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Title: ACES Journal May 2012
File Type: Journal Paper
Issue:Volume: 27      Number: 5      Year: 2012
Download Link:Click here to download PDF     File Size: 6717 KB

Title: ACES Journal May 2012 Front/Back Matter
File Type: Journal Paper
Issue:Volume: 27      Number: 5      Year: 2012
Download Link:Click here to download PDF     File Size: 618 KB

Title: Comparative Study of Analytical and Numerical Techniques in Modeling Electromagnetic Scattering from Single and Double Knife-Edge in 2D Ground Wave Propagation Problems
Abstract: This paper presents a comparative study of some analytical and numerical techniques in the solution of a classical problem of electromagnetic scattering from single and double knife edge above ground. The results of the analytical exact and asymptotic techniques (such as uniform theory of diffraction, parabolic equation diffraction method) are compared with the two-way split-step parabolic equation method (SSPE), through several numerical simulations. Salutary discussions on their capabilities and limitations are presented. Codes used in the simulations are provided in the end.
Author(s): O. Ozgun, L. Sevgi
File Type: Journal Paper
Issue:Volume: 27      Number: 5      Year: 2012
Download Link:Click here to download PDF     File Size: 1785 KB

Title: Numerical Prepackaging with PMC Lid - Efficient and Simple Design Procedure for Microstrip Circuits Including the Packaging
Abstract: The paper presents an efficient method for the design of printed microstrip circuit with packaging in mind, referred to as numerical prepackaging with a perfectly magnetic conductive (PMC) lid. The method comprises making the design including the packaging from the start by using a PMC lid, rather than first designing the open-aired circuit; and thereafter, considering the packaging effect and the often required retuning of the circuits themselves. The advantage is that no parallel plate modes can propagate between the perfect electric conductor (PEC) ground plane and the PMC lid plate if the spacing is smaller than an effective quarter of wavelength. This provides a limited computational volume so that the computation time is significantly reduced in the case of the finite element method (FEM) or the finite difference time domain method (FDTD). By using numerical packaging with PMC lid, the ideal PMC lid has to be realized afterwards e.g. by using a lid of nails, which is a minor task as compared to existing approaches.
Author(s): A. Kishk, A. U. Zaman, P. S. Kildal
File Type: Journal Paper
Issue:Volume: 27      Number: 5      Year: 2012
Download Link:Click here to download PDF     File Size: 1021 KB

Title: Generalized Formulation for the Scattering from a Ferromagnetic Microwire
Abstract: In this paper, we present a full wave analysis for the scattering of an obliquely incident plane wave of an arbitrary polarization angle due to an infinite magnetized ferromagnetic microwire. The analysis is based on expanding the incident and scattered waves as infinite sets of cylindrical waves and matching the corresponding modes on the surface of the microwire to obtain the unknown amplitudes of the scattered fields. The gyromagnetic properties of the ferromagnetic material introduce a coupling between the electric and magnetic field components inside the microwire. This coupling is the reason of cross polarization in the scattered field.
Author(s): A. M. Attiya, M. A. Alkanhal
File Type: Journal Paper
Issue:Volume: 27      Number: 5      Year: 2012
Download Link:Click here to download PDF     File Size: 688 KB

Title: An Equivalent Dipole-Moment Method Based Multilevel Fast Multipole Algorithm for Dielectric Objects
Abstract: An equivalent dipole-moment method (EDM) based multilevel fast multipole algorithm (MLFMA), namely EDM-MLFMA, is proposed for the electromagnetic scattering from threedimensional (3D) dielectric objects. In this scheme, the MLFMA is employed to accelerate the interactions of equivalent dipoles in the far regions by expanding the 3D dyadic Green's function into a multipole expression. The memory requirement and CPU time of the conventional EDM are reduced from O(N2 ) to O(N log N) , where N is the number of unknowns. Numerical results are presented to validate the efficiency and accuracy of this method.
Author(s): X. Chen, C. Gu, J. Ding, X. Deng, Z. Niu, Z. Li
File Type: Journal Paper
Issue:Volume: 27      Number: 5      Year: 2012
Download Link:Click here to download PDF     File Size: 589 KB

Title: Improved Weakly Conditionally Stable Finite-Difference Time-Domain Method
Abstract: To circumvent the inaccuracy in the implementation of the perfect-electric-conductor (PEC) condition in the weakly conditionally stable finite-difference time-domain (WCS-FDTD) method, an improved weakly conditionally stable (IWCS) FDTD method is presented in this paper. In this method, the solving of the tridiagonal matrix for the magnetic field component is replaced by the solving of the tridiagonal matrix for the electric field components; thus, the perfectelectric- conductor (PEC) condition for the electric field components is implemented accurately. The formulations of the IWCS-FDTD method are given, and the stability condition of the IWCSFDTD scheme is presented analytically. Compared with the WCS-FDTD method, this new method has higher accuracy in the implantation of the PEC condition, which is demonstrated through numerical examples.
Author(s): J. Chen
File Type: Journal Paper
Issue:Volume: 27      Number: 5      Year: 2012
Download Link:Click here to download PDF     File Size: 588 KB

Title: Dual Band-Notch Small Square Monopole Antenna with Enhanced Bandwidth Characterestics for UWB Applications
Abstract: This article proposes a novel printed monopole antenna for ultra wideband applications with dual band-notch function. The antenna consists of a square radiating patch with four rectangular slits and a ground plane with a pair of T-shaped parasitic structures, which provides a wide usable fractional bandwidth of more than 165% (2.79-14.83 GHz). In order to generate single band-notch characteristics, we use two rectangular slits in the corners of square radiating patch. By adding two rectangular slits in the center of the modified radiating patch, a dual band notch function is achieved and also by inserting a pair of T-shaped parasitic structures in the ground plane, additional resonances are excited and hence much wider impedance bandwidth can be produced, especially at the higher band. The measured results reveal that the presented dual band-notch monopole antenna offers a very wide bandwidth with two notched bands, covering all the 5.2/5.8GHz WLAN, 3.5/5.5 GHz WiMAX and 4- GHz C bands. The designed antenna has a small size of 1218 mm2 .
Author(s): M. Ojaroudi, N. Ojaroudi, Y. Ebazadeh
File Type: Journal Paper
Issue:Volume: 27      Number: 5      Year: 2012
Download Link:Click here to download PDF     File Size: 1546 KB

Title: Optimal Design of an Ultra-Wideband Antenna with the Irregular Shape on Radiator using Particle Swarm Optimization
Abstract: An ultra-wideband antenna with an irregular shape radiator for ultra-wideband applications has been designed by particle swarm optimization along with the simulator, HFSS. The proposed antenna design process is automated. Also, the better results can be obtained efficiently. The proposed antenna is fed by a coplanar waveguide line. The optimized antenna has a compact substrate size of 34.0 mm by 33.35 mm. Results show that the optimized irregular shape of the proposed antenna outperforms the antennas with uniform rectangular shapes in impedance matching. The optimized antenna can cover the spectrum of ultra-wideband (3.1 GHz - 10.6 GHz). The current distributions are investigated for describing the antenna characteristics. Moreover, the proposed UWB antenna has good characteristics of radiation, transmission, and impedance bandwidth.
Author(s): W. C. Weng
File Type: Journal Paper
Issue:Volume: 27      Number: 5      Year: 2012
Download Link:Click here to download PDF     File Size: 1271 KB

Title: A Novel Harmonic Suppression Antenna with Both Compact Size and Wide Bandwidth
Abstract: A novel CPW-fed harmonic suppression antenna with both compact size and wide bandwidth is proposed and investigated in this paper. The second and third harmonic frequencies are suppressed effectively with square-shaped lattices inserted in the ground plane. Furthermore, by exploiting the Vivaldishaped structure and two simple rectangular slots, wide bandwidth (1.86GHz) ranging from 1.9GHz to 3.76GHz is also obtained with rather compact size of 10mm 10mm, which is much smaller than that have ever been reported before. Eventually, the measured results confirmed the simulated dates.
Author(s): Z. L. Zhou, L. Li, J. S. Hong, B. Z. Wang
File Type: Journal Paper
Issue:Volume: 27      Number: 5      Year: 2012
Download Link:Click here to download PDF     File Size: 998 KB

Title: A Novel Circular Disc Monopole Antenna for Dual-Band WLAN Applications
Abstract: This paper presents a novel and simple circular disc monopole antenna with a tunable Hshaped ground plane which provides two separate resonant modes to achieve 2.4- and 5.5-GHz dualband operation for wireless local area network (WLAN) applications. The proposed antenna is printed on a low cost substrate FR4 (?r=4.4) and excited using a 50 ? microstrip transmission line. Lower resonant mode of the antenna has an impedance bandwidth (|S11|<-10 dB) of 700 MHz (2250-2950 MHz), and the upper resonant mode has a bandwidth of 1100 MHz (4900-6000 MHz). For validation purposes, an antenna prototype was fabricated and tested. The measured and simulated results show relatively good agreement and confirm satisfactory radiation characteristics. Effects of varying the widths of the arms of the Hshaped ground plane on antenna performance have also been studied.
Author(s): B. Li, J. S. Hong, B. Z. Wang
File Type: Journal Paper
Issue:Volume: 27      Number: 5      Year: 2012
Download Link:Click here to download PDF     File Size: 1122 KB

Title: Electric Field Distribution in a Biological Cell for Various Electrode Configurations-A Simulation Study
Abstract: Electroporation or electropermeabilization (EP) is a non-viral physical process of inducing and/or increasing permeability of biological membranes by the application of high intensity and short duration electrical pulses. The resulting high field strength in the membrane can lead to the formation of regions of increased permeability, often called pores that allow transmembrane transport of macromolecules, such as DNA and chemo drugs. The efficacy of EP depends on a number of parameters, such as electric field strength, duration, number of pulses, size of target cell, and type of drug or DNA to be fed, to mention a few parameters. While electric field strength, duration, and number of pulses are the dominant parameters for the electroporation effect, the electric field distribution also depends on the shape, the size, and the material of electrodes used. The various electrodes used in practice are the parallel plate electrodes, the needle electrodes, the needle array electrodes, and the caliper electrodes. Both six needle array and parallel plate electrodes were used in the skin cancer trials. The electric field distribution varies with the type of electrode. The choice of electrodes depends upon the type of application. For example, parallel plate electrodes produce good results in human clinical trials and the distance between the electrodes can be easily varied. Needle electrodes are the simplest, but due to their configuration, the field distribution is highly nonlinear; there is higher field strength around the needle tip. That is one of the reasons for using multiple needles or needle arrays to make the field distribution as uniform as possible. It is of practical interest to study the electric field distribution of various electrodes to make a more informed choice of which electrodes to use. This paper presents the results of a study of the electric field distribution in biological tissues for various electrode configurations. Magwel was used in this study. For the same voltage applied, the triangular and arc electrode configuration developed the highest electric field strength. Specifically, we develop simulation results that enhance or enable the acquisition of information from cells.
Author(s): M. O. Goni
File Type: Journal Paper
Issue:Volume: 27      Number: 5      Year: 2012
Download Link:Click here to download PDF     File Size: 910 KB