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Title: ACES Journal July 2014 Cover
File Type: Journal Paper
Issue:Volume: 29      Number: 7      Year: 2014
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Title: ACES Journal July 2014 Front/Back Matter
File Type: Journal Paper
Issue:Volume: 29      Number: 7      Year: 2014
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Title: ACES Journal July 2014 Full
File Type: Journal Paper
Issue:Volume: 29      Number: 7      Year: 2014
Download Link:Click here to download PDF     File Size: 7023 KB

Title: Uniaxial Dielectric Waveguide Filter Design Accounting for Losses Using Mode Matching Technique
Abstract: Dielectric filters can provide compact solutions for filter design problems. However, most dielectrics exhibit uniaxial properties, as well as, losses that will undoubtedly affect performance if not accounted for. This paper derives dispersion relations for lossy uniaxial media in dielectric waveguides and also accounts for lossy conducting walls. The waveguide discontinuity problem in the presence of lossy uniaxial media and finite conductivity waveguide walls, is calculated by mode matching technique and the results are applied to a Ka band filter. The design specifications for the proposed filter are a 32.5 GHz center frequency with 6%. Good agreement between simulated and measured results are shown.
Author(s): L. Murphy, J. Mautz, M. Yazdani, E. Arvas, S. Tozin
File Type: Journal Paper
Issue:Volume: 29      Number: 7      Year: 2014
Download Link:Click here to download PDF     File Size: 856 KB

Title: Electromagnetic Shielding of Resonant Frequency-Selective Surfaces in Presence of Dipole Sources
Abstract: The shielding problem consisting in the interaction between a dipole source and a Frequency-Selective Surface (FSS) is investigated. The Array Scanning Method (ASM) is adopted to take into account all the propagating and evanescent waves, which constitute the spectrum of the dipole and all the propagating and evanescent Floquet modes, which constitute the spectrum of the diffracted field by the FSS. The main differences with respect to the shielding of a conventional plane-wave source are pointed out, especially in terms of resonant frequencies, operating bandwidth and transmission levels.
Author(s): G. Lovat, R. Araneo, S. Celozzi
File Type: Journal Paper
Issue:Volume: 29      Number: 7      Year: 2014
Download Link:Click here to download PDF     File Size: 826 KB

Title: Physical Optics Analysis for RCS Computation of a Relatively Small Complex Structure
Abstract: High-frequency methods are well known as a convenient approach for treating Electromagnetic (EM) problems regarding electrically large structures. In this paper however, this method is proposed as a proper tool for computing the mono-static Radar Cross Section (RCS) of a relatively small complex structure. This claim has been verified via simulation through a frequency range of 100 MHz to 10 GHz and measurement for the structure of this work. In this regard, initially, RCS computation via the Method of Moments (MoM) has been executed. As this method leads to rigorous and time consuming computations, Physical Optics (PO) has been utilized for the same purpose. These computations have been carried out by employing the Integral Equation (IE) and asymptotic solver of CST Microwave Studio (MWS). PO proves to be timeefficient compared to MoM. Graphs comparing PO and MoM-computed RCS are illustrated. In addition, the similarity of the results obtained by PO and MoM has been thoroughly discussed. Correlation between these results has been observed. Also, mean and standard deviation values for PO RCS-error have been provided for the entire simulation frequency. As dimension to wavelength ratio (D/?) of the structure increases, the convergence of these two methods for RCS computation becomes satisfactory. Finally, measurement has been accomplished at frequency of 8.5 GHz to validate PO computations. Index Terms ? Complex structure, Integral Equation (IE), Method of Moments (MoM), Physical Optics (PO) and Radar Cross Section (RCS).
Author(s): A. B. Gorji, B. Zakeri, R. C. Janalizadeh
File Type: Journal Paper
Issue:Volume: 29      Number: 7      Year: 2014
Download Link:Click here to download PDF     File Size: 622 KB

Title: Small Reconfigurable Monopole Antenna Integrated with PIN Diodes for Multimode Wireless Communications
Abstract: A new printed reconfigurable monopole antenna with multi-resonance and switchable dual band-notched performances is presented, whose frequency characteristics can be reconfigured electronically to have both a single or dual-band notch function to block interfering signals from Wireless Local Area Network (WLAN) for 5-6 GHz and/or X-band communications around 9-10 GHz. The presented antenna consists of a square radiating patch with H-shaped slot and a ground plane with a pair of Lshaped parasitic structures. We use two PIN diodes across the antenna configuration that by changing the on/off conditions of the PIN diodes, the antenna can be used for multimode applications. In the proposed structure, when D1=ON & D2=OFF, an UWB antenna with a multi-resonance characteristic can be achieved and we can give additional resonances at higher frequency bands that provides a wide usable fractional bandwidth of more than 125% (3.02- 12.43). By changing the condition of integrated diodes to D1=OFF & D2=ON, the pair of rotated T-shaped slots at radiating patch have converted to H-shaped slot and the L-shaped parasitic structures have converted to inverted ?-shaped structure. The proposed antenna can be used to generate either single or dual notch band to isolate and block any interference in the UWB frequency range.
Author(s): N. Ojaroudi, Y. Ojaroudi, S. Ojaroudi, Y. Ebazadeh, M. Shirgir
File Type: Journal Paper
Issue:Volume: 29      Number: 7      Year: 2014
Download Link:Click here to download PDF     File Size: 700 KB

Title: Evolutionary Design of a Wide Band Flat Wire Antenna for WLAN and Wi-Fi Applications
Abstract: This paper presents a wire antenna for multi-band WLAN application, having a very simple geometry, designed using the StructureBased Evolutionary Programming; an innovative antenna design technique, based on evolutionary programming. The chosen fitness function includes far-field requirements, as well as wideband input matching specifications. The latter requirements, which must be present in every useful antenna design, allow to stabilize the algorithm and to design both optimal and robust antennas. The antenna has been analysed with NEC-2 during the evolutionary process and the outcome of the procedure shows a very good performance; with a -10dB bandwidth that covers the required frequencies for multi-band WLAN applications (2.4/5.2/5.8 GHz) and beyond, and an end-fire gain greater than 10 dB. The NEC-2 results have been also compared to the ones obtained by a well-assessed, general purpose, 3D electromagnetic software, HFSS by Ansys, showing a very good agreement.
Author(s): G. A. Casula, G. Montisci, A. Fanti, P. Maxia, G. Mazzarella
File Type: Journal Paper
Issue:Volume: 29      Number: 7      Year: 2014
Download Link:Click here to download PDF     File Size: 791 KB

Title: Compact UWB Antenna with Dual Functionality
Abstract: A novel Ultra-Wideband (UWB) monopole antenna is proposed that exhibits stopband functionality at the WLAN frequency band. It consists of an annular ring shaped radiating patch that is excited with a 50 ? feedline. The stop-band is generated by etching a parasitic ring on the reverse side of the antenna’s substrate. The antenna’s impedance bandwidth was enhanced by including a semi-circular notch in the trapezoidal shaped ground-plane in the vicinity of the parasitic ring. The measured results confirm the impedance bandwidth covers a frequency range between 2.42- 11.4 GHz for VSWR?2, which corresponds to a fractional bandwidth of 130%. The UWB antenna is omni-directional in the xz-plane and approximately bi-directional in the yz-plane. The antenna is compact in size with overall dimensions of 30×30×1.6 mm3 .
Author(s): M. Shokri, Z. Amiri, M. Pilevari, M. Masoumi, S. Asiaban, B. Virdee
File Type: Journal Paper
Issue:Volume: 29      Number: 7      Year: 2014
Download Link:Click here to download PDF     File Size: 656 KB

Title: A Simple Coupled-Line Wilkinson Power Divider for Arbitrary Complex Input and Output Terminated Impedances
Abstract: A simple and analytical design methodology for a novel coupled-line power divider with arbitrary complex terminated impedances is proposed in this paper. Because of the usage of a single-section coupled line, the additional odd-mode characteristic impedance increases the design degree of freedom and makes the isolation structure still use a single resistor when terminated impedances are extended from real values (such as 50 Ohm) to arbitrary complex values. To design this generalized coupled-line power divider, the electrical parameters including electrical lengths and characteristic impedances can be redesigned by the provided closed-form mathematical expressions when complex terminated impedances are known. The validity of this given design methodology has been confirmed by simulation and measurement of two typical microstrip examples.
Author(s): Y. Wu, J. Li, Y. Liu
File Type: Journal Paper
Issue:Volume: 29      Number: 7      Year: 2014
Download Link:Click here to download PDF     File Size: 720 KB

Title: Band-Rejected UWB Monopole Antenna with Bandwidth Enhancement
Abstract: In this study, we present an UltraWideband (UWB) monopole antenna with bandnotched function. The proposed antenna is fed by a microstrip line. By using two modified forkshaped slots in the ground plane, bandwidth is increased that provides a wide usable fractional bandwidth of more than 135% (2.82-15.63). In order to achieve band-rejected performance, a cross-ring slot was inserted at the square radiating patch and a frequency band-notched of 5.11-5.97 GHz has been received. Simulated and experimental results obtained for this antenna show that it exhibits good radiation behavior within the UWB frequency range. The designed antenna has a small size.
Author(s): S. Ojaroudi, Y. Ojaroudi, N. Ojaroudi, N. Ghadimi
File Type: Journal Paper
Issue:Volume: 29      Number: 7      Year: 2014
Download Link:Click here to download PDF     File Size: 583 KB

Title: A New Compact Rectangle-Like Slot Antenna with WiMAX and WLAN Rejection
Abstract: In this manuscript, a new CPW-fed slot antenna with two band-notches for ultra-wideband communication systems is proposed. The antenna contains a trapezoid-shaped patch and a slotted ground plane. To achieve two notched bands, both of the inverted L-shaped strip and triangle-shaped element connecting to patch by a via are used. The designed antenna is printed on an FR4 substrate with compact size of 20×27 mm2 . Moreover, the antenna has been successfully fabricated and measured, indicating extended impedance bandwidth (3-11.2 GHz, VSWR?2) and dual band-notched (3.2-3.9 GHz and 5-5.9 GHz), respectively.
Author(s): M. Akbari, M. Kohdaee, S. Zarbakhsh, A. Sebak
File Type: Journal Paper
Issue:Volume: 29      Number: 7      Year: 2014
Download Link:Click here to download PDF     File Size: 868 KB

Title: Electromagnetic Scattering by Multiple Cavities Embedded in the Infinite 2D Ground Plane
Abstract: This paper is concerned with the mathematical analysis and numerical computation of the electromagnetic wave scattering by multiple open cavities, which are embedded in an infinite two-dimensional ground plane. By introducing a new transparent boundary condition on the cavity apertures, the scattering problem is reduced to a boundary value problem on the two-dimensional Helmholtz equation imposed in the separated interior domains of the cavities. The existence and uniqueness of the weak solution for the model problem is studied by using a variational approach. A block Gauss-Seidel iterative method is introduced to solve the coupled system. Numerical examples are presented to show the efficiency and accuracy of the proposed method.
Author(s): P. Li, A. W. Wood
File Type: Journal Paper
Issue:Volume: 29      Number: 7      Year: 2014
Download Link:Click here to download PDF     File Size: 518 KB