ACES Publication Search
There are 35 search results for:
| Title: | ACES Journal February 2018 Cover |
| File Type: | Journal Paper |
| Issue: | Volume: 33 Number: 2 Year: 2018 |
| Download Link: | Click here to download PDF File Size: 2168 KB |
| Title: | ACES Journal February 2018 Front/Back Matter |
| File Type: | Journal Paper |
| Issue: | Volume: 33 Number: 2 Year: 2018 |
| Download Link: | Click here to download PDF File Size: 287 KB |
| Title: | ACES Journal February 2018 Full |
| File Type: | Journal Paper |
| Issue: | Volume: 33 Number: 2 Year: 2018 |
| Download Link: | Click here to download PDF File Size: 19364 KB |
| Title: | Half-Loop Segmented Antenna with Omnidirectional Hemispherical Coverage for Wireless Communications |
| Abstract: | Segmented antennas loaded with reactance elements at the junctions between segments provide additional parameters for shaping antenna characteristics. The design procedure consists of first, circuit analysis of the multiport antenna description to determine the initial values of the lumped element reactances and second, of fine tuning the antenna dimensions full-wave simulation software. Measured results show that a good matching and an omnidirectional radiation pattern in the vertical plane is maintained up to ? = 70º with a circular ground plane of 1m diameter. |
| Author(s): | P. Nayeri, A. Z. Elsherbeni, R. Hasse, D. Kajfez |
| File Type: | Journal Paper |
| Issue: | Volume: 33 Number: 2 Year: 2018 |
| Download Link: | Click here to download PDF File Size: 1702 KB |
| Title: | Computational Electromagnetic Modelling of Compact Antenna Test Range Quiet Zone Probing |
| Abstract: | This paper extends the authors previous simulation study [1, 2] that predicted the quality of the pseudo plane wave of an offset compact antenna test range (CATR). In this paper, the quiet-zone performance predictions are extended to rigorously incorporate the effects of probing the CATR quiet-zone using various field probes. This investigation leads to recommendations as to the optimal field probe choice and measurement uncertainties. The results of these new simulations are presented and discussed. |
| Author(s): | C. G. Parini, R. Dubrovka, S. F. Gregson |
| File Type: | Journal Paper |
| Issue: | Volume: 33 Number: 2 Year: 2018 |
| Download Link: | Click here to download PDF File Size: 1640 KB |
| Title: | Enhanced Artificial Immune System Algorithm and Its Comparison to Bio-Inspired Optimization Techniques for Electromagnetics Applications |
| Abstract: | This paper introduces an enhanced artificial immune system algorithm (EAIS) that benefits from a hybrid approach by integrating concepts from the genetic algorithm (GA) and particle swarm optimization (PSO). The potential of the EAIS algorithm is demonstrated by comparing its performance with other bio-inspired optimization algorithms; namely the particle swarm optimization (PSO) and the conventional artificial immune system (AIS) when applied to two electromagnetics applications, such as the design of antireflective surfaces, and microstrip electromagnetic band gap (EBG) structures. |
| Author(s): | O. Kilic, Q. M. Nguyen |
| File Type: | Journal Paper |
| Issue: | Volume: 33 Number: 2 Year: 2018 |
| Download Link: | Click here to download PDF File Size: 1661 KB |
| Title: | Experimental Benchmarking of Unstructured Transmission Line Modelling (UTLM) Method in Modelling Twisted Wires |
| Abstract: | In this paper the Unstructured Transmission Line Modelling (UTLM) method based on a tetrahedral mesh has been applied to modelling of the coupling between a single wire and a twisted wire pair. The effects of wire twisting on the crosstalk and coupling between wires are modelled by explicitly meshing wire geometries; simulation results are compared with experimental ones. Excellent agreement between simulated and measured results validates the viability and accuracy of the UTLM method and indicates the potential of the UTLM method for modelling complex wire structures. |
| Author(s): | X. Meng, P. Sewell, N. H. A. Rahman, A. Vukovic, T. M. Benson |
| File Type: | Journal Paper |
| Issue: | Volume: 33 Number: 2 Year: 2018 |
| Download Link: | Click here to download PDF File Size: 1650 KB |
| Title: | Four-Stage Split-Step 2D FDTD Method with Error-Cancellation Features |
| Abstract: | We develop a methodology that enables the proper introduction of high-order spatial operators in an unconditionally-stable, split-step, finite-difference timedomain scheme. The proposed approach yields spatial approximations that guarantee better balancing of space-time errors, compared to standard fourth-order expressions. The latter are not as efficient as expected, due to their unmatched order with the scheme’s secondorder temporal accuracy. Our technique treats the dispersion relation as an error descriptor, derives spatial formulae that change with the cell shape and time-step size, and rectifies the performance over all frequencies. |
| Author(s): | T. T. Zygiridis, N. V. Kantartzis, T. D. Tsiboukis |
| File Type: | Journal Paper |
| Issue: | Volume: 33 Number: 2 Year: 2018 |
| Download Link: | Click here to download PDF File Size: 1571 KB |
| Title: | A 3-D Polynomial-Chaos FDTD Technique for Complex Inhomogeneous Media with Arbitrary Stochastically-Varying Index Gradients |
| Abstract: | An enhanced finite-difference time-domain algorithm featuring the polynomial chaos representation is introduced in this paper for problems with stochastic uncertainties. Focusing on the solution of the governing partial differential equations, the new 3-D method uses the Karhunen-Loève expansion to effectively decorrelate random input parameters denoted by stochastic processes. So, the space dimension is seriously reduced and high accuracy levels are attained, even for media with abrupt and fully unknown statistical variations. These profits are verified via a detailed numerical study. |
| Author(s): | G. G. Pyrialakos, T. T. Zygiridis, N. V. Kantartzis |
| File Type: | Journal Paper |
| Issue: | Volume: 33 Number: 2 Year: 2018 |
| Download Link: | Click here to download PDF File Size: 2602 KB |
| Title: | The Success of GPU Computing in Applied Electromagnetics |
| Abstract: | In the field of electromagnetic modeling, whether it is the complex designs for engineered materials or devices and components integrated within their natural environments, there is a big drive for highly efficient numerical techniques to model the performance of complex structures. This often cannot be achieved by conventional computer systems, but rather through using the so-called high performance computing (HPC) systems that utilize hardware acceleration. We review recent General Purpose Graphics Processing Units (GPGPU) computing strategies introduced in four fields of computational electromagnetics: Finite-Difference Time-Domain (FDTD), Finite Elements Method (FEM), Method of Moments (MoM) and ElectroMagnetic Ray Tracing (EMRT). |
| Author(s): | A. Capozzoli, O. Kilic, C. Curcio, A. Liseno |
| File Type: | Journal Paper |
| Issue: | Volume: 33 Number: 2 Year: 2018 |
| Download Link: | Click here to download PDF File Size: 1501 KB |
| Title: | Benefits and Challenges of GPU Accelerated Electromagnetic Solvers from a Commercial Point of View |
| Abstract: | This paper discusses the benefits but also challenges of GPU accelerated electromagnetic solvers from a commercial point of view, namely using FEKO as example. Specifically, the effects of some of the complex interdependencies between different components are presented. It is shown that despite the advances made in the field of GPGPU computing, and impressive speedups for parts of a program or simplified problems, there are a number of factors to consider before these techniques can be applied to a commercial product that is expected to be robust and, most importantly, to always give trustworthy results for a wide variety of problems. |
| Author(s): | U. Jakobus |
| File Type: | Journal Paper |
| Issue: | Volume: 33 Number: 2 Year: 2018 |
| Download Link: | Click here to download PDF File Size: 1591 KB |
| Title: | GPU Acceleration of Nonlinear Modeling by the Discontinuous Galerkin Time-Domain Method |
| Abstract: | A discontinuous Galerkin time-domain (DGTD) algorithm is formulated and implemented to model the third-order instantaneous nonlinear effect on electromagnetic fields due the field-dependent medium permittivity. The nonlinear DGTD computation is accelerated using graphics processing units (GPUs). Two nonlinear examples are presented to show the different Kerr effects observed through the third-order nonlinearity. With the acceleration using MPI + GPU under a large cluster environment, the solution times for nonlinear simulations are significantly reduced. |
| Author(s): | H.-T. Meng, J.-M. Jin |
| File Type: | Journal Paper |
| Issue: | Volume: 33 Number: 2 Year: 2018 |
| Download Link: | Click here to download PDF File Size: 1569 KB |
| Title: | Multilevel Inverse-Based Factorization Preconditioner for Solving Sparse Linear Systems in Electromagnetics |
| Abstract: | We introduce an algebraic recursive multilevel approximate inverse-based preconditioner, based on a distributed Schur complement formulation. The proposed preconditioner combines recursive combinatorial algorithms and multilevel mechanisms to maximize sparsity during the factorization. |
| Author(s): | Y. Bu, B. Carpentieri, Z. Shen, T. Huang |
| File Type: | Journal Paper |
| Issue: | Volume: 33 Number: 2 Year: 2018 |
| Download Link: | Click here to download PDF File Size: 1687 KB |
| Title: | Porting an Explicit Time-Domain Volume Integral Equation Solver onto Multiple GPUs Using MPI and OpenACC |
| Abstract: | A scalable parallelization algorithm to port an explicit marching-on-in-time (MOT)-based time domain volume integral equation (TDVIE) solver onto multi-GPUs is described. The algorithm makes use of MPI and OpenACC for efficient implementation. The MPI processes are responsible for synchronizing and communicating the distributed compute kernels of the MOT-TDVIE solver between the GPUs, where one MPI task is assigned to one GPU. The compiler directives of the OpenACC are responsible for the data transfer and kernels’ offloading from the CPU to the GPU and their execution on the GPU. The speedups achieved against the MPI/OpenMP code execution on multiple CPUs and parallel efficiencies are presented. |
| Author(s): | S. Feki, A. Al-Jarro, H. Bagci |
| File Type: | Journal Paper |
| Issue: | Volume: 33 Number: 2 Year: 2018 |
| Download Link: | Click here to download PDF File Size: 1930 KB |
| Title: | Parallel Realization of Element by Element Analysis of Eddy Current Field Based on Graphic Processing Unit |
| Abstract: | The element by element parallel finite element method (EbE-PFEM) applied to engineering eddy current problem is presented in this paper. Unlike classical finite element method (FEM), only element matrix is needed to store for EbE method. Thereby more storage memory saved. Element by element conjugated gradient (EbE-CG) method is used to solve the equations which are discretized from elements level. Considering the ill-conditioned character of system equations, highly parallel Jacobi preconditioned (JP) method is used to accelerate the convergence. Besides, the process of dealing with boundary condition based on EbE theory is introduced. To validate the method, a 2D eddy current problem in complex frequency domain is used. The numerical analysis is carried out on the graphic processing units (GPU) with a compute unified device architecture (CUDA) parallel programming model to accelerate the convergence. And the results demonstrate that the JP method and GPU platform are effective in solving eddy current field with improved convergence. |
| Author(s): | D. Wu, X. Yan, R. Tang, D. Xie, Z. Ren |
| File Type: | Journal Paper |
| Issue: | Volume: 33 Number: 2 Year: 2018 |
| Download Link: | Click here to download PDF File Size: 1590 KB |
| Title: | GPU-based Electromagnetic Optimization of MIMO Channels |
| Abstract: | Strategies to accelerate MIMO channel capacity optimization on GPUs are outlined. The optimization scheme is dealt with by properly facing the main computational issues. In particular, the propagation environment is described by ultrafast Geometrical Optics (GO), singular values are computed by a very fast scheme and the optimizer is a parallel version of the differential evolutionary algorithm. The unknowns are given proper representations to reduce the number of optimization parameters. |
| Author(s): | A. Breglia, A. Capozzoli, C. Curcio, S. Di Donna, A. Liseno |
| File Type: | Journal Paper |
| Issue: | Volume: 33 Number: 2 Year: 2018 |
| Download Link: | Click here to download PDF File Size: 1635 KB |
| Title: | Fast and Parallel Computational Techniques Applied to Numerical Modeling of RFX-mod Fusion Device |
| Abstract: | This paper presents fast computational techniques applied to modelling the RFX-mod fusion device. An integral equation model is derived for the current distribution on the active coils of the conducting structures, and the input-output transfer functions are computed. Speed-up factors of about 200 can be obtained on hybrid CPU-GPU parallelization against uniprocessor computation. |
| Author(s): | D. Abate, B. Carpentieri, A. G. Chiariello, G. Marchiori, N. Marconato, S. Mastrostefano, G. Rubinacci, S. Ventre, F. Villone |
| File Type: | Journal Paper |
| Issue: | Volume: 33 Number: 2 Year: 2018 |
| Download Link: | Click here to download PDF File Size: 1517 KB |
| Title: | Parallel Implementations of Multilevel Fast Multipole Algorithm on Graphical Processing Unit Cluster for Large-scale Electromagnetics Objects |
| Abstract: | This paper investigates solving large-scale electromagnetic scattering problems by using the Multilevel Fast Multipole Algorithm (MLFMA). A parallel implementation for MLFMA is performed on a 12-node Graphics Processing Unit (GPU) cluster that populates NVidia Tesla M2090 GPUs. The details of the implementations and the performance achievements in terms of accuracy, speed up, and scalability are shown and analyzed. The experimental results demonstrate that our MLFMA implementation on GPUs is much faster than (up to 37x) that of the CPU implementation. |
| Author(s): | N. Tran, O. Kilic |
| File Type: | Journal Paper |
| Issue: | Volume: 33 Number: 2 Year: 2018 |
| Download Link: | Click here to download PDF File Size: 1785 KB |
| Title: | Effect of Lorentz Force on Motion of Electrolyte in Magnesium Electrolysis Cell |
| Abstract: | Magnesium production process is highly energy intensive. Electrolysis process provides an effective route to reduce the energy consumption. In this paper, a three-dimensional electro-magneto-hydrodynamics coupling model of a 120 kA magnesium electrolysis cell using finite element method is presented. In this model, the electric field, magnetic field, and flow field are included. This paper concerns the effects of the Lorentz force on the motion of the electrolyte in the cell. The model predicts that the magnitude of Lorentz force is at its maximum near the region between the anode and cathode. The direction of the Lorentz force is beneficial to the motion of the electrolyte in the magnesium electrolysis cell. |
| Author(s): | C.-L. Liu, Z. Sun, G.-M. Lu, X.-F. Song, J.-G. Yu |
| File Type: | Journal Paper |
| Issue: | Volume: 33 Number: 2 Year: 2018 |
| Download Link: | Click here to download PDF File Size: 1965 KB |
| Title: | Metamaterial-Inspired Split Ring Monopole Antenna for WLAN Applications |
| Abstract: | This paper describes the design of a compact dual band monopole antenna for WLAN (2.4/5.2/5.8 GHz) applications. The antenna is printed on a 22.5×24×0.8 mm3 FR-4 substrate with a partial ground plane and is fed by a microstrip line. The proposed structure consists of a simple hexagonal ring with a split arm along its center. The split in the arm in turn creates a quarter wavelength resonance in the higher frequency range. It also induces magnetic resonance which accounts for band notch between the WLAN lower (2.4 GHz) and upper bands (5.2/5.8 GHz). The extraction of negative permeability of the split ring structure is also discussed. A prototype of the proposed structure is fabricated and the measured results comply greatly with the simulated results. The antenna has consistent radiation pattern and stable gain over all the working region. |
| Author(s): | S. I. Rosaline, S. Raghavan |
| File Type: | Journal Paper |
| Issue: | Volume: 33 Number: 2 Year: 2018 |
| Download Link: | Click here to download PDF File Size: 1854 KB |
| Title: | The Equivalent Circuit Extraction and Application for Arbitrary Shape Graphene Sheet |
| Abstract: | In this work, for the first time the electromagnetic features of graphene are characterized by a circuit model derived instead of fitted from the electric field integral equation (EFIE). The atomically thick graphene is equivalently replaced by an impedance surface. When it is magnetized, the impedance surface is anisotropic with a tensor conductivity. Based on EFIE, the graphene’s circuit model can be derived by the partial element equivalency circuit (PEEC) concept. The anisotropic resistivity is modeled using a serial resistor with current control voltage sources (CCVSs). From the derived circuit model, electromagnetic properties of graphene can be conveniently analyzed. This work also provides a new characterization method for dispersive and anisotropic materials. |
| Author(s): | Y. S. Cao, L. J. Jiang, A. E. Ruehli |
| File Type: | Journal Paper |
| Issue: | Volume: 33 Number: 2 Year: 2018 |
| Download Link: | Click here to download PDF File Size: 1689 KB |
| Title: | A Subwavelength Perfect Absorbing Metamaterial Patch Array Coupled with a Molecular Resonance |
| Abstract: | A perfectly absorbing metamaterial (PAMM) coupled with vibrational modes has varied applications ranging from surface-enhanced vibrational spectroscopy to biological sensing. This endeavor considers a subwavelength PAMM sensor design and analysis using a commercially available finite element method (FEM) solver and analytically with temporal coupled mode theory (TCMT). A carbon double oxygen bond (C=O) at 52 THz or 1733 cm-1 that resides in poly(methyl methacrylate), PMMA, will be used as a stand-in analyte. Normal mode splitting that results from the resonant coupling between the PAMM and analyte’s molecular resonance is investigated and analyzed. |
| Author(s): | M. F. Finch, B. A. Lail |
| File Type: | Journal Paper |
| Issue: | Volume: 33 Number: 2 Year: 2018 |
| Download Link: | Click here to download PDF File Size: 2152 KB |
| Title: | Unmanned Aerial Vehicle Platform Stabilization for Remote Radar Life Sensing |
| Abstract: | Unmanned Aerial Vehicle (UAV) platforms are increasingly ubiquitous and an ideal platform for rapid deployment to conduct remote sensing. However, for radar sensors that measure the phase of the signal of interest, the platform must be stabilized to avoid signal distortion. Measurement of respiratory motion with a continuous wave Doppler radar sensor is vulnerable to platform motion and requires a stable platform and postdetection motion compensation signal processing. We have investigated feedback stabilization techniques via simulation and empirical measurements using a bench top test fixture to remove the motion noise, where we observed a 86% reduction in motion, resulting in a SNR improvement of 29 dB after motion compensation. |
| Author(s): | R. H. Nakata, B. Haruna, S. K. Clemens, D. Martin, C. Jaquiro, V. M. Lubecke |
| File Type: | Journal Paper |
| Issue: | Volume: 33 Number: 2 Year: 2018 |
| Download Link: | Click here to download PDF File Size: 1838 KB |
| Title: | Radar Noise Floor Method for Occupancy Detection |
| Abstract: | A 2.4 GHz continuous wave Doppler radar sensor is utilized to carry out occupancy detection through detection of human presence over an empty room based on time domain root-mean-square (RMS) values. An existing system-on-chip with custom-made baseband board is employed for developing the radio. |
| Author(s): | P. Nuti, E. Yavari, O. Boric-Lubecke |
| File Type: | Journal Paper |
| Issue: | Volume: 33 Number: 2 Year: 2018 |
| Download Link: | Click here to download PDF File Size: 1696 KB |
| Title: | UAV-Radar System for Vital Sign Monitoring |
| Abstract: | Feasibility and fabrication of components of a life-sign radar system on unmanned aerial vehicle (UAV) has been studied. A signal conditioning circuit has been simulated, fabricated, and tested for data preparation and acquisition. Application such as, vitalsign detection, using UAV in real-time requires wireless transmission of baseband data to the monitoring station. Methods have been devised to achieve this goal. A quadrature Doppler radar has been assembled using two single channel x-band MDU1020 radars. The united radars can avoid null point distortion in physiological monitoring. Examinations were performed with both mechanical targets. |
| Author(s): | A. Rahman, Y. Ishii, V. Lubecke |
| File Type: | Journal Paper |
| Issue: | Volume: 33 Number: 2 Year: 2018 |
| Download Link: | Click here to download PDF File Size: 2020 KB |
| Title: | Efficient Electromagnetic Simulation Including Thin Structures by Using Multi-GPU HIE-FDTD Method |
| Abstract: | This paper describes an efficient simulation method to solve the large scale electromagnetic problems with thin unit cells in the finite-difference time-domain (FDTD) simulation. The proposed method is based on the hybrid implicit-explicit and multi-GPU techniques, which can choose a larger time step size than that in the conventional one, and using the multiple graphic processing units (GPUs). In the proposed method, the computational time is significantly reduced. |
| Author(s): | Y. Inoue, H. Asai |
| File Type: | Journal Paper |
| Issue: | Volume: 33 Number: 2 Year: 2018 |
| Download Link: | Click here to download PDF File Size: 1554 KB |
| Title: | On The Beam Forming Characteristics of Linear Array Using Nature Inspired Computing Techniques |
| Abstract: | Beamforming is a serious problem in wireless communication. Many deterministic and numerical techniques are proposed to achieve beamforming. However, the application of evolutionary computing techniques produced better results over many existing conventional methods. In this paper, one such attempt of applying a novel nature-inspired technique known as Firefly algorithm (FFA) to demonstrate beamforming in linear arrays and compared with particle swarm optimization (PSO). The desired objectives of the synthesis process are defined as sidelobe level (SLL) suppression and null positioning. The optimal set of amplitude distribution for the elements in the linear array is obtained using the technique in order to achieve the desired objectives. The results are evaluated in terms of radiation pattern plots. |
| Author(s): | S. Mubeen, A. M. Prasad, A. Jhansi Rani |
| File Type: | Journal Paper |
| Issue: | Volume: 33 Number: 2 Year: 2018 |
| Download Link: | Click here to download PDF File Size: 1688 KB |
| Title: | Bandwidth Enhancement of Dipole Antennas using Parasitic Elements |
| Abstract: | Dipole antennas have a limited bandwidth which restricts their use to narrow bandwidth applications. To improve the functionality of a dipole antenna, additional wire elements can be added to the dipole antenna to increase the impedance matching and bandwidth. A design for a modified dipole antenna is proposed and analyzed using multiple computational electromagnetic software to determine how the additional wire elements affect the input impedance bandwidth and radiated fields. The antenna was then fabricated and tested and compared to simulation results. The modified dipole antenna shows a bandwidth improvement of more than four times, approaching 31%, while maintaining radiation patterns similar to a traditional dipole antenna with slightly higher gain. |
| Author(s): | G. Hoch, A. Elsherbeni, P. Nayeri |
| File Type: | Journal Paper |
| Issue: | Volume: 33 Number: 2 Year: 2018 |
| Download Link: | Click here to download PDF File Size: 1843 KB |
| Title: | CUDA-MPI Implementation of Fast Multipole Method on GPU Clusters for Dielectric Objects |
| Abstract: | This paper investigates the Fast Multipole Method (FMM) for large-scale electromagnetics scattering problems for dielectric objects. The algorithm is implemented on a Graphical Processing Unit (GPU) cluster using CUDA programming and Message Passing Interface (MPI). Its performance is investigated in terms of accuracy, speedup, and scalability. The details of the implementation and the performance achievements are shown and analyzed, demonstrating a scalable parallelization while maintaining a good degree of accuracy. |
| Author(s): | N. Tran, T. Phan, O. Kilic |
| File Type: | Journal Paper |
| Issue: | Volume: 33 Number: 2 Year: 2018 |
| Download Link: | Click here to download PDF File Size: 1908 KB |
| Title: | Vector Control of PMSM Take Over by Photovoltaic Source |
| Abstract: | This article established with the modeling and the field oriented control of permanent magnet synchronous machines, with a focus on their applications in variable speed domain in photovoltaic source. |
| Author(s): | T. Yuvaraja, K. Ramya |
| File Type: | Journal Paper |
| Issue: | Volume: 33 Number: 2 Year: 2018 |
| Download Link: | Click here to download PDF File Size: 1641 KB |
| Title: | Non-uniform Surface Impedance Absorbing Boundary Condition for FDTD Method |
| Abstract: | Recently, we reported a novel absorbing boundary condition (ABC), surface impedance absorbing boundary (SIABC). SIABC has a comparable absorbing performance compared to CPML, but requires a sufficient long distance between the boundary and the scatter. In this paper, we focus on this issue and introduce the nonuniform SIABC. Non-uniform SIABC archives a similar absorbing performance as the uniform SIABC at a same distance, while the number of the air buffer cells is much smaller. Therefore, it is possible for us to make it more efficient relative to uniform SIABC or CPML. An example of a patch antenna is discussed to explore the accuracy and efficiency of non-uniform SIABC. We also compare the memory usage for uniform SIABC, nonuniform SIABC, and 10-layers CPML. All the results indicate that non-uniform SIABC requires much less memory, needs much less time for simulations, which makes it a potential of being one of the most popular ABCs in FDTD method. |
| Author(s): | Y. Mao, A. Z. Elsherbeni, S. Li, T. Jiang |
| File Type: | Journal Paper |
| Issue: | Volume: 33 Number: 2 Year: 2018 |
| Download Link: | Click here to download PDF File Size: 1586 KB |
| Title: | Time-Dependent Adjoint Formulation for Metamaterial Optimization using Petrov-Galerkin Methods |
| Abstract: | A time-dependent discrete adjoint algorithm for electromagnetic problems is presented. The governing equations are discretized with a semi-discrete Petrov- Galerkin method. Time advancement is accomplished using an implicit, second-order backward differentiation formula (BDF2). An all-dielectric metamaterial is proposed and gradient-based shape design optimization is conducted. Hicks-Henne functions are utilized for shape parameterization to ensure smooth surfaces, and linear elasticity employed to adapt interior mesh points to boundary modifications. The cost function used in the design optimization attempts to widen the bandwidth of the metamaterial over a desired frequency range. Optimization results demonstrate an increase of the full width at half maximum (FWHM) of reflection from 111 THz to 303 THz. |
| Author(s): | X. Zhang, J. C. Newman III, W. Lin, W. K. Anderson |
| File Type: | Journal Paper |
| Issue: | Volume: 33 Number: 2 Year: 2018 |
| Download Link: | Click here to download PDF File Size: 1788 KB |
| Title: | A Non-Focal Rotman Lens Design to Support Cylindrically Conformal Array Antenna |
| Abstract: | Rotman lenses offer broad bandwidth, and render to planar structures making them ideal for a variety of applications. However, a limitation of the Rotman lens is that it is based on the assumption of supporting linear arrays. In this paper, we develop a new design technique to enable the lens to feed a conformal array antenna. |
| Author(s): | T. K. Vo Dai, T. Nguyen, O. Kilic |
| File Type: | Journal Paper |
| Issue: | Volume: 33 Number: 2 Year: 2018 |
| Download Link: | Click here to download PDF File Size: 1815 KB |
| Title: | Efficient MCF Evaluation in a Turbulent Atmosphere over Large Structure Constant Interval |
| Abstract: | A fast and accurate method is derived and simulated to compute the mutual coherence function (MCF) of an electromagnetic beam wave propagating through atmospheric turbulence over a large interval of structure constant. This method is based on expanding the integral equation solution for one value of structure constant into its Pade’ approximation to cover large fluctuation interval. The expansion is compared with numerical results, and a very good agreement was obtained. Such computations are important in practical fields as remote sensing, imaging systems, and optical communications. |
| Author(s): | N. A. Abu-Zaid |
| File Type: | Journal Paper |
| Issue: | Volume: 33 Number: 2 Year: 2018 |
| Download Link: | Click here to download PDF File Size: 1777 KB |
| Title: | Multi-Frequency T-Slot Loaded Elliptical Patch Antenna for Wireless Applications |
| Abstract: | In this paper, a multi frequency microstrip antenna (MSA) for wireless applications is designed. The proposed MSA comprised of elliptical patch antenna with T-slot. This antenna is fed by coaxial probe. The design parameters are major and minor axis of elliptical patch, length and width of T-slot and feeding point of probe. The proposed antenna can provide optimized multi frequency by varying the above design parameters. FR-4 substrate with dielectric constant 4.4 is chosen. The multi frequencies are 1.57 GHz, 1.96 GHz and 3.4 GHz, which covers the applications such as GPS and 4G LTE. The simulation of the antenna is performed using the ANSOFT HFSS and it is analyzed for S11 (dB) and radiation pattern. The prototype antenna is fabricated for optimized dimensions and tested using vector network analyzer. Simulation and experimental results are compared with each other. |
| Author(s): | S. Murugan, B. Rohini, P. Muthumari, M. Padma Priya |
| File Type: | Journal Paper |
| Issue: | Volume: 33 Number: 2 Year: 2018 |
| Download Link: | Click here to download PDF File Size: 1861 KB |