This paper presents a simple analytical model to estimate the radiated field for broadband Power line communication (PLC) or metallic wire structures. In our approach, we avoid to discretize the line and compute the current for each segment (dipole). We consider only near and far end currents and their derivatives (voltages) to express analytically the radiated electromagnetic field. The case of multiple conductor power line is considered with simplified hypothesis: cables are not insulated and the surrounding media is homogenous. The basic electromagnetic equations are formulated and applied to the line to provide analytical expressions able to compute fields in near and far zones which is not usually treated. The main purpose of this paper is to provide an analytical model applied to bare wires corresponding to classical outdoor transmission lines. The advantage of this method is that we do not need to know the current along the line to calculate the radiated fields; therefore, in our study we use only the currents and voltages at the terminations. The calculation time is strongly reduced compared to dipoles conventional method. Results obtained from the proposed closed-form formulation agree with Feko simulation. For indoor configurations, cables are usually insulated and the surrounding media is no more homogeneous; this case is treated with a generalized approach and will be proposed in future paper.
Fractal arrays are used to increase the bandwidth of the antenna and to reduce grating lobes. The frequency range from 3.1 to 10.6 GHz is specially allocated for the UWB applications. In this paper, a novel antenna based on fractal concepts for ultra wideband (UWB) applications is analyzed, designed, fabricated and tested. Further the antenna is analyzed using the emerging fractal concepts and transmission line method (TLM). The proposed antenna has a good gain bandwidth with broadside radiation pattern. This design is suitable for 3D IC inter-chip and intra-chip communication, and medical imaging applications. This is called Levy's antenna.
In the received signal strength (RSS) based indoor wireless localization system, RSS measurements are very susceptible to the complex structures and dynamic nature of indoor environments, which will result in the system failure to achieve a high location accuracy. In this paper, we investigate the indoor positioning problem in the existence of RSS variations without prior knowledge about the localization area and without time-consuming off-line surveys. An adaptive sparsity-based localization algorithm is proposed to mitigate the effects of RSS variations. The novel feature of this method is to adjust both the overcomplete basis (a.k.a. dictionary) and the sparse solution using a dictionary learning (DL) technology based on the quadratic programming approach so that the location solution can better match the actual RSS scenario. Moreover, we extend this algorithm to deal with the problem of positioning targets from multiple categories, a novel problem that few works have ever concerned before. Simulation results demonstrate the superiority of the proposed algorithm over some state-of-art environmental-adaptive indoor localization methods.
Effect of cold electron beam for Whistler mode waves have been studied for relativistic and non- relativistic subtracted bi-Maxwellian distribution and in the presence of perpendicular AC electric field to magnetic field by using the method of characteristic solutions and kinetic approach. The detailed derivation and calculations has been done for dispersion relation and growth rate for magnetosphere of Uranus. Parametric analysis has been done by changing plasma parameters: thermal velocity, ac frequency, temperature anisotropy etc. The effect of AC frequency on the Doppler shifting frequency and comparative study of relativistic and non- relativistic effect on growth rate are analyzed. The new results using subtracted bi-Maxwellian distribution function are found and discussed in relation to bi-Maxwellian distribution function. It is seen that the effective parameters for the generation of Whistler mode wave are not only the temperature anisotropy but also the relativistic factor, AC field frequency, amplitude of subtracted distribution and width of the loss-cone distribution function which has been discussed in result and discussion section.
A method to design planar multilayer meander-line polarizers is given. The proposed procedure is based on transmission line circuit theory and on full-wave unit cell analysis in frequency domain. The hybrid combination of those two techniques paves the way for the polarizer design process and avoids heavy full-wave optimizations. This procedure is originally aimed for polarizers acting on lens antennas and is suitable for plane waves impinging with arbitrary angles on the polarizer. To validate the proposed method, two polarizers have been manufactured in Ka-band, one for normal and one for oblique incidence. Designs, prototypes and measurements made on a complete Ka-band lens antenna subsystem are shown in this paper.
The multifractal characteristics of return signals from aircraft targets in conventional radars offer a fine description of dynamic characteristics which induce the targets' echo structure; therefore they can provide a new way for aircraft target classification and recognition with low-resolution surveillance radars. On basis of introducing the mathematical model of return signals from aircraft targets in conventional radars, the paper analyzes the multifractal characteristics of the return signals as well as the extraction method of their multifractal features by means of the multifractal analysis of measures, and puts forward a multifractal-feature-based classification method for three types of aircraft targets (including jet aircrafts, propeller aircrafts and helicopters) from the viewpoint of pattern classification. The analysis shows that the conventional radar return signals from the three types of aircraft targets have significantly different multifractal characteristics, and the defined characteristic parameters can be used as effective features for aircraft target classification and recognition. The results of classification experiments validate the proposed method.
The increasing popularity of a so-called transient motor current signature analysis requires the fault diagnostics parameters which could not be exposed to other factors irrelevant to the fault to make a precise assessment of the failure severity level. This challenging task needs a precise modeling of faulty motor behavior in various operating conditions at different fault severity levels. This paper introduces a new approach to a finite element analysis of an induction motor with broken rotor bars during startup. The approach is based on the principle of superposition and contributes to examination of the fault rotor backward rotating magnetic field and current components produced by such field separating them from stator currents. It gives a new sight on the behavior of a faulty motor during startup for the diagnosis purposes. Further analysis of the simulation data by means of the Extended Park's Vector Approach and the continuous wavelet transform and its experimental validation is also represented in the paper.
Feature aided maneuver detector is popular for its low detection delay and high detection probability in decision-based single-model maneuvering target tracking (MTT) algorithms. We propose a switching model-set approach based on the feature aided maneuver detector for MTT. The filtering error dynamics in terms of detection delay are presented and a upper bound for detection delay with given standard Kalman filtering errors is accessed. Subsequently, a feature aided maneuver detector is introduced to enhance detection performance, and the filtering algorithm is proposed, including detailed filtering steps and computational formulae. Simulation results show that the proposed algorithm outperforms the popular autonomous multiple model (AMM) and interacting MM (IMM) algorithms.
This work studies the influence of material coatings, especially combined natural and metamaterials, on the radiation properties of a practical dipole like antenna, represented by a slotted conducting sphere. The selected geometry allows an exact solution to the problem, and thus the development of exact expressions for the antenna parameters, like the radiated power and directivity. It is shown that for materials with combined positive and negative parameters, mode resonances can occur at thinner coatings, the thickness of which can be made diminishingly small by proper selection of coating parameters. In particular, at these resonances the antenna directivity, while being finite, becomes independent of the antenna size and coating parameters.
Considering Radio Frequency (RF) heating as a viable alternative for the in-shell heating of eggs, Finite Element Modeling and simulation of RF heating of in-shell eggs at 27.12 MHz were carried out to assess the feasibility and heating uniformity of the process. According to the recommendations of USDA-FSIS for the pasteurization of eggs, egg white must be heated up to 57.5°C, and the egg yolk has to be heated up to 61.1°C for 2 min. The objective of the simulation was to determine the locations of hot and cold spots generated due to non-uniform heating. A parallel plate setup for Radio Frequency heating was simulated for different electric field strength levels and orientations of the egg (long axis parallel and long axis perpendicular to the plates). The simulation results were experimentally verified and the simulation procedure was validated using a laboratory parallel plate RF setup. A coaxial cavity design was simulated with a similar approach. Results indicated that both the parallel and coaxial cavity designs were suitable for in-shell pasteurization of eggs provided that the eggs were rotated to maintain the uniformity in heating. After the simulation of RF heating process, the process optimization was carried out to determine the most effective procedure for the process. The varying parameters obtained by using different modeling techniques for radiofrequency heating of in-shell eggs, were optimized using MATLAB. Laboratory scale experimental trials were conducted to test the validity and effectiveness of the optimized parameters. The optimal parameters set forth were found to be more efficient in terms of heating time and uniformity.
Reverberation chamber (RC) test facility allows to determine the absorbing cross section (ACS) of lossy materials under a random field excitation. Measurements are based on the quality factor variation produced by the sample under test presence with respect to the empty chamber condition. Simulations are based on the representation of the RC electromagnetic field by means of a random plane wave superposition. A finite-difference time-domain code is used to compute the material absorbed power and to recover a numerical ACS. The method sensibility is stressed by application to small size samples. Comparison between numerical and experimental data reveals a satisfactory agreement. Results for different materials are presented in the paper: soft foam absorbers, carbon foam sheets, and carbon/carbon sheets.
In this manuscript, a simple synthesis method of single square loop frequency selective surface (SSLFSS) is discussed, which may find the suitable application in the fast analysis and fabrication of the frequency-selective surface. The presented technique is used to design SSLFSS at 3 GHz, 15 GHz, 22 GHz and 26 GHZ. At every frequency of interest, the analytical result is very close to the required result. Moreover, a way to control the reflection at any frequency is discussed, which may find an application in controlling the reflection level at any frequency. However, we have proposed two simple, cheaper and lightweight structures at 3 GHz and 22 GHz for the application in various satellite communications. The proposed process has been extended to the analysis of bandpass structure and desired results have been achieved, which indicates the utility of the method of synthesis of both the bandpass and bandstop structures.
Singular value decomposition and information theoretic criterion based clutter reduction is proposed for ground penetrating radar imaging. The scheme is capable of discriminating target, clutter and noise subspaces. Information theoretic criterion is used with conventional singular value decomposition to nd target singular values. Proposed scheme works also for extracting multiple targets in heavy cluttered images. Simulation results are compared on the basis of mean square error, peak signal to noise ratio and visual inspection.
We consider the benchmark problem of magnetic energy density enhancement in a small spatial region by varying the shape of two symmetric conducting scatterers. We view this problem as a prototype for a wide variety of geometric design problems in electromagnetic applications. Our approach for solving this problem is based on shape optimization and isogeometric analysis. One of the major difficulties we face to make these methods work together is the need to maintain a valid parametrization of the computational domain during the optimization. Our approach to generating a domain parametrization is based on minimizing a second order approximation to the Winslow functional in the vicinity of a reference parametrization. Furthermore, we enforce the validity of the parametrization by ensuring the non-negativity of the coefficients of a B-spline expansion of the Jacobian. The shape found by this approach outperforms earlier design computed using topology optimization by a factor of one billion.
This paper presents a low-cost pattern-reconfigurable microstrip antenna. The proposed design strategy uses a slotted patch antenna on a bi-layer structure as basic element of a switched parasitic array. Reconfigurability is obtained by means of PIN diodes used to vary the resonance frequency of the parasitic patches. Experimental results referring to a prototype consisting of an array of three elements optimized for the Ultra High Frequency (UHF) band of Radio Frequency IDentification (RFID) systems are presented and discussed. It is demonstrated that the proposed antenna exhibits a main beam that can be reconfigured into three different directions.
We derive an expression for the torque exerted on an electric/magnetic dipole moving in an electromagnetic field, which contains two new velocity-dependent terms that to our knowledge were not reported before. A physical meaning of various torque components is discussed in terms of Lorentz force law and hidden momentum contribution.
In this paper, a partial coherent approach is used to study the third and fourth Stokes parameters in passive microwave remote sensing of Sastrugi snow surface over layered snow structures. The incoherent part of the model consists of using radiative transfer theory for the snow layers. The coherent part of the model is using numerical solutions of Maxwell equations to derive the bistatic scattering and transmission coefficients of conical scattering by sastrugi surfaces which have large heights and large slopes. We then use the rough surface boundary conditions of conical scattering from the coherent part, in the incoherent radiative transfer equations. The radiative transfer equations are then solved iteratively that includes multiple interactions between the layered structures and the rough surfaces. Simulation results indicate that large third and fourth Stokes parameters are obtained because of the coupling of large angle transmissions of the rough surfaces with the internal reflections of layered structures. The partial coherent approach also eliminates the coherent interference patterns in angular variations from multiple reflections of layer boundaries that were present in the fully coherent approach.
In this paper, the effect of rain attenuation on the FSS allocation in the 7250- 7750 MHz in the Space-to-Earth direction is studied for a satellite at 78.5°E longitude. A simulation model based on the ITU-R P618-10 rain model is used to predict the rain attenuation in the C-, Ku- and X-bands in 15 different locations with varying rainfall intensities of between 145-300 mm/hr in East and West Malaysia. The simulations assume a 1.8 m receive antenna with 65% aperture efficiency, QPSK modulation and use of either vertical or horizontal polarization. The downlink centre frequencies used in this study are 4200 MHz, 7750 MHz and 11200 MHz for C-, X- and Ku-bands respectively. The average free-space path loss calculated for each band is used to estimate the signal attenuation due to rain and the corresponding Eb/N0 (dB) is computed at varying rain intensities. The results show that when using vertical receive polarization, all 15 locations of study with a rainfall intensity of up to 200 mm/hr could receive the X-band signal. At 200mm/hr rain intensity in the horizontal receive, most of the X-band links could achieve the threshold Eb/No of 7.68 dB with a ULPC adjustment of approximately 1.5dB where required. At 300 mm/hr rain intensity, video signals in the X-bands were no longer receivable in both polarizations. At 145 mm/hr rain intensity, only one location with high satellite elevation and greater height above mean sea level maintained the Ku-band link in the horizontal receive. In the vertical receive, the Ku-band link was receivable at all locations at 145 mm/hr but were no longer receivable at 200 mm/hr. The study concluded that the elevation angle towards the satellite is a major factor in determining the quality of the signal in the X-band. The other factors that affected the receive Eb/No was the polarization, depth of rain and height of the earth station above mean sea level. In comparison to the Ku-band, the X-band was able to maintain a good quality satellite link in rain intensities of up to 200 mm/hr in the vertical receive. The results indicate that there is high potential for the use of X-band to provide for video transmission over Malaysia in spite of the high rain intensities.
Radio Frequency Energy harvesting is a research topic of increasing interest, related to sustainability, which could become a promising alternative to existing energy resources. The paper will show all the activities addressed to design a wideband system to recover wideband energy from electromagnetic sources present in the environment. The main idea is to develop battery-free wireless sensors able to capture the available energy into the mentioned bandwidth. The final goal is to realize self-powered Wireless Networks based on Ultra Lower Power - ULP sensors minimizing the need of dedicated batteries. This last feature is particularly attractive in different kind of applications, ranging from military to civil cases. A first system prototype is shown and discussed. Conclusion follows.
This work focuses on the use of metal foams, a relatively new class of materials, for high added-value electromagnetic (EM) shields. First, the Shielding Effectiveness (SE) of aluminum foam slabs is experimentally evaluated, showing very good shielding properties. Successively, accurate numerical models of metal foams are proposed and used in a proprietary Variable-Mesh Parallel Finite Difference Time Domain code, in order to characterize the EM properties of slabs of such materials. Afterwards, a third approach is adopted. It consists in the application of the effective medium theories in order to obtain an analytical EM model of the metal foams; this way, their SE can be evaluated with a negligible computational time by using common mathematical tools. Finally, a methodology to design/analyze customized metal foams for EM shield applications is suggested. It takes advantage from the joint use of the numerical and analytical presented approaches, thus allowing a computationally efficient evaluation of SE and other electromagnetic properties of metal foams. Results demonstrate the suitability of metal foam structures for effective EM shielding in many industrial applications, as well as the accuracy of the proposed analytical and numerical approaches.