The main task of this method was to assess annual risk for overhead transmission lines using failure rates estimated from historical failure data and then modifying these estimated failure rates by reanalysis data and a Bayesian updating scheme. For this purpose, a comprehensive database of structural failures was collected for climatic, geologic, and man-made hazards to overhead transmission lines. Risk denotes the probability of exceeding the sum of direct losses due to repair costs of overhead transmission line components and indirect losses due to energy not supplied or unplanned power-off after outages. The performance of the proposed method was evaluated in a case study of a target area. The results showed that climatic hazards contributed the most to total losses in the study area. Furthermore, when using indirect losses to estimate the annual loss, the average annual loss may increase by up to about 45% relative to direct losses, depending on the type of hazard. This demonstrates the importance of investigating indirect losses from structural failures in the risk assessment of overhead transmission lines.

Experimental study on bearing capacity of corroded angle steel members of in-service transmission towers

The tower is the load-bearing structure of the overhead transmission line. Due to the complex operating environment and other factors, the transmission tower is prone to corrosion, which weakens the bearing capacity of the tower and affects the safe operation of the power grid. Through the investigation of the corrosion situation of the transmission towers in service, the angle steel members were removed from the in-service transmission towers, and the axial compression bearing capacity test was carried out. As the corrosion rate increases, the bearing capacity of components shows a decreasing trend, and due to the existence of corrosion, and at the same corrosion rate, due to the location of corrosion, The corrosion depth and corrosion area are different, and the axial compression bearing capacity of the components fluctuates greatly.

Software package for analysis and design of overhead power transmission line structures

The article describes an algorithm for calculating wires and cables implemented by determining the loads on the supports, taking into account the compatibility of deformations of structural elements of an overhead power line (overhead line), atmospheric conditions and the profile of the route for all possible modes of operation of overhead lines. Wires and cables are exposed to the load from their own weight, as well as additional impacts in the form of horizontal wind load and the weight of icy deposits. Using the reduced equation of state of the wire (lightning-proof cable), the amount of tension in the operational state is determined if the voltages in the initial state and the values of loads and temperatures are known. It is revealed that for small spans, the voltage value is greatly influenced by temperature, and for large spans by load, which means there must be such a boundary (critical) span value at which the influence of temperature and load on the voltage value will be the same. As a result, software has been developed to solve the problem of determining the stress-strain state of wires and cables and collecting loads on overhead line supports. The developed calculation subsystems can function independently or be included in the software package as components written in the algorithmic language FORTRAN. In contrast to the traditional calculation, emergency loads for anchor-corner supports are determined not only in the ice regime, but also at minimum and average operating temperatures. The calculation in the software package allows us to consider the alternate breakage of all phases of wires and cables in both the left and right spans.

Defected microstrip structure-based near-end and far-end crosstalk mitigation in high-speed PCBs for mixed signals

PurposeThe design, fabrication and experimental validation of defected microstrip structure (DMS) are proposed to address the problem of near-end crosstalk (NEXT) and far-end crosstalk (FEXT) between the microstrip transmission lines in a printed circuit board.Design/methodology/approachThe proposed DMS evolved with the combination of spur line (L-shaped DMS) and U-shaped DMS topologies. This technique reduces the strength of electromagnetic coupling and suppresses crosstalk by optimizing the capacitive and inductive coupling ratio between the linked microstrip lines. The practical inductance value is much more significant in DMS than in defected ground structures (DGS), but the capacitance value remains the same.FindingsA DMS unit is etched on the aggressor microstrip line instead of the DGS circuit. Because there is no leakage via the ground plane and the circuit size is far smaller than with DGS, the enclosure issue is disregarded. DMS structures have a larger effective inductance and are resistant to electromagnetic interference. A tightly coupled transmission line structure with minimal separation between the coupled microstrip line is designed using DMS. Further research must be conducted to improve the NEXT, FEXT and spacing between the transmission lines.Originality/valueSimulation and actual measurement results show that the proposed DMS structure can effectively suppress crosstalk by analysing the S-parameters, namely, S_12, S_13 and S_14, with measured values of 1.48 dB, 20.65 dB and 21.099 dB, respectively. The data rate is measured to be 1.34 Gbps as per the eye diagram characterization. The results show that the NEXT and FEXT are reduced by approximately 20 dB in the frequency range of 1–11 GHz for mixed signals. The substantial measured results in the vector network analyser coincide with the computer simulation technology microwave studio suite simulation results.

Research on influence of new structural design regulations on general design of steel towers

This work describes the main revision content of the power industry standard (DL/T 5486-2020) (Technical specification for the design of steel supporting structures of overhead transmission line). And the effects of the new revision standard (DL/T 5154-2012) Technical code for the design of tower and pole structures of overhead transmission line (DL/T 5154-2012), on the general design of 35kV~750kV steel towers are analyzed in depth. Subsequently, the optimization suggestions of general design of the steel tower are proposed.

Modeling and simulation for determining the characteristic impedance of transmission and distribution line structures

The characteristic impedance of structures is an important parameter used in the development of overvoltage protection studies and in the insulation coordination in electrical systems. The transmission line towers shapes and the poles shapes make it difficult to calculate the characteristic impedance analytically, or even measuring in laboratory. Thus, this paper presents a methodology to calculate the characteristic impedance of concrete poles in distribution networks and transmission line towers. A model was developed in Q3D Extractor software to run these simulations. A comparison between simulations and an analytical method is made, considering two types of structures, a distribution pole, and a transmission tower. The results show divergences between the calculated values by the various analytical methods and those obtained in this work. At the end, it is concluded that the determination of the characteristic impedance using the proposed methodology is more accurate due to the degree of structure details considered.

Interpolatory proper order decomposition of nonlinear transmission line circuits

PurposeThe paper is concerned with interpolatory proper orthogonal decomposition (IPOD) methods for nonlinear transmission line circuits. This paper aims to examine several factors that must be considered when applying such model reduction techniques to this kind of circuit.Design/methodology/approachTwo types of POD will be implemented. In each case, the choice of the order of the reduced model and the order of the interpolation space shall be considered. The stability of the models shall be explored.FindingsThe results indicate that the order for the reduced model to obtain accurate results depends on the chosen method when considering nonlinear transmission lines. The results also indicate that the structure of the nonlinear transmission line is crucial for determining the stability of the reduced models.Originality/valueThe work compares two IPOD methods and discusses the issues involved in achieving an accurate and stable reduced-order model for a nonlinear transmission line.

Multibeam antennas with customized elevation angles based on near-field magnetic field coupling of metamaterials

In this paper, we propose the design of multibeam antennas with customized elevation angles based on near-field magnetic field coupling of metamaterials. The antenna consists of a monopole feed and four identical metamaterial transmission-line (MTL) structures surrounding the feed. The MTL structure is composed of two pairs of broadside-coupled omega rings (BCORs) that are connected by two straight strip-lines. Under such a framework, magnetic fields within the near-field zone of the monopole feed can be coupled efficiently by the inner BCOR, converted to travelling waves along the double strip-lines, guided toward the outer end of the MTL structure, and radiated by the outer BCOR like a loop antenna. Due to travelling wave nature of the MTL structure, there is phase lag along the MTL structure and the radiation main lobes are tilted towards the outward direction. By arranging several MTL structures around the feed monopole, multi-beam directional radiation can be realized. More interestingly, by adjusting structural parameters and pitch angles of the MTL structures, elevation angle of the radiation main lobes can be customized. To validate the design, we simulated, fabricated and measured four prototypes with pitch angles 0°, 15°, 30° and 45°. Both the simulated and measured results verify the design and show that multiple-beam radiation with customized elevation angle can be obtained. This work provides an alternative method of designing multi-beam antennas and may find applications in communication, surveillance, etc.

GPU and CPU-Based Parallel FDTD Methods for Frequency-Dependent Transmission Line Models

Finite-difference time-domain (FDTD) is a popular method utilized for solving frequency-dependent transmission line structures. It is also conveniently applicable to nonuniform wires. The FDTD algorithm discretizes the transmission line problem into a finite number of space-segments and solve for the voltage and current of each segment at every time-step. Therefore, they inherently involve more computations per timestep than conventional terminal based models. In this letter, parallel implementations of a modified FDTD algorithm for a frequency-dependent transmission line problem using multicore CPU and GPU architectures are proposed in order to increase its computational efficiency. Accuracy and performance of the parallel FDTD methods are discussed with examples. The results indicate that a speedup of a few folds compared to serial execution is achieved by the parallel implementation using multicore CPU architecture whereas a massive speedup is achieved by using GPU. The proposed model is also suitable for modelling transmission lines in massively parallel electromagnetic transient (EMT) simulation methods.

Characterization of high impedance of multilayer coplanar waveguide transmission line design for integration with nanodevices

Terahertz technology has recently attracted the attention of the researchers due to its wide range of applications such as security and military, biomedicine and health care, astronomy and biology. There are many scrutinized research papers among the terahertz applications with nanodevices such as self-switching devices. They need monolithic microwave integrated circuits for integration. It is evident that the system impedance of transmission lines is 50 Ω. However, the main limitation of self-switching diodes is high level of impedance in megaohms which is a huge value and is not so easy to implement. Paper focuses on the design and simulation of the coplanar waveguide transmission line structures with higher impedance by applying multilayer technology for the integration with self-switching diodes. Using multilayer technology in design allows wide range of impedances. Two approaches have been targeted such that meets all the requirements of integration with nanodevice. First approach is a widening the gap of the polyimide dielectric layers used in the fabrication of these components. Several design structures have been considered such as positioning the location of signal and grounds contacts with respect to the position of the dielectric layers. As the result the highest characteristic impedance of about 90 Ω was achieved at operating frequency of 110 GHz. Secondly, novel coplanar waveguide transmission line structure was investigated where the V – shape structure was joined with the signal elevated structure. The terahertz application research may effect on high data transmission rate of no less than 10 GBit/s and thereby in increase of traffic volume.

Communication—Novel Verification of an Impedance Model Considering Electrode Porosity and Li-Ion Diffusion in Lithium-Ion Batteries

A model composed of a transmission-line structure with a Randles-type circuit is regarded as a useful model for lithium-ion battery electrodes. However, when used for the impedance fitting analyses, the parameters needed to be given for calculations, the parameters to be practically obtained, and the accuracy of the obtained values have not been clarified yet. Herein, we reveal that parameters in this model can practically be obtained simultaneously from the impedance fitting calculations when the values of transmission-line length and diffusion length are provided. Then, their accuracy is investigated by examining the correlations between the parameters in the fitting calculations.

Engineering the thin film characteristics for optimal performance of superconducting kinetic inductance amplifiers using a rigorous modelling technique

Background: Kinetic Inductance Travelling Wave Parametric Amplifiers (KITWPAs) are a new variant of superconducting amplifier that can potentially achieve high gain with quantum-limited noise performance over broad bandwidth, which is important for many ultra-sensitive experiments. In this paper, we present a novel modelling technique that can better capture the electromagnetic behaviour of a KITWPA without the translation symmetry assumption, allowing us to flexibly explore the use of more complex transmission line structures and better predict their performance. Methods: In order to design a KITWPA with optimal performance, we investigate the use of different superconducting thin film materials, and compare their pros and cons in forming a high-gain low-loss medium feasible for amplification. We establish that if the film thickness can be controlled precisely, the material used has less impact on the performance of the device, as long as it is topologically defect-free and operating within its superconducting regime. With this insight, we propose the use of Titanium Nitride (TiN) film for our KITWPA as its critical temperature can be easily altered to suit our applications. We further investigate the topological effect of different commonly used superconducting transmission line structures with the TiN film, including the effect of various non-conducting materials required to form the amplifier. Results: Both of these comprehensive studies led us to two configurations of the KITWPA: 1) A low-loss 100 nm thick TiN coplanar waveguide amplifier, and 2) A compact 50 nm TiN inverted microstrip amplifier. We utilise the novel modelling technique described in the first part of the paper to explore and investigate the optimal design and operational setup required to achieve high gain with the broadest bandwidth for both KITWPAs, including the effect of loss. Conclusions: Finally, we conclude the paper with the actual layout and the predicted gain-bandwidth product of our KITWPAs.

A Circuit-Based Wave Port Boundary Condition for the Nodal Discontinuous Galerkin Time-Domain Method

Waveguide-like transmission line (WLTL) structures, including rectangular waveguides, circular waveguides, and coaxial lines, have been widely used in microwave engineering. Determining how to efficiently model WLTLs has become vital for the design of various WLTL-based devices. In this paper, a circuit-based wave port boundary condition (CWPBC) is developed and applied in the discontinuous Galerkin time-domain (DGTD) method to accurately simulate these structures for the first time. In the CWPBC, modal voltages and currents of a WLTL are defined, and circuits based on modal voltages and currents are introduced. By co-simulating the modal circuit and the WLTL modeled using the DGTD method, various modal fields can be excited in the WLTL, and at the same time, the WLTL can be terminated without reflections. No extra costs or approximations are used in the proposed CWPBC, and there is no requirement of either the extension of the computational domains widely used in perfectly matched layer (PML) termination or the longitudinal field continuity used in the reported DGTD method. The proposed method can easily obtain the postprocessing parameters, including S-parameters and port power. Numerical results, including rectangular waveguide filters, circular waveguide horns, and coaxial-fed electromagnetic bandgaps (EBG), are given to validate the effectiveness of the proposed CWPBC.