Length Of Transmission Line Research Articles

An F-Band $n$ -Probe Standing Wave Detector for Complex Reflection Coefficient Measurements in 40-nm CMOS

This article presents an F-band-integrated standing wave detector for complex reflection measurements. The complex reflection coefficient is derived from a standing wave, measured by 312 power detectors coupled from underneath a transmission line (TL), taking the loss of the TL into account. For the proposed method of reflection coefficient derivation, the tradeoff between TL length and number of probes is shown through simulation. The standing wave detector is fabricated in the 40-nm CMOS process, and the measurements show complex reflection coefficient for input powers down to −20 dBm at 120 GHz while only consuming $112~{\mu }\text{W}$ of dc power. In measurements, the complex reflection detection is shown for multiple impedances achieving an absolute phase error of 8.3° with a sigma of 1.5° and a magnitude error of 0.33 dB with a sigma of 0.21 dB, compared to a VNA reference measurement.

A Low-Noise Transmission-Type Yttrium Iron Garnet Tuned Oscillator Based on a SiGe MMIC and Bond-Coupling Operating up to 48 GHz

Wideband and low-noise tunable oscillators at microwave frequencies are crucial within microwave frequency synthesizers and key to high-end measurement systems based on electromagnetic sensing in the microwave range as well as in the terahertz (THz) and sub-THz range. This paper presents a novel, wideband, and low-noise differential yttrium iron garnet (YIG) tuned oscillator. It is based on a SiGe monolithic microwave integrated circuit and a transmission-type YIG resonator. The integrated circuit contains a fully differential amplifier as a part of the oscillator core. The resonator was realized by two orthogonal, crossed pad-to-pad bonds and an YIG sphere, which is positioned between those bonds and the integrated circuit. To design and optimize the oscillator, an equivalent circuit modeling the resonator was developed. Concerning the tuning range and the phase noise, the results of the circuit simulations are in good agreement with the measurements. Two oscillators with different lengths of the inductive load transmission line were realized. First, the oscillator with a short transmission line offers very high-oscillation frequencies with a tuning range from 32.0 to 48.2 GHz. It exhibits an excellent phase noise of less than -119dBc/Hz at an offset frequency of 100kHz for oscillation frequencies up to 42GHz. Second, the oscillator with a longer transmission line length offers a tuning range from 19.1 to 41.4 GHz. This configuration exhibits an excellent phase noise of less than -120dBc/Hz at an offset frequency of 100 kHz for oscillation frequencies up to 38GHz.

An Automatic Placement and Routing Methodology for Asynchronous SFQ Circuit Design

This article proposes an automatically placed and routed methodology for asynchronous single flux quantum (SFQ) circuits using passive transmission line lines and utilizing a commercial electronic design automation (EDA) tool, Cadence Innovus. At the cell level, dual rail SFQ asynchronous cells were developed to be implemented in the place and route methodology. Scripts were written that could convert any single rail netlist synthesized from behavioral Verilog using an EDA tool (such as Design Vision) containing single rail cells into dual rail asynchronous cells. Then, automatic placement and routing using Innovus was achieved through specific cell layout design choices that allowed the finished circuit design layout to pass checks by layout vs schematic and design rule check. Finally, back annotation was performed by reincorporating transmission line lengths from place and route stage in analog simulation to verify correct functionality of the design. As an example, a 4-b arithmetic logic unit design is used to illustrate the various stages of the methodology.

Selectivity improved directional filters using cross-coupling introduced transmission zeros

ABSTRACTIn this paper, the realization of traveling-wave directional filters allowing for selectivity improvement without increasing filter’s order is presented and studied. It is shown that the introduction of loose cross-coupling between #(n-1)th loop resonator and isolated port of the nth-order directional filter allows for generating transmission zeros in the bandpass branch and thus to improve the filter`s roll-off. Moreover, the electrical length of the cross-coupling connecting transmission line allows for adjusting the location of transmission zeros and realizing symmetric or asymmetric frequency response. The presented approach is theoretically analyzed and experimentally verified. Exemplary second- and third-order directional filters with symmetrically placed transmission zeros were designed to operate at f0 = 1 GHz, manufactured and measured. The obtained results prove their applicability towards the realization of frequency multiplexers.

PCB에 제작된 광대역 소형 평면 발룬 설계

The design of a novel broadband 180° phase shifter, with the main transmission line length of λ/4, which is smaller than a conventional broadband 180° phase shifter with a main transmission line length of λ/2, is proposed in this study. The proposed compact broadband planar balun, consisting of the λ/4 broadband 180° phase shifter and a 3 dB Wilkinson power divider, is implemented on a single-layer PCB and its characteristics are measured. The impedance bandwidth with a return loss of more than 15 dB at the input port is 52.1 %(7.62~13 GHz), and the bandwidth of the phase differences between the two output ports within the phases 175° and 185° is 56.6 %(7.09~12.7 GHz). The characteristics of the λ/4 broadband planar balun implemented in this paper are similar to those of the conventional λ/2 broadband planar balun. The length of the λ/4 broadband planar balun is lesser than that of the conventional λ/2 broadband planar balun, thus reducing the overall size by more than 11.6 %.

Antenna Array Design using Hybrid Feed for High Frequency Application

The objective of this paper to design eight elements (4×2) antenna array with hybrid feed structure. A number of microstrip antenna arrays such as microstrip antenna with inset feed, 2×1 antenna array, 4×1 antenna array and 4×2 antenna array have been designed using Rogers RT/duroid 5880 as dielectric materials are proposed to enhanced gain and bandwidth in practical measurement. The simulated gain is 14.917 dB obtained with hybrid feed structure and bandwidth of the design is 396.8 MHz and 523.5 MHZ at 9.4 GHz and 11.6 GHz resonating frequency. A prototype of the antenna is also constructed and tested, the tested results shows a bandwidth of 500 MHz. Loss increases due to long feed transmission line which reduce the gain of the antenna when we use thicker substrate. So hybrid feed structure is used in this design to reduce the length of transmission line. The application of this design is in radio location.

Impact of Electrical Topology, Capacity Factor and Line Length on Economic Performance of Offshore Wind Investments

In this study, an economic performance assessment of offshore wind investments is investigated through electrical topology, capacity factor and line length. First, annual energy yield production and electrical system losses for AC and DC offshore wind configurations are estimated by using Weibull probability distributions of wind speed. A cost model for calculating core energy economic metrics for offshore wind environment is developed by using a discount cash flow analysis. A case study is then conducted for a projected offshore wind farm (OWF) rated 100 MW and 300 MW sizes situated in the Aegean sea. Finally, a sensitivity analysis is performed for AC and DC OWFs with three different capacity factors (e.g., 45%, 55% and 60%) and various transmission line lengths ranging from 20 km to 120 km. The OWF is found to be economically viable for both AC and DC configurations with the estimated levelized cost of electricity (LCOE) ranging from 88.34 $/MWh to 113.76 $/MWh and from 97.61 $/MWh to 126.60 $/MWh, respectively. LCOEs for both options slightly change even though the wind farm size was increased three-fold. The sensitivity analysis reveals that, for further offshore locations with higher capacity factors, the superiority of AC configuration over the DC option in terms of LCOE reduces while the advantage of DC configuration over the AC option in terms of electrical losses is significant. Losses in the AC and DC configurations range from 3.75% to 5.86% and 3.75% to 5.34%, respectively, while LCOEs vary between 59.90 $/MWh and 113.76 $/MWh for the AC configuration and 66.21 $/MWh and 124.15 $/MWh for the DC configuration. Capacity factor was found to be more sensitive in LCOE estimation compared to transmission line length while line length is more sensitive in losses estimation compared to capacity factor.

Tri‐section stepped impedance resonator with adjustable length and improved second harmonic characteristics

AbstractIn this study, we present a novel tri‐section stepped impedance resonator (SIR) with two different lengths (θ1 and θ2). The lengths of the first and the last transmission lines of the proposed tri‐section SIR were intentionally chosen. We compared the properties of the proposed SIR and the existing SIR. In the same impedance ratios (K1 and K2), the second harmonics of the proposed SIR were improved by 1.05‐1.11 times compared to the existing SIR. In addition, the length of the first transmission line, θ1, could be extended by more than twice the length of the existing SIR. That was very advantageous for tight coupling in a coupled line. Finally, a parallel‐coupled line band‐pass filter (PCL BPF) was developed using the proposed SIR, and the design equations were derived. The second harmonic of the PCL BPF was measured with an error of 2.67% compared to the theoretical value. The center frequency was almost identical. A series of processes, including design, simulation, fabrication, and measurement using the proposed structure, was carried out. An analysis of the results of each step proved the validity of our proposal.

Design of 3-Bit Digital RF Phase Shifter for Wireless Communication

In this paper, a 3-bit digital phase shifter based on switched transmission line technique using coplanar waveguide is proposed. The design has the resonant frequency of 10 GHz which can be used in wireless communication applictaions. Recent developments in radio frequency components development has raised as a significant way for constructing low loss phase shifters. MEMS phase shifters whose insertion loss is low and high isolation uses minimum power. This helps to bring low cost and light weighted phased array antennas. The transmission line length and wavelength decides the characteristics of phase shift. The phase shifter design consists of coplanar waveguides having center conductor width of 100µm and the gap of 14 µm on a FR-4 epoxy substrate with thickness of 1.6mm. The design is simulated using ADS to yield phase shift of 45, 90 and 180. The benefits of digital phase shifters include achieving flat phase over a wide bandwidth as well as having higher power handling and linearity with uniform performance. The phase shifters are used in different fields which includes microwave devices, feeder of radio system, phased array antenna, coherent radio system, etc.

Design of 3-Bit Digital RF Phase Shifter for Wireless Communication

In this paper, a 3-bit digital phase shifter based on switched transmission line technique using coplanar waveguide is proposed. The design has the resonant frequency of 10 GHz which can be used in wireless communication applictaions. Recent developments in radio frequency components development has raised as a significant way for constructing low loss phase shifters. MEMS phase shifters whose insertion loss is low and high isolation uses minimum power. This helps to bring low cost and light weighted phased array antennas. The transmission line length and wavelength decides the characteristics of phase shift. The phase shifter design consists of coplanar waveguides having center conductor width of 100μm and the gap of 14 μm on a FR-4 epoxy substrate with thickness of 1.6mm. The design is simulated using ADS to yield phase shift of 45, 90 and 180. The benefits of digital phase shifters include achieving flat phase over a wide bandwidth as well as having higher power handling and linearity with uniform performance. The phase shifters are used in different fields which includes microwave devices, feeder of radio system, phased array antenna, coherent radio system, etc.

Optimal Design of 1200 kV UHV AC Transmission Lines in India using Newly Developed Standalone MATLAB GUI

Owing to tremendous growth in requirement of electrical power in the country, technological advancement in transmission systems is essential for transmission of bulk amount of power over long distances. Deciding value of corridor width for transmission lines are greatly influenced by magnitudes of electric and magnetic fields along its length. The precise evaluation of the electromagnetic fields and effects of corona like Radio Interference and Audible Noise generated by overhead transmission lines are thus of greater interest. This paper presents implementation of a novel GUI based technique to compute the fields generated by power transmission lines using three dimensional techniques. Actual case of Ultra High Voltage AC (UHVAC) line is considered for study. Transmission lines are analyzed by using newly developed software that facilitates computation and plotting of electromagnetic fields and corona effects in 3D coordinates. MATLAB is used as platform for development of GUI based software to analyze the fields along the entire length of transmission lines under study. It uses concept of charge simulation method (CSM) along with most fundamental Maxwell’s potential coefficient theory and 3D integration techniques.

Application of modal‐phase domain relations to estimate transmission line parameters

The accuracy of transmission line parameters (TLPs) allows the proper response to faults or load variations and the monitoring of common fault indicators, such as the conductor's temperature and sag. TLP estimation methodologies based on modal decomposition theory are restricted to specific tower configurations in which the transmission line transformation matrix is known. This paper proposes a non-linear system of equations to estimate the parameters of a generic three-phase transmission line while using modal-phase relations for an unknown transformation matrix and known voltages and current phasors at the terminals of the line. The Newton–Raphson (NR) method is implemented to solve this proposed system of equations and accurately estimate the TLPs. The relative error of the estimated parameters shows the methods’ accuracy and the influence of the line representation as lumped elements. The results demonstrate the robustness and efficiency of the proposed method for transmission lines of different lengths.

A new on-line technique to identify fault location within long transmission lines

Identification of fault location within transmission lines is essential in order to restore service rapidly, reduce unplanned outage time, minimise revenue loss, and improve network reliability. Several transmission line fault-locating techniques based on travelling waves, apparent impedance and direct circuit analysis have been introduced in the literatures. However, these methods are either impractical or too expensive to implement. In this paper, a new online technique is introduced to accurately detect the fault location within transmission lines. The technique relies on constructing a voltage-current (V-I) locus diagram that could be measured at every power frequency cycle to provide up-to-date condition state of the line. The technique does not call for special equipment as it utilises the existing metering or protection devices connected to the sending and receiving ends of the transmission line to monitor the voltage and current at both ends. To assess the robustness of the proposed technique, various types of faults have been simulated on transmission lines of various lengths and voltage levels using DIgSILENT PowerFactory software. Variations in load conditions, effect of fault resistance, different line configurations are also investigated. Results reveal the ability of the proposed technique to detect fault locations in transmission lines with high accuracy. In contrary with existing fault-locating techniques that are only employed to identify the location of faults after their occurrence, the proposed technique has the potential to detect high impedance faults. Thus an early warning signal can be issued to avoid any catastrophic consequences. The proposed technique is cost effective and easy to implement for new and existing transmission line installations.

Forecasting China’s Renewable Energy Terminal Power Consumption Based on Empirical Mode Decomposition and an Improved Extreme Learning Machine Optimized by a Bacterial Foraging Algorithm

The energy consumption pattern dominated by traditional fossil energy has led to global energy resource constraints and the deterioration of the ecological environment. These challenges have become a major issue all over the world. At present, the Chinese government aims to significantly reduce the fossil energy consumption contribution in the terminal energy consumption. The development of renewable energy in the terminal energy and energy conversion links has significantly increased the proportion of clean low-carbon energy. In order to accurately get the proportion of renewable energy terminal power consumption, firstly, this paper selects a primary influencing-factors set including the gross GDP, fixed investment in renewable energy industry, total length of cross-provincial and cross-regional high-voltage transmission lines, etc. as influencing factors of China’s electricity consumption fraction produced by renewable energy based on a multitude of papers. Secondly, from the perspective of signal decomposition, the data inevitably has a lot of interference and noise. This paper uses the empirical mode decomposition (EMD) algorithm to reduce the degree of signal distortion and decomposes the signal into natural modes including several intrinsic mode functions (IMFs) and a residual term (Res); afterwards, a new extreme learning machine (ELM) forecasting model optimized by an Inverse Square Root Linear Units (ISRLU) activation function is proposed, and the ISRLU function is used to replace the implicit layer activation function in the original ELM algorithm. Then, a new bacterial foraging algorithm (BFOA) is applied to optimize the parameters of the optimized ELM forecasting model. After multiple learning and training operations, the optimal parameters are obtained. Finally, we superimpose the output of each IMF and Res training task to get the amount of China’s power consumption produced by renewable energy. Some statistical indicators including root mean squard error (RMSE) are applied to compare the accuracy of several intelligent machine forecasting algorithms. We prove that the proposed forecasting model has higher prediction accuracy and achieves faster training speed by an empirical analysis. Finally, the proposed combined forecasting algorithm is applied to predict China’s renewable energy terminal power consumption from 2018 to 2030. According to the forecasting results, it is found that China’s renewable energy terminal power consumption shows a gradual growth trend, and will exceeded 3300 billion kWh in 2030, which will represent a renewable energy terminal power ratio of about 38% in 2030.

A protection technique for series capacitor compensated 400 kV double circuit transmission line based on wavelet transform including inter-circuit and cross-country faults

In this paper, wavelet transform based technique is introduced to detect and classify the faults in a series capacitor compensated double circuit transmission line. The three phase currents of both circuits measured at only one end of the series compensated double circuit transmission line are used to calculate the approximate and high frequency detail coefficients including wavelet energy content of each phase current signal. To evaluate the performance of proposed fault detection technique, simulation studies have been carried out on a series capacitor compensated double circuit transmission line test system. The major advantage of this proposed scheme is that it offers protection to entire transmission line length using one end fault current data only. The test results prove that all types of faults are correctly detected and the faulty phase is accurately identified using proposed technique. This technique is robust to the variation in fault type, fault inception time, fault resistance, ground resistance and fault location.Keywords: Fault detection, fault classification, series capacitor compensated double circuit transmission line, wavelet transform

Role of non-linear effects and standing waves in microwave spectroscopy: Corbino measurements on superconductors and VO2.

Broadband microwave spectroscopy can probe material properties in wide spectral and temperature ranges. The quality of such measurements crucially depends on the calibration, which also removes from the obtained spectra signatures of standing waves. Here we consider cryogenic Corbino-type reflection measurements on superconductors close to the critical temperature. We show that the non-linear sample response, which relates to sample heating, can lead to strong signatures of standing waves even in a well-calibrated Corbino spectrometer. We demonstrate our findings with microwave measurements as a function of frequency, power, and temperature and for different lengths of the microwave transmission line. Finally, we note such non-linear effects beyond the case of superconductors by probing a VO2 thin film at the insulator-metal transition.

A financial comparative study of solar and regular irrigation pumps: Case studies in eastern and southern Iran

While pressurized irrigation systems can be effectively powered using renewable energy sources, no serious related study is found in Iran in this regard. In the present study, in two different climatic conditions in Iran, development of small-scale solar irrigation were evaluated financially and compared with that of systems powered by the fossil fuel and electricity grid. Financial analysis of systems was provided using life cycle cost (LCC) method. Results showed that in the case of 4.5 and 5.5 kW pumps (for citrus orchard and a vineyard, respectively), photovoltaic irrigation pumps with batteries for energy storage are comparable to the systems in which the electricity used to drive pumps is transmitted through 0.25 km and 1.8 km private lines. It was concluded that, generally, if the required power of irrigation pumps exceeds 3 kW, the electricity supplied by a private power transmission line is more affordable than in-situ generated photovoltaic electricity, if the length of transmission line is less than 2 km. It was also observed that for required power less than 4.5 kW, photovoltaic energy is somewhat comparable to fossil fuel. As Iran is dependent upon its highly subsidized fossil fuels, the financing of solar irrigation projects will not be possible without the help of new policies and laws.

Study on characteristics of slow‐front overvoltage of ±1100 kV UHVDC transmission lines

The ±1100 kV Zhundong–Wannan ultra high-voltage direct current (UHVDC) transmission project is under construction in China, which has the highest operating voltage in the world. The length of the UHVDC overhead transmission line is greater than 3000 km. The electromagnetic transient process caused by grounding faults might have significantly impact on the overvoltage level of DC transmission line, which is crucial for the external insulation configuration of the overhead transmission line. This paper presents a detailed electromagnetic transient simulation model for the UHVDC transmission system using an open-loop extinction angle control principle. The simulation results demonstrate that the single pole grounding fault into a bipolar system causes the most serious damage. The maximum overvoltage is 1.628 p.u. and the 2% statistic overvoltage is 1.635 p.u., while the reference value is 1122 kV. The influence of DC filters for line overvoltage is also analysed here. Furthermore, results show that adding a no gap line arrester at the midpoint of transmission line can suppress line overvoltage, while the maximum overvoltage reduces by 0.138 p.u. The results obtained provides a reference for the optimisation of the external insulation configuration.

PROPOSED TRAVELLING WAVE TUNNETT AMPLIFIER AND OSCILLATOR FOR AIRBORNE RADARS

Two travelling wave TUNNETT diode structures are propoposed. The first one is a distributed TUNNETT which is proposed in order to overcome the inherent limitations on the power output of the discrete TUNNETT structure. ItAs shown that this structure can be used as resonant lengths of transmission line in order to tune out the diode depletion layer capacitance. Therefore, the distributed structure can have a much higher impedance, a larger area and a higher output power than the discrete one and will be much easier to match. It is found that a relatively high substrate resistivity gives better performance. It is also found that for a given substrate resistivity there is an optimum value of substrate thickness. Design graphs for the proposed device are presented. An output power of about 12 watts has been optained at a frequency of 30 GHz which is an important result. The second proposed structure is a multistream TUNNETT structure which is based on the space charge interactions of electron streaming layers. Each layer has a different average velocity due to a properly chosen concentration gradiant along the direction transverse to the motion of electrons. A numerical analysis is used to determine the gain of the proposed structure when it is used as a travelling wave amplifier. It is found that this gain decreases with increasing the diode thickness and slightly increases with the operating frequency in the frequency range considered. The proposed devices suffer no transit-time limitations sotheir bandwidth is much wider than that of a discrete TUNNETT. The possible applications of the proposed devices in airborne radars are indicated.

Reconfigurable Compact Bandpass Microstrip Filter of Bandwidth 1.54GHz

A new compact Bandpass Microstrip filter with very wide band is presented using Reconfigurable Bandpass Microstrip Filter, it is reconfigured and simulated to Reconfigured Compact Bandpass Microstrip (RCBM) Filter to minimize the size of the filter and to enhance its bandwidth (BW). The achieved BW is 1.54GHz with minimum amount of insertion loss of -0.5dB and compactness of 1/3^rd size reduction in the filter compared to its original filter size. In this methodology- varying the spacing, length and width of transmission lines of this RCBM is done. Hence by the variation of its dimensions the size of the filter is reduced with enhanced BW. These filters are used in handheld communication systems- here the size of each component, size of overall system and incorporating more number of features to that system is the main goal in recent research of handheld communication and these are the most important parameters. For this purpose compact filters are required, hence the proposed work is to achieve the compactness of the Microstrip Bandpass Filter by reconfiguring the compact Bandpass micro strip filter and increasing their performance. The proposed RCBM Filter is successfully realised in theory and verified by full wave electromagnetic simulation and the experiment. The simulated and measured results are in excellent agreement.