ACES Publication Search
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| Title: | ACES July 2011 Full Journal |
| File Type: | Journal Paper |
| Issue: | Volume: 26 Number: 7 Year: 2011 |
| Download Link: | Click here to download PDF File Size: 5036 KB |
| Title: | ACES July 2011 Front/Back Matter |
| File Type: | Journal Paper |
| Issue: | Volume: 26 Number: 7 Year: 2011 |
| Download Link: | Click here to download PDF File Size: 1020 KB |
| Title: | A Wideband U-Slot Loaded Modified E-Shape Microstrip Patch Antenna and Frequency Agile Behavior by Employing Different Height Ground Plane and Ribbon Type Switches |
| Abstract: | This paper presents investigation results on a wideband U-slot loaded modified Eshape (USLMES) microstrip patch antenna with frequency agile behavior by employing different height ground plane and ribbon type copper switches. The USLMES patch is excited using the notch feed mechanism by a 50 ? coaxial probe outside the patch surface so that coaxial probe does not contribute significantly to the peak-crosspolarization levels. The parametric study results are presented for the wideband patch antenna design and important parameters have been noted. The proposed wideband patch antenna offers impedance (S11 = ?10 dB) and 3dB gain bandwidths of at least 35% (3.09GHz to 4.42GHz) with stable radiation patterns and acceptable crosspolarization levels. The effect of ground plane height variation not only alters operating frequency, but also, Gain and impedance bandwidth. Frequency agility is also achieved from 3.02GHz to 4.95 GHz by turning different combination of switches ON/OFF. The prototype antennas were fabricated and experimentally verified for both wideband patch performance and frequency agility by implementing different ground plane heights. The simulated performance is in reasonable agreement with the measured results. |
| Author(s): | R. Bakshi, S. K. sharma |
| File Type: | Journal Paper |
| Issue: | Volume: 26 Number: 7 Year: 2011 |
| Download Link: | Click here to download PDF File Size: 1506 KB |
| Title: | Combined Field and Circuit Theories in Squirrel-Cage Induction Motors Based on Micro-T Circuit Model |
| Abstract: | This paper presents an equivalent circuit derived directly from Maxwell's equations in a manner to show the amalgamation of field models and the circuit theory. A micro-T equivalent circuit is obtained from the solution of Maxwell’s equations for a cylindrical representation of a squirrel cage induction motor. First, a general form of the field solution is obtained using transfer matrices. A variable transformation is then applied, which makes it possible to derive a circuit for each annular region in the motor. By joining the equivalent circuits in cascade, a complete equivalent circuit for the motor is obtained. The voltages and currents in the equivalent circuit relate directly to the field quantities within the actual motor. Accuracy of the method is verified with comparisons against finite elements and a commercial motor design program. |
| Author(s): | L. Qaseer, F. de León, S. Purushothaman |
| File Type: | Journal Paper |
| Issue: | Volume: 26 Number: 7 Year: 2011 |
| Download Link: | Click here to download PDF File Size: 1308 KB |
| Title: | Efficient Direct Solution of EFIE for Electrically Large Scattering Problems using H-LDLT and PE Basis Function |
| Abstract: | Method of moments (MoM) solution of the electric field integral equations (EFIE) encounters the large memory requirements and the slow convergence rate of the iterative solver. A direct method based on hierarchical (H-) matrix algorithm and phase extracted (PE) basis function is proposed to overcome these obstacles. A recompressed adaptive cross approximation (ACA) technique is employed to generate a datasparse representation of the dense EFIE system matrix, i.e., so-called H-matrix. H-matrix formatted LDLT-decomposition (H-LDLT) can be implemented in nearly optimal complexity, which provides an efficient way for the direct solution of EFIE. PE basis function, containing the propagating wave phase factor and defined on large patches, is introduced to further reduce the computational costs. Numerical results demonstrate the accuracy and efficiency of the proposed method for electrically large scattering problems. |
| Author(s): | T. Wan, R. Chen, X. Hu, Y. Chen, Y. Shen |
| File Type: | Journal Paper |
| Issue: | Volume: 26 Number: 7 Year: 2011 |
| Download Link: | Click here to download PDF File Size: 1058 KB |
| Title: | Scan Blindness Elimination Using Composite Defected Ground Structures and Edge-coupled Split Ring Resonators |
| Abstract: | A novel compact composite structure, composed of double-U shaped defected ground structure (DGS) and edge-coupled split ring resonator (E-SRR), is presented in this paper. The composite structure is integrated into microstrip array to reduce the interelement mutual coupling, with the aim to eliminate the scan blindness and improve the scanning performance. The three kinds of two-element arrays (without composite structure, with only DGS and with composite structure) are thoroughly simulated, measured, and compared. The results show that, the reduction in mutual coupling of 11 dB between elements in E-plane is obtained with the use of composite structure. It is worth mentioning that, approximately 2dB gain improvement and 2.4dB side lobe suppression are both attained, in comparison with the array with only DGSs. Finally, the scan properties of three kinds of infinite microstrip phased arrays are studied by the waveguide simulator method. The results indicate that the scan blindness in an infinite microstrip phased array can be well eliminated by virtue of the effect of the proposed composite structures, in accordance with results obtained by active patterns of the centre element in 9×5 array. |
| Author(s): | M. C. Tang, S. Xiao, C. J. Li, C. Wei, B. Wang |
| File Type: | Journal Paper |
| Issue: | Volume: 26 Number: 7 Year: 2011 |
| Download Link: | Click here to download PDF File Size: 1531 KB |
| Title: | An Efficient Finite-Element Time-Domain Method via Hierarchical Matrix Algorithm for Electromagnetic Simulation |
| Abstract: | An efficient finite-element timedomain (FETD) method based on the hierarchical (H-) matrix algorithm is presented. The FETD method is on the basis of the second-order vector wave equation, obtained by eliminating one of the field variables from Maxwell’s equations. The time-dependent formulation employs the Newmark-beta method which is known as an unconditional stable time-integration method. H- matrix algorithm is introduced for the direct solution of a large sparse linear system at each time step, which is a serious handicap in conventional FETD method. H-matrix algorithm provides a data-sparse way to approximate the LU triangular factors of the FETD system matrix. Using the H-matrix arithmetic, the computational complexity and memory requirement of H-LU decomposition can be significantly reduced to almost logarithmic-linear. Once the H-LU factors are obtained, the FETD method can be computed very efficiently at each time step by the H-matrix formatted forward and backward substitution (H- FBS). Numerical examples are provided to illustrate the accuracy and efficiency of the proposed FETD method for the simulation of three-dimension (3D) electromagnetic problems. |
| Author(s): | T. Wan, R. Chen, J. She, D. Ding, Z. Fan |
| File Type: | Journal Paper |
| Issue: | Volume: 26 Number: 7 Year: 2011 |
| Download Link: | Click here to download PDF File Size: 1082 KB |
| Title: | Mutual Coupling Compensation in Non-Uniform Antenna Arrays using Inter-Element Spacing Restrictions |
| Abstract: | In the antenna array synthesis problems, most of the works in literature utilize isotropic elements. Thus, the mutual coupling effects between the array elements are neglected. It is obvious that an array antenna synthesized by neglecting the coupling effects cannot be used in the real world applications due to the possible incompatibilities between the desired and realized radiation patterns. In this work, two array antenna synthesis papers from literature are investigated in terms of mutual coupling effects so the necessary constraints are determined for the array geometry in order to compensate the coupling effects. Here, the same objectives of these two papers are achieved using the generalized pattern search (GPS) algorithm by considering the determined constraints for the inter-element spacings between the array elements. The resulted radiation patterns are validated with the computer simulation technology (CST) software with the aim of detecting possible incompatibilities due to the mutual coupling effects between the array elements. The simulation results verify that by using the constraints determined in this work, the radiation patterns obtained by pattern multiplication can provide the desired radiation demands also in the practical applications. |
| Author(s): | F. Tokan, F. Gunes |
| File Type: | Journal Paper |
| Issue: | Volume: 26 Number: 7 Year: 2011 |
| Download Link: | Click here to download PDF File Size: 1007 KB |
| Title: | Reduction of Sensitivity to Measurement Errors in the Derivation of Equivalent Models of Emission in Numerical Computation |
| Abstract: | In this paper, the accuracy of an equivalent dipole model for representing electromagnetic emissions from printed circuit boards (PCB) is studied. The optimization of nearfield measurement parameters and required PCB parameters for building a numerical model are discussed and their impact on the accuracy of emission predictions is examined. |
| Author(s): | X. Tong, D. W. P. Thomas, A. Nothofer, C. Christopoulos, P. Sewell |
| File Type: | Journal Paper |
| Issue: | Volume: 26 Number: 7 Year: 2011 |
| Download Link: | Click here to download PDF File Size: 1205 KB |
| Title: | Study on Coupling Characteristics of Electromagnetic Wave Penetrating Metallic Enclosure with Rectangular Aperture |
| Abstract: | The coupling characteristics of the electromagnetic wave penetrating the metallic enclosure with a rectangular aperture are studied using the hybrid approach which applies the mode-matching technique and the mixed potential integral equation based on the method of moments. The aperture thickness, the polarization direction of incident wave, and high-order modes are all considered in the simulation. The calculated electric field at the centre of the enclosure is compared with data obtained by measurement and other numerical techniques to validate the accuracy and the efficiency of the proposed approach. The electric field distributions inside the metallic enclosure are also presented. Furthermore, this approach is extended to account for the effects of narrow aperture thicknesses and polarization directions. The results demonstrate that the electric field is enhanced around the aperture at the resonant frequency and the coupling electric field amplitude at the center point of the enclosure is also higher than that in the ambient area. It is also noted that the variation of the narrow aperture thicknesses and the different polarization directions act on the coupling characteristics significantly. |
| Author(s): | G. Wu, Z. Q. Song, X. G. Zhang, B. Liu |
| File Type: | Journal Paper |
| Issue: | Volume: 26 Number: 7 Year: 2011 |
| Download Link: | Click here to download PDF File Size: 1141 KB |
| Title: | Design of a Novel Dual-Beam Scanning Leaky-Wave Antenna |
| Abstract: | In this article, a novel dual-beam scanning leaky-wave antenna is proposed and investigated. Antenna parameters, such as return loss, radiation patterns, gain, efficiency and scanning angles, are provided and discussed. Besides its low profile and miniaturized size, the proposed antenna can realize dual-beam scanning and quasi-omnidirectional radiation. Moreover, it provides much design flexibility for real applications. Different simulation software are adopted to verify the accuracy of our design. |
| Author(s): | J. C. Liu, W. Shao, B. Z. Wang |
| File Type: | Journal Paper |
| Issue: | Volume: 26 Number: 7 Year: 2011 |
| Download Link: | Click here to download PDF File Size: 978 KB |
| Title: | Compact Bandpass Filters with Bandwidth Control using Defected Ground Structure (DGS) |
| Abstract: | This paper presents new compact microstrip bandpass filters with bandwidth control by employing DGS resonators. The proposed bandpass filters consists of two coupled DGS resonators with a microstrip excitation. The bandwidth can be controlled by choosing the coupling structure between the two DGS resonators. The wider bandwidth can be achieved by adding a strip conductor between the two DGS resonators. However, the narrow bandwidth can be obtained by etching a slot in the strip conductor placed between the DGS resonators. The widths of the strip conductor and the etched slot control the filter bandwidth. Fractional bandwidth (FBW) from about 2.5% or less to more than 22% can be achieved by this design approach. The concept has been validated through the design and implementation of two filters with FBW of 6% and 12.9%. Measurements agree well with theoretical results. |
| Author(s): | |
| File Type: | Journal Paper |
| Issue: | Volume: 26 Number: 7 Year: 2011 |
| Download Link: | Click here to download PDF File Size: 1269 KB |