Transmission Line Sections Research Articles

Faults Signature Extraction in Wind Farm Integrated Transmission Line Topology

<p>The integration of Renewable Green Energy Sources (RGES) like Wind Farm Generators (WFG), and Photo Voltaic (PV) systems into convention power system as a future solution to the increase in global energy demands, generation cost reduction, and limited climate impact. The innovation introduced protection compromise challenges in power system due to in-feeds fault current penetration from RGES on existing system, leading to an undesired trip of the healthy section of TL, equipment damages, and safety failure. A comparison study of extracted faults signature from two proposed Transmission Line (TL) network topologies with and without WFG integration, for onward fault identification, and classification model design. Descrete wavelet multiresolution Analysis (DWMRA) of extracted one-cycle fault signal signatures from 11 faults type’s scenarios in Matlab. Result demonstrated a unique fault signatures across all simulated faults scenarios harness for future work of an adaptive unit protection model for this new area of DG integration.</p>

A Novel Dual-Sided Fly-By Topology for 1–8 DDR With Optimized Signal Integrity by EBG Design

A novel dual-sided fly-by topology is proposed for one controller to multiple memory systems by choosing interconnected transmission line sections of alternate impedance and length. After suitable big data analysis of automatic simulation, peak distortion analysis for eye height, followed by artificial neural network optimization, the best design guideline can be deduced, which is found to be consistent to the electromagnetic bandgap (EBG) theory. The topology may greatly enhance the eye height by 20%–100% while the total length is reduced by half, compared with the conventional fly-by topology. The general design method, relevant simulation, and analysis from EBG are also provided. Measurement has been performed to validate the new design, demonstrating 53% improvement in eye height over the conventional one.

Harmonic suppression in branch‐line couplers based on slow‐wave transmission lines with simultaneous inductive and capacitive loading

AbstractA compact branch‐line hybrid coupler with harmonic suppression based on slow‐wave microstrip lines is presented in this paper. These slow‐wave artificial transmission lines are implemented by simultaneously loading a host line with series inductors and shunt capacitors. By this means, the effective capacitance and inductance of the line are increased and, consequently, the phase velocity and signal wavelength are reduced. This slow‐wave effect, useful for device miniaturization, is applied to reduce the size of the coupler. Particularly, by implementing the reactive elements through capacitive patches and inductive strips, 64% size reduction, as compared to the conventional coupler, is achieved. Moreover, due to the filtering capability of the inductors and capacitors, the first and second harmonic responses of the coupler are completely suppressed. A detailed design methodology based on the schematic of the proposed slow‐wave transmission line is reported. The work includes a simple analysis to justify that two unit cells per transmission line section are necessary to suppress the harmonic bands leaving unaltered the coupler response in the region of interest. The fabricated device is fully planar, does not use vias, and the ground plane is kept unaltered.

Effectiveness of Sensors Contact Metallization (Ti, Au, and Ru) and Biofunctionalization for Escherichia coli Detection.

In designing a bacteria biosensor, various issues must be addressed: the specificity of bacteria recognition, the immobilization of biomolecules that act as the bacteria receptor, and the selectivity of sensor surface. The aim of this paper was to examine how the biofunctionalized surface of Ti, Au, and Ru metals reacts in contact with strains of Escherichia coli (E. coli). The focus on metal surfaces results from their future use as electrodes in high frequency biosensors, e.g., resonant circuits or transmission-line sections. First, the surfaces of different metals were chemically functionalized with 3-aminopropyltriethoxysilane (APTES) and glutaraldehyde or with 3-glycidylooxypropyltrimethoxysilane (GPTMS) followed by N-(5-amino-1-carboxypentyl) iminodiacetic acid (AB-NTA) and NiCl2. Secondly, the lipopolysaccharide binding protein (LBP), polyclonal anti-Escherichia coli antibody and bacteriophage protein gp37 were tested as bacteria receptors. The selectivity and specificity have been confirmed by the Enzyme-Linked Immunosorbent Assay (ELISA) and visualized by scanning electron microscopy at low landing energies. We noticed that LBP, polyclonal antibody, and gp37 were successfully immobilized on all studied metals and recognized the E. coli bacteria selectively. However, for the antibody, the highest reactivity was observed when Ti surface was modified, whereas the bacteria binding was comparable between LBP and gp37 on the functionalized Ru surfaces, independent from modification. Thus, all surfaces were biocompatible within the scope of biosensor functionality, with titanium functionalization showing the best performance.

Improved broadband (75–110 GHz) radio frequency characteristics of MEMS shunt switches on quartz substrate

This paper presents improved W-band (75–110 GHz) radio frequency characteristics of micro-electromechanical switches in T and π-matched configurations. The switch structures consist of Au metallic bridge (s) suspended over the coplanar waveguide (CPW) signal line drawn on quartz substrate. Here, a high impedance transmission line is introduced on both the sides of the bridge structure to reduce the return loss. To further tune up the broadband RF response the bridge width (40–80 µm) as well the dielectric thickness (0.15–0.18 µm) are varied. At optimum condition (bridge width: 60 µm; dielectric thickness: 0.18 µm), the T-matched RFMEMS switch structure exhibits return loss better than − 20 dB; insertion loss ~ − 0.2 dB and isolation better than − 30 dB in full W-band frequency range. In π-match configuration, a short section of high impedance transmission line is being introduced between two switch structures for impedance matching. RF parameters of the π-matched shunt switch structure are studied as a function of width (10–40 µm) and length (30–180 µm) of the high impedance transmission line. At optimum condition (line width: 30 µm; length: 130 µm), the π-matched switch structure exhibits return loss: better than − 15 dB; insertion loss: better than − 0.5 dB; and isolation: better than − 45 dB over the entire W-band. From the equivalent circuit modeling, the equivalent inductance, capacitance and resistance values for the optimized switch structures are also reported.

Delta models of oscillatory structures and passband filters

Introduction . Oscillatory circuits and resonant sections of transmission line (TL) are the basic signals frequency filtering structures. Oscillatory circuits belong to lumped oscillatory structures with one resonant frequency. A set of connected one-resonant oscillatory structures forms a structure with several resonant frequencies used in band-filtering. In various scientific and technical areas the approach based on $\delta$-functions is widely used for simulation. In the presented paper the approach based on $\delta$-models expand on oscillatory structures and bandpass filters. Delta-models of oscillatory structures . Models of oscillatory circuits and resonant TL sections as impedance resonant δ -inhomogeneities are proposed. These models are called δ-models. It is shown that resonant δ-barrier is equivalent to series oscillatory circuit and resonant δ-well - to parallel oscillatory circuit. Resonance δ-inhomogeneities are characterized by three parameters - direction determining the resonance nature (series or parallel), its own resonant frequency and parameter directly proportional to the quality factor. Comparison of TL resonant section and δ-model characteristics . TL section and δ-model frequency characteristics are compared. It is shown that with increasing of the difference between transmission line and section impedances section characteristic approaching δ-model characteristic. Delta models of coupled resonant structures . Delta-models of coupled oscillatory circuits are presented. Comparison of transmission coefficient of two coupled δ-models with frequency response of two identical coupled circuits illustrate their accordance. Delta models of bandpass filters. Delta-models of bandpass filter formed by series and parallel oscillatory circuits are presented. Delta models simplify filter analysis and for the filter with quarter-wave links between oscillatory structures allow finding a solution with fewer quality factor values and lower quality factor maximum, which simplifies filter design. Conclusion . The proposed δ-models of oscillatory structures in the form of resonant impedance δ-heterogeneities allows to simulate single lumped and distributed oscillatory structures, coupled oscillatory structures, and also filters on their basis. Delta models simplify the analysis of oscillatory structures and filters and, as in the case of reactive elements δ-models, prompt new filter solutions; in the case considered with improved constructive parameters.

Compact filtering power divider with wide passband bandwidth

AbstractIn this article, a compact filtering power divider (PD) with wide passband bandwidth and high selectivity is designed and analyzed. The filtering PD is constructed by quarter‐ wavelength three‐conductor parallel‐coupled line structure terminated with two stepped impedance transmission line sections as well as an isolation resistor loaded on unique location. The even‐odd mode analysis is adopted to explain the operating mechanism of signal splitting, filtering, and isolating. Then, a practical design procedure is introduced. For verification, a wideband filtering PD centered at 3.0 GHz with a fractional bandwidth of 62% is designed and fabricated. The measured results agree well with the simulated ones.

Design and implementation of fractional‐order microwave differentiator

The new design of a fractional-order microwave differentiator is proposed. It is first of its kind and uses short-circuited stub and transmission line sections to emulate the behaviour of an ideal fractional-order differentiator. Least mean square error-based objective function is formulated to obtain the transfer function of the proposed design, using the chain scattering parameters of line elements in the Z-domain. During the optimisation process, impedance values of equal-electrical-length line elements are considered in the range 10-150 Ω, such that they are practically realisable on the microstrip format. The structure is implemented on the FR4 substrate with permittivity of 4.4 having 1.6 mm thickness. The measured result for the magnitude response of the transmission coefficient is found to be in good agreement with ideal one in the operating frequency range from 0.8 to 6.6 GHz.

Bridged-T Coil for Miniature Dual-Band Branch-Line Coupler and Power Divider Designs

In this paper, a new design method for bridged-T coil (BTC) is proposed such that it can be made equivalent to two different transmission line sections at two different frequencies. In this way, on-chip dual-band branch-line coupler and dual-band power divider designs with very compact circuit sizes can be made possible through the use of BTCs. Specifically, the proposed 2.45/5.8-GHz dual-band branch-line coupler realized using the integrated passive device (IPD) process features a compact circuit size of only $2.8~\text {mm} \times 1.4$ mm while the proposed 2.4/5.5-GHz dual-band power divider in IPD exhibits a very small circuit size of only $1.8~\text {mm} \times 1.7$ mm. To the best of our knowledge, the proposed dual-band branch-line coupler is the smallest one ever reported while the circuit size of the proposed dual-band power divider is comparable to the smallest in the literature.

A transmission line decoupling technique for enhancement of port isolation of dual-band MIMO antennas

In this paper, a transmission line decoupling network (TLDN) technique is presented to enhance the isolation of a dual-band multiple input and multiple output (MIMO) antenna. The MIMO antenna with enhanced isolation is designed by the following steps: Firstly, each port of an initial 2-port MIMO antenna is connected with an admittance transformer formed by two transmission line sections. The length and the width of the admittance transformer are designed to retrieve mutual admittance between ports having only imaginary part. The two ports are then connected in parallel electrically with the proposed TLDN to cancel the resultant imaginary mutual admittance. At the final stage, a simple dual-band matching network is added to each port to improve matching performance. The proposed method is applied to two designs of dual-band printed MIMO antenna working at 2.45 GHz/5.25 GHz and 1.8 GHz/3.5 GHz. For the purpose of verification, the two designs were fabricated and measured. The measured results are in good agreement with the simulation ones. Both designs yielded a high isolation, low envelop correlation coefficient, simple structures for design and fabrication. These features demonstrated the feasibility of the technique in implementing MIMO antennas.

Miniature Multi-Band Absorptive Bandstop Filter Designs Using Bridged-T Coils

In this paper, miniature absorptive bandstop filters (ABSFs) with one to three stopbands are demonstrated. First, the proposed single-band ABSF is realized by the introduction of one lossy resonator to a conventional stub bandstop filter, while the circuit size is largely reduced by employing bridged-T coils to replace the transmission line sections. Next, by employing the dual-band design of bridged-T coil, a miniature dual-band ABSF can be achieved. The proposed tri-band ABSF is then implemented through the cascade of the proposed single- and dual-band ABSFs. As a demonstration, three proposed single-, dual-, and triple-band ABSFs are implemented in a commercial GaAs pHEMT process. Much smaller circuit size than the conventional multi-band ABSFs and good measured performance are achieved.

Miniaturization of Broadband Stub Bandpass Filters Using Bridged-T Coils

In this paper, broadband stub bandpass filters (BPFs) with very compact circuit sizes are proposed. Specifically, the circuit size of the conventional broadband stub BPF is largely reduced by replacing all transmission line sections with bridged-T coils. In addition, the design consideration regarding the use of cascaded bridged-T coils is investigated in detail. The proposed broadband BPF designs are based on lumped elements only, and they can be implemented using the integrated passive device process to achieve very compact circuit sizes. As an example, a miniature 7th-order broadband BPF with a passband from 4 to 12 GHz, which is to be used at the mixer’s IF output of a radio astronomical receiver, is presented. The in-band insertion loss is within 2.46 ± 0.46 dB and the circuit size is only 2.30 mm $\times$ 2.03 mm. The long-lasting problem of large circuit size for conventional stub BPFs is thus solved.

Low-cost multiband compact branch-line coupler design using response features and automated EM model fidelity adjustment

Design closure of compact microwave components is a challenging problem because of significant electromagnetic (EM) cross-couplings in densely arranged layouts. A separate issue is a large number of designable parameters resulting from replacement of conventional transmission line sections by compact microstrip resonant cells. This increases complexity of the design optimization problem and requires employment of expensive high-fidelity EM analysis for reliable performance evaluation of the structure at hand. Consequently, neither conventional numerical optimization algorithms nor interactive approaches (e.g., experience-driven parameters sweeps) are capable of identifying optimum designs in reasonable timeframes. Here, we discuss application of feature-based optimization for fast design optimization of dual- and multiband compact couplers. On one hand, design of such components is difficult because of multiple objectives (achieving equal power split and good matching and port isolation for all frequency bands of interest). On the other hand, because of well-defined shapes of the S-parameter responses for this class of components, feature-based optimization seems to be well suited to control multiple figures of interest as demonstrated in this work. Two-level EM modeling is used for further design cost reduction. More importantly, we develop a procedure for automated determination of the low-fidelity EM model coarseness that allows us to find the fastest possible model that still ensures sufficient correlation with its high-fidelity counterpart, which is critical for robustness of the optimization process. Our approach is illustrated using two dual-band compact couplers. Experimental validation is also provided.

Dual-band devices based on coupled striplines for different power distribution in the frequency bands

The approach to the development of dual-band power distribution devices with different power division ratios in different frequency bands, based on the method of a dual-frequency equivalent replacement, is considered in the article. For its implementation, an equivalent four-terminal network based on a section of coupled microstrip transmission lines is proposed in addition to the T- and P-type circuits. Relations for calculating the electrical parameters of the circuit elements of these four-pole devices are obtained. The relations allow replacing the transmission line section with different values of the wave impedance in different frequency bands. The electrical length of such a section can vary and be different from p/2. Examples of modeling of non-equilateral power distribution devices with unequal branches such as two-channel balanced dividers and a ring divider (ring coupler) with power division coefficients of 2.0 and 1.0 in frequency bands with center frequencies of 2.0 and 3.6 GHz are given. Experimental measurement of characteristics of the designed models of the two devices showed good agreement between the experiment and the simulation results.

Composite right-/left-handed leaky-wave antenna utilizing coupled-line sections

A novel method of realization of composite right-/left-handed leaky-wave antennas featuring through broadside-beam-scanning capability and utilizing coupled-line sections has been proposed. The unique feature of the presented concept is that it allows to adjust both the beam-scanning bandwidth and the distance between consecutive unit cells thanks to the introduction of additional identical transmission-line sections to the unit cell. The concept has been theoretically analyzed as well as experimentally verified by the simulations and measurements of the developed antenna operating with the transition frequency of 3 GHz.

A novel design of a low-voltage low-loss T-match RF-MEMS capacitive switch

This paper presents a novel design, optimization and analysis of capacitive radio frequency (RF) micro-electromechanical system (MEMS) switch. The design incorporates a novel membrane and beams' structure with two short high-impedance transmission-line (T-line) sections added on either side of the switch (namely T-match switch) to improve its RF performance, while maintaining low-actuation voltage. The short high-impedance T-line section has narrower width and higher impedance than the coplanar waveguide (CPW)'s signal line, behaves as series inductor to compensate the switch's up-state capacitance and provides excellent matching at the design frequency. This high-impedance T-line section was designed, simulated and optimized using finite-element-modelling (FEM) tool of electromagnetic (EM) simulator of AWR Design EnvironmentTM. The optimized T-line section's width and length is 10 µm and 70 µm, respectively. The RF-MEMS switch is actuated by electrostatic force with low-actuation voltage of 2.9 V, has maximum von Mises stress of 13.208 MPa which is less than aluminium's yield stress and can be operated in robust conditions. Compared to the normal capacitive RF-MEMS switch, this T-match capacitive RF-MEMS switch with two sections of optimized high-impedance T line has improved the performance of return loss and insertion loss, at switch-on state, by 45.83% and 55.35%, respectively; while at the switch-off state, the isolation is increased by 24.05%; only the switch-off return loss is degraded by 11.7% but the value (ź 0.5519 dB) is still located in the range of design specifications. The RF-MEMS switch's actuation time was simulated to be ~ 27 µs with amplitude of 5 V up-step voltage.

МОДЕЛИРОВАНИЕ ПРОЦЕССА ИЗМЕРЕНИЯ ПОЛОЖЕНИЯ ГРАНИЦЫ РАЗДЕЛА ДВУХ СРЕД В ЕМКОСТИ С ПРИМЕНЕНИЕМ РАДИОЧАСТОТНОГО МЕТОДА

The article describes modeling of the process for measurement of interface position between two media, in particular two immiscible liquids with different density, one over the other, contained in a tank using radiofrequency method. In this case it is provided invariance of measurement results to electrical parameters of both media. Independent sections of transmission lines with end horizontal sections are used as sensors. To provide invariance to electrical parameters of the lower medium there are used natural resonance frequencies of the two sections of a transmission line or phase shifts of electromagnetic waves with fixed frequency excited and received at the section inputs and reflected from section ends. Functional conversion of informative parameters helps to determine interface position between two media in the tank. In the modeled measurement process in order to provide invariance to electrical parameters of two liquids there are placed vertically three sections of a coaxial or two-wire transmission line. Due to the availability of horizontal end sections at all three transmission line sections, there is no uncertainty of measurement results when measuring the interface position at its zero-, or close to zero, readings in the course of functional processing of resonance frequencies of the three transmission line sections. These sections may be done identical with equal end horizontal parts of a fixed length but with different reactive loads at the ends of horizontal parts. Between parallel outer conductors of coaxial line sections up to the ends of their horizontal parts, electromagnetic oscillations are excited as in a two-conductor line section having end reactive load that is different from the end reactive loads of coaxial line sections. This provides the difference of three dependencies of corresponding resonance frequencies on coordinate of interface position between two media. Determination of interface position in the modeled measurement process on the base of this method is characterized by higher measurement accuracy, easy realization of radiofrequency devices and is free from shortcomings of other radiofrequency methods.

Feasibility of fast restoration of power systems by micro‐grids

This study shows that with fast and flexible power electronic converter interfaces, micro-grids can quickly re-energise blacked-out transmission lines without overvoltage. After the transmission lines are re-energised, micro-grids can speed up (i) the reconnections of generators and loads; (ii) the re-synchronisation of severed transmission line sections back to the original grid. Micro-grids have active power to energise auxiliary motors of large thermal plants in black start. Faster restoration is limited by steam-turbine plants because they cannot be speeded up beyond thermodynamic constraints.

Microwave Microfluidic Sensor Based on a Microstrip Splitter/Combiner Configuration and Split Ring Resonators (SRRs) for Dielectric Characterization of Liquids

A microwave microfluidic sensor for dielectric characterization of liquids in real time is presented in this paper. The sensor is implemented in microstrip technology and consists of a symmetric splitter/combiner configuration loaded with a pair of identical split ring resonators (SRRs) and microfluidic channels placed on top of them (gap region). The sensor works in differential mode and sensing is based on frequency splitting. Thus, if the structure is unloaded or if it is symmetrically loaded with regard to the axial plane, only one transmission zero (notch) in the frequency response appears. However, if the axial symmetry is disrupted (e.g., by the presence of different liquids in the channels), two transmission zeros arise, and the difference in magnitude (notch depth) and frequency between such transmission zeros is indicative of the difference in the dielectric properties (complex dielectric constant). A circuit schematic, including transmission line sections to describe the distributed components, lumped elements to account for the SRRs and their coupling to the lines and lumped elements to model the liquid properties, is presented and validated. After proper calibration, the functionality of the proposed sensor is demonstrated by measuring the complex permittivity in solutions of deionized water and ethanol as a function of the ethanol content.

A ${Z}$ -Transform Method for Synthesis of Unequal-Length Multisection Transmission Lines for Multiband Applications

A method based on the $Z$ -transform is demonstrated to cascade transmission line sections of unequal lengths and achieve multiband and/or wideband properties. Unlike previous methods based on the $Z$ -transform, the proposed method associates the $z^{-1}$ term with the infinitesimal length of the unit segment. Consequently, any electrical length can be expressed in the $z^{-1}$ form. Therefore, while the previous methods are restricted to cascading lines of a commensurate length only, the proposed method can be applied to those of incommensurate lengths. Furthermore, the $z$ -polynomials for triple or more bands can be constructed by multiplying a combination of single- and dual-band polynomials, which remarkably simplifies the entire procedure to develop multiband and/or wideband circuits with virtually no limitation in terms of the number and/or combination of frequencies. The validity and practicality of the proposed method is verified with experimental results for various impedance transformers for real loads and Wilkinson power dividers; the results show the independence in the number and combination of operating frequencies as well as a dual-band operation with a center frequency ratio as large as 7.75.