This paper presents a new approach for solving accurate approximate analytical solution for strong nonlinear oscillators. The new algorithm offers a promising approach by Hamiltonian for the nonlinear oscillator. We find that these attained solutions are not only with high degree of accuracy, but also uniformly valid in the whole solution domain.

On the base of conductor-backed coplanar waveguide (CBCPW) structure, a novel CB-CPW structure is proposed and analyzed, which is realized by using the UC-PBG structure to replace the back conductor of CB-CPW. From 1.3 GHz to 2.8 GHz, The transmission characteristic of the proposed CB-CPW is better than that of CBCPW, and is similar to that of CPW, therefore, this novel CB-CPW not only owns the advantage of CB-CPW, such as good mechanical strength and good heat yield, but also owns the advantage of CPW, such as good transmission characteristic. At last, a dual-band antenna based on this novel CB-CPW is designed and computed, the numerical results validate that this novel CB-CPW is feasible in microwave application.

A band pass filter with a linearly periodic refractive index profile is discussed in analogy with Kroning Penney model in band theory of solids. The suggested filter is a one-dimensional ternary periodic structure and provides better control in dispersion relation as compared to a binary structure because it has two more controlling parameters relative to those of the binary one. Since three layers are involved in the formation of band gaps a much broader range of dispersion control is obtained. Both refractive index modulation and optical thickness modulation are considered. A mathematical analysis is presented to predict allowed and forbidden bands of wavelength with variation of angle of incidence. It is also possible to get desired ranges of the electromagnetic spectrum filtered with this structure by manipulating the value of the lattice parameters.

In the view of measuring directional fluctuations of a thin laser beam sent through a heated turbulent jet, an optical method using interference and diffraction with the out coming beam is proposed. The experimental set-up is described. A new technique for separating directional fluctuations of the laser beam is explained. From the measurement of the interference pattern perturbations, are deduced the Rms of the laser beam deflection angle, the spectrum of directional fluctuations of the laser beam, and the value of a scattering coefficient characterizing the heated turbulent jet. The measured spectrum reveals a -8/3 power law and the value obtained for that coefficient is nearly equal to that found in previous works. This agreement enables to conclude that the experimental technique used is efficient and satisfactory.

We experimentally studied the guidance properties of the S-shaped metamaterial slabs. A peek of transmitted power due to the bulk guidance modes is observed in the negative band of the metamaterial, which is larger than a conventional dielectric waveguide made of FR4. The peek transmission frequency is shown related with the change of the negative band of the S-shaped metamaterial slab. Our results show good agreement with the theoretical predictions.

Ametho d based on concurrent neuro-fuzzy system (CNFS) is presented to calculate simultaneously the resonant frequencies of the rectangular, circular, and triangular microstrip antennas (MSAs). The CNFS comprises an artificial neural network (ANN) and an adaptive-network-based fuzzy inference system (ANFIS). In a CNFS, neural network assists the fuzzy system continuously (or vice versa) to compute the resonant frequency. The resonant frequency results of CNFS for the rectangular, circular, and triangular MSAs are in very good agreement with the experimental results available in the literature.

A novel slot antenna that consists of an H-shaped slot encompassed by a rectangular metallic wall and a pair of C-shaped slots outside the wall is proposed. It features a unidirectional pattern, small electrical dimensions and medium gain. The H-shaped slot radiates as an inductively loaded magnetic dipole while the induced electric currents on the vertical wall radiates as electric dipoles. The front-to-back ratio (FBR) of the antenna can be controlled by proper constructive and destructive interferences of radiating fields of the magnetic and electric dipoles. The size of the ground plane can be reduced by the use of the C-shaped slots that confine the currents to the proximity of the metallic wall. Two prototype antennas operating at 2.4 GHz were designed. By adjusting the structure parameters, the front-to-back ratio of the antenna can be conveniently altered. The first prototype has an impedance bandwidth (BW) of 3.8% for SWR ≤ 2, a 4.6 dBi gain, a 10-dB FBR and a ground size of 0.84λ₀ × 0.64λ₀ where λ₀ is the free-space wavelength at the center frequency. The corresponding figures of the second prototype are 1.83%, 4.1 dBi, over 20 dB and 0.64λ₀ × 0.64λ₀. Both antennas have a height of 0.128λ₀.

This study investigated the relationship between temperature elevation and spatial-average SAR (specific absorption rate) in a head model of a Japanese male due to a dipole antenna. The frequencies considered are in the range between 800MHz and 3 GHz, which are used in wireless communications. Our attention focuses on the average mass of SAR which maximizes the correlation with local temperature elevation. Computational results suggested that an appropriate averaging mass of SAR did not exist over wide frequencies, which was attributed to the frequency-dependent penetration depth of electromagnetic waves. For most cases considered in this study the SAR averaging over 10 g was better than that for 1-g from the standpoint of correlating the temperature elevation. The dominant factor influencing this averaging mass is the thermal diffusion length which largely depends on the blood perfusion rate. Additionally, the heat evolved in the pinna played an important role in the correlation between spatialaverage SAR and temperature elevation.

In this paper, the Parallel Finite-Difference Time-Domain (FDTD) method based on MPI (Message Passing Interface) is applied to analyze the EMC problems of the electrically large platforms accurately and quickly, which is a full-wave numerical method. The MPI library and domain decomposition method are applied to implement the Parallel FDTD method, so that the computation resource is expanded. The method can analyze the EMC problems by modeling the electrically large platforms accurately. Then the network theory is introduced to compute the isolation between antennas combined with the Parallel FDTD method firstly, which avoids the complexity of sweeping frequency and reduce the computing time greatly. Numerical results show that the method is correct and efficient. Finally, the EMC problems of antennas mounted on electrically large platforms are analyzed and some useful conclusions are obtained.

Exploitation of the backscattered field polarization over the wide electromagnetic spectrum, from visible to microwave frequencies, provides an approach to advanced target recognition in remote sensing applications. The framework for full coherent characterization of the scattered field that is established here, maximizes the extracted target information. It is also shown that such a methodology, which is theoretically similar to the concept of "partial or compact polarimetry", yields comparable results to full or quadrature-polarized systems by incorporating judicious assumptions and assuming/implementing optimal transmitted or illumination field polarizations. On this basis, common characteristic features, interworking and fusion of different polarimetric sensor products in different regions of spectrum, e.g., radar/SAR and Electro-Optical, are investigated and formulated within a robust framework based on full coherent treatment of the scattered field.

This paper deals with the design of beam-forming networks (BFN) for scannable multibeam antenna arrays using Coherently Radiating Periodic Structures (CORPS). This design of CORPS-BFN considers the optimization of the complex inputs of the feeding network by using the Differential Evolution (DE) algorithm. Simulation results for different configurations of CORPS-BFN for a scannable multibeam linear array are presented. The results shown in this paper present certain interesting characteristics in the array factor response for the scannable multibeam linear array and the feeding network implification for the design of BFN based on CORPS.

Effects of different optical losses (auger recombination, cooperative up-conversion, excited state absorption (ESA) and Si- Nc induced loss) on amplification parameters including net gain and population inversion in Si-Nc Er doped fibber are studied. Optical loss due to up-conversion effect has critical role in the mentioned optical amplifiers. Simple modeling of this effect can be done by 2C_upN₂², where C_up and N₂ are up-conversion coefficient and population of level 2 respectively. In traditional considered cases C_up are assumed to be constant, but in practical situation this is hard to be realized. In practice distribution of Er ions is inhomogeneous and especially the Gaussian. So, from our point of view the suitable model should consider position dependence up-conversion coefficient. In this paper we considered this subject and by simulation modeling tries to show effect of inhomogeneous distribution of up-conversion coefficient on optical net gain and population inversion. It is shown that life times of first and second excited states are decreased and so the population inversion is decreased too. Thus optical net gain near to center of the Gaussian distribution is deceased strongly. The observed gain lowering is suitable description of the reported experimental results. Also, it is observed that in high level Si-Nc density the obtained optical gain is decreased against traditional description which C_up is assumed to be constant. The core diameter is considered R = 10μm.

The discrete complex image method is one of the most prominent techniques that handle the Sommerfeld integrals encountered in the integral equation formulations of multilayered media. The extraction of surface waves extends the validity of the method to the far field. These surface waves are expressed in terms of Hankel functions that suffers a singularity problem at the origin which contaminates the results in the near field. In this work,w e use a formulation developed recently by the author to derive a new expression for the surface waves. The new expression is shown to obviate the singularity of the Hankel functions at the origin,and hence leads to accurate results in the near field.

The characteristics of radiating longitudinal slots in a rectangular waveguide have been studied. A moment method solution is used with entire basis expansion and testing functions (Galerkin) including the effect of wall thickness. It is shown in this paper. 1) The determination of different parameters like VSWR, reflection coefficients and insertion loss are calculated with the results of normalize reactance and conductance. 2) The Taylor distribution approach with specific SLL for desired linear aperture array antenna. The resonant conductance or resistances are calculated from desired amplitude distribution. The formulation uses transmission matrix approach. The computed result shows excellent agreement with measured results. CST Microwave studio is used for the simulation and is totally based on FIT techniques.

A novel dualband frequency selective surface (FSS) with both a dielectric substrate and superstrate constructed by double-fourlegged loaded slots (DFLLSs) is investigated, in which each periodic cell consists of two neighboring DFLLSs with different dimensions, its resonant frequencies occur at 183 GHz and 220 GHz. Good selectivity performance can be easily achieved both in lower passband and higher passband by tuning the dimensions of the DFLLSs. Besides, the passbands are mainly determined by the neighboring perturb cells and can be designed independently. According to the explicit physical concept and some formulas, the design process become straightforward and simple. Its frequency performance is obtained by using numerical simulation software CST based on finite difference time domain method (FDTD). The simulated results show the good stability of the resonant frequencies and bandwidths at different polarization states and various incident angles.

This paper presents the design of a dual stacked microstrip antenna over the frequency range of 9.5-16 GHz. Investigations show that in the new structure the impedance bandwidth of the antenna is increased to 44% and the thickness of the antenna decreases to 0.14λ. Furthermore, the gain bandwidth of the antenna (above 8 dB) is increased to 5.1 GHz (40%).

This paper presents a novel elliptic shape defected ground structure (DGS) for low pass filter (LPF) applications. An equivalent RLC circuit model is presented and its corresponding parameters are also extracted from the measured S-parameters. The filter presents the advantages of compact size,high selectivity; low insertion loss and high out-band suppression from 5.15 GHz to 10 GHz below -31 dB. Good agreement with response of equivalent circuit, electromagnetic simulation, and measurement is demonstrated.

The permittivity tensor of an anisotropic material can be predicted with use of the presented technique. A slab of this substance possessing infinitesimal thickness is illuminated by a normally incident plane wave and rigorous expressions for the transmission coefficients are obtained. The derived formulas are linearly expanded with respect to the small thickness of the slice, while simple approximations of the material permittivities are produced by measuring the transmission coefficients for suitable polarizations. These simplified expressions provide a physical intuition about the use and the function of the anisotropy parameters which cannot be achieved via more precise but also more complex patterns. Some diagrams of the prediction error with respect to the dielectric constants, the size of the slab and the operating frequency are included and discussed.

In RFID system, tag collision is a main problem for fast tag identification. On the base of binary search algorithm of backtracking, an enhanced binary anti-collision search algorithm for radio frequency identification (RFID) system is presented in this paper. By dynamically transferring the ID of the tag, the length of the data transferred can be decreased dramatically. Mathematical simulation result shows that compared with the binary search algorithm of backtracking, the proposed algorithm can save channel by more than 43.75% when handling multiple RFID tags simultaneously. Finally the proposed algorithm is successfully applied to a RFID device, which validates itself.

In this paper, an integrated and manifold study of the combined electromagnetic and thermal effects, caused by human exposure to microwave radiation is carried out. In essence, we numerically calculate the amount of electromagnetic power absorbed by biological tissues for various exposure conditions and types of emitting sources, utilizing a detailed model of the human head. The severity of the obtained results is evaluated via comparisons with the guidelines of international safety standards, while further insight is gained by investigating the induced thermal effects. The latter are properly quantified through the solution of the bioheat equation, when combined with the outcome of the electromagnetic simulations. Spatial distributions of the corresponding temperature changes are thus calculated, their relation to the dissipated power is established, and the thermal response of human tissues in marginal cases of exposure is predicted.