ACES Publication Search
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| Title: | ACES February 2011 Full Journal |
| File Type: | Journal Paper |
| Issue: | Volume: 26 Number: 2 Year: 2011 |
| Download Link: | Click here to download PDF File Size: 10461 KB |
| Title: | ACES February 2011 Front/Back Matter |
| File Type: | Journal Paper |
| Issue: | Volume: 26 Number: 2 Year: 2011 |
| Download Link: | Click here to download PDF File Size: 941 KB |
| Title: | An Improved MM-PO Method with UV Technique for Scattering from an Electrically Large Ship on a Rough Sea Surface at Low Grazing Angle |
| Abstract: | An improved MM-PO-UV hybrid method is developed to calculate the bistatic scattering from the two-dimensional (2-D) composite model of an electrically large ship (ELS) on a one-dimensional (1-D) rough sea surface at a low grazing angle (LGA). The subdivision of the MM and PO region is performed flexibly according to the physical considerations. The MM region contains not only the ship but also a small portion of the neighboring sea region where the surface currents need to be modeled accurately. An iterative solution BiCGSTAB is adopted to solve the final matrix equation of a large dimension caused by the ELS. Then, a UV matrix decomposition technique is applied as the fast algorithm to accelerate the matrix-vector productions and the matrix elements filling in. The improved method makes it possible for the Monte-Carlo simulation of large-scale complex target/rough surface problems under an LGA. The accuracy is validated in comparison with the traditional MOM method. |
| Author(s): | S. Y. He, C. Li, F. Zhang, G. Q. Zhu, W. D. Hu, W. X. Yu |
| File Type: | Journal Paper |
| Issue: | Volume: 26 Number: 2 Year: 2011 |
| Download Link: | Click here to download PDF File Size: 1223 KB |
| Title: | The PMC-Amended DB Boundary – A Canonical EBG Surface |
| Abstract: | Replacing realistic materials and structures by their ideal counterparts, canonical surfaces, is of great interest for initial and conceptual electromagnetic (EM) studies. The recently introduced DB boundary is defined by a set of simple boundary conditions forcing the normal components of the D- and B- fields to be zero at the boundary. We show that this DB boundary produces many 2-D scattering results that are similar to how practical so-called electromagnetic bandgap (EBG) surfaces behave within the bandgap. Still, it is not directly useable as a canonical EBG surface, because, as we demonstrate in this paper, it is incomplete, creating an anomaly for normal incidence which causes unphysical field solution for 3-D field problems. We have removed this anomaly by introducing the PMC-amended DB boundary. This works in the same way as a practically realized EBG surface for both 2-D and 3-D problems within the bandgap, and is therefore a canonical EBG surface. |
| Author(s): | P. Kildal, A. Kishk, M. Bosiljevac, Z. Sipus |
| File Type: | Journal Paper |
| Issue: | Volume: 26 Number: 2 Year: 2011 |
| Download Link: | Click here to download PDF File Size: 1539 KB |
| Title: | Miniature Printed Magnetic Photonic Crystal Antennas Embedded into Vehicular Platforms |
| Abstract: | In this paper, a miniature printed antenna utilizing magnetic photonic crystal (MPC) modes is presented. Typically, MPC modes are supported by a combination of anisotropic dielectric and ferrimagnetic layers. Here, these modes are emulated using coupled printed lines on a grounded dielectric substrate with small, biased ferrimagnetic inclusions. The resonant antenna is formed by cascading two unit cells excited with a probe feed. A recessed, cavity-backed version of this antenna is embedded into a vehicular platform with a goal to minimize platform effects. Several locations on the vehicle are studied and antenna placement is optimized using a combination of two commercially available electromagnetic simulators. |
| Author(s): | E. Irci, K. Sertel, J. L. Volakis |
| File Type: | Journal Paper |
| Issue: | Volume: 26 Number: 2 Year: 2011 |
| Download Link: | Click here to download PDF File Size: 1546 KB |
| Title: | Performance Comparison between Rigorous and Asymptotic Techniques Applied to the Analysis of Wind Turbines |
| Abstract: | The scattering field analysis of wind turbines using asymptotic and rigorous techniques is presented. Several simulations considering different configurations and frequencies are conducted to compare the performance of the electromagnetic techniques. These predictions are very useful for studying the influence of wind farms in terrestrial radio systems. On the other hand, not only a static analysis has been done but also a study of the scattered fields when the blades are in movement. The Doppler effect due to the blade movement has been taken into account to achieve some simulation results. Modules FASANT and MONURBS of NEWFASANT computer tool have been used. FASANT is based on the geometrical theory of diffraction (GTD) on its uniform theory of diffraction (UTD) formulation and MONURBS is based on the method of moments (MoM) and physical optics (PO). A comparison of the results obtained with both codes is shown, as well as the CPU-time and computer memory required. |
| Author(s): | A. Tayebi, J. Gómez, I. González, L. Lozano, M. Jesús Algar, E. García, Í. Etayo, F. Cátedra |
| File Type: | Journal Paper |
| Issue: | Volume: 26 Number: 2 Year: 2011 |
| Download Link: | Click here to download PDF File Size: 696 KB |
| Title: | Dielectric Characterization and Optimization of Wide-band, Cavity-Backed Spiral Antennas |
| Abstract: | This paper presents a novel approach to facilitate the design of wideband, cavity-backed spiral antennas. Using this approach, first, a 2-18 GHz, two-arm cavity backed Archimedean spiral antenna has been designed in FEKO. A multilayer dielectric absorber has been introduced in the cavity to facilitate unidirectional operation of the antenna. In order to incorporate the frequencydependent complex permittivity data of the absorbing materials inserted in the cavity, precise microwave instrumentation has been used to determine these parameters experimentally. Based on this data, a genetic algorithm optimization procedure has been applied to derive the most favorable geometry of the absorbing cavity. Our results show that a design thus optimized significantly improves key performance parameters, maximizes the co-polarized gain, and minimizes the cross-polarized gain of the antenna across its operational bandwidth. We have then extended the approach to the design of a zigzagged 2-arm Archimedean spiral antenna and also a 1.5:1 ratio elliptical spiral antenna and presented the radiation characteristics here. |
| Author(s): | N. Rahman, A. Sharma, M. Asfar, S. Palreddy, R. Cheung |
| File Type: | Journal Paper |
| Issue: | Volume: 26 Number: 2 Year: 2011 |
| Download Link: | Click here to download PDF File Size: 788 KB |
| Title: | Modeling of CPW Based Passive Networks using Sonnet Simulations for High Efficiency Power Amplifier MMIC Design |
| Abstract: | In this paper, the capabilities of the Sonnet software for accurate modeling and design of CPW based lumped-element resonators and matching networks is studied. A systematic method for design of complex matching networks using Sonnet is presented and good overall agreement between Sonnet simulations and measured s-parameter data from fabricated resonators and matching networks was obtained. |
| Author(s): | V. Zomorrodian, U. K. Mishra, R. A. York |
| File Type: | Journal Paper |
| Issue: | Volume: 26 Number: 2 Year: 2011 |
| Download Link: | Click here to download PDF File Size: 1202 KB |
| Title: | Design and SAR Reduction of the Vest Antenna using Metamaterial for Broadband Applications |
| Abstract: | One of the most important obstacles that portable antennas are facing is their harmful effect on the user’s body. In this paper, besides proposing a UWB vest antenna with a bandwidth of at least 500MHz, we try to reduce the specific absorption ratio (SAR) due to the proposed antenna on the human body. In order to achieve the mentioned goal, we modeled the human body after designing the antenna. In order to have simulation results closer to reality, we have used a 3-layer model of the human body instead of the 1- layer model. In our model of the human body, all of the body parts, except the torso, are modeled with three layers of bone, fat, and muscle. Since the torso has a different structure from other body parts and is close to the place of the antenna feed, we modeled it using four layers of air, bone, fat and muscle. As the next step in our simulation process, the antenna was installed on the human body and then the antenna parameters and its SAR were obtained again. In the last stage, SAR due to the proposed antenna is reduced using metamaterial |
| Author(s): | M. Fallah, A. A. Heydari, F. H. Kashani, A. R. Mallahzadeh |
| File Type: | Journal Paper |
| Issue: | Volume: 26 Number: 2 Year: 2011 |
| Download Link: | Click here to download PDF File Size: 1632 KB |
| Title: | Nonstandard Finite Difference Time Domain Algorithm for Berenger’s Perfectly Matched Layer |
| Abstract: | The nonstandard (NS) finite difference time domain (FDTD) algorithm provides remark- ably high accuracy on a coarse grid by optimiz- ing to monochromatic wave propagation within each uniform region. But, an effective absorb- ing boundary condition (ABC) is also necessary to accurately calculate electromagnetic fields. Al- though Berenger’s perfectly matched layer (PML) is a highly effective ABC, there is still no NS- formulation of it. In this paper, we develop a NS- version of the PML (NS-PML). We compare the NS-PML with other ABCs and demonstrate its excellent absorption. |
| Author(s): | N. Okada, J. B. Cole |
| File Type: | Journal Paper |
| Issue: | Volume: 26 Number: 2 Year: 2011 |
| Download Link: | Click here to download PDF File Size: 993 KB |
| Title: | Modified Adaptive Cross Approximation Algorithm for Analysis of Electromagnetic Problems |
| Abstract: | In order to efficiently analyze the large dense complex linear system arising from electric field integral equations (EFIE) formulation of electromagnetic scattering problems, the adaptive cross approximation (ACA) is applied to accelerate the matrix-vector multiplication operations. Although the ACA is already efficient compared with the direct method, this paper utilizes a novel technique to further reduce the setup time and storage memory. This method applies the predetermined interaction list supported oct tree (PILOT) to form a new far field interaction list. Using the new far field interaction list, less setup time representation of the far field matrix is obtained. The numerical results of complex objects are used to demonstrate that the memory requirement of the modified ACA is also less than that of the traditional ACA. An efficient preconditioning technique is combined into the inner-outer flexible generalized minimal residual (FGMRES) solver to further speed up the matrix-vector multiplication. |
| Author(s): | R. S. Chen, Z. H. Fan, Y. Y. An, M. M. Zhu, K. W. Leung |
| File Type: | Journal Paper |
| Issue: | Volume: 26 Number: 2 Year: 2011 |
| Download Link: | Click here to download PDF File Size: 802 KB |
| Title: | Gain and Bandwidth Limitations of Reflectarrays |
| Abstract: | In reflectarray antenna designs, it is important to find the gain and bandwidth for a desired application. In this paper, two analysis methods are illustrated, which can provide quick estimations on the reflectarray gain and bandwidth. A quantitative comparison on these two different approaches is made in terms of accuracy and computation time. Parametric studies are performed to provide design guidelines for selecting appropriate f/D ratio and feed pattern of a center-fed reflectarray in order to optimize the antenna gain and bandwidth. A gain and bandwidth comparison between the broadside and offset fed reflectarray antennas is presented. Furthermore, the effect of element bandwidth on the performance of an X-band reflectarray is given both numerically and experimentally. |
| Author(s): | B. Devireddy, A. Yu, F. Yang, A. Z. Elsherbeni |
| File Type: | Journal Paper |
| Issue: | Volume: 26 Number: 2 Year: 2011 |
| Download Link: | Click here to download PDF File Size: 686 KB |