International Journal of Applied Electromagnetics and Mechanics - Volume 47, issue 3

Authors: Bu, Yinggang | Nishiyama, Masahiro | Yamamoto, Tatsuya | Mizuno, Tsutomu | Tsuchiya, Shigeaki

Article Type: Research Article

Abstract: The use of magneto-plated wire (MPW) allows for reduction of winding loss component from the proximity effect. compared with a copper wire (COW). A MPW is a COW with a circumference that is plated with a magnetic thin film. In this paper, we clarify the basic characteristics and the efficiency characteristics of a transformer using a MPW and a COW. We found that the resistances of a primary coil made of COW and MPW at a frequency f=500 kHz …are 1.56 Ω and 1.12 Ω, respectively, and decreased 28%. The short circuit inductances of the COW and the MPW at a frequency f=500 kHz are 26 μH and 29.6 μH, respectively, and increased 13.8%. The efficiencies of an LLC resonant converter using the COW and the MPW at a frequency f=500 kHz are 90.2% and 92.2%, respectively, and increased 2%. Show more

Keywords: Magnetoplated wire, copper wire, AC resistance, LLC resonance, transformer

DOI: 10.3233/JAE-140070

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 47, no. 3, pp. 719-727, 2015

Authors: Dincer, Furkan | Karaaslan, Muharrem | Unal, Emin | Sabah, Cumali

Article Type: Research Article

Abstract: Tunable and multi-band metamaterial (MTM) based perfect microwave absorber (MA) is designed, implemented, and characterized. Firstly, dual-band MA with has two distinct resonances is investigated both numerically and experimentally which is also tested according the incident angle and polarization independencies. Then, the modified versions of MA are investigated and compared with respect to their absorbance, mechanical tunability, and multi-band characters. As a result, the suggested MAs with perfect absorption (including incident angle …and polarization independencies) display good performance among their counterparts and can be used in myriad potential applications such as high frequency and sensor applications which are also presented. Show more

Keywords: Absorber, dual-band, metamaterial, tunable, sensor

DOI: 10.3233/JAE-140073

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 47, no. 3, pp. 729-735, 2015

Authors: Cong, Haoxi | Li, Qingmin | Chen, Quan | Xing, Jinyuan

Article Type: Research Article

Abstract: Secondary arc is a complicated and critical physical phenomenon with power transmission lines. An arc chain model was employed with a view to establish the governing velocity equations, in which the multiple forces impacts upon each element were specifically incorporated including electromagnetic force, wind load, air resistance and thermal buoyancy. Based on the proposed model for secondary arc dynamics, simulations were then carried out and further validated through physical experiments on a test platform, …which showed good coincidence between the two. The research can provide fundamentals for understanding the physical nature especially the extinction mechanism of secondary arcs, and lays theoretical basis for optimal design of the transmission lines' auto-reclosing strategy. Show more

Keywords: Secondary arc, arc column form, motion characteristics, mathematical modeling

DOI: 10.3233/JAE-140079

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 47, no. 3, pp. 737-746, 2015

Authors: Zhang, Zhi-Ya | Zuo, Shao-Li | Zhao, Jia-Yue | Wang, Shao-Chuan | Fu, Guang

Article Type: Research Article

Abstract: The paper proposes a wideband bowtie antenna for indoor base station applications. By using the inverted L-shaped coupling feed structure, the impedance bandwidth of the lower band is improved; while using the four tuning stubs, the upper band is enhanced. Thus, a wide impedance bandwidth of about 77.8% (VSWR les; 2) ranging from 1.38 to 3.14 GHz is obtained. In addition, by connecting two folded elements to the patches of the bowtie dipole, the compact dimensions …of the antenna can be achieved. It also provides stable peak gain, unidirectional radiation patterns and low cross-polarization over the whole operating band. Owing to these good performances, the proposed antenna is very suitable for the recent indoor base station wireless communication services such as 3G, WiFi, WiMax, Bluetooth and LTE applications, etc. Show more

Keywords: Wideband bowtie antenna, inverted L-shaped coupling feed, tuning stubs, impedance bandwidth

DOI: 10.3233/JAE-140086

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 47, no. 3, pp. 745-752, 2015

Authors: Zhou, Guohua | Liu, Shengdao | Xiao, Changhan | Liu, Daming

Article Type: Research Article

Abstract: Integral equation method is widely used in magnetic field modeling of ships, but its nonsymmetric and dense coefficient matrix results in low computation efficiency and large memory, which limits its application in large scale problems. An approach for a fast computation of induced magnetic field created by ships was presented based on multiple layers fast multipole method and vector integral equation method. The numerical implementation of the proposed approach was described in detail. It is shown …by an analytical sphere example and a simplified mock-up experiment that the proposed approach can reduce computation time and memory cost in induced magnetic field modeling of ferromagnetic objects. Show more

Keywords: Vector integral equation method, fast multipole method, induced magnetic field, magnetic silencing

DOI: 10.3233/JAE-140113

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 47, no. 3, pp. 753-765, 2015

Authors: Wang, Jian | Xia, Yin-Shui | Wang, Lun-Yao

Article Type: Research Article

Abstract: Electromagnetic responses of a metallic conical frustum cabin with one coaxial feeding monopole antenna, illuminated by an intentional electromagnetic pulse (IEMP), are studied in this paper. There are several slots on the cabin wall with different sizes and orientations. The mathematical treatment is based on novel hybrid finite difference time domain (FDTD) method, where coaxial feeding, transfer impedance coupling and thin wire antenna models are integrated together for handling such a complex three-dimensional (3D) …composite structure. The revised antenna port coupling model is verified by comparing the calculated terminal voltage responses of the coaxial feeding cable with that of commercial CST Microwave Studio. Parametric studies are further carried out to show the variations of its terminal voltages for different IEMP waveforms, incident directions and polarizations. Show more

Keywords: Intentional electromagnetic pulse (IEMP), hybrid FDTD method, coaxial feeding cable, transfer impedance

DOI: 10.3233/JAE-140112

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 47, no. 3, pp. 765-776, 2015

Authors: Xu, Zheng | Meng, Kaikai | Cheng, Jiangyan

Article Type: Research Article

Abstract: This study presents a high-performance single-sided portable nuclear magnetic resonance (NMR) sensor. The magnet array, which is composed of five identical cuboid permanent magnet blocks and two passive shimming sheets, generates a highly uniform B_{0} field in a 10 × 10 mm^{2} lateral area. Along the two orthogonal lines in this lateral area, the measured B_{0} strength variation is less than 338 ppm. Vertically, the …measured B_{0} magnitude decreases from 144.387 mT to 130.603 mT, with a constant gradient of 4.6 T/m from 0.15 mm to 3.15 mm above the magnet surface. A planar radiofrequency coil is optimized according to the signal-to-noise ratio level of the coil. A one-dimensional profiling experiment on an oil film shows that a vertical resolution of approximately 1.7 μm can be achieved. As an application, the silicone rubber insulators are measured using the NMR sensor. Results demonstrate that the silicone rubber insulators with different service times can be distinguished through the transverse relaxation time T_{2} of the silicone rubber insulators. Show more

Keywords: Single-sided NMR, high uniformity, constant gradient, aging level, silicone rubber insulator

DOI: 10.3233/JAE-140123

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 47, no. 3, pp. 777-790, 2015

Authors: Yang, Fan | Dai, Feng | Liu, Xinghua | Yang, Yongming | He, Wei

Article Type: Research Article

Abstract: When HVDC transmission lines operate in the monopole ground return mode or asymmetric bipolar mode, DC current flows in the earth and DC magnetic bias will arise in neutral point grounding (NPG) transformers. In this work, the model to calculate the potential distribution for multi-layer soil structure is set up, then the magnetic bias current (MBC) is calculated. The magnetic field distribution in the NPG transformer is obtained according to MBC, and electromagnetic energy and force in the …transformer are calculated. Finally, the influence on MBC, electromagnetic energy and force caused by soil parameters are investigated. Results indicate that thickness of the first layer and resistivity of the second layer have a greater contribution to MBC, electromagnetic energy and force. To avoid excessive vibration of the NPG transformer, the soil at grounding electrode with a greater thickness in the first layer and lower resistivity in the second layer is preferred. Show more

Keywords: DC current, electromagnetic energy, force, magnetic bias current (MBC), transformer

DOI: 10.3233/JAE-140122

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 47, no. 3, pp. 791-804, 2015

Authors: Ghaffar, A. | Alkanhal, Majeed A.S.

Article Type: Research Article

Abstract: In this paper, analysis and theoretical formulations are developed for the reflected and the transmitted waves from a planar interface of isotropic chiral-uniaxally anisotropic chiral media with optical axis normal to interface. General expressions for the reflection and transmission coefficients for right circularly polarized (RCP) and left circularly polarized (LCP) incident waves are derived. The results of the reflected and transmitted powers for materials with different isotropic chirality and uniaxial chirality values …for both RCP and LCP incident waves are presented. The effects of the uniaxial chirality on three other cases of dielectric constant combinations are also studied. The numerical results computed by the developed transfer matrix technique expressions are found to coincide with published results obtained by computational techniques for special material cases. Show more

DOI: 10.3233/JAE-130161

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 47, no. 3, pp. 805-817, 2015

Authors: Fan, Fang-Fang | Yan, Ze-Hong | Wang, Jin-Hiu

Article Type: Research Article

Abstract: A wideband microstrip planar radial 1:19 power divider is developed in this study. The power divider design is simple with conventional impedance-transformation method, and a single substrate is employed, thereby reducing the cost for the antenna. To verify our design, the power divider was fabricated and tested. It can be observed that it achieves an impedance bandwidth of 29.4{\% (1.98 GHz–2.67 GHz) (VSWR ⩽ 2), the transmitted magnitude and phase imbalance for 19 outputs are ± 0.1 dB and ± 1 deg, respectively. The power divider is also integrated into the 19-element circularly polarized (CP) antenna array as the feed …network; the simulated results show that the power divider can apply appropriate amplitudes and phases for the antenna array to obtain the good CP performance. Show more

Keywords: Planar power divider, radial power divider, array antenna

DOI: 10.3233/JAE-140075

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 47, no. 3, pp. 819-825, 2015