Journal of Electromagnetic Analysis and Applications

Journal Information
ISSN / EISSN : 19420730 / 19420749
Current Publisher: Scientific Research Publishing, Inc. (10.4236)
Total articles ≅ 506
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Latest articles in this journal

Ruiwen Chen, Kaichen Wang
Journal of Electromagnetic Analysis and Applications, Volume 12, pp 1-5; doi:10.4236/jemaa.2020.121001

Abstract:
Electromagnetic propulsion provides a non-contact way for delivering goods. The projectile typically does not contain explosives, which has apparent advantages over traditional methods. Due to the multi-physics nature, simulation is expensive and time-consuming. We established a simplified model in time domain incorporating mechanics and electromagnetics to study electromagnetic propulsion. Results show that important physical parameters such as force, velocity, acceleration, etc. can be extracted from the model without time-consuming efforts. We hope this model could help the exploration of electromagnetic propulsion.
Xiaoyu Peng, Lei Wang, Jinbo Zhang, Jiawen Chen, Bingzhe Dai
Journal of Electromagnetic Analysis and Applications, Volume 12, pp 15-28; doi:10.4236/jemaa.2020.122003

Abstract:
In this paper we have studied the effect of strike to a cone-shaped mountain surrounded by two chains of hills on the lightning vertical electric field and azimuthal magnetic field at different distances, by using two-dimensional finite-difference time-domain (2-D FDTD) method in cylindrical coordinate systems. In order to analyze the electrostatic shielding effect of strike to a cone-shaped mountain surrounded by two chains of hills on the lightning, we chose three mountains, and the left one is stroke by lightning, and the right one is near the obervation site, and the middle one with the top heights increasing from 0 to 2 km is between them. For the observed point, the electrostatic shielding effect of the right one on the lightning vertical electric field is the most serious, and the electric field is much less than that for strike to flat ground level; compared with the electric field, the shielding effect of the right one on the lightning azimuthal magnetic field becomes less, for most cases, the lightning magnetic field at the observed site is larger than that for flat ground cases mainly due to that of the increment caused by strike to the right mountain. With the increase of distance (e.g., 20 km from the lightning strike point), the shielding effect of the right mountain on the lightning field becomes less, because the reflected wave from the right mountain bottom plays a more important role over intermediate ranges, and the far radiation electromagnetic field peak value becomes larger due to such a reflecting wave. Therefore, in the lightning detecting technique, we should pay more attention to the effect caused by chains of hills on the lightning location and the estimation of lightning current peak.
Aldhubaib Faisal, Faisal Aldhubaib
Journal of Electromagnetic Analysis and Applications, Volume 12, pp 29-42; doi:10.4236/jemaa.2020.123004

Abstract:
The paper assesses how multiple-static scattering mitigates the effect of late-time onset on the robustness of the extracted resonance modes in the context of radar target classification. The assessment exploits the mode distribution vs onset shift to verify the sensitivity of the mode’s extraction to the selected onset, especially higher-order, to onset. However, within some bistatic directions, the modes have enhanced energies with lesser specular energy, making the modes estimate less sensitive to onset shifts. Also, the mode distribution per bistatic and polarization configuration has demonstrated different onset windows of accurate and consistent mode extraction. Notably, the distribution of the mode energy distribution reveals that classification performance degrades with poorly selected onset.
Kirill V. Dobrego, Mikhail A. Chumachenko, Olga V. Boiprav, Nikolay N Grinchik, Halina A. Pukhir
Journal of Electromagnetic Analysis and Applications, Volume 12, pp 7-14; doi:10.4236/jemaa.2020.122002

Abstract:
Measurement of the electrical conductivity of electrolytes and heterogeneous materials containing them is accompanied by numerous physical and electrochemical processes, complicating measuring and interpretation of data. As a result, the measurement of the electrical conductivity of such a system is a difficult and not finally resolved problem. The new method of resistance measurement of the electrolytic systems is substantiated and tested on example of heterogeneous electrolytic system “lignin-calcium chloride water solution” in this article. The method is based on measurement of resistance of the electrolytic system at different voltages (DC) on the cell and the consequent approximation of the acquired data taking into consideration volume charges and potential barriers arising on the boarders of electrodes and electrolytic materials. Extrapolation of the resistance to the limiting small current lets one obtain a characteristic value of the active resistance of the electrolytic system. The method is technically simple, inexpensive and has several advantages compared to the methods based on AC measurements.
Steffen Kühn
Journal of Electromagnetic Analysis and Applications, Volume 12, pp 71-87; doi:10.4236/jemaa.2020.126007

Abstract:
Based on classical circuit theory, this article develops a general analytic solution of the telegrapher’s equations, in which the length of the cable is explicitly contained as a freely adjustable parameter. For this reason, the solution is also applicable to electrically short cables. Such a model has become indispensable because a few months ago, it was experimentally shown that voltage fluctuations in ordinary but electrically short copper lines move at signal velocities that are significantly higher than the speed of light in a vacuum. This finding contradicts the statements of the special theory of relativity but not, as is shown here, the fundamental principles of electrical engineering. Based on the general transfer function of a transmission line, the article shows mathematically that an unterminated, electrically short cable has the characteristics of an ideal delay element, meaning that an input signal appears at the output with a slight delay but remains otherwise unchanged. Even for conventional cables, the time constants can be so small that the corresponding signal velocities can significantly exceed the speed of light in a vacuum. The article also analyses the technical means with which this effect can be conveyed to very long cables.
Dibor Faye, Sega Gueye, Mor Ndiaye, Mamadou Lamine Ba, Ibrahima Diatta, Youssou Traore, Masse Samba Diop, Gora Diop, Amadou Diao, Gregoire Sissoko
Journal of Electromagnetic Analysis and Applications, Volume 12, pp 43-55; doi:10.4236/jemaa.2020.124005

Abstract:
This work deals with determining the optimum thickness of the lamella wafer of silicon solar cell. The (p) base region makes up the bulk of the thickness of the wafer. This thickness has always been a factor limiting the performance of the solar cell, as it produces the maximum amount of electrical charges, contributing to the photocurrent. Determining the thickness of the wafer cannot be only mechanical. It takes into account the internal physical mechanisms of generation-diffusion-recombination of excess minority carriers. They are also influenced by external factors such as temperature and magnetic field. Under these conditions, magneto transport equation is required to be applied on excess minority carrier in lamella base silicon solar cell. It yields maximum diffusion coefficient which result on Lorentz law and Umklapp process. Then from photocurrent, back surface recombination velocity expressions are derived, both maximum diffusion coefficient and thickness dependent. The plot of the back surface recombination calibration curves as function of lamella width, leads to its maximum values, trough intercept points. Lamella optimum width is then obtained, both temperature and magnetic field dependent and expressed in relationships to show the required base thickness in the elaboration process.
Dalia Elsheakh, Mina Farouk, Hala Elsadek, Hani Ghali
Journal of Electromagnetic Analysis and Applications, Volume 12, pp 57-70; doi:10.4236/jemaa.2020.125006

Abstract:
The design of multiband microstrip rectenna for radio frequency energy harvesting applications is presented in this paper. The designed antenna has good performance in the GSM-900/1800, WiFi and WLAN bands. In addition, the rectifier circuit is designed at multi resonant frequencies to collect the largest amount of RF ambient power from different RF sources. The developed antenna is matched with the rectifier at four desired frequencies using several rectifier branches to collect the largest of RF power. The proposed rectenna is printed on FR4 substrate with modified ground plane to achieve suitable impedance bandwidth. The proposed antenna consists of elliptical radiating plane with stubs and stepped modified ground plane. The rectenna resonates at quad frequency bands at (GSM 900/1800, WiFi band and WLAN bands) with rectifier power conversion efficiency up to 56.4% at 0 dBm input power using the HSMS-2850 Schottky diode. The efficiency is more enhanced by using SMS-7630-061 Schottky diode which is characterized by a low junction capacitance and a low threshold voltage to achieve higher conversion efficiency up to 71.1% at the same 0 dBm input power for the same resonating frequency band.
Cheikh Thiaw, Mamadou Lamine Ba, Gora Diop, Ibrahima Diatta, Mor Ndiaye, Gregoire Sissoko
Journal of Electromagnetic Analysis and Applications, Volume 12, pp 103-113; doi:10.4236/jemaa.2020.127009

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Ronda Silvia, Martinez Oibar, Oliver Clara, Marquez Patricia, Miranda Jose Miguel
Journal of Electromagnetic Analysis and Applications, Volume 12, pp 89-102; doi:10.4236/jemaa.2020.127008

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Brian Nlong Zhao
Journal of Electromagnetic Analysis and Applications, Volume 11, pp 17-23; doi:10.4236/jemaa.2019.112002

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