ACES Publication Search





There are 12 search results for:



Title: ACES June 2011 Full Journal
File Type: Journal Paper
Issue:Volume: 26      Number: 6      Year: 2011
Download Link:Click here to download PDF     File Size: 10506 KB

Title: ACES June 2011 Front/Back Matter
File Type: Journal Paper
Issue:Volume: 26      Number: 6      Year: 2011
Download Link:Click here to download PDF     File Size: 1720 KB

Title: Miniaturization of Conical Helical Antenna via Optimized Coiling
Abstract: Conical helices are extensively used in multifunctional antenna platforms for UHF and VHF frequencies because of their broadband characteristics. Therefore, there is strong interest to reduce their size as much as possible. In this paper, a conical helix with metallic ground plane is considered and reduced in size by as much as 30% via coiling (equivalent to inductive loading). The coiling is obtained via genetic algorithms subject to customized criteria for best ultrawideband realized gain.
Author(s): T. Peng, S. Koulouridis, J. L. Volakis
File Type: Journal Paper
Issue:Volume: 26      Number: 6      Year: 2011
Download Link:Click here to download PDF     File Size: 2051 KB

Title: A Dual-Band Metamaterial Design using Double SRR Structures
Abstract: Based on a periodic array of interspaced conducting split ring resonators (SRRs) and continuous wires, a composite structure is proposed to hold a dual-band in the microwave regime. With simultaneously negative values of effective permeability and permittivity, the composite structure displays a negative refractive index characteristic in a dual-band. The location of the two resonant frequencies is investigated by adjusting the distance between the neighboring asymmetrical SRRs in a single array element. Numerical results show the impact of the distance on the resonant frequencies due to coupling effects. Different simulation softwares 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: 6      Year: 2011
Download Link:Click here to download PDF     File Size: 1598 KB

Title: A PML for Electroacoustic Waves in Piezoelectric Materials Using FDTD
Abstract: A perfectly matched layer (PML) is introduced for elastodynamic waves in piezoelectric materials. A matching condition is derived for the PML equations to reduce spurious reflections from the boundary. The finite difference time domain (FDTD) is used to model the propagation of the wave in the piezoelectric material. The results show good performance of the proposed PML boundary.
Author(s): A. O. Montazeri, M. H. Bakr, Y. M. Haddara
File Type: Journal Paper
Issue:Volume: 26      Number: 6      Year: 2011
Download Link:Click here to download PDF     File Size: 4441 KB

Title: Beam Scanning Antenna Using a Reflectarray as Sub-Reflector
Abstract: In this paper, a dual-reflector antenna based on a main parabolic reflector and a reconfigurable reflectarray as subreflector is proposed for beam scanning applications. The beam deflecting is achieved by modifying the phase introduced by each element of the subreflectarray. The required phase distribution for each scan angle is obtained through a synthesis technique based on the analysis of the antenna in receive mode. The design technique has been applied to the particular cases of beam scanning in azimuth and elevation planes. Patches aperturecoupled to delay lines, which provide low losses and cross-polar levels, are proposed as elements for the reflectarray subreflector, allowing the easy implementation of electronic control devices in the microstrip delay lines. The results show that the beam can be scanned in a range 6 by inserting switches on the delay line to provide a 3-bit quantization.
Author(s): M. Arrebola, E. Carrasco, J. A. Encinar
File Type: Journal Paper
Issue:Volume: 26      Number: 6      Year: 2011
Download Link:Click here to download PDF     File Size: 3306 KB

Title: Application of the Wheeler Incremental Inductance Rule for Robust Design and Modeling of MMIC Spiral Inductors
Abstract: A physics based model using Wheelers incremental inductance rule for calculating the change in inductance due to variations in line width and thickness for planar circular spiral inductors is given. It is shown that the series resistance of an MMIC inductor can be used as a figure of merit for the robustness of the inductor against etching variations in line width during fabrication. Circular inductors are shown to have less inductance variation than rectangular inductors. This model can be evaluated quickly using a circuit simulator without the need for expensive EM analysis. In the electromagnetic modeling of MMIC inductors, a fine grid and several sheets are used to accurately model the current distribution and determine the resistance. SonnetTM is used to accurately model the 3D characteristics of thick conductors such as loss and effects of physically thick metal. A procedure based on the Richardson extrapolation method is used to extract the resistance values without long computation time. Applications include calculating the change in inductance due to overor under-etching of metal lines during fabrication. For 2 to 4 turn inductors with variations in line width of +/-20% of the nominal width, the average variation in modeled inductance is within 8% of the EM simulated variation.
Author(s): G. A. Ellis
File Type: Journal Paper
Issue:Volume: 26      Number: 6      Year: 2011
Download Link:Click here to download PDF     File Size: 1693 KB

Title: Parametric Design of Parabolic Reflector Antenna with Switchable Cosecant-Squared Pattern
Abstract: This paper deals with the parametric analysis of multi-beam parabolic reflector antennas employed for air and coastal surveillance radars. Novel designs are introduced to obtain electronically switchable cosecant-squared and pencil beam radiation patterns, without making any changes on the reflector geometry. The analytical regularization method (ARM) is used as a fast and accurate way to solve the problem of Epolarized wave diffraction by parabolic shaped perfectly electrical conductive (PEC) cylindrical reflector with finite thickness. The numerical procedure is initially verified by the analytical and numerical methods, and the calculated radiation characteristics are presented for the proposed antenna configurations.
Author(s): A. S. Turk, O. Yurduseven
File Type: Journal Paper
Issue:Volume: 26      Number: 6      Year: 2011
Download Link:Click here to download PDF     File Size: 1578 KB

Title: Polarimetric Scattering from a 3-D Rectangular Crack in a PEC Covered by a Dielectric Layer
Abstract: A novel direct approach for calculation of the polarimetric scattering fields from a narrow 3-D rectangular crack in an infinite ground plane underneath a dielectric layer is presented. Since the electromagnetic fields are directly calculated and thus the approach in inversible, this technique is suitable for microwave NDT applications where cracks of narrow width, arbitrary length and depth under a dielectric layer are frequently encountered. A set of coupled field integral equations (FIE) with logarithmic and hypersingular kernels are derived and then descritized by a collocation method based on Chebyshev polynomials. The results of this direct approach are in good agreement with noninversible full numerical FEM and MoM results.
Author(s): M. Bozorgi, A. Tavakoli
File Type: Journal Paper
Issue:Volume: 26      Number: 6      Year: 2011
Download Link:Click here to download PDF     File Size: 1808 KB

Title: An Adaptive Preconditioning Technique using Fuzzy Controller for Efficient Solution of Electric Field Integral Equations
Abstract: For efficiently solving large dense complex linear systems that arise in the electric field integral equation (EFIE) formulation of electromagnetic scattering problems, a new adaptive preconditioning technique using fuzzy controller (FC) is introduced and used in the context of the generalized minimal residual iterative method (GMRES) accelerated with the multilevel fast multipole method (MLFMM). The key idea is to control the choice of the preconditioner to be used in an iterative solver by using fuzzy controller. This approach allows the expert knowledge to be taken into account on the controller design and utilizes feedback to tune the cores of the fuzzy set. Numerical results show that the best preconditioner can be selected while maintaining low cost for adaptive procedures.
Author(s): Z. Liu, J. Chen, R. Chen
File Type: Journal Paper
Issue:Volume: 26      Number: 6      Year: 2011
Download Link:Click here to download PDF     File Size: 1518 KB

Title: Design Optimization of Microwave Structures Using Low-Order Local Cauchy-Approximation Surrogates
Abstract: A robust and computationally efficient microwave design optimization procedure is presented. This procedure integrates low-order Cauchy-approximation surrogate models with coarse-discretization EM simulations. The optimization engine is space mapping (SM). Instead of setting up a single surrogate model valid for the entire design variable space, a sequence of surrogate models is established in small hyper-cubes containing the optimization path. This allows us to substantially limit the number of training points necessary to create the surrogates and, therefore, reduce the cost of the optimization process. Moreover, our approach eliminates the need for circuit-equivalent coarse models traditionally used by SM algorithms. Our algorithm is successfully illustrated through the efficient design of a number of microwave filters.
Author(s): S. Koziel, M. H. Bakr
File Type: Journal Paper
Issue:Volume: 26      Number: 6      Year: 2011
Download Link:Click here to download PDF     File Size: 1685 KB

Title: Design of Miniaturized Unequal Split Wilkinson Power Divider with Harmonics Suppression Using Non-Uniform Transmission Lines
Abstract: In this paper, a design of an unequal split Wilkinson power divider (WPD), with high power split ratio, using non-uniform transmission lines (NTLs) is presented. The design is based on using NTLs in each branch of the divider instead of the conventional uniform ones. Besides the achievement of high power split ratio, the size of the designed WPD is reduced. The design procedure is presented for arbitrary design frequency and arbitrary power split ratio. For verification purposes, a 10:1 WPD is designed and fabricated. Good isolation between the output ports, input/output ports matching, and transmission responses are achieved at the design frequency. The experimental and full-wave simulation results show the validity of the designed NTL-WPD. Compared to the conventional design, it is noticed that the proposed divider is more likely suitable for narrowband applications.
Author(s): K. A. Shamaileh, A. Qaroot, N. Dib, A. Sheta
File Type: Journal Paper
Issue:Volume: 26      Number: 6      Year: 2011
Download Link:Click here to download PDF     File Size: 1758 KB