PIER B | PIER Journals

2024-08-30

PIER B

Vol. 108, 31-45, 2024

download: 16

Design and Optimization of Integrated Symmetrical Coil Structure for Dynamic Wireless Power Transmission System for Autonomous Rail Rapid Transit

Yu Cheng , Wei Shi , Zhongqi Li , Jianbin Wang and Zhenhui Wu

In this paper, to address the low transmission efficiency problem caused by large magnetic leakage and insufficient anti-deviation performance, an integrated symmetrical coil (ISC) structure is proposed. The ISC structure eliminates the need for an external active shielding coil to counteract the leaked magnetic field, and enhances anti-offset performance by utilizing an integrated coil. Additionally, a deep learning-based method for optimizing the coil structure is employed to determine the optimal parameters. The theoretical simulation is validated using Maxwell software, and based on this, the design and parameters of the ferrite structure are adjusted to improve the magnetic shielding effect and transmission efficiency of the coil. Subsequently, a 2 kW prototype experiment is conducted to validate the findings. Results indicate that when the ISC structure is offset by 200 mm in the X-direction, the research demonstrates that the coupling coefficient fluctuation remains below 5%, achieving a transmission efficiency of up to 96.37%. Furthermore, the magnetic leakage is significantly reduced to below 27 μT at 800 mm on both sides of the door in the X-direction.

Design and Optimization of Integrated Symmetrical Coil Structure for Dynamic Wireless Power Transmission System for Autonomous Rail Rapid Transit

2024-08-22

PIER B

Vol. 108, 17-30, 2024

doi:10.2528/PIERB24062303

download: 21

A Microwave Subsystem (MS) Capable of Realizing Functional Change with the Aid of 2D-Shaped Liquid Metal (LM)

Xiaochuan Fang , Shaker Alkaraki and James Robert Kelly

This paper presents the first microwave subsystem (MS) capable of changing its function, in this case between resonator and antenna, using liquid metal (LM). This is achieved by filling/emptying fluidic channels with Gallium-based LM and forming LM into different 2D shapes. The manufactured prototype of the proposed MS performs as a slot antenna, when the fluidic channels are empty of LM. On the other hand, it operates in resonator mode, when the fluidic channels are filled with LM. We also connected two MSs along with a microstrip resonator to realize functional change between complex functions i.e., antenna and filter. The proposed connection of MSs can act as a filter when the fluidic channels are filled with LM or as an antenna when LM is withdrawn from the fluidic channels. When operating in the antenna mode the proposed connection of MSs provides a measured peak realized gain of 7.23 dBi and a simulated total efficiency of 84%. When operating in the filter mode the connection of MSs provides a band pass response and exhibits a minimum insertion loss of 1.9 dB, within the passband. The filters 10 dB return loss bandwidth, of 340 MHz, ranges from 2.28 GHz to 2.62 GHz.

A Microwave Subsystem (MS) Capable of Realizing Functional Change with the Aid of 2D-shaped Liquid Metal (LM)

2024-08-15

PIER B

Vol. 108, 1-16, 2024

doi:10.2528/PIERB24042703

download: 73

A Structured Basis to Determine Equivalent Dielectric Properties of Homogeneous Phantom Liquid Representing Multilayer Biological Tissues for SAR Measurement

Ardhendu Kundu , Kaushik Patra , Bhaskar Gupta and Amirul Islam Mallick

In today's era of wireless communication, interaction of electromagnetic energy and living biological systems is unavoidable - both in far field and in near field of the radiating antenna. Consequent basic safety limits on radiation levels are enforced through Specific Absorption Rate (SAR) limits. Practical measurement and validation of these SAR values require the deployment of phantom models containing tissue equivalent dielectric liquids - these liquids are conventionally single layer and homogeneous in nature. However, structured basis to formulate these custom made homogeneous phantom liquids representing arbitrary combinations of stacked tissue layers has not been properly reported in literature. To address the issue, this paper develops and illustrates a novel structured technique to define equivalent permittivity and loss tangent of homogeneous phantom liquid representing arbitrary combinations of stacked tissue layers - both in far field and in near field exposure scenarios. Electric field distribution and later on point SAR distribution inside different tissue layers have been attempted to replicate as closely as possible using equivalent homogeneous phantom liquid with properly tuned permittivity and loss tangent values. The fitting procedure involves minimization of the absolute/normalized maximum difference (of electric field and point SAR) between the original multilayer tissue and the modelled single layer homogeneous equivalent. This generalized technique is applied to two distinct multilayer (four layers are considered) biological models at 2.45 GHz where one is composed of four layers of equal thicknesses while the other one has four layers with unequal thicknesses. Moreover, the proposed technique has been tested and validated in the two abovementioned multilayer biological models for both far field (plane wave irradiation) and near field (in close proximity to antenna) exposure scenarios. This technique is quite successful in achieving equivalent dielectric liquids in which original point SAR data and its overall distribution across different layers can be realistically replicated while attempting point wise matching at several spatial points. In some cases, the original electric field/point SAR values are achieved with reduced precision near layer interfaces with significant dielectric contrast. Thus, the proposed technique can significantly contribute to accurately measure, validate and reflect the true spatial SAR distributions in original multilayer biological models using the derived homogeneous tissue equivalent phantom liquids.