Impedance Matching System Research Articles

Design and Evaluation of a T-Shaped Adaptive Impedance Matching System for Vehicular Power Line Communication

The quality of the communication links in VPLC (vehicular power line communication) suffer from an impedance mismatch resulting from fluctuating VPLN (Vehicular Power Line Network) access impedance, which renders the fixed impedance matching circuit inefficient. In this paper, we designed a T-shaped adaptive impedance matching system on the basis of the resonance- and absorption-based T-shaped network complex impedance matching approach. We identified the load-Q (quality factor) for different matching situations to facilitate designing T-shaped networks with broad bandwidths. The designed T-shaped adaptive impedance matching system adjusts the component values of the T-shaped network to implement adaptive impedance matching between the VPLC modem and VPLN. A set of simulations are conducted for 1 MHz-100 MHz, which demonstrates that the designed adaptive matching system with a simple circuit structure and control logic is capable of significantly improving signal power transfer.

A Real-Time Range-Adaptive Impedance Matching Utilizing a Machine Learning Strategy Based on Neural Networks for Wireless Power Transfer Systems

In this article, the implementation of a machine learning (ML) strategy based on neural networks for the real-time range-adaptive automatic impedance matching of wireless power transfer (WPT) applications is discussed. This approach for the effective prediction of the optimal parameters of the tunable matching network and the selection of range-adaptive transmitter coils (Tx) is introduced in this article, aiming to achieve an effective automatic impedance matching over a wide range of relative distances. We propose a WPT system consisting of a tunable matching circuit and three Tx coils that have different radii and are simultaneously controlled by trained neural network models, returning an output set of matching capacitances as well as the optimal single transmitter among the three transmitters. In addition, a proof-of-concept prototype of the entire real-time range-adaptive automatic impedance-matching system is built and characterized. Finally, the proposed approach achieves a power transfer efficiency (PTE) of around 90% for ranges within 10–25 cm.

Theoretical Research of Single Ferrite Tuner Systems with Magnetic Field Modulation in the Ion Cyclotron Range of Frequency

Ion cyclotron resonance heating is a reliable tool for high-power and long-pulse operation in fusion reactors. However, a sudden increase in the reflected radio-frequency (RF) power poses serious problems such as L- to H-mode transition or edge-localized modes that must be solved for future fusion reactors. It is necessary to place an impedance matching system between the RF generator and antenna to mitigate the adverse effects of the variations. The idea of a fast-response ferrite stub tuner was developed to trace the load variation of the antenna. This study presents theoretical calculation of the suitable normalized mechanical length of the ferrite stub tuner using transmission line theory and numerically analyzes the impedance matching parameters of the single ferrite stub antenna system. The present study demonstrates the feasible investigation of the magnetic field modulation, which can lead to the effective reduction in the reflected RF power fraction during the large change in plasma resistance.

Метод уменьшения площади кристалла для систем согласования импедансов в высокоскоростных каналах передач

Метод уменьшения площади кристалла для систем согласования импедансов в высокоскоростных каналах передач

Testing and Validation of Adaptive Impedance Matching System for Broadband Antenna

Broad RF impedance matching is challenging; however, the need for broadband matching is found frequently in modern RF and wireless systems with multiple wireless standards. Moreover, in 5G technology, multiple frequency bands are used, and these systems typically employ a broadband antenna or multiple antennas. Antenna impedances vary from design targets for many reasons including manufacturing process variations or antenna environment changes. An adaptive impedance matching system (AIMS) for testing and validation is introduced, and its implementation is shown in this paper. The AIMS can control impedance matching tuner settings to provide an arbitrary impedance frequency-varying load that meets user-defined conditions. This AIMS provides a testing and validation system for broadband antennas that can be characterized by various settings of the impedance matching tuner. As a device under test (DUT), a three-stub reconfigurable filter was used as the impedance matching tuner on a RT/Duroid 6010 RF board. It was integrated with a control circuit board. This AIMS implementation also included an antenna impedance tuner that can vary the distance between the antenna and the ground plane. This model represents practical antenna impedance variations. The AIMS controls a network analyzer and the impendence matching tuner. The adaptive control program on a PC was developed to perform an effective two-pass tuning strategy. This article presents the successful automated tuned results and their numerical evaluations of three cases that were generated by the antenna impedance tuner.

Impedance matched electrical capacitance tomography system: front-end design and system analysis

Electrical capacitance tomography (ECT) is a well-established technique for process monitoring, which enables the visualization of spatial material distributions within a region of interest, e.g. a pipeline. Switched capacitor (SC) circuits or continuous displacement current measurements are used to measure the coupling capacitances within the ECT sensor. In order to measure the coupling capacitances with high accuracy, the circuit concepts make use of fast excitation signals, e.g. fast transients in SC circuits or high excitation frequency signals in continuous displacement current measurements. For industrial process tomography in harsh environments a spatial separation between the sensor and the front-end circuitry is favorable. Consequently, the measurement circuitry and the sensor are connected by means of coaxial cables. For high excitation frequencies, transmission line effects like standing waves, reflections, or impedance transformation effects appear, leading to undefined signal conditions in the measurement system. It can be shown that the undefined signal propagation can lead to significant measurement errors. In this paper we present an impedance matched front-end circuitry, i.e. the source impedance of the excitation source and the input impedance of the measurement circuitry are matched to the wave impedance of the transmission lines. Due to the matching the signal propagation becomes defined, allowing the use of arbitrary cable lengths and excitation signals. We present the design of an impedance matched front-end for ECT and study the behavior of the excitation system and the measurement system. Comparative measurements from a demonstrator are presented. Finally we study the measurement error of the system and show the validity of the impedance matched system approach.

A Demonstrator for Impedance Matching Systems in Transmission Lines With Time and Frequency Simulation [Education Corner

This article describes a software tool developed to demonstrate several impedance-matching systems using at least one section of transmission line. The tool is intended for use in the classroom as a teaching resource and by students to verify the solutions of homework exercises, prepare for examinations, assist with laboratory work, and consolidate concepts in transmission-line theory. The implementation allows a very flexible and realistic load impedance definition, calculates the frequency response, and performs the animation of the traveling waves through all line sections of the matching system. The frequency response invites the students to have a more critical view of the physical circuit and improves their general skills in distributed and concentrated radio-frequency (RF) circuits. The time simulation offers a more detailed view of what is occurring inside the matching system, highlighting a few interesting conclusions. The tool is available online to be freely used, modified, or improved by the education community.

Automatic Impedance Matching Method With Adaptive Network Based Fuzzy Inference System for WPT

In a wireless power transfer system via coupled magnetic resonance, the power transfer efficiency (PTE) drastically decreases with the transfer distance and the changing load. To solve this problem, an automatic impedance matching system is usually embedded in an intelligent algorithm. However, the traditional algorithm cannot dynamically track the impedance due to its slow matching speed. In this paper, an automatic impedance matching method based on adaptive network based fuzzy inference system (ANFIS) is proposed to overcome this disadvantage. A simulation system is constructed, and results show that the efficiency of the proposed ANFIS method is 80.26% higher than that of the genetic algorithm. Moreover, an automatic impedance matching prototype is built and dynamic matching experiments are carried out, showing that the PTE is up to 84.76% when the distance increases from 4.5 to 50 cm. The simulation and experimental results are basically consistent, which prove the validity of the novel method.

An Adaptive Impedance Matching Transmitter for a Wireless Intraoral Tongue-Controlled Assistive Technology

A robust wireless communication is critical for wireless intraoral devices since it is adversely affected by the external radio frequency (RF) interference and impedance variations of the transmitter (Tx) antenna in the dynamic mouth environment. We present a three-band (27 MHz, 433 MHz, and 915 MHz) Tx with an adaptive antenna impedance matching system for a wireless intraoral tongue controlled assistive technology (AT), the intraoral tongue drive system (iTDS), to establish a robust wireless link between the intraoral device and an external receiver (Rx). With a built-in super-regenerative receiver (SR-Rx), the Tx can switch the carrier frequency to avoid RF interference without the users’ involvement. The upper two bands, 433 MHz and 915 MHz, are equipped with adaptive matching networks and a matching algorithm to automatically correct impedance variations of the Tx antenna without any assistance from off-chip components. The Tx chip was fabricated in a 0.35- $\mu \text{m}$ CMOS process. Measurement results show the tuning range of the proposed network can cover up to VSWR = 4 with 4.7 dB and 3.8 dB output power improvement at 433 MHz and 915 MHz, respectively.

An Online Impedance Analysis and Matching System for Ultrasonic Transducers.

Electrical impedance matching of ultrasonic transducers is important in optimizing the energy consumption as well as guaranteeing equipment safety for ultrasonic systems in both laboratories and industries. The existing solutions usually rely on expensive instruments to conduct off-line impedance measurements and deploying static impedance matching networks for each specific transducer across a target frequency band. Here, we present an initial prototype of an online impedance analysis and matching system (OIAMS). In this system, an improved voltage-current method and a phase-difference method were integrated for online impedance measurement in real time, and an L-type matching circuit with variable components helped to achieve dynamic impedance matching. A feedback protocol was embedded in a microcontroller to adjust the matching strategies based on dynamic measurements, while the whole system was controlled through a software interface developed on a LabVIEW platform. Online measurement results showed that OIAMS conducted accurate impedance measurements with a relative error within 3.90% for amplitude and 13.11% for phase across the 100% bandwidth of the tested transducers. After matching, the reflected acoustic power of a 1.00-MHz transducer was reduced by over 50%, increasing the generated sound pressure level by over 2.8 dB across its 70% bandwidth.

Developing a small photovoltaic power supply system with adaptive technologies for rural Africa: Design, cost and efficiency analyses

The objective of this study was to design a small-scale photovoltaic system to support electricity supply to a rural village in the Republic of Congo. A simple impedance-matching system and an innovative panel-tilting system were implemented as adaptive technologies to increase the power output of the system and reduce its capital and running costs. The experimentally obtained results showed that the daily energy output of a four-panel, 400 W photovoltaic system could be increased by 15% through a series parallel impedance match configuration, and by 36% from 3.3 kWh per day to approximately 4.5 kWh per day through implementing an automated panel tilting system with always normal incidence of solar irradiation on the panels in an equatorial environment. Implementing these technologies accordingly reduced the cost of energy supplied by the same percentages, with an eventual electricity cost of about ZAR 3.60 per kWhr, as calculated over an operation time of ten years, and an initial capital outlay of ZAR 37 per watt. These costs are much lower than for installing power grid lines to the village, and the technology also ensures complete autonomy of power supply to the community. The study also identified the potential to generate many new business and job opportunities locally in this community, as well as in the rest of Africa.

Developing a small photovoltaic power supply system with adaptive technologies for rural Africa: Design, cost and efficiency analyses

The objective of this study was to design a small-scale photovoltaic system to support electricity supply to a rural village in the Republic of Congo. A simple impedance-matching system and an innovative panel-tilting system were implemented as adaptive technologies to increase the power output of the system and reduce its capital and running costs. The experimentally obtained results showed that the daily energy output of a four-panel, 400 W photovoltaic system could be increased by 15% through a series parallel impedance match configuration, and by 36% from 3.3 kWh per day to approximately 4.5 kWh per day through implementing an automated panel tilting system with always normal incidence of solar irradiation on the panels in an equatorial environment. Implementing these technologies accordingly reduced the cost of energy supplied by the same percentages, with an eventual electricity cost of about ZAR 3.60 per kWhr, as calculated over an operation time of ten years, and an initial capital outlay of ZAR 37 per watt. These costs are much lower than for installing power grid lines to the village, and the technology also ensures complete autonomy of power supply to the community. The study also identified the potential to generate many new business and job opportunities locally in this community, as well as in the rest of Africa.

Tunable biasing magnetic field design of ferrite tuner for ICRF heating system in EAST

Ion cyclotron range of frequency (ICRF) heating has been used in tokamaks as one of the most successful auxiliary heating tools and has been adopted in the EAST. However, the antenna load will fluctuate with the change of plasma parameters in the ICRF heating process. To ensure the steady operation of the ICRF heating system in the EAST, fast ferrite tuner (FFT) has been carried out to achieve real-time impedance matching. For the requirements of the FFT impedance matching system, the magnet system of the ferrite tuner (FT) was designed by numerical simulations and experimental analysis, where the biasing magnetic circuit and alternating magnetic circuit were the key researched parts of the ferrite magnet. The integral design goal of the FT magnetic circuit is that DC bias magnetic field is 2000 Gs and alternating magnetic field is ±400 Gs. In the FTT, E-type magnetic circuit was adopted. Ferrite material is NdFeB with a thickness of 30 mm by setting the working point of NdFeB, and the ampere turn of excitation coil is 25 through the theoretical calculation and simulation analysis. The coil inductance to generate alternating magnetic field is about 7 mH. Eddy-current effect has been analyzed, while the magnetic field distribution has been measured by a Hall probe in the medium plane of the biasing magnet. Finally, the test results show the good performance of the biasing magnet satisfying the design and operating requirements of the FFT.

Frequency-tuning radiofrequency plasma source operated in inductively-coupled mode under a low magnetic field

A radiofrequency (rf) inductively-coupled plasma source is operated with a frequency-tuning impedance matching system, where the rf frequency is variable in the range of 20–50 MHz and the maximum power is 100 W. The source consists of a 45 mm-diameter pyrex glass tube wound by an rf antenna and a solenoid providing a magnetic field strength in the range of 0–200 Gauss. A reflected rf power for no plasma case is minimized at the frequency of ∼25 MHz, whereas the frequency giving the minimum reflection with the high density plasma is about 28 MHz, where the density jump is observed when minimizing the reflection. A high density argon plasma above cm−3 is successfully obtained in the source for the rf power of 50–100 W, where it is observed that an external magnetic field of a few tens of Gauss yields the highest plasma density in the present configuration. The frequency-tuning plasma source is applied to a compact and high-speed silicon etcher in an Ar–SF6 plasma; then the etching rate of m min−1 is obtained for no bias voltage to the silicon wafer, i.e. for the case that a physical ion etching process is eliminated.

Adaptive RFID Impedance Matching Based on Phase Difference for Oil Well Applications

Severe impedance mismatch problems due to the various environmental issues in downhole can greatly degrade the reliability of the radio-frequency identification (RFID) control system. In this brief, a new adaptive RFID impedance-matching system for oil well applications is presented, in which the measured real-time phase difference is employed to track the impedance mismatch information, while a variable capacitor array combined with a frequency sweep is used to rematch the mismatched impedance. Experiments have been performed and the results show that the impedance can be rematched perfectly when affected by from the various environmental influences.

An Adaptive Impedance-Matching System for Vehicular Power Line Communication

Vehicular power line communication (VPLC) is being considered as a potential solution to mitigate the increase of complexity and cost of the automotive wiring harness caused by the growth of the number of electronic devices and sensors deployed inside vehicles. This is because VPLC reuses power cables for data communication and, thus, avoids the need for additional communication wires. However, this reuse does not come without problems. One of the challenges for VPLC is the time, frequency, and location dependence of the access impedance, which can cause severe impedance mismatch for the communication signal. Impedance mismatch degrades the signal-to-noise-power ratio at the communication receiver and thus affects transmission reliability. Due to the variable nature of the access impedance, a fixed matching circuit will be inefficient. Hence, in this work, we present an adaptive impedance-matching system, which improves the communication-signal transfer from the transmitting to the receiving device. The system is evaluated via simulations for a wide range of access-impedance test points and $S$ - parameters of VPLC networks obtained in previous measurement campaigns. Our simulation results demonstrate that the presented adaptive matching system is able to achieve VPLC signal-power transfer within 30% of the theoretical optimum. This translates to a power gain, up to a factor of 10, which is larger than that of other solutions reported in the literature.

Continuous-Wave Single-Photon Transistor Based on a Superconducting Circuit.

We propose a microwave frequency single-photon transistor which can operate under continuous wave probing and represents an efficient single microwave photon detector. It can be realized using an impedance matched system of a three level artificial ladder-type atom coupled to two microwave cavities connected to input-output waveguides. Using a classical drive on the upper transition, we find parameter space where a single photon control pulse incident on one of the cavities can be fully absorbed into hybridized excited states. This subsequently leads to series of quantum jumps in the upper manifold and the appearance of a photon flux leaving the second cavity through a separate input-output port. The proposal does not require time variation of the probe signals, thus corresponding to a passive version of a single-photon transistor. The resulting device is robust to qubit dephasing processes, possesses low dark count rate for large anharmonicity, and can be readily implemented using current technology.

Stabilization of Impedance Matching System using RF Transformer

Stabilization of Impedance Matching System using RF Transformer

水中音響通信に用いる圧電トランスデューサの能動的インピーダンス整合システムの開発に関する研究

Underwater acoustic (UWA) communication is a critical technology for underwater activities. However, UWA communication systems do not always operate in an ideal state due to impedance mismatching of an UWA transducer. To cope with this problem, we propose an adaptive impedance matching system. The proposed system consists of a tuning circuit with a variable inductive load, voltage and current probes, and an adaptive controller. By measuring the impedance state of the transducer and controlling the inductive load, the proposed system is able to always maintain an optimal impedance matching state of the communication system. The performance of the proposed system was evaluated in experiments, which confirmed that the proposed system can actively optimize the impedance matching state of the communication system, and can provide efficient UWA communication.

A Dynamically Adaptable Impedance-Matching System for Midrange Wireless Power Transfer with Misalignment

To enable the geometrical freedom envisioned for wireless power transfer (WPT), fast dynamic adaptation to unpredictable changes in receiver position is needed. In this paper, we propose an adaptive impedance-searching system that achieves good impedance matching quickly. For fast and robust operation, the proposed method consists of three steps: system calibration, coarse search, and fine search. The proposed WPT system is characterized using distance variation and lateral and angular misalignment between coils. The measured results indicate that the proposed method significantly reduces searching time from a few minutes to approximately one second. Furthermore, the proposed system achieves impedance matching with good accuracy. The robust impedance-searching capability of the proposed system significantly improves power transfer efficiency. At 6.78 MHz, we achieve a maximum efficiency of 89.7% and a high efficiency of >80% up to a distance of 50 cm. When the center-to-center misalignment is 35 cm, the efficiency is improved from 48.4% to 74.1% with the proposed method. At a distance of 40 cm, the efficiency is higher than 74% for up to 60° of angular rotation. These results agree well with the simulated results obtained using a lumped-element circuit model.