A hybrid method of boundary element method (BEM) combined with conformal transformation (CT) is presented to calculate the capacitance of the unscreened slab lines. Conformal transformation transforms the infinite boundary boundary-value problem with the unscreened slab line into a finite boundary one that can be solved by the BEM, then the capacitance of the unscreened slab line is obtained by the BEM. Three representative computational examples, unscreened cylindrical single-bar slab line, unscreened rectangular single-bar slab line and unscreened cylindrical-bar coupled slab line, are given to validate the accuracy and efficiency of the CT-BEM hybrid method.

Polarimetric SAR Interferometry can be used for parameter inversion of ground. An appropriate model is of most importance for parameters inversion. This paper derives a series of scattering model that can be used for parameter inversion of forestry area, such as RV, RVoG, OV and OVoG. These models can reveal the characteristics of forestry area as well as establish the relationship between observed data and parameters of test area. Finally, a multi-layer random scattering model that can be used for parameter inversion of forestry area containing a man-made target is derived. An improved model is examined by the simulated data of the singlebaseline polarimetric SAR interferometry. The result turns out that the improved RVoG scattering model is correct.

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.

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).

Radiation of a Hertzian dipole in a short-ended conducting circular cylinder with narrow circumferential slots is presented. Modematching and Fourier transform were utilized to derive a system of simultaneous equations for modal coefficients. Computations were performed to confirm the fast convergence of the series solution.

A novel uni-planar electromagnetic Band Gap (EBG) structure incorporated with inter-digital capacitor and meandered line inductor (ML-ID-EBG) is presented, this novel structure significantly enlarges the fringe capacitance to reduce sized cells, as well as increases the equivalent inductance to widen the relative bandwidth. Its design is detailed in this paper, and several experimental results are presented, the improved properties of the proposed ML-ID-EBG are examined, as compared with a conventional UC-EBG and a novel EBG incorporated only with inter-digital capacitor (ID-EBG).

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.

An ultra-wideband (UWB) U type monopole antenna fed by a coplanar waveguide (CPW) is proposed. It has low profile and very compact size (14.48mm×28.74mm×0.8 mm). It provides an wide impedance bandwidth ranging from 3.08 GHz to about 12.75 GHz adjustable by variation of its parameters, such as the relative permittivity and thickness of the substrate, width, and feed and ground plane dimensions. Parametric study is presented. Details of the proposed ultra-wideband design are described. Simulation results are presented and discussed in this paper.

The adiabatic parameter dynamics of non-Kerr law optical solitons is obtained in this paper by the aid of soliton perturbation theory. The various kinds of perturbation terms that arise exhaustively in the context of optical solitons are considered in this paper. The new conserved quantity is also used to obtain the adiabatic dynamics of the soliton phase in all cases of non-Kerr laws studied in this paper. The non-Kerr law nonlinearities that are considered in this paper are power law, parabolic law as well as the dual-power law.

A tunnel diode integrated E-shaped patch antenna is proposed and analyzed using equivalent circuit concept. It is found that bias voltage of tunnel diode controls the performance of the antenna. Various tunable frequency bands are obtained by selecting suitable bias voltage while antenna topology remains unchanged. Bandwidth of the tunnel diode integrated patch improves to 40.26% over the 32.58% bandwidth of the patch. The radiation pattern also varies with bias voltage and a considerable improvement in beamwidth is observed however radiated power remains almost same.

This paper presents a square cylindrical monopole antenna easily fabricated using a cross-shaped metal plate for wideband omnidirectional operation. A prototype of the proposed antenna with a cross-sectional area of 8 × 8mm² is implemented, and the antenna provides a wide operating bandwidth of about 7.5 GHz (1.8-9.4 GHz here), making it very promising for WMAN operation with the 802.16e standard in the 2 to 6 GHz. In addition, over the operating bandwidth, the antenna shows very good omnidirectional radiation patterns.

The estimation of the directions-of-arrival (DoAs) of multiple signals is a topic of great relevance in smart antenna synthesis and signal processing applications. In this paper, a memory-based method is proposed to compute the maximum likelihood (ML) DoA estimates. Such a conceptually-simple technique is based on the datasupported optimization (DSO) and the estimation of signal parameters via rotational invariance technique (ESPRIT), but fully exploits a memory mechanism for improving the estimation accuracy especially when dealing with critical scenarios characterized by low signal-tonoise ratios (SNR) or/and small number of snapshots. Simulation results assess the potentialities and limitations of the proposed approach that favorably compares with state-of-the-art methods.

In this paper, a new evolutionary learning algorithm based on a hybrid of improved real-code genetic algorithm (IGA) and particle swarm optimization (PSO) called HIGAPSO is proposed. In order to overcome the drawbacks of standard genetic algorithm and particle swarm optimization, some improved mechanisms based on non-linear ranking selection, competition and selection among several crossover offspring and adaptive change of mutation scaling are adopted in the genetic algorithm, and dynamical parameters are adopted in PSO. The new population is produced through three approaches to improve the global optimization performance, which are elitist strategy, PSO strategy and improved genetic algorithm (IGA) strategy. The effectiveness of the proposed algorithm has been compared with GAs and PSO, synthesizing a circular array, a linear array and a base station array. Results show that the proposed algorithm is able to adapt itself to different electromagnetic optimization problems more effectively.

The problem of wide bandwidth management in ultra-high resolution SAR systems can be solved by adopting stepped chirps and applying synthetic bandwidth approach. However, high resolution SAR image formation is a non-separable 2-D impulse compression processing, so the synthetic bandwidth procedure should be modified correspondingly with the image formation algorithm adopted. This paper demonstrates the application of synthetic bandwidth approach in SAR Polar Format Algorithm (PFA) using the deramp technique. The problem of motion compensation between the sub-pulses within a burst is discussed, and the signalpro cessing flows are investigated in detail. The presented approach is validated by point target simulation.

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.

In this communication, we theoretically report the reflection properties of a photonic crystal with alternate layers of air and GaAs for specified values of the lattice parameters. By employing the transfer matrix approach, the reflection spectra of the layered media are obtained for chosen sets of number of unit cells and incident angles. It is observed that the photonic crystals with different number of unit cells completely reflect a wide band in the infrared region of radiation. Also, we find that the reflectivity decreases and the completely reflected bands are shifted towards lower wavelength side with increase in the incident angle. Further, the reflected broadbands in the reflection spectra correspond to the forbidden ranges of wavelength obtained by using the analogy of Kronig-Penney model. It indicates that the completely reflected ranges are forbidden bandgaps, which is considered as an important feature of the proposed photonic crystals.

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.

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.

This paper proposes a novel beamforming technique to form an arbitrary-shaped cell for the high altitude platforms (HAPs) mobile communications. The new technique is based on pattern summation of individual low-sidelobe narrow-beams which constitute the desired cell pattern weighted by an amplitude correcting function. The new cell pattern can be adapted to cover the main highways forming worm-shaped cells which may cover the highway for long distances up 100km and it will has an important role in reducing frequent handoffs and signaling traffic of location updating from moving users over the long highways.

The electronic structure of finite parabolic GaAs/Al_xGa_1-xAs superlattices is studied. A detailed analysis of the miniband formation is given and the importance of all system parameters is discussed. The dependence of the equidistant miniband separation on the superlattice size is revealed. A comparison with different theoretical methods and experimental data is presented. The calculations are conducted in the framework of the semi-empirical sp³s^* tight-binding model including spin applying the Green function formalism and the Surface Green Function Matching Method (SGFM) method.