Compact transition enabled broadband propagation of spoof surface plasmon polaritons based on the equivalent circuit model

In this paper, a strategy to develop a compact transition of the spoof surface plasmon polariton (SSPP) transmission line (TL) is proposed. First, an equivalent distributed circuit model is employed for the theoretical analysis and optimization design of the SSPP unit. The mapping relation between the unit performance and the geometric parameters is deduced from the transmission matrix. The calculated results are compared with the numerical ones from the three-dimensional (3D) simulations for validation. Then, a compact transition (only 0.26λg) is built with only two matching units and a tapered strip through optimizations. The optimizations are implemented with the circuit simulations based on the equivalent model, which can remarkably save time in comparison with the 3D simulations. The transition principle is also explained by quantitatively extracting the dispersion properties and impedance characteristics. Finally, a prototype of the proposed SSPP TL is fabricated and measured for demonstration. The measured operating band (0-7.7 GHz) is almost up to the cut-off frequency (about 8 GHz), which remains the inherent broadband low-pass transmission characteristics. Meanwhile, the measured in-band return loss is almost higher than 10dB, which verifies the high-efficiency propagation. This work can pave the way for building up a new SSPP-based framework of microwave circuits.

OPERATIONAL CHARACTERISTICS OF SMALL-SIZED ANTENNA DEVICES OF THE MEDIUM FREQUENCY RANGE IN MINES

Представлены результаты исследования трех малогабаритных антенн (электрического,магнитного и магнитоэлектрического типов)СВ-диапазона с целью определения особенностей их эксплуатации в рудниках и шахтах,т.е. в диспергирующих средах. Рассмотрены импедансные характеристики и изменение частотных зависимостей коэффициента стоячей волны в ближней зоне антенн, обусловленное непостоянством электрических характеристик горных пород при перемещении антенн вдоль горной выработки. Проведена оценка стабильности работы портативных радиостанций при подводимой к малогабаритной антенне мощности 1 Вт с учетом времени,характерного для сеансов связи. Даны рекомендации по эксплуатации антенн в условиях рудников и шахт. The article investigates three main types of small antennas (electric, magnetic and magnetoelectric) of the medium frequency range in order to determine the features of their operation in mines, i.e. in dispersing media. The impedance characteristics and the change in the frequency dependences of the standing wave ratio are considered when the situation in the near zone changes. An assessment of the stability of the operation of portable radio stations at an input power of 1 W has been carried out, taking into account the time characteristic of communication sessions. Recommendations for the operation of antennas in mines are given.

Optimal Design of Antenna for Radio Frequency Energy Acquisition System

At present, many sensors are gradually developing in the direction of ultra-low power consumption, miniaturization, and low cost, which makes radio frequency energy acquisition technology a popular research field with a wide range of applications. However, traditional sensors are generally powered by batteries, which greatly increases the size of the device. Furthermore, antenna is an important module for radio frequency energy acquisition, and optimization of its sensitivity and other performance is particularly important. This article uses HFSS electromagnetic simulation software to simulate antenna elements and arrays made of PTFE, and simulates various parameters. And optimization, an antenna array element whose port impedance characteristics and unit antenna gain both meet the design requirements is constructed. Finally, the gain of the 2×2 array antenna after parameter optimization is 13.8dB, which greatly improves the gain of the receiving antenna.

Frequency tracking and tuning control of wireless power transfer system

A tuning control method with frequency tracking function is proposed to improve the degradation of efficiency caused by coil detuning in magnetically-coupled resonant wireless power transfer. Firstly, the detuning mechanism is studied by combining the AC impedance characteristics of the series resonant circuit, and the feedback control circuit is constructed by using a modified phase-locked loop, which outputs a variable frequency PWM wave to regulate the operating frequency of the high frequency inverter and maintains the phase difference between the inverter output voltage and the original side current within the error range. The Matlab/Simulink simulation results show that the design can successfully transfer the system to a new resonant state with short regulation period and high control accuracy, which can effectively improve the transmission efficiency and load power of the system.

Equivalent Impedance Calculation Method for Control Stability Assessment in HVDC Grids

A major challenge in the development of multi-vendor HVDC networks are converter control interactions. While recent publications have reported interoperability issues such as persistent oscillations for first multi-vendor HVDC setups with AC-side coupling, multi-terminal HVDC networks are expected to face similar challenges. To investigate DC-side control interactions and mitigate possible interoperability issues, several methods based on the converters’ and DC network’s impedances have been proposed in literature. For DC network’s impedance modelling, most methods require detailed knowledge of all converters’ design and controls. However, in multi-vendor HVDC networks, converter control parameters are not expected to be shared due to proprietary reasons. Therefore, to facilitate impedance-based stability analyses in multi-vendor MTDC networks, methods that do not require the disclosure of the existing converter controls are needed. Here, detailed impedance measurements can be applied; however, they are time-consuming and require new measurement for a single configuration change. This paper proposes an equivalent impedance calculation method suitable for multi-vendor DC networks, which for available black-box models or converter impedance characteristics can be modularly applied for various network configurations, including different control settings and operating points, while significantly reducing the required time for obtaining an equivalent DC network impedance.

Analysis of a method for measuring deposit impedance parameters using charge amplifier and lock-in voltmeter

Parameters such as capacitance and conductivity are measured to describe the properties of a medium, including its moisture content. These methods do not deliver highly accurate results in materials that are characterized by low homogeneity, varied porosity, high conductivity and high water content. This study proposes a more accurate method for estimating the parameters of any medium. In the experimental setup, a charge amplifier and a phase-sensitive voltmeter were applied to determine resistance and capacitance parameters of a medium based on the signals received by the measuring system. The proposed method can be applied to non-homogeneous media containing both dielectric and conductive materials. The described measuring system is composed of two flat electrodes whose size can be adapted to the dimensions of the analyzed medium. A method for processing the sensing signal to determine the impedance characteristics of a medium with the use of a phase-sensitive voltmeter was described. The measuring system was modeled in Matlab/Simulink, and the results were discussed.