International Journal of Applied Electromagnetics and Mechanics - Volume 42, issue 2

Authors: Abdelhafeez, Ali M. | Nemat-Alla, M.M. | El-Sebaie, M.G.

Article Type: Research Article

Abstract: Finite element modeling of electromagnetic forming includes modeling of mechanical aspects, modeling of electromagnetic aspects, and a coupling method between the two models. The electromagnetic problem is to determine the magnetic pressure and its temporal and spatial distribution. Whereas the mechanical problem is to find out workpiece deformation resulting from the magnetic pressure applied on this workpiece. Nonetheless complications in the simulation exist due to pressure variation with workpiece deformation. These difficulties …can be resolved by using one of the known coupling algorithms; loose coupling, or strong coupling. But these coupling strategies either have low accuracy of results or take long simulation time. The current research introduces an enhanced loose coupling algorithm for simulation of electromagnetic sheet metals bulging. The proposed coupling strategy takes into account deformation effects on pressure without the need for solving the updated electromagnetic model every new time step. Comparison between present simulation results and experimental results of other researchers showed good agreement. Effective plastic strain, and effective plastic strain rate distribution and evolution were presented in addition to thickness and deflection evolution of the workpiece. Show more

Keywords: Electromagnetic forming, sheet metal forming, FEM, enhanced loose coupling, high strain rates

DOI: 10.3233/JAE-131653

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 42, no. 2, pp. 157-169, 2013

Authors: Bhuyan, Satyanarayan | Panda, Sanjib K. | Hu, Junhui

Article Type: Research Article

Abstract: Wireless drive of piezoelectric component by electric field has been proposed and experimentally investigated. The electric field is generated by a spiral coil antenna-like electric field generator. Wireless electric energy transmission to the piezoelectric component can be enhanced when the spiral coil antenna is in electric resonance with a capacitor. It has been found that the output power achieved wirelessly by the piezoelectric component depends on the operating frequency, electrical load, distance and electric field. At …resonant frequency of 772 kHz and optimum electrical load resistance of 350 Ω, a maximum power of 0.362 mW has been received wirelessly by the piezoelectric plate operating in the thickness vibration mode, placed 4 mm away from antenna plane with input source power of 1.294 W. The excitation of the piezoelectric component is done remotely, so as the component does not require any wiring to the source and can be used in various sensors and actuators applications. Show more

Keywords: Electric field, resonance, piezoelectricity, spiral antenna, wireless energy transmission

DOI: 10.3233/JAE-131654

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 42, no. 2, pp. 171-178, 2013

Authors: Perić, Mirjana T. | Ilić, Saša S. | Aleksić, Slavoljub R. | Raičević, Nebojša B.

Article Type: Research Article

Abstract: The hybrid boundary element method is applied for the calculation of the characteristic impedance of 2D microstrip lines with a finite width dielectric layer and with finite width or infinite ground planes. Even though these forms of microstrips are very typical in practice, they have not been investigated very often. The basic idea of this method is that an arbitrary shaped electrode can be replaced by equivalent electrodes, and an arbitrary shaped boundary surface between any …two dielectric layers can be replaced by discrete equivalent total line charges placed in the air. The discretization technique is similar to the method of moments and is well known. As a contribution to the boundary element method, we combine it with the equivalent electrodes method, creating in that way a new hybrid boundary element method. This method could be applied to a large variety of very complex 2D problems, regarding microstrip lines with or without symmetry. The quasi TEM analysis is applied. We compare values of characteristic impedance obtained applying our method with the corresponding ones obtained by the finite element method and values already reported in the literature. Relative error less than 0.5%, fast convergence of the results and several times shorter computation time comparing to the time required by finite element method make our method very efficient in the calculation of parameters of 2D microstrip lines. Show more

Keywords: Boundary element method, characteristic impedance, equivalent electrodes method, finite element method, hybrid boundary element method

DOI: 10.3233/JAE-131655

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 42, no. 2, pp. 179-190, 2013

Authors: Ansari, M.S. | Ravindranath, S.V.G. | Bhatia, M.S. | Singh, B. | Navathe, C.P.

Article Type: Research Article

Abstract: This paper presents mathematical analysis and measurement results of electromagnetic couplings through a pair of intentional apertures in a metallic enclosure and its effect on the electromagnetic shielding effectiveness. The enclosure houses an electro-optical device (Pockles cell) and its high voltage drive circuitry. Two different aperture shapes i.e. rectangular and circular of equal areas are compared over frequency range of 200 MHz to 2 GHz. Pockels cells are commonly used in applications involving fast switching of …polarization to block or transmit laser light. Pockels cell assemblies are housed in metallic enclosures to reduce noise emissions from high voltage pulser circuits driving the cell and to minimize the field couplings from external sources which may result into spurious switching of the cell. However, apertures are required in the enclosure to enable the laser beam to be incident on the Pockels cell and for onward transmission of the modulated beam. The apertures result into reduced shielding effectiveness of the metallic enclosure and increase in noise couplings. There is a need to understand the effect of apertures and to properly select their shapes and sizes such that the electromagnetic noise couplings are kept to a minimum acceptable level. Apart from the functional requirements of a reliable and noise free system operation, this issue is also important to meet the growing and stringent demands of electromagnetic compatibility. The analysis and measurements presented in this work pertain to the noise couplings from an external source into the enclosure through two differently shaped apertures i.e. rectangular and circular. For the comparison purpose, the planar areas of the apertures for the two cases are kept equal. The analysis and measurement techniques described in this work will be of interest to designers of electrical and electro-optical components for laser systems. Show more

Keywords: Shielding effectiveness, electromagnetic noise couplings, rectangular and circular apertures, pockels cell

DOI: 10.3233/JAE-131656

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 42, no. 2, pp. 191-199, 2013

Authors: Singh, R.K.

Article Type: Research Article

Abstract: A circular waveguide with axially periodic thin metal disc inserts for its potential application in a gyro-TWT has been investigated for dispersion, form factor, power flowing through the structure, interaction impedance, and gain. The structure has been field analysed for its dispersion characteristics with due care to include the rigour of considering the effect of higher order space and modal harmonics. Dispersion characteristics reveal that the structure under study has like band-pass characteristics. Effect of …variation of structure parameters on the dispersion characteristics has been observed in order to shape the waveguide-mode curve for wideband operation of the device. With the help of form factor which decides the extent of coupling between beam and wave, optimum beam position has been decided where maximum interaction between beam and wave takes place. For the structure under study, the value of azimuthal interaction impedance increases with the introduction of metal discs in the waveguide except at higher frequencies, where it decreases rapidly to a value that is lower than that for a smooth-wall circular waveguide. Gain-frequency response observation shows that the dispersion characteristics are readily reflected in the gain-frequency response. It has been found that the disc-hole radius is more effective in controlling the device gain while it is disc-periodicity which is the most effective structure parameter in controlling the device bandwidth. Results have been verified against published results and found to be in very close agreement. Show more

Keywords: Dispersion, form factor, gain, gyro-TWT, interaction impedance, periodic structures

DOI: 10.3233/JAE-131657

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 42, no. 2, pp. 201-214, 2013

Authors: Xi, Li | Lin, Yang | Shang, Jun-Ping | Xi, Chen | Feng, Xue-Yong | Yi, Wang

Article Type: Research Article

Abstract: This paper presents a new design for wide slot circularly polarized (CP) antenna (WSCPA). Compared with existing WSCPA, the proposed design possesses much wider return loss S_{11} bandwidths and CP bandwidths. The main features of the antenna structure include a machine-gun-shaped CPW feeding line and a wide symmetric-aperture along the diagonal axis. Wideband return loss and CP radiations have been achieved by properly tuning circular-shaped aperture and feeding line. The measured …bandwidths of 10 dB return loss and 3 dB axial ratio (AR) are around 110.2% (2.2–7.6 GHz) and 105.9% (2–6.5 GHz), respectively. Throughout this letter, the improvement process of the AR and S_{11} properties is completely presented and discussed. Show more

Keywords: Broadband, CPW-fed, circularly polarized antenna

DOI: 10.3233/JAE-131658

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 42, no. 2, pp. 215-225, 2013

Authors: Lindh, Pia | Vaimann, Toomas | Kallaste, Ants | Pyrhönen, Juha | Vinnikov, Dmitri | Naumanen, Ville

Article Type: Research Article

Abstract: Permanent magnet (PM) machines with tooth coil windings are designed and analyzed. We study how the slot wedge material affects the behavior of PM losses when using tooth coil windings, which generate a significant air gap flux density harmonic content. The losses and cogging torques of a surface permanent magnet rotor and an interior permanent magnet rotor are compared in no-load and load situations. A finite element analysis applying Cedrat's Flux2D is made. Motors of this …size can have high permanent magnet eddy current losses, and therefore, segmented magnets are often preferred even though interior magnets and semi-magnetic wedge material are used. The study shows that tooth coil windings may benefit from using semi magnetic material as a wedge material as it decreases the stator iron losses and, especially, losses in the permanent magnets. Show more

Keywords: Interior permanent magnet machines, concentrated winding

DOI: 10.3233/JAE-131659

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 42, no. 2, pp. 227-236, 2013

Authors: Shu, Liang | Wu, Guichu | Zhu, Xiangou | Chen, Dingfang | Zhao, Sheng

Article Type: Research Article

Abstract: A new approach considering the nonlinearity of the electric core is proposed to analyze the magnetic field and magnetic force of 3D electromagnetic contactors. The nonlinear constitutive law is established by measuring the B-H curve of the core experimentally. Finite element method is used to model the electromagnetic responses of the system, in which the 3D Ampère's circuital law is implemented in PDE weak form. In order to analyze the nonlinear responses of the magnetic field …and magnetic force, the measured constitutive law is incorporated with the weak form equation by numerical interpolation. Both the static and transient responses of the electromagnetic system are studied by solving the coupled weak form equations step by step. Experimental results show that the proposed model has good predictions of the magnetic force. The saturation due to the nonlinearity of the B-H curve can be described as well. This modeling framework offers an advantage to solve the nonlinear responses of 3D electromagnetic systems without theoretical modeling the complex constitutive law of the electric core. Show more

Keywords: Electromagnetic contactor, nonlinear constitutive law, magnetic force, energy consumption

DOI: 10.3233/JAE-131660

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 42, no. 2, pp. 237-248, 2013

Authors: Patel, Shobhit K. | Kosta, Y.P.

Article Type: Research Article

Abstract: In this paper, for the very first time, four corners truncated triple band square patch antenna loaded with Split ring resonator (SRR) structure has been reported. Based on truncated square patch antenna, it has a double split square ring resonant structure embedded in the center of the substrate of the square patch antenna. The resonant structure has a strong electric response in a certain frequency of interest, and can be used to construct metamaterial. The antenna …is designed to function in triple bands in the frequency range of 0.5–2.0 GHz. The comparison of the metamaterial design with the conventional dielectric material design is also shown in the paper. Design results are obtained by a High Frequency Structure Simulator which is used for simulating microwave passive components. Show more

Keywords: Metamaterial, SRR, microstrip, single negative (SNG), double negative (DNG)

DOI: 10.3233/JAE-131661

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 42, no. 2, pp. 249-258, 2013

Authors: Rani, Shweta | Singh, A.P.

Article Type: Research Article

Abstract: In this paper the proposed structure is based on a modified planar Koch curve antenna, whose geometrical parameters are determined by iterative function system algorithm for fractal curve generation. Compared with conventional antenna with same dimensions, modified Koch curve antenna provides additional frequency resonances. The asymmetrical ground plane has been optimized by means of bacterial foraging optimization (BFO) to make the proposed antenna feasible for wide band operation. In addition to miniaturization …of about 40%, the optimized reference ground plane provides multi and ultra-wide band with high impedance matching throughout the frequency bands covering various wireless telemedicine applications. In order to assess the reliability of the antenna, measurements have been performed on the fabricated prototype and the obtained results shows good agreement with simulated results. Show more

Keywords: BFO, fractal antenna, ground plane

DOI: 10.3233/JAE-131662

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 42, no. 2, pp. 259-267, 2013