Vol. 118
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2011-07-14
PIER
Vol. 118, 527-539, 2011
A Grating-Based Plasmon Biosensor with High Resolution
Ziqian Luo Taikei Suyama Xun Xu Yoichi Okuno
We present an idea of grating-based plasmon biosensor utilizing phase detection to realize high resolution in finding a refractive index of a material put on the surface of a metal grating. Considering a trade-off between high resolution and experimental practicability, we show a table of recommended setup that covers a wide range of the index. Keeping the diffraction efficiency no less than 10-3 and assuming the resolution in phase detection to be 2.5x10-2 degrees, we estimate the resolution of the biosensor as 7.5x10-7 refractive index units. We also discuss the possible improvement to realize a predicted superior limit of resolution around 10-8.
2011-07-14
PIER
Vol. 118, 505-525, 2011
RCS Computation Using a Parallel in-Core and Out-of-Core Direct Solver
Daniel Garcia-Donoro Ignacio Martinez-Fernandez Luis E. Garcia-Castillo Yu Zhang Tapan Kumar Sarkar
Application to RCS computation of a higher order solver based on the surface integral approach is presented. The solver uses a direct method to solve the corresponding algebraic system of equations. Two versions of the solver are available: in-core and out-of-core. Both are efficiently implemented as parallel codes using Message Passing Interface libraries. Several benchmark structures are analyzed showing the reliability, performance, and versatility to run in a wide variety of computer platforms, of the solver. The results shown are illustrative of what is the maximum frequency of analysis of the structures for a given type of simulation platform.
2011-07-13
PIER
Vol. 118, 487-504, 2011
Study of Nonreciprocal Devices Using Three-Strip Ferrite Coupled Line
Wojciech Marynowski Jerzy Mazur
This paper presents the investigations of nonreciprocal devices employing a novel ferrite coupled line junction. The structure is designed using coplanar line technology with the ground half-planes reduced to the strips. The investigated junction is composed of one ferrite section placed in between of two dielectric sections. In the ferrite section the longitudinally magnetized ferrite slab is located at the top or the bottom of the strips and is covered with the dielectric layers. In the dielectric sections the ports of the junctions are located. The wave parameters and field distributions of the modes propagated in the dielectric and ferrite sections are obtained from spectral domain approach. In order to determine the scattering matrix of the junction the mode matching method is utilized. The investigation of the circulator and isolator designed based on the S-matrix of the junction are presented. The obtained results are verified by comparing them with HFSS simulations and own measurements of the fabricated devices. In both cases a very good agreement is observed.
2011-07-13
PIER
Vol. 118, 461-486, 2011
A Bimodal Reconstruction Method for Breast Cancer Imaging
Daniel Flores-Tapia Martin O'Halloran Stephen Pistorius
Breast Microwave Radar (BMR) has been proposed as an alternative modality for breast imaging. This technology forms a reflectivity map of the breast region by illuminating the scan area using ultra wide band microwave waveforms and recording the reflections from the breast structures. Nevertheless, BMR images require to be interpreted by an experienced practitioner since the location and density of the breast region can make the detection of malignant lesions a difficult task. In this paper, a novel bimodal breast imaging reconstruction method based on the use of BMR and Electrical Impedance Tomography (EIT) is proposed. This technique forms an estimate of the breast region impedance map using its corresponding BMR image. This estimate is used to initialize an EIT reconstruction method based on the monotonicity principle. The proposed method yielded promising results when applied to MRI-derived numeric breast phantoms.
2011-07-13
PIER
Vol. 118, 441-459, 2011
Attenuation in Extended Structures Coated with Thin Magneto-Dielectric Absorber Layer
Marina Koledintseva Alexander G. Razmadze Aleksandr Y. Gafarov Victor V. Khilkevich James Drewniak Takanori Tsutaoka
Thin absorbing layers containing magnetic alloy or ferrite inclusions can be effectively used for attenuating common-mode currents on extended structures, such as power cords, cables, or edge-coupled microstrip lines. An analytical model to evaluate attenuation on the coaxial line with the central conductor coated with a magneto-dielectric layer is proposed and validated by the experiments and numerical modeling. The analytical model is validated using available magneto-dielectric samples of different thicknesses. This model can serve for comparing and predicting the absorptive properties of different samples of magneto-dielectric materials, whose compositions may be unknown, but dielectric and magnetic properties can be determined by independent measurements over the specified frequency ranges. From modeling the absorption in a coaxial line with a wrapped central conductor, it could be concluded whether it is reasonable to use this particular material in such applications as a shield on an Ethernet or other cable, for reducing potential common-mode currents and unwanted radiation in the frequency range of interest.
2011-07-11
PIER
Vol. 118, 425-440, 2011
Comparison of Surface Integral Equations for Left-Handed Materials
Marta Gomez Araujo Jose Taboada Javier Rivero Fernando Obelleiro
A wide analysis of left-handed material (LHM) spheres with different constitutive parameters has been carried out employing different integral-equation formulations based on the Method of Moments. The study is focused on the accuracy assessment of formulations combining normal equations (combined normal formulation, CNF), tangential equations (combined tangential formulation, CTF, and Poggio-Miller-Chang-Harrington-Wu-Tsai formulation, PMCHWT) and both of them (electric and magnetic current combined field integral equation, JMCFIE) when dealing with LHM's. Relevant and informative features as the condition number, the eigenvalues distribution and the iterative response are analyzed. The obtained results show up the suitability of the JMCFIE for this kind of analysis in contrast with the unreliable behavior of the other approaches.
2011-07-11
PIER
Vol. 118, 415-423, 2011
Polarization-Invariant Directional Cloaking by Transformation Optics
Krishna Agarwal Xudong Chen Li Hu Hongyu Liu Gunther Uhlmann
We propose a three-dimensional directional cloak for arbitrarily polarized incoming electromagnetic waves, motivated by the fact that there will be negligible scattering when the direction of impinging wave coincides with the axial direction of a very thin and elongated perfectly electric conducting (PEC) scatterer. The performance of the cloak under different polarizations of incoming waves are numerically investigated. The case in which the direction of incoming wave is perturbed off the ideal direction is also quantitatively studied. Numerical simulations show that the directional cloaking device is able to tolerate a large range of tilted angles of incoming waves.
2011-07-07
PIER
Vol. 118, 397-414, 2011
A Quasi Three-Dimensional Ray Tracing Method Based on the Virtual Source Tree in Urban Microcellular Environments
Zhong-Yu Liu Li-Xin Guo
The increase in mobile communications traffic has led to heightened interest in the use of ray tracing (RT) methods together with digital building databases for obtaining more accurate and efficient propagation prediction in urban microcellular environments. In this paper, a novel quasi three-dimensional (3-D) RT algorithm is presented by taking into account the advantages of both the image theory (IT) and the shooting-and- bouncing ray (SBR) method. It is based on creating a new virtual source tree in which the relationship between neighbor nodes is a left-son-and-right-brother one. Our theoretical results of the signal path loss along the streets are compared with measurements which have been reported for city streets in Tokyo and Ottawa City for various values of the propagation parameters. The good agreement with these measurements indicates that our prediction model works well for such microcellular communication applications. The proposed method can provide the reliable theory basis for radio-wave propagation prediction and network planning in urban microcellular environments.
2011-07-07
PIER
Vol. 118, 379-396, 2011
Theoretical Investigation of Rectangular Patch Antenna Miniaturization Based on the Dps-Eng BI-Layer Super-Slow TM Wave
Jiang Xiong Hui Li Bing-Zhong Wang Yi Jin Sailing He
The TM0 surface mode in an infinitely long parallel-plate waveguide filled with a double-positive (DPS) and epsilon-negative (ENG) metamaterial bi-layer is studied. With proper constitutive parameters and thicknesses of the two layers, the slow-wave factor (SWF) for such a parallel-plate waveguide can tend to infinity as the frequency decreases. A 2-D cavity based on the DPS-ENG bi-layer waveguide is constructed and studied to evaluate the radiation ability of its corresponding patch antenna. Based on the cavity model analysis of patch antennas, we show that good efficiency for broadside radiation of such a cavity-based rectangular patch antenna can be achieved when one layer of the cavity is shielded (or partially shielded) by PEC boundaries. Taking practical loss and dispersion into consideration, a miniaturized cavity-based rectangular patch antenna is proposed as an example. With the super-slow TM0 surface mode excited in the bi-layer by a simple coaxial line feeding, the antenna has a dimension of only 0.107λ0×0.129λ0×0.045λ0. The patch antenna produces broadside radiation, and fairly good radiation efficiency is achieved. The PEC-Partially-Shielded-ENG-Cavity based rectangular patch antenna with a further miniaturization but reduced radiation efficiency is also discussed.
2011-07-07
PIER
Vol. 118, 355-377, 2011
Field Synthesis in Inhomogeneous Media: Joint Control of Polarization, Uniformity and SAR in MRI b 1-Field
Elia Amedeo Attardo Tommaso Isernia Giuseppe Vecchi
The homogeneity of the amplitude of one of the polarizations of the RF field B1 is a crucial issue in Magnetic Resonance Imaging (MRI), and several methods have been proposed for enhancing this uniformity (Shimming''). The existing approaches aim at controlling the homogeneity of B+1 and limiting the Specific Absorption Rate (SAR) of the RF field by independently controlling magnitude and phase of individual excitation currents in MRI scanners, either birdcage or TEM coil system. A novel approach is presented here which allows a joint control of B+1 uniformity, SAR, and purity of polarization of the total RF B1 field. We propose a convex optimization procedure with convex constraints, and special attention has been devoted to the issue of convexity of the proposed functional. The method is applied to MRI brain imaging; numerical tests have been performed on a realistic head model at low, medium, and high RF field in order to assess the effectiveness of the proposed method. We found that maintaining a specific polarization plays an important role also in maintaining the homogeneity of B+1 amplitude.
2011-07-06
PIER
Vol. 118, 335-354, 2011
Electric Field Discontinuity-Considered Effective-Permittivities and Integration-Tensors for the Three-Dimensional Finite-Difference Time-Domain Method
Yong-Gu Lee
Electric field Discontinuity-Considered Effective-Permittivities and Integration-Tensors (DC-EP&IT) for the three-dimensional Finite-Difference Time-Domain (FDTD) method are derived using a contour-path approach that considers the jump in the electric field at the interface of two dielectric materials. This is a natural but not so obvious extension to the work by Mohammandi et al. [1] from two to three-dimensions. Proposed method is verified by comparing with the exact Mie theory as well as the staircase, volume-averaged and subpixel methods.
2011-07-06
PIER
Vol. 118, 321-334, 2011
Design and Optimization of Equal Split Broadband Microstrip Wilkinson Power Divider Using Enhanced Particle Swarm Optimization Algorithm
Dong Wang Hong Zhang Tanghong Xu Hao Wang Guoguang Zhang
An enhanced particle swarm optimization (EPSO) algorithm is proposed. To improve convergence accuracy and velocity, we introduce a quadratic interpolation method and perturbation to personal best particles in EPSO. Then, a design procedure based on the EPSO is proposed for the design and optimization of equal split broadband microstrip Wilkinson power dividers (MWPDs). A set of numerical examples and fabricated samples are presented to validate the improvement of the proposed EPSO. Even-odd mode analysis is incorporated in the design procedure to calculate the scattering matrix of the MWPD on the basis of the dispersion and dissipation microstrip line model. A fitness function is then constructed according to the scattering parameters. The optimized widths and lengths of microstrip lines and values of isolation resistors are directly obtained by minimizing the fitness function. EPSO is also compared with the genetic algorithm (GA), standard particle swarm optimization (PSO) and improved particle swarm optimization (IPSO).
2011-07-06
PIER
Vol. 118, 303-319, 2011
ANN-Based Pad Modeling Technique for MOSFET Devices
Xiuping Li Yushan Li Junhui Zhao
In this paper, an approach for the pad modeling of the test structure for Metal Oxide Semiconductor Field Effect Transistor (MOSFET) up to 40\,GHz is presented. The approach is based on a combination of the conventional equivalent circuit model and artificial neural network (ANN). The pad capacitances and series resistors are directly obtained from EM (electromagnetic) simulation of the $S$ parameters with different size of pad and operating frequency. The parasitic elements in the test structure can be modeled by using a sub artificial neural network (SANN). So the pad capacitances and series resistors can be regarded as functions of the dimensions of the pad structure and operating frequencies by using SANN. Good agreement between the ANN-based modeling and EM simulation results has been demonstrated. In order to remove the impact of the parasitic elements, the de-embedding procedure for MOSFET device using ANN-based pad model is also demonstrated.
2011-07-05
PIER
Vol. 118, 287-301, 2011
A Slow Light Fishnet-Like Absorber in the Millimeter-Wave Range
Miguel Navarro-Cia Victor Torres Landivar Miguel Beruete Mario Sorolla Ayza
A novel route to achieve a narrowband free-space electromagnetic absorber in any range of the spectrum based on stacked subwavelength hole arrays is proposed. The absorption is obtained by means of a slow light mode inside a fishnet-like engineered structure and exploiting the unavoidable misalignments and bucklings of the free-standing stack. An incoming pulse becomes permanently trapped in the structure due to the near zero group velocity which causes an enhancement of the radiation-structure interaction that leads to a huge increment of losses arising from the finite conductivity of the metal as well as arrangement tolerances. This approach is studied not only by simulation but also experimentally under normal incidence at millimeter wavelengths. Moreover, a basic grasp about the angular dependence of the structure is given by analyzing the 2D dispersion diagram. It shows that this scheme may also display high absorption under oblique incidence for s-polarization (or TE-polarization), whereas $p$-polarization (TM-polarization) would degrade its performance.
2011-07-05
PIER
Vol. 118, 273-286, 2011
Impedance-Mismatched Hyperlens with Increasing Layer Thicknesses
Xuan Li Yuqian Ye Yi Jin
Structure with non-negative effective permittivities in the radial and tangential directions can also perform far-field imaging beyond the diffraction limit since the dispersion curves can be long and flat enough and utilized to transfer the subwavelength information. Thus we propose an impedance-mismatched hyperlens with such a dispersion curve and increasing thicknesses (from the innermost layer to the outermost) to reduce reflection losses due to the impedance difference between the nearby layer pairs. Compared with the hyperlens with same thickness for each period, the resolution ability of the hyperlens with varying thicknesses can be improved dramatically, while the image intensity is weaker. Furthermore, the influence of the layer number on the imaging is also analyzed to improve the performance of the system and an improved hyperlens with repeated thickness setting is also utilized to increase the intensity of the magnified image.
2011-07-05
PIER
Vol. 118, 253-271, 2011
A Compact Dual-Polarized Broadband Antenna with Hybrid Beam-Forming Capabilities
Hong-Li Peng Wen-Yan Yin Jun-Fa Mao Di Huo Xu Hang Liang Zhou
A broadband dual-polarized four-port (DPFP) antenna is presented in this paper, which consists of a radiation element and a feed network. It is very compact in size, with the diameter of 150.0 mm and the height of 47.0 mm, with the following unique properties: (1) it has hybrid beam-forming capability and operates at two modes, which depends on its excitation; (2) its operating frequency range is from 0.96 to1.78 GHz, and the return loss is about 10 dB; (\ref{eq3}) its insertion loss is (3±0.5) dB, with its balanced power splitting over the relative bandwidths of 37% at Mode 1 (180°±5° phase shifting) and 55% at Mode 2 (±5° phase shifting), respectively; (\ref{eq4}) an isolation of 30 dB at Mode 1 is obtained between the dual polarized ports, with the gain of 7.6 dBi and 42° of the 3 dB-bandwidth at 1.25 GHz; and (5) the gain difference between Modes 1 and 2 is about 7 dB, within the angle of -15° ≤ θ ≤ 15° for the same polarization at 1.25 GHz. For the application of DPFP, a hybrid beam forming algorithm is proposed with an angular precision of 3°, as validated by measurement.
2011-07-03
PIER
Vol. 118, 243-251, 2011
Efficient Proper Orthogonal Decomposition for Backscatter Pattern Reconstruction
Chao-Fu Wang
A novel approach is presented for efficiently solving electromagnetic (EM) scattering problems using proper orthogonal decomposition (POD). As a proof of concept and demonstration of how to use the POD to solve EM scattering problems, two ways of implementing the POD procedure have been proposed and realized for calculating EM scattering from PEC targets. Numerical results obtained show that the POD is quite accurate for reconstructing backscatter patterns over wide range of frequencies and angles of interest based on the given snapshots.
2011-07-03
PIER
Vol. 118, 223-241, 2011
A Higher Order Analysis of a Class of Inhomogeneously Filled Conducting Waveguides
Ehsan Khodapanah Saeid Nikmehr
A higher order analysis is applied to solve the problem of a class of inhomogeneously-filled conducting waveguides. This includes an arbitrary but smooth hollow conducting waveguides and waveguides filled with layered inhomogeneous materials. The method employs a set of spline-harmonic basis functions and leads to one-dimensional integrals for system matrix elements. This fact along with the higher order nature of the basis functions provides an accurate method for the analysis of the aforementioned waveguides. The accuracy and the convergence behavior of the method are studied through several numerical examples and the results are compared with the exact solutions and with the results of Ansoft HFSS simulator to establish the validity of the proposed method.
2011-07-03
PIER
Vol. 118, 205-221, 2011