Conventional Transmission Line Research Articles

Microstrip Quasi-Elliptic Absorptive Bandpass Filter with Ultra-Wide Reflectionless Range and Compact Size

Absorptive bandpass filters (ABPFs) are highly attractive in modern microwave communication systems due to their ability to internally absorb the harmful stopband RF-power reflections. This paper reports an approach to designing quasi-elliptic ABPFs with ultra-wide reflectionless range, enhanced selectivity, and compact size. The method is realized based on a fourth-order quasi-elliptic absorptive lowpass filter (ALPF) prototype with a simplified structure. This ALPF prototype exhibits both good impedance-matching over the whole normalized frequency domain and an adjustable transmission zero close to the passband. By applying an equivalent impedance transformer model, a coupled-line-based ABPF scheme is devised from the ALPF prototype, which eliminates conventional dispersive transmission line inverters, resulting in an ultra-wide reflectionless range and a compact size. Closed-form equations are derived to support the filter synthesis. A 2.45 GHz microstrip ABPF with 30% fractional bandwidth is designed for verification. The measured minimum in-band insertion loss is 0.83 dB and the reflectionless range of return loss better than 10 dB is from DC to 12.88 GHz. Both the upper and lower stopband suppression exceed 20 dB, with the upper stopband extending up to 6.80 GHz. The upper and lower out-of-band roll-off rates are 93.9 and 121.4 dB/GHz, respectively. The overall circuit size is 0.12 λg2.

Ka-Band Miniaturized 90 nm Complementary Metal Oxide Semiconductor Wideband Rat-Race Coupler Using Left-Handed and Right-Handed Transmission Lines

The traditional rat-race coupler comprises a quarter-wavelength transmission line and a three-quarter-wavelength transmission line. In this design, the slow-wave structure transmission line is employed to replace the conventional quarter-wavelength transmission line, and the three-quarter-wavelength transmission line is substituted with the left-handed transmission line. By using the TSMC CMOS 90 nm fabrication process, a circuit is created with a chip size of 300 μm × 200 μm, corresponding to the electrical size at 39 GHz of 0.039λ0 × 0.026λ0. The measured results demonstrate that the operating bandwidth is 35 to 43 GHz, with an amplitude imbalance of around 0 dB, a phase error within 1°, a return loss of less than 26 dB, and an isolation better than 40 dB.

Research and Analysis of the Cost of Right of Way for Conventional Overhead Transmission Lines and Power Transmission Cable

The study explores the pros and cons of adding these advanced conductors to transmission lines. This study examines the costs of procuring RoW for standard overhead transmission lines and power transmission cables. The report details the costs and considerations of obtaining land for power transmission infrastructure. Research has two main parts. The document begins with transmission asset owner’s RoW acquisition methods and rules. It explains the regulatory framework and mechanisms for securing land rights for power transmission infrastructure. The second section analyses costs in detail. It compares the economics of installing overhead transmission lines with power transmission cables, focusing on subsurface XLPE cables. The study examines how RoW acquisition affects adjacent land prices and the economic effects on TAOs and surrounding communities. The research also evaluates transmission line dismantling costs, including waste metal value, considering metal price changes. RoW costs persist after the transmission line's tenure. The paper also examines a replacement model that estimates RoW costs for switching from overhead transmission lines to underground XLPE cables for outmoded transmission infrastructure. This analysis seeks to illuminate RoW Acquisition's financial elements for power transmission decision-makers.

A multi-area intra-day dispatch strategy for power systems under high share of renewable energy with power support capacity assessment

Long-distance power support through High-voltage Direct Current (HVDC) has provided feasible solutions for power dispatch and control problems in multi-area power systems under high share of renewable energy. In this paper, an advanced multi-area intra-day dispatch strategy for power systems with high penetration of renewable energy considering power support capacity is established to increase the accommodation of wind power and enhance the stability of the power system. At first, a novel assessment method of regional active power support capacity is carried out in this paper, which can sufficiently quantify the regional power margin (RPM), the DC dispatchable power (DCDP), and the regional power support distance (RPSD) of a power system. Subsequently, a multi-area intra-day dispatch strategy based on power support capacity analysis is proposed, where constraints on conventional units, wind farms, transmission lines, and RPSD are developed. Finally, to enable the development of the dispatch model, a model predictive control (MPC) scheme is used to update the power support capacity indicators dynamically and improve model reliability. The effectiveness and superiority of the proposed strategy are verified by case studies. Numerical results show a 7.02% cost reduction and overload risk reduction by using the proposed strategy compared to conventional global optimization methods.

An Introduction to Horizontal Directional Drill Installation of High-Voltage Transmission Lines and Other Duct Banks: Improving on Conventional Overhead Transmission Lines

Horizontal Directional Drill (HDD) installation of high-voltage (HV) transmission has proven practical, and in some cases, less costly than traditional overhead options. Petrochemical facilities located on waterways provide excellent opportunities for underwater HDD-installed transmission lines. These designs can provide significant safety advantages as well as improve system reliability. They eliminate the height restrictions associated with overhead lines, reduce air traffic obstructions, and reduce the weather-related concerns typically associated with traditional overhead transmission lines, especially highly elevated transmission line crossings over waterways. They also offer significant opportunities when expanding existing facilities and designing for Prevention through Design by eliminating the overhead transmission and their associated contact risks throughout the life of the installation. Each HDD-installed transmission line is different and can create significant challenges; however, the benefits associated with this technology can significantly outweigh the effort. This article reviews some of the challenges associated with long, high-capacity transmission line installations, along with their associated solutions as incorporated in previous projects. This article does not cover the smaller and shorter HDD installations typically associated with electrical distribution commonly used to cross streets, highways, or feed commercial facilities.

A 16.5-31 GHz Area-Efficient Tapered Tunable Transmission Line Phase Shifter

This paper presents a Tapered Tunable Transmission Line (Tapered TTL) phase shifter that achieves a higher area efficiency than conventional Tunable Transmission Line (TTL) phase shifters while maintaining the same phase shift range with similar insertion losses. A systematic methodology is provided for the optimum design of the proposed phase shifter to maximize its area efficiency while providing the desired phase shift range and satisfying the maximum allowed input/output return and insertion losses. To verify the efficacy of the proposed solution, an eleven-cell phase shifter is fabricated in a standard 65-nm Complementary Metal–Oxide–Semiconductor (CMOS) technology and the measurement results are reported. The fabricated circuit provides a 180-degree phase shift over the frequency range of 16.5 to 31 GHz with an average insertion loss of 7.2 dB. The proposed design presents a 25 percent reduction in the chip area per unit delay in comparison to the conventional design with the same average insertion loss.

Compact, High Power Capacity, and Low Insertion Loss Millimeter-Wave On-Chip Limiting Filter With GaAs PIN Technology

In this paper, a collaborative design of compact, high-power capacity, and low insertion loss millimeter-wave limiting filter using gallium arsenide (GaAs) PIN technology is presented. Parallel topology is employed to distribute the PIN diodes of the first stage of limiting circuit for high power handling capacity. In order to reduce the circuit size, the filtering function structure is incorporated into the limiter. Four transmission zeros (TZs) are introduced to improve the out-of-band suppression performances of the limiting filter. By utilizing the inductive short-circuited stub, a parallel resonator is introduced to exhibit the passband characteristic. Semi-lumped and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\pi $ </tex-math></inline-formula> -type topologies are employed to reduce the size of the conventional quarter-wavelength transmission line and introduce several TZs within the stopband. An on-chip limiting filter sample is fabricated by the GaAs PIN process and occupies an area of only <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1.1\times 0.9$ </tex-math></inline-formula> mm2. It is measured with the insertion loss of 1.67 dB at the center frequency of 35 GHz, the stopband suppression of better than 20 dB, and the tolerable input power of greater than 40 dBm. Compared with the traditional designs, good features of high-power capacity, low insertion loss, and miniaturization are obtained with the presented on-chip limiting filter.

A Phased Array Antenna with Novel Composite Right/Left-Handed (CRLH) Phase Shifters for Wi-Fi 6 Communication Systems

A linear phased array antenna excited with a novel composite right/left-handed (CRLH) phase shifters structure is proposed. The phase of the conventional CRLH transmission line is controlled with magnetically aligned micron-sized particles embedded inside the unit cell of the CRLH transmission line. The cascading of unit cells produces the desired phase shifts for the main beam scanning of the linear antenna array operating at a 5.5 GHz center frequency for Wi-Fi 6 applications. The proposed phase shifter design has a very low insertion loss (0.5–2 dB), excellent matching characteristics with the antenna array (less than −10 dB) and a small phase error (1–2 degrees). A 1 × 4 linear patch antenna phased array operating at a 5.5 GHz center frequency of the Wi-Fi 6 band is simulated using the Method of Moments (MoM) simulator platform. Then, the array is driven with the proposed novel CRLH phase shifters for the main beam at broadside and the main beam steered at 15- and 30-degree scan angles toward the desired users. For experimental validation, multiple unit cells of the proposed phase shifters are fabricated, and the 1 × 4 patch antenna array is fed with these fabricated unit cells of the phase shifters. The phased array radiation patterns are measured using an in-house fully calibrated anechoic chamber and were compared with simulated phased array patterns. The measured phased array patterns are in good agreement with the simulated patterns. As compared with commercially available phase shifters, the proposed novel CRLH phase shifters do not need external complex biasing circuitry, which is a major advantage in space constraint limitations at the router side of multi-user MIMO-OFDM systems.

A Dual-Band Branch-Line Coupler with Ultra-Wideband Harmonic Suppression

A dual-band branch-line coupler with ultra-wideband harmonic suppression is proposed in this paper. The conventional quarter-wavelength transmission lines are replaced with π-shaped lines to achieve a dual band. In addition, ultra-wideband harmonic suppression is obtained by the frequency-selecting coupling structure (FSCS) providing three transmission zeros. The two operating frequencies are 0.9 GHz and 2.0 GHz, and the corresponding -10 dB bandwidth at 0.9 GHz and 2.0 GHz is 18.9% and 10.5%, respectively. A wide harmonic suppression band is generated from 3.7 GHz to 8.3 GHz. The simulation and measurement results are in good agreement.

Travelling waves in discrete electrical lattice with nonlinear symmetric capacitor

We study the propagation of voltage in a model of the conventional right-handed transmission line with a nonlinear symmetric capacitor. Applying the quasidiscrete approximation to the nonlinear voltage equation of the line, we derive a nonlinear Schrödinger equation and find the bright and dark solutions which are used as the initial condition for the integration of the nonlinear lattice model. The full integration of the lattice shows the propagation of the nonlinear voltage on the right-hand side and its robustness in time. The density energy of the lattice at each time has a node around which bright voltage is localized while in the case of dark voltage, it has a node where it seems to drop to zero at the soliton center. The plane phases allow proposing the characteristic of bright and dark solitons around the zero voltage.

Transient response of nonparallel frequency-dependent transmission lines due to nearby lightning strikes in the presence of finitely-conducting ground

Overvoltage transients due to lightning strikes is a common occurrence in power transmission lines which can ultimately lead to line outages. Simulation of transmission line networks under the influence of lighting plays a vital and essential role in predicting their transient behaviour . The transient behaviour of uniform transmission lines due to lightning has been studied extensively. However, in modern transmission line networks, nonuniformities and discontinuities such as nonparallel wire, line crossings or bends are becoming increasingly common. Therefore, in such cases, inaccuracies might be present in analysis performed using conventional uniform transmission line approaches. A recent publication by the authors analysed the transient behaviour of nonparallel and crossing transmission lines above perfect electric conductor (PEC) ground. However, the PEC assumption can only be used in a limited scope. In this paper a nonuniform transmission line model with external field coupling is presented to analyse the transient behaviour of a nonuniform wire structure due to the field coupling from a nearby lightning strike in the presence of lossy ground. Simulation results generated by the proposed model is compared with full-wave simulations and results published by other researchers. A case study to compare the results from the proposed model with a conventional uniform transmission line model under various ground-conductivity values and terminating conditions is also performed. The study indicates that the presence of nearby nonparallel lines can cause the transient behaviour of the structure to deviate from the behaviour predicted using uniform approaches. • The transient behaviour of a nonuniform wire structure a nearby lightning strike in the presence of lossy ground is studied. • Simulation results generated by the proposed model is compared with full-wave simulations and results published by other researchers. • Results from the proposed model have been compared with a conventional uniform transmission line model. • The study indicates that the presence of nearby nonparallel lines intensify the transient behaviour.

325 GHz to 500 GHz Single-Layer Planar Goubau-Line Antenna With Endfire Radiation Based on Substrate Mode

This article presents a 325–500 GHz single-layer planar Goubau-line antenna with endfire radiation based on substrate mode. The electromagnetic (EM) fields along the Goubau line will penetrate into the substrate due to the substrate modes, which cannot operate well compared with the conventional transmission line. The undesired <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$E_{\text{z}}^{11}$ </tex-math></inline-formula> substrate mode is engineered here to achieve vertically polarized endfire radiation. Since the higher substrate mode is excited and there is a deviation between the propagation constants of the Goubau line and the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$E_{\text{z}}^{11} $ </tex-math></inline-formula> substrate mode, the phase difference between the center and edges of the truncated aperture will deteriorate the antenna radiation at higher frequencies. Inspired by the conventional Goubau-line divider, the branches can compensate the wavefront and increase the antenna gain by 2 dB at higher frequencies. This terahertz (THz) antenna on a 300 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{m}$ </tex-math></inline-formula> thick quartz substrate ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.4~\lambda _{0}$ </tex-math></inline-formula> at 400 GHz) possesses robust mechanical properties and consists of single-layer metal, reducing the fabrication complexity. The proposed THz antenna was fabricated and measured, which can operate in a 325–500 GHz band with endfire radiation and achieve 8.5–11.3 dBi gain.

Advanced impedance modeling for micropatterned polymer electrolyte membrane fuel cells

Cathode patterning is an effective means of improving the oxygen reduction reaction in polymer electrolyte membrane fuel cells. Because the conventional one-dimensional transmission line model cannot be applied to micropatterned electrodes, impedance modeling for micropatterned electrodes is conducted using a two-dimensional transmission line matrix model. In this study, the charge transfer resistance is considered a function of proton potential in the equivalent circuit based on the Butler–Volmer equation. Micropatterned membrane electrode assemblies (MEAs) with three different pattern depths are fabricated, and electrochemical measurements are performed on them. The measured and simulated impedances are evaluated using the distribution of relaxation times analysis results. This study validates the proposed model by comparing the simulated and measured impedances of the MEAs. The experimental and matrix model simulation results confirm that cathode patterning reduces both the charge transfer and proton conduction resistances. For each MEA, the charge transfer resistances obtained by fitting the matrix model to the measured impedances are plotted on a straight line; thus, the Tafel slope is obtained. The matrix model demonstrated in this study leads to the design of patterned electrodes through the impedance analysis of various patterned electrodes.

Design and fabrication of a miniaturized Gysel power divider using improved T‐shaped resonator

AbstractA high‐performance Gysel power divider showcasing high suppression factor and low insertion loss at 540 MHz has been designed, investigated, and fabricated in this paper. The proposed Gysel power divider is made up of replacing six identical resonators with conventional transmission lines. The proposed resonators, which have been analyzed using LC equivalent circuit analysis, are designed to have a small size, low insertion loss, wide stopband, and narrow transition band. The final tested results have indicated that the suggested power divider is able to suppress nine harmonics; moreover, it has only an insertion loss of 0.4 dB. Another positive feature of the power divider is its small size in comparison with a conventional power divider at this operating frequency, where it occupies 34.5 × 63.8 mm2 equaling to 0.188 × 0.102 , where is the wavelength guide at 540 MHz. This figure is 25% of a conventional Gysel, considered as a remarkable point.

A Review on SIW and Its Applications to Microwave Components

Substrate-integrated waveguide (SIW) is a modern day (21st century) transmission line that has recently been developed. This technology has introduced new possibilities to the design of efficient circuits and components operating in the radio frequency (RF) and microwave frequency spectrum. Microstrip components are very good for low frequency applications but are ineffective at extreme frequencies, and involve rigorous fabrication concessions in the implementation of RF, microwave, and millimeter-wave components. This is due to wavelengths being short at higher frequencies. Waveguide devices, on the other hand, are ideal for higher frequency systems, but are very costly, hard to fabricate, and challenging to integrate with planar components in the neighborhood. SIW connects the gap that existed between conventional air-filled rectangular waveguide and planar transmission line technologies including the microstrip. This study explores the current advancements and new opportunities in SIW implementation of RF and microwave devices including filters, multiplexers (diplexers and triplexers), power dividers/combiners, antennas, and sensors for modern communication systems.

분할 공동 구조를 이용한 고 종횡비 인쇄회로기판 내 전송선 층 변환 구조의 신호 무결성 개선 설계 및 모델링

This paper proposed a layer transition design for high-speed signal transmission in high aspect ratio printed circuit boards (PCBs). The proposed design employed a segmented cavity structure to suppress the group cavity resonance that degrades a wide bandwidth range of high-speed transmission lines with signal vias for layer transition. To predict the transfer characteristic of the proposed design, equivalent circuit models were developed based on the combination of resonant cavity models, lumped via models, and conventional transmission line models. The proposed design and equivalent circuit models were validated with a noticeable improvement in the signal integrity performance by simulation and measurement results up to 30 GHz.

Surface wave transmission line theory for single and many wire systems

Examining cables using the many conductor transmission line theory has shed light on the modes supported by various cable types. However, so far, the theory disregards the fundamental surface wave mode whose lateral confinement increases with frequency and hence is expected to play an important role in high-frequency applications. To address this issue, we propose an extension to the theory that incorporates surface waves on uncoated, cylindrical wires. Crucially, this requires new definitions of the per unit length transmission line parameters, which are derived using the single wire surface wave solution. By closely examining a two-wire and a three-wire system, we show that these new parameters can predict surface waves as well as modes found using conventional many conductor transmission line theory. Furthermore, all calculated modes are validated experimentally by diagonalization of a measured coupling matrix. Additionally, the propagation constants for the modes predicted by the model are validated against full numerical simulations. Good agreement is observed when proximity effects can be neglected.

Compact dual-band RF rectifier for wireless energy harvesting using CRLH technique

&lt;p&gt;In this paper, a new dual-band radio frequency (RF) rectifier was designed. The proposed design is a low-profile structure with dimensions of &lt;br /&gt; 5×5.5 mm&lt;sup&gt;2&lt;/sup&gt; owing to the use of lumped elements rather than the conventional transmission lines which occupy large footprints. This property can be potentially exploited to use the proposed rectifier in high dense rectenna arrays to generate high output direct current (DC) voltages. Furthermore, the proposed design adopts the composite right/left-handed composite right left-handed (CRLH) technique to realize the dual-band structure at frequencies of 1.8 and 2.4 GHz. Afterward, the matching circuit was optimized to make sure that it offers good matching. The frequency response shows good matching at both bands which are about -22 and -25 dB respectively. Eventually, the simulated circuit has a conversion efficiency of 52% and output voltages of 0.5 V at -5 dBm for the two bands.&lt;/p&gt;

Transient Overvoltage on HVDC Overhead Transmission Lines With Background DC Space Charges and Impulse Corona

The space charges around a HVDC transmission line may not only lead to electromagnetic environmental problems but also affect the occurrence of impulse corona and then the transient overvoltage propagation. This paper derives the equations governing the transient overvoltage propagation along a HVDC transmission line when there is either space charges surrounding the line or impulse corona. In contrast to conventional transmission line equations, the proposed equations adopted the dynamic capacitance C ′ and conductance G to characterize the corona discharge in all cases, which can be obtained by a time-domain finite element method. A finite-difference time-domain method is introduced to solve the nonlinear transmission line equations. The validity of the proposed approach is verified by comparison with the lightning overvoltage waveforms measured in a literature. The transient overvoltage propagation along a long UHVDC transmission line surrounded by space charges is analyzed.

비아를 이용한 CRLH 전송선로 안테나 소형화

In this study, miniaturization of composite right-left handed (CRLH) transmission line (TL) antennas using via structure is proposed. The proposed CRLH TL antenna replaces the planar interdigital capacitor structure of the conventional CRLH TL antenna using vias in the printed circuit board multilayer structure. Via structure derives series capacitance values by replacing the finger-shaped patterned parts that comprise the conventional interdigital capacitor. The proposed model reduces the increased length of 8.34 mm to 2.66 mm for every one-cell increase based on an operating frequency of 2.9 GHz. Unlike the three-cell conventional model that utilizes 5.17 dBi at a size of 47.79 mm, the proposed four-cell model utilizes 5.35 dBi at a size of 33.41 mm.