PIER B | PIER Journals

2008-01-05

PIER B

Vol. 3, 315-329, 2008

download: 214

Autofocus Algorithms Performance Evaluations Using an Integrated SAR Product Simulator and Processor

Tien Sze Lim , Chee Siong Lim , Voon Koo , Hong-Tat Ewe and Hean-Teik Chuah

The design and development of synthetic aperture radar (SAR) system for a particular application often requires redesign of software and hardware to optimize the system performance. In addition, evaluations of the performance of existing autofocus and image formation algorithms are required for the SAR system designers to select a most suitable algorithm for a given image quality requirements. This is a time-consuming taskwithout a reconfigurable and comprehensive software package. Thus, a comprehensive SAR integrated simulator and processor software is needed to aid the system designers in optimizing all the system parameters and performance. This paper presents an integrated SAR simulator and processor (iSARSIMP) software package and the performance of three selected SAR autofocus algorithms has been evaluated as examples to demonstrate the usefulness of the iSARSIMP for SAR system designers. In the performance evaluation, simulated and actual SAR raw data were used for further analysis and comparison of the three selected autofocus algorithms.

AUTOFOCUS ALGORITHMS PERFORMANCE EVALUATIONS USING AN INTEGRATED SAR PRODUCT SIMULATOR AND PROCESSOR

2008-01-05

PIER B

Vol. 3, 295-314, 2008

doi:10.2528/PIERB07121005

download: 223

Optimizing Included Angle of Symmetrical V-Dipoles for Higher Directivity Using Bacteria Foraging Optimization Algorithm

Biswa Mangaraj , Iti Misra and A. Barisal

Recently the social foraging behavior of E. coli bacteria has been used to solve optimization problems. This paper presents an approach involving Bacterial Foraging (BF) to find appropriate included angle (ψ) and there by two other slant angles (θ₁, θ₂) for which the V-dipole provides higher directivity in comparison to straight dipole. Symmetrical V and Straight dipole is analyzed completely using Method of Moments (MoM). MoM codes in MATLAB environment have been developed both for straight dipole and Vdipole to obtain impedance, directivity, and radiation patterns in both E-plane and H-plane. Then MoM codes is coupled with well known Bacteria Foraging Algorithm (BFA) to get best included angle. Moreover, some modification of BFA is done for the faster convergence.

OPTIMIZING INCLUDED ANGLE OF SYMMETRICAL V-DIPOLES FOR HIGHER DIRECTIVITY USING BACTERIA FORAGING OPTIMIZATION ALGORITHM

2008-01-03

PIER B

Vol. 3, 283-293, 2008

doi:10.2528/PIERB07121407

download: 268

Compact UWB Bandnotch Antenna with Transmission-Line-Fed

Mahdi Naghshvarianjahromi

Abstract-In this paper, a compact band-notched UWB planar antenna with Transmission-Line-fed is presented and I'm using a new technique by etching a narrowband resonance H-shape slot in the ground plane of the antenna. This antenna is capable reducing the interference at the WLAN bands by eliminating the 4.85-6.17 GHz band. The proposed antenna has compact size of 16 × 22mm² including the ground plane and because of miniature dimensions, good radiation patterns with monopolar characteristics are obtained in the frequency band of interest i.e., at least 10 dB isolation exists between co-polarization and cross-polarization. The gain is suppressed very well in WLAN bands. The maximum suppression is in 5.4 GHz that is 13.6 dB less than the gain of normal antenna.

COMPACT UWB BANDNOTCH ANTENNA WITH TRANSMISSION-LINE-FED

2007-12-29

PIER B

Vol. 3, 271-281, 2008

doi:10.2528/PIERB07122402

download: 328

Design of Band-Pass Waveguide Filter Using Frequency Selective Surfaces Loaded with Surface Mount Capacitors Based on Split-Field Update FDTD Method

Seyed Mohammad Amjadi and Mohammad Soleimani

A new band-pass narrow-band, miniaturized and single resonance within a wide range of frequency band frequency selective surface structure with lumped capacitors suitable for low frequency and narrowband waveguide filter applications is presented. The filter structure consists of five unit cells in one direction with notch square ring elements each consists of two lumped capacitors placed on the transverse plane of the rectangular waveguide. To reduce the simulation time in design procedure, split-field update FDTD method is used for the analysis of the unit cell of the analogous infinite frequency selective surface at different oblique incidence of plane waves to predict the FSS performance in the waveguide. As an application, a waveguide filter has been designed to be used in an easy to fabricate and inexpensive S-band band-pass filter. By using lumped capacitors, several undesirable higher order resonance frequencies near the dominant resonance frequency are eliminated and the waveguide filter dimensions are reduced considerably in one direction compared with the analogous waveguide filter without lumped capacitors.

DESIGN OF BAND-PASS WAVEGUIDE FILTER USING FREQUENCY SELECTIVE SURFACES LOADED WITH SURFACE MOUNT CAPACITORS BASED ON SPLIT-FIELD UPDATE FDTD METHOD

2007-12-29

PIER B

Vol. 3, 255-269, 2008

doi:10.2528/PIERB07121408

download: 213

Frequency Domain Interference Cancellation for Single Carrier Cyclic Prefix CDMA System

Faisal Al-Kamali , Moawad Ibrahim Dessouky , Basioun Sallam and Fathi Abd El-Samie

In this paper, we propose a low complexity receiver structure for Single-input Multiple-output (SIMO) downlink cyclic prefix CDMA (CP-CDMA) systems. It employs an interference cancellation scheme to suppress the interference caused by the multipath fading channel. Also, the proposed scheme is developed for Multiple-input Multiple-output (MIMO) CP-CDMA system. All filters in the proposed receiver are implemented in the frequency domain. The performance of the proposed receiver is studied and compared. Our results show a large performance improvement when using such an interference cancellation scheme relative to the rake receiver, and frequency domain Equalization (FDE).

FREQUENCY DOMAIN INTERFERENCE CANCELLATION FOR SINGLE CARRIER CYCLIC PREFIX CDMA SYSTEM

2007-12-27

PIER B

Vol. 3, 227-253, 2008

doi:10.2528/PIERB07120803

download: 222

Combination of Mls , GA & Cg for the Reduction of RCS of Multilayered Cylindrical Structures Composed of Dispersive Metamaterials

Homayoon Oraizi and Ali Abdolali

In this paper the electromagnetic wave scattering from multilayered cylindrical structures is studied for a normally incident plane wave with linear (TE or TM), circular and elliptical polarizations. The cylindrical layers may be composed of any combination of dispersive common materials and metamaterials. The addition theorems for the cylindrical waves are used for the EM wave analysis. The objective of this study is to decrease or increase the Radar Cross Section (RCS) in an ultra wide band width. The optimization is based on the Method of Least Squares (MLS), employing a novel combination of the Genetic Algorithm (GA) and Conjugate Gradient (CG), where the global search for the minimization point is performed by GA and the local search is done by CG, which greatly speeds up the search algorithm. The behaviors of various combinations of common materials and metamaterials for reduction of RCS are studied. Furthermore, the procedures for selection of correct signs for metamaterial parameters, namely ε, μ, k and η are presented.

COMBINATION OF MLS , GA & CG FOR THE REDUCTION OF RCS OF MULTILAYERED CYLINDRICAL STRUCTURES COMPOSED OF DISPERSIVE METAMATERIALS

2007-12-23

PIER B

Vol. 3, 219-226, 2008

doi:10.2528/PIERB07121702

download: 505

Factors Affecting the Performance of the Radar Absorbant Textile Materials of Different Types and Structus

A. Hebeish , M. Elgamel , R. Abdelhady and Abdelmonem Abdelaziz

In the military applications, electro-optics and electromagnetics features of the cloths made of special textile structures and certain fibers play an important role in producing textile characterized with high ability of camouflage. This means not allowing enemy to precisely determine the moving and mute targets using available radar or any other electro-optics sensors. The aim of this paper is to determine the effect of the composite fabrics structure parameters on the fabrication of a resistive sheet used in many radar applications. The objective sheet can be used as a lossy sheet in absorbing mechanism. The radar absorbing mechanism has been studied with emphasis on the single layer structure mechanism with a resistive sheet. Fabric structure of the resistive sheet was accurately chosen and coated with lossy material. For coating, several formulas of fabrics using carbon black were tested to determine the best chemical treatment in accordance with their functional performance. Lab measurements have been done to get optimum formulas and optimum fabrics structures for high radar absorption performance.

FACTORS AFFECTING THE PERFORMANCE OF THE RADAR ABSORBANT TEXTILE MATERIALS OF DIFFERENT TYPES AND STRUCTUS

2007-12-22

PIER B

Vol. 3, 207-218, 2008

doi:10.2528/PIERB07121303

download: 269

New Numerical Method for Determining the Scattered Electromagnetic Fields from Thin Wires

Saeed Hatamzadeh and Mohammad Naser-Moghadasi

In this paper an effective numerical method for determining the scattered electromagnetic fields from thin wires is presented and discussed. This problem is modeled by the integral equations of the first kind. The basic mathematical concept is the method of moments. The problem of determining these scattered fields is treated in detail, and illustrative computations are given for several cases.

NEW NUMERICAL METHOD FOR DETERMINING THE SCATTERED ELECTROMAGNETIC FIELDS FROM THIN WIRES

2007-12-22

PIER B

Vol. 3, 189-206, 2008

doi:10.2528/PIERB07121107

download: 435

Electromagnetic Scattering from Conducting Circular Cylinder Coated by Meta-Materials and Loaded with Helical Strips Under Oblique Incidence

Laila Hady and Ahmed Kishk

The asymptotic strip boundary condition (ASBC) is applied to analyze the solution of the electromagnetic scattering from a conducting cylinder coated with a homogeneous linear material layer and loaded with conducting helical strips. Such homogeneous material layer can be implemented by a conventional dielectric material, a single negative (SNG) or double negative (DNG) meta-material layer. A study of different materials' constitutive parameters is presented with accordance to Drude and Lorentz material modeling. The boundary condition assumes that the strips are rounded around the coated cylinder in a helical form and both the strip's period and the spacing between the helix turns are very small and mathematically approaching the zero. Scattering due to normal and oblique incident plane waves (θ_i, φ_i) of arbitrary polarization using the series solution is also computed. A number of parametric studies were investigated to illustrate the advantages of using metamaterials compared with conventional coating materials in terms of strip's rounding pitch angle and coating layer electrical thickness variations. It is also shown that for SNG materials, modified Bessel functions are used to accept negative arguments. Coating with metamaterials proves to achieve higher forward scattering compared with conventional materials for the same electrical coating thickness.

ELECTROMAGNETIC SCATTERING FROM CONDUCTING CIRCULAR CYLINDER COATED BY META-MATERIALS AND LOADED WITH HELICAL STRIPS UNDER OBLIQUE INCIDENCE

2007-12-20

PIER B

Vol. 3, 173-187, 2008

doi:10.2528/PIERB07120405

download: 208

Bandwidth Considerations for a Microstrip Reflectarray

Marek Bialkowski and Khalil Sayidmarie

The paper describes a theoretical investigation into a limited bandwidth operation of a microstrip reflectarray. Two main factors limiting the bandwidth are considered. One is related to the requirement of phase compensation to convert a spherical wavefront launched by a feed into a planar wavefront. The other one is linked to the limited phasing range of microstrip antenna elements. The two factors contribute to the reflectarray phasing errors that in turn reduce its gain as a function of frequency. Simple formulas for an upper bound of gain bandwidth are derived, assuming the phase compensation by the elements is independent of frequency changes and verified against the results produced by other researchers. It is shown that the phase errors incurred in the path equalization to obtain conversion from spherical to planar wavefronts have a more profound effect on the reduction of operational bandwidth of the reflectarray than the phase truncation implemented on the required phase from each element.

BANDWIDTH CONSIDERATIONS FOR A MICROSTRIP REFLECTARRAY

2007-12-19

PIER B

Vol. 3, 157-172, 2008

doi:10.2528/PIERB07121404

download: 304

An Integral Equation Modeling of Electromagnetic Scattering from the Surfaces of Arbitrary Resistance Distribution

Saeed Hatamzadeh and Mohammad Naser-Moghadasi

In this paper the problem of electromagnetic scattering from the resistive surfaces is carefully surveyed. We model this problem by the integral equations of the second kind. A new set of orthogonal basis functions is used to solve these integral equations via collocation method. Numerical solutions of these equations are given for some cases of resistance distributions. Presented method in this paper can be easily generalized to apply to other cases.

AN INTEGRAL EQUATION MODELING OF ELECTROMAGNETIC SCATTERING FROM THE SURFACES OF ARBITRARY RESISTANCE DISTRIBUTION

2007-12-19

PIER B

Vol. 3, 143-156, 2008

doi:10.2528/PIERB07120901

download: 218

Analysis of Periodically Loaded Suspended Substrate Structures in Millimeter Wave

Masum Fardis and Ramin Khosravi

This paper presents a comprehensive study on the hybrid mode analysis of a periodic structure in a Suspended Microstrip and Broadside-coupled Suspended Stripline. The analysis has been use of Floquet's theorem in special harmonics to express the field equations in various sub regions of the periodic loaded suspended substrate. Their characteristic equation is derived, using the Galerkin's procedure. The unknown electric field distribution in the substrate region, corresponding to one unit cell of the periodic structure is specified in terms of suitable basis functions. The characteristic of slow wave properties, resonance behavior and the passband-stopband characteristics are at the millimeter wave frequencies as a various structural parameters are presented.

ANALYSIS OF PERIODICALLY LOADED SUSPENDED SUBSTRATE STRUCTURES IN MILLIMETER WAVE

2007-12-18

PIER B

Vol. 3, 131-141, 2008

doi:10.2528/PIERB07121003

download: 225

Novel Design of Dual -Mode Bandpass Filter Using Rectangle Structure

Li-Peng Zhao , Xin Zhai , Bian Wu , Tao Su , Wei Xue and Chang-Hong Liang

A compact dual-mode filter is proposed by using rectangle structure. The filter has the characteristics of compact structure,lo w insertion loss and so on. Several attenuation poles in the stopband are realized to improve the selectivity of the proposed bandpass filter. The experimented results were in good agreement with simulated results.

NOVEL DESIGN OF DUAL -MODE BANDPASS FILTER USING RECTANGLE STRUCTURE

2007-12-18

PIER B

Vol. 3, 115-130, 2008

doi:10.2528/PIERB07120403

download: 269

An Effective Excitation Matching Method for the Synthesis of Optimal Compromises Between Sum and Difference Patterns in Planar Arrays

Paolo Rocca , Luca Manica and Andrea Massa

In this paper, the extension of the Contiguous Partition Method (CPM) from linear to planar arrays is described and assessed. By exploiting some properties of the solution space, the generation of compromise sum-difference patterns is obtained through an optimal excitation matching procedure based on a combinatorial method. The searching of the solution is carried out thanks to an efficient path-searching algorithm aimed at exploring the solution space represented in terms of a graph. A set of representative results are reported for the assessment as well as for comparison purposes.

AN EFFECTIVE EXCITATION MATCHING METHOD FOR THE SYNTHESIS OF OPTIMAL COMPROMISES BETWEEN SUM AND DIFFERENCE PATTERNS IN PLANAR ARRAYS

2007-12-17

PIER B

Vol. 3, 95-104, 2008

doi:10.2528/PIERB07120601

download: 195

To Analyze Inhomogeneous Planar Layers by Cascading Thin Linear Layers

Mohammad Khalaj-Amirhosseini

A new method is introduced to analyze lossy Inhomogeneous Planar Layers (IPLs) for both TE and TM polarizations in this paper. The IPLs are subdivided into several thin linear layers instead of uniform ones. The chain parameter matrix of linear layers is obtained by expressing the electric and magnetic fields in power series expansion. This method is applicable to all arbitrary lossy IPLs. The accuracy of the proposed method is verified using a comprehensive example.

TO ANALYZE INHOMOGENEOUS PLANAR LAYERS BY CASCADING THIN LINEAR LAYERS

2007-12-17

PIER B

Vol. 3, 73-94, 2008

doi:10.2528/PIERB07112502

download: 241

Diffraction of Hybrid Modes in a Cylindrical Cavity Resonator by a Transverse Circular Slot with a Plane Anisotropic Dielectric Layer

Peter Kukharchik , Vladimir Serdyuk and Joseph Titovitsky

A rigorous solution of the homogeneous Maxwell equations for hybrid modes of a microwave cylindrical cavity with a transverse annular slot in the perfectly conducting walls of arbitrary thickness and a plane infinite anisotropic dielectric passing through the slot is constructed based on eigenfunction expansion. In each of the field existence regions (the cavity itself, the interior of a slot and outer space), the field solution is constructed as a superposition of natural piecewise harmonic and exponential modes that allow for reflection and refraction at the plane boundaries of the dielectric.The dependence of the complex wave number of free oscillations of a resonant system on its geometrical parameters and on complex permittivity of the dielectric is investigated. It is shown that a cylindrical cavity with a transverse annular slot is a stable and high-sensitive system for online measuring of dielectric parameters.

DIFFRACTION OF HYBRID MODES IN A CYLINDRICAL CAVITY RESONATOR BY A TRANSVERSE CIRCULAR SLOT WITH A PLANE ANISOTROPIC DIELECTRIC LAYER

2007-12-13

PIER B

Vol. 3, 63-72, 2008

doi:10.2528/PIERB07120404

download: 219

Influence of Even Order Dispersion on Soliton Transmission Quality with Coherent Intereference

Aleksandra Panajotovic , Daniela Milovic and Anjan Biswas

The transmission speed of optical networks strongly depends on the impact of higher order dispersion. In the presence of coherent interference which can't be kept under control by optical filtering, the impact of higher order dispersion becomes more serious. In this paper we give general expressions that describe pulse deformation due to even higher order dispersion in a single-mode fiber. The impulsive responses for even order dispersion in the presence of coherent interference are characterized by symmetrical waveforms with long trailing skirts. Individual and joint influence of second and fourth order dispersion on the transmission quality is studied. Pulse shape and eye diagram are obtained.

INFLUENCE OF EVEN ORDER DISPERSION ON SOLITON TRANSMISSION QUALITY WITH COHERENT INTEREFERENCE

2007-12-12

PIER B

Vol. 3, 47-62, 2008

doi:10.2528/PIERB07112201

download: 584

A Practical Miniaturized U-Slot Patch Antenna with Enhanced Bandwidth

Farhad Gh. Khodaei , Javad Nourinia and Changiz Ghobadi

In this paper, an asymmetric U-slot patch antenna with low probe diameter is presented. It will be shown that reduction in probe diameter causes in reduction in bandwidth. One of the characteristics of this antenna is keeping the bandwidth in 30% in spite of reduction in antenna size and use of low probe diameter compared to antenna presented in [1]. The presented antenna in this paper has been fabricated by pcb technique and tested. The far-field results have also been presented based on simulation and measurement. Although the antenna has high cross polarisation level, in the case of using circular polarisation, the use of this antenna can be recommended because of its reduced size, high impedance bandwidth, high total gain in spite of having low size, and ease of fabrication.

A PRACTICAL MINIATURIZED U-SLOT PATCH ANTENNA WITH ENHANCED BANDWIDTH

2007-12-11

PIER B

Vol. 3, 35-46, 2008

doi:10.2528/PIERB07112703

download: 212

Breast Cancer Detection Using a Hybrid Finite Difference Frequency Domain and Particle Swarm Optimization Techniques

Saber Zainud-Deen , Walaa Hassan , Emadeldeen Hassan and Kamal Awadalla

A hybrid technique based on Finite-difference frequency domain and particle swarm optimization techniques is proposed to reconstruct the breast cancer cell dimension and determines its position. Finite-difference frequency domain is formulated to calculate the scattered field after illuminating the breast by a microwave transmitter. Two-dimensional and three-dimensional models for the breast are used. The models include randomly distributed fatty breast tissue, glandular tissue, 2-mm thick skin, as well as chest wall tissue. The models are characterized by the dielectric properties of the normal breast tissue and malignant tissue at 800 MHz. Computer simulations have been performed by means of a numerical program; results show the capabilities of the proposed approach.

BREAST CANCER DETECTION USING A HYBRID FINITE DIFFERENCE FREQUENCY DOMAIN AND PARTICLE SWARM OPTIMIZATION TECHNIQUES

2007-12-11

PIER B

Vol. 3, 23-34, 2008

doi:10.2528/PIERB07112906

download: 223

Electromagnetic Scattering from Two Eccentric Metamaterial Cylinders with Frequency-Dependent Permittivities Differing Slightly Each Other

Constantinos Valagiannopoulos

The interaction between a metamaterial cylindrical structure and an incident plane wave is investigated. The structure is comprised of two cylinders, one embedded into the other, whose effective characteristics vary with the operating frequency following similar laws. Such a model can be used to describe periodic structures, constituting metamaterials, with slightly different features. The well-known eigenfunction expansions are adopted, while the boundary conditions are manipulated with help of the translation theorem for cylindrical coordinates. A first-order perturbation solution is obtained leading to simple and computationally efficient formulas. The fluctuations of near-field and far-field responses with respect to the position of the internal cylinder, the permittivities and the frequency are observed and discussed.

ELECTROMAGNETIC SCATTERING FROM TWO ECCENTRIC METAMATERIAL CYLINDERS WITH FREQUENCY-DEPENDENT PERMITTIVITIES DIFFERING SLIGHTLY EACH OTHER

2007-12-08

PIER B

Vol. 3, 1-22, 2008

doi:10.2528/PIERB07112806

download: 228

Quasi-Static Models Based on Artificial Neural Neworks for Calculating the Characteristic Parameters of Multilayer Cylindrical Coplanar Waveguide and Strip Line

Celal Yildiz and Mustafa Turkmen

In this paper, two different neural models are proposed for calculating the quasi-static parameters of multilayer cylindrical coplanar waveguides and strip lines. These models were basically developed by training the artificial neural networks with the numerical results of quasi-static analysis. Neural models were trained with four different learning algorithms to obtain better performance and faster convergence with simpler structure. When the performances of neural models are compared with each other, the best test results are obtained from the multilayered perceptrons trained by the Levenberg- Marquardt algorithm. The results obtained from the neural models are in very good agreements with the theoretical results available in the literature.