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This paper introduces Craziness-based particle swarm optimization (CRPSO), an enhanced Particle Swarm Optimization method, to study the best antenna design for an Elliptical Cylindrical Array (ECA). Heuristic methods such as the PSO algorithm has two key benefits: it employs minimal control parameters and converges quickly. However, PSO performance can be, hampered by early convergence and stagnation. This study modifies the PSO algorithm to address these issues by a "craziness" factor represented by a craziness variable. The CRPSO approach to minimizing the Side Lobe Level (SLL) by determining the optimal configuration of active and inactive elements without preset, First Null Beam Width (FNBW) parameters. Additionally, SLL variation with various element spacings. Results show a significant decrease in SLL up to −42.83 dB, and comparing the results to PSO and existing literature shows superior SLL reduction. [ABSTRACT FROM AUTHOR]

A sparse array synthesis method based on improved wind-driven optimization algorithm (IWDO) and fast Fourier transform (FFT) for the purpose of sidelobe suppression was introduced. First, the uniform linear array was sparse by the FFT algorithm. Then the amplitude excitation weighting of array elements was optimized by IWDO algorithm based on probability factor chaotic map. During the optimization process, the minimum peak sidelobe level was used as the fitness function. By comparing with the simulation results of classic Chebyshev weighting method, the method proposed in this paper has better performance. [ABSTRACT FROM AUTHOR]

This paper presents an efficient implementation of the inversion algorithm based on the conjugate-gradient method (CGM) for solving inverse scattering problems. The original CGM provides good image reconstruction and robustness to noise-corrupted data. This method requires the solution of the forward scattering problem and the Fréchet derivative operator of the cost function at each iteration step. However, these procedures can make the computational cost prohibitive, even for moderately sized problems. To avoid the computational burden, a two-step conjugate gradient fast Fourier transform (CG-FFT) procedure is proposed. Such an approach reduces the computational cost and storage requirements of the CGM implementation. The efficient CGM is found to share a computational complexity similar to the distorted-Born iterative method (DBIM). Thus the convergence speed and accuracy of the CGM is compared with the DBIM. Numerical tests using both synthetic and experimental data show effectiveness for solving 2D inverse scattering problems. [ABSTRACT FROM AUTHOR]

This paper proposes a novel method for the impedance measurement of balanced UHF RFID tag antennas. The traditional method used a wire balun-connected probe to measure balanced antennas. But this technique has a system error that results from the wire balun effects. This paper presents a novel method to de-embed the wire balun effects and improve the accuracy of measurement based on algorithm. Comparing with other de-embed methods, the novel method does not need the inner structure of fixture or rely on the accuracy of modelling the measurement fixture. [ABSTRACT FROM PUBLISHER]

The identification of different plastic materials in pellet form using a microwave negative-order-resonance sensor along with the evaluation of classification algorithms from machine learning is presented in this paper. Operation of the sensor is within the unlicensed ISM 2.5 GHz band, and identification of the materials is based on the measured resonant parameters from the sensor. Several classifiers are used to process the resonant parameters having uncertainty factors involved in pellet measurements (air gaps, pellet positions, dimensions and shapes), and performance comparison between the algorithms is carried out in terms of accuracy in the classification. Moreover, the presented measurement method is proposed as a fast, non-destructive, and low-power consumption way to identify plastic raw materials using a low-profile circuit having a high potential of being used in industrial processes. [ABSTRACT FROM AUTHOR]

In this paper, how to parallelize the Pre-corrected FFT algorithm for solving the scattering problem of large scale is presented and discussed. The P-FFT technique developed by our group earlier was extended in the current analysis. To show the efficiency of the MPI-based parallelization algorithm, the experiment results are given in the latter part of the paper and various comparisons are made for such a demonstration. [ABSTRACT FROM AUTHOR]

An E-shaped conformal microstrip antenna array mounted on an irregular curved surface which is similar to an aerocraft cavity in shape is developed in this paper. In view of the narrow bandwidth of the microstrip antenna, an E-shaped element is applied instead of the traditional rectangular element. Furthermore, an element structure of uneven thickness is adopted in order to take into account the effects of the carrier on the resonance frequency and bandwidth of the conformal array. Then, an 8-element conformal microstrip antenna array is designed and the radiation pattern is synthesized using the modified genetic algorithms (MGAs). Compared with the standard genetic algorithms (SGAs), MGAs has a much more fast convergence speed and need less computational time to reach the expected value. The result shows that the optimized azimuth radiation pattern is almost omnidirectional and the elevation radiation pattern is concentrated in the horizontal direction. It can be seen that the proposed method of MGAs is an effective means for designing the conformal antenna array on an irregular curved surface. [ABSTRACT FROM AUTHOR]

This paper introduces, for the first time, an extended modal integral technique for reliable characterization of multilayered symmetrical/asymmetrical planar structures built on arbitrary number of uniaxial electric/magnetic anisotropic layers. Based on a simple but efficient recursive algorithm devoted to composite substrates, the proposed hybrid mode analysis involves the Galerkin's procedure combined with the formalism concept of mathematical operators to more conveniently formulate the boundary conditions. By properly selecting adequate trial functions, the technique was demonstrated through a close agreement between the obtained results and published data. [ABSTRACT FROM AUTHOR]

In this paper, pixelated Frequency Selective Surface (FSS) layer embedded in two carbonyl iron-filled silicon rubber (CISR) sheets are used for design of broadband microwave absorber in frequency range of 3.95 to 8.2 GHz. Top and bottom layers of CISR sheets are prepared with 24% and 33% of Carbonyl Iron (CI) powder by volume, respectively. Reflectivity of microwave absorber, complex permittivity and complex permeability of CISR sheets are evaluated using two Rectangular Dielectric Waveguide (RDWG) measurement systems in 3.95 to 5.85 GHz frequency band (WR-187) and 5.85 to 8.2 GHz frequency band (WR-137). An algorithm was developed using Geometry-Refinement Method (GRM) and Genetic Algorithm (GA) optimization technique to design pixelated FSS layer. Measured as well as simulated reflectivity of composite microwave absorber is better than −10 dB at normal incidence in the frequency range of 3.95–8.2 GHz. For oblique incidence from 0 ∘ to 40 ∘ , simulated reflectivity of TE and TM polarizations carried out for all angles of incidence. [ABSTRACT FROM AUTHOR]

Identifying the core of the convective cloud is paramount important to the identification of the Mesoscale Convective System (MCS) and its evolution is of great significance in the weather and climate system. To study the initiation and development of convective core systems, an automatic tracking algorithm named "Convective cell Identification and TRAcking (CITRA)" has been developed to identify and track the convective cells in MCSs using Doppler Weather Radar reflectivity images based Optical Character Recognition using Long Shortterm Memory Neural Network. Further, CITRA algorithm calculates the convective cell physical properties such as centroid, convective core size and area, duration, maximum extent, distance and direction from the Radar centre. CITRA algorithm tested on 1255 convective cells identification and tracked 90 distinct convective system families along with physical properties through their evolution during the monsoon periods of 2017–2019. The details of CITRA algorithm is described in the present paper. [ABSTRACT FROM AUTHOR]

Sparse arrays play an important role in the widely used acoustic and electromagnetic applications such as sonar, radar, and satellite. In this paper, a recently proposed swarm intelligence algorithm, salp swarm algorithm (SSA), is introduced for design of both linear and planar sparse antenna arrays with optimum sidelobe level (SLL). The design of sparse antenna arrays can be regarded as a nonlinear optimization problem, which the main optimization goal is finding optimum excitations and positions for antenna elements to achieve antenna array beam pattern with desired SLL. The SSA is a new kind of swarm intelligence algorithm which inspired by the swarming behavior of salps. Compared to other evolutionary algorithms, the SSA requires few algorithm-specified tuning parameters, which makes it simple and easy to use for engineering. Illustrative examples of both linear and planar arrays are given to verify the validity of the SSA for SLL reduction of sparse arrays. [ABSTRACT FROM AUTHOR]

In this paper, we present an improved wave concept iterative process (WCIP) algorithm for the analysis of anisotropic graphene. Then, we use it to investigate a novel type of terahertz microstrip circulator based on graphene. In this algorithm, we propose a new technique for modeling of magnetized graphene layers, which consists of redefining the boundary conditions of graphene in terms of waves and integrating the surface conductivity without involving volumetric discretization. Numerical examples are presented to verify the efficiency of the proposed algorithm. The numerical simulations demonstrate that the performances of the circulator can be adjusted by applying an electric or magnetic field bias. [ABSTRACT FROM AUTHOR]

In this paper, fundamental properties of solutions to fractional-order (FO) Maxwell's equations are analysed. As a starting point, FO Maxwell's equations are introduced in both time and frequency domains. Then, we introduce and prove the fundamental properties of electromagnetic field in FO electromagnetics, i.e. energy conservation, uniqueness of solutions, and reciprocity. Furthermore, the algorithm of the plane wave simulation is developed and implemented in software, which allows us to demonstrate the general properties of electromagnetic field in the media described by FO models (FOMs). The differences in interpretation of the fundamental theorems of electromagnetics (i.e. Poynting's theorem, the uniqueness theorem and the Lorentz reciprocity theorem) in comparison to integer-order electromagnetics are analysed. It is demonstrated that all the properties of electromagnetic field, related to these fundamental theorems are preserved when time derivatives are generalized towards FO in Maxwell's equations. [ABSTRACT FROM AUTHOR]

Range profile (RP) is an effective one-dimensional radar signature used to recognize a tar-get, and many research results have been published regarding the classification of RPs of targets engaged in solo flight. However, because targets fly in formation with complicated motion parameters, further study is required to identify multiple targets simultaneously. This paper presents a method of recognizing multiple targets that are flying closely spaced in a formation using separate RPs of each target. However, it is very difficult to extract RPs from each target which uses reflected signals from several aircraft in a formation at several aspect angles. In this paper, RPs of each target are separated by using the segmentation method based on the range-Doppler algorithm. Classification results from using five targets that are composed of point scatterers prove the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

In this paper, an additional degree of freedom "time" is introduced into conventional linear arrays with unequal element spacing forming the time modulated unequally spaced linear arrays (TMUSLAs). The differential evolution (DE) algorithm is adopted to optimize the positions and switch-on times of elements in the TMUSLAs to suppress the sidelobe levels (SLLs), sideband levels (SBLs) and constrain the beamwidth, simultaneously. Numerical results show that lower SLLs and SBLs are obtained by the proposed method than those by the published results. [ABSTRACT FROM AUTHOR]

In this paper, a novel wavelet algorithm has been proposed for solving second order electromagnetic problems both in time and space domains. The algorithm has been used to solve four different problems, i.e. the transmission line problem, the problems associated with electromagnetic waves travelling in different media, the problem related to uniform plane wave in lossy dielectric and problem associated with the telegrapher's equation. The comparison between the results obtained using the proposed approach and the conventional numerical techniques demonstrate that the proposed technique exhibits better time complexity. In essence, the proposed algorithm possesses complexity of order O (n) whereas the conventional technique possesses complexity order of O (n 2). Furthermore, the memory requirement of the proposed algorithm is significantly lower when compared to the conventional technique. [ABSTRACT FROM AUTHOR]

This paper presents new and accurate synthesis formulas for the multilayer homogeneous coupling structure with ground shielding (MHCS-WGS). The synthesis formulas are obtained by means of a differential evolution algorithm (DEA), and are useful to microwave engineers for accurately calculating the physical dimensions of MHCS-WGS. The average percentage error is calculated to be 0.8% for 13614 MHCS-WGS samples having different electrical parameters and physical dimensions, as compared with the results of quasi-static analysis. [ABSTRACT FROM AUTHOR]

A new time domain algorithm which combines alternating-direction implicit (ADI) technique and the multi-domain pseudospectral time domain (PSTD) algorithm is presented in the paper. This algorithm not only maintains accuracy and flexibility of PSTD for an accurate treatment of arbitrarily curved objects but also effectively improves the stability problem. Some numerical examples of two dimensional scattering are given to illustrate the accuracy and stability of the proposed approach in this paper. [ABSTRACT FROM AUTHOR]

Five different Nicolson–Ross–Weir (NRW) extracting techniques are used to extract the dielectric constants of Teflon, Rexolite, Glass (borosilicate and soda-lime), Paper, and Ultralam 3850HT fromS-parameters. The results of these extraction techniques are used to train the Artificial Neural Networks. In order to improve the accuracy of the results, the weights of ANNs are calculated using artificial bee colony estimation method. The results are compared with that obtained using NRW, Newton–Raphson, and genetic algorithm. The obtained results indicate that the proposed model gives good extracted parameters as compared with the previously published results. [ABSTRACT FROM AUTHOR]

In order to efficiently solve large dense complex linear systems arising from electric field integral equations (EFIE) of electromagnetic problems, matrix decomposition algorithm-singular value decomposition (MDA-SVD) is used to accelerate the matrix-vector product (MVP) operations and decrease memory usage. Based on the symmetry of the impedance matrix resulting from the discretization of the EFIE, we introduce a compressed representation of MDA-SVD in this paper. We obtain a sparse representation of the far-field interaction parts of impedance matrix and perform a fast MVP operation. Numerical experiments demonstrate that the compressed representation of MDA-SVD can reduce both the MVP time and memory usage by around 50% with similar accuracy. [ABSTRACT FROM AUTHOR]

In this paper, equivalence principle algorithm (EPA) with grid-robust higher order vector basis (GRHOVB) is proposed to solve the multiscale problems. The EPA is a kind of domain decomposition method which transforms the interaction of objects into the interaction between virtual equivalence surfaces. Compared with traditional Curvilinear Rao–Wilton–Glisson function, GRHOVB can be used on the equivalence surface to reduce the number of unknowns and also to improve the accuracy. The tap basis is utilized to deal with current continuity when the object is intercepted by an equivalence surface. The equations are simplified further to improve the tap basis scheme. Moreover, to accelerate the solution, multilevel fast multipole algorithm is utilized in EPA. Numerical results are shown to demonstrate the accuracy and efficiency of the proposed method. [ABSTRACT FROM AUTHOR]

Rigorous Coupled Wave Analysis (RCWA) in bipolar coordinates for the first time is used to study electromagnetic (EM) scattering from eccentric, circular, multi-cylinder systems for which spatially, non uniform material (dielectric permittivity) occupies the regions between the interfaces of the cylinders. The bipolar RCWA algorithm presented herein consists of three basic steps which are; (1) solving Maxwell's equations in bipolar coordinates using a state variable (SV) formulation; (2) solving Maxwell's equations in the spatially uniform regions exterior to the inhomogeneous scattering object in terms of circular, cylindrical Bessel-Hankel functions; and (3) enforcement of EM boundary matching equations which leads to a final matrix equation solution of the system. In the paper extensive use of the residue theorem of complex variable theory was made in order to find fast and exact evaluations of the EM boundary interaction integrals that arose between the bipolar, SV solutions and the Hankel Bessel solutions. In this paper very extensive reliance on the work of A. A. Kishk, R. P. Parrikar and A. Z. Elsherbeni [22] who studied EM scattering from uniform material multi-eccentric circular cylinders (called herein the KPE algorithm) was made in order to validate the numerical results of the bipolar RCWA algorithm. In this paper, two important system transfer matrices, called the Bessel transfer matrix (based on the KPE algorithm) and called the bipolar SV transfer matrix, were developed in order to validate the numerical accuracy of the RCWA algorithm. The Bessel and SV transfer matrices were very useful for validation purposes because, from the way they were both formulated, they could be meaningfully compared to one another, matrix element to matrix element. In the paper extensive numerical results are presented for EM scattering from spatially uniform and non uniform multi-eccentric, composite cylinder systems, including calculation of three dimensional plots of the electric and magnetic fields and including calculation of the back and bistatic scattering widths associated with the scattering systems. Also included are three tables of data documenting peak and RMS errors that occur between the KPE and RCWA algorithms when the number of modes are changed, the number of layers in the RCWA algorithm are varied and when the angle of incidence is varied. [ABSTRACT FROM AUTHOR]

Stochastic media problems present a severe impact on the properties of the electromagnetic fields that usually deterministic methods tend to overlook. In this paper, we present a finite-difference time-domain (FDTD) technique, which is free from time step restrictions and manages to efficiently calculate the statistics of the involved fields in one realization. The proposed algorithm is a variation of the Stochastic FDTD method and exhibits satisfactory outcomes in high density grids. Numerical results verify the validity of our scheme compared to other methods, such as the Stochastic FDTD and the Monte Carlo techniques. [ABSTRACT FROM AUTHOR]

This article describes a new method to determine the directions of the zero fields in antenna radiation measurements. Zero-field detection is important when there are null constraints in antenna analysis or synthesis. To identify the directions of the zero fields, the general practice is to measure the propagating field in a number of small incremental angles in 2D space. For an antenna with narrow beam characteristics, even more sampling is necessary for accuracy. As a result, the time efficiency is decreased. In order to speed up the process, an optimization algorithm may be employed such that the measurements may converge to the zero-field locations faster. However, the difficulty is that many optimization algorithms require the use of derivatives of the pattern function. The algorithm proposed in this paper is derivative free and utilizes only the amplitude data, hence it is suitable and applicable to antenna measurements providing time efficiency. [ABSTRACT FROM AUTHOR]

A comparison between different modern multi-objective optimization methods applied to the design of concentric rings antenna arrays is presented in this paper. This design of concentric rings antenna arrays considers the optimization of the amplitude and phase excitations across the antenna elements in order to generate the trade-off curves between side lobe level and directivity for a scannable pattern with optimal performance in the whole azimuth plane. Simulation results by using evolutionary multi-objective optimization methods, such as: NSGA-II, DEMO, and EM-MOPSO are provided in this document. Furthermore, a comparative analysis of the performance between these algorithms is presented. [ABSTRACT FROM AUTHOR]

In this paper, an efficient method based on the sequential quadratic programming (SQP) algorithm for the pattern synthesis of concentric rings antenna arrays to reduce side lobe levels (SLL) by controlling only the amplitude excitations of each array element was presented. SQP algorithm is a deterministic method of multi-objective optimization. It is the most widely used for the resolution of nonlinear problems. It consists of transforming the nonlinear problem to sequence of quadratic sub-problems by using a quadratic approximation of the Lagrangian function. In order to illustrate the performance of the proposed method, several examples of planar concentric rings antenna array patterns with almost one-half wavelength spaced isotropic elements to reduce the SLL and to norrow the half power beam width are presented. The results shown in this paper and compared with those obtained by the application of uniform, Hamming and Blackman weighting, demonstrate the effectiveness of this optimization method based on the SQP algorithm. [ABSTRACT FROM AUTHOR]

Synthetic aperture radar (SAR) techniques are typically used to achieve a high azimuth resolution, but conventional monostatic SAR is not applicable in forward direction because of azimuth ambiguities and poor Doppler resolution. This paper focuses on SAR imaging processing in a novel forward-looking bistatic configuration that a pilotless plane transmits signals and a guided missile receives echo which can avoid image ambiguities and to improve the azimuth resolution. A fourth-order range equation and a fourth-order phase term are adopted to improve the accuracy in the approximation of the range history and two-dimensional spectrum for forward-looking bistatic SAR, respectively. The spectrum is used for high-order phase compensation, range compression, secondary range compression, range cell migration correction, and azimuth compression. Especially, the proposed algorithm is able to focus the translational variant bistatic configuration where the transmitter and receiver platforms are moving in parallel tracks with different velocities and high squints. Finally, simulations validate the effectiveness of the algorithm. [ABSTRACT FROM AUTHOR]

In through-the-wall imaging, wall reflections are so strong that targets behind walls are usually obscured and invisible in the image, which severely affects the detection and further processing. Aimed at the wall clutter mitigation problems in through-the-wall MIMO radar application, the information of the signal characteristics and antennas' geometric relationship is deeply analyzed and optimally used. Based on this information, two variables "dealing signal" and "reference signal" are defined. Then a wall clutter method is proposed and its algorithm flow is given. The method can be efficient to mitigate the wall clutter and easy to realize. Full numerical electromagnetic simulations validate the efficiency of the method. [ABSTRACT FROM AUTHOR]

An algorithm is proposed to exploit the Shuttle Radar Topography Mission (SRTM) digital elevation model (DEM) in the interferometric synthetic aperture radar (InSAR) data pro-cessing. The proposed algorithm includes three steps: (1) patching the void cells in the SRTM DEM; (2) determining a one-to-one correspondence between the interferogram and the SRTM DEM; (3) eliminating the phase trend between the original and the simulated interferogram. This algorithm can be used to facilitate phase unwrapping problem. Conven-tional techniques treat phase unwrapping as an optimization problem, in which the total branch cuts or the gradient errors are to be minimized. The phase unwrapping is considered as a blind procedure in these techniques and carried out without any external assistance. The purpose of this paper is to provide a knowledge-based technique by introducing the SRTM DEM as an assistance to the phase unwrapping. Some experimental results with JERS data verify the theoretical analysis and show that the method can improve the perfor-mance of phase unwrapping to a great extent. [ABSTRACT FROM AUTHOR]

An electromagnetic cloak based on a coordinate transformation approach is always inhomogeneous and anisotropic. In this paper, we investigate the sensitiveness of different cloaking schemes, when EM parameters are limited to a range more plausible to realize. Numerical experiments show that the imperfect cloak under moderate compression presents low anisotropy and is a candidate scheme more insusceptible to changes in EM parameters. When devising the cloak using dispersive lossy metamaterials, the unavoidable deviation in material parameters favors a lower anisotropic model such as the imperfect cloaking model. [ABSTRACT FROM AUTHOR]

-Electrical capacitance tomography (ECT) is a noninvasive technique that aims to reconstruct images of internal permittivity values of a volume of interest, based on measurements taken on the external boundary. Since most reconstruction algorithms rely on model-based approximations, it is important to ensure numerical accuracy for the model being used. Finite element methods (FEM) are the most commonly used modelling technique for the ECT forward problem. Due to the characteristic of the ECT technique, the size of the electrodes needs to be built as big as possible so as to cover the entire image area. To accurately solve the forward model a large number of elements are required in and around electrodes. Notably complete sensor model (CSM) will provide the best solution of the forward model. It is also known that denser mesh provides more accurate solution; however, it also requires longer computation time. This paper demonstrates the advantages of the incorporating discretisation and modelling error in 3D ECT problem. The approximation error model (AEM) has been used to account for discretisation error, and this allows using a coarse mesh for the forward model and achieving the reconstruction accuracy close to that of denser mesh. [ABSTRACT FROM AUTHOR]

Matched filtering of phase history data is the optimum reconstruction algorithm to bistatic synthetic aperture radar (SAR) image formation. However, it comes at great computational expense scaled with complexity O (M2 N2), where M N is the number of pixels in the image. Based on the plane wave assumption, bistatic polar format algorithm (PFA) approximates the matched filtering kernel appropriately, so that the computational complexity in image formation is considerably reduced. In this paper, we propose a novel PFA for bistatic SAR processing. This imaging algorithm is to use non-uniform fast Fourier transform (NUFFT) to compute the matched filtering reconstruction image according the plane wave signal model of bistatic SAR, which scales with complexity O (M Nlog2M N). Numerical simulations are performed to validate the proposed algorithm. The results prove that, compared with the direct computing of matched filtering, the presented algorithm can provide almost identical imaging performance in a relatively very short computation time. [ABSTRACT FROM AUTHOR]

Compared to the common monostatic synthetic aperture radar (SAR), the bistatic SAR data are more challenging to process because of their complicated flight geometry. Although several bistatic SAR image formation algorithms have been presented, most of them are only able to handle azimuth-invariant bistatic configuration where the transmitter and receiver platforms are moving in parallel tracks with identical velocities. This paper proposes an Omega-K algorithm to handle a general case of bistatic SAR data. The two-dimensional frequency spectrum expression derived by the method of series reversion is rewritten to a new form with explicit geometric significance. Based on this new frequency spectrum expression, the frequency mapping function can be derived by making use of the multivariable Taylor's theorem. After data mapping operation, the coupling between the range and azimuth can be eliminated, and the final focused image can be obtained using FFT technology. Numerical simulations are performed to validate the proposed algorithm. [ABSTRACT FROM AUTHOR]

In this paper, we investigate the basic design parameters and propose a two-phase localization algorithm for full-body human locomotion tracking systems using ultra wideband (UWB) radios. The proposed localization is divided into two measurement phases namely, the initial and core phases. The initialization phase is based on the linear least-squares (LS) localization. The proposed initial localization phase has a localization accuracy of 0.247 mm. For core phase, we investigate the use of classical multidimensional scaling (C-MDS) localization and show that the achievable accuracy is approximately 0.47 mm (1 mm and sub-millimeter reported for current optical tracking systems). The reported accuracy in the literature for UWB-based systems is ≈ 400 mm. Thus, the proposed localization technique provides a substantial improvement over existing systems, which makes it suitable for accurate kinematic parameter measurement. Results presented for system performance and design parameters are investigated using simulations and actual measurements. Ultimately, the proposed system is suitable for taking accurate measurements and for tele-rehabilitation. [ABSTRACT FROM AUTHOR]

Waves, winds and currents can be extracted from the Doppler power Spectra of HF Radar. Worldwide research has been done for this purpose during the last 4 decades. A new multi-frequency HF (MHF) radar is applied to enrich this study in a ten-day experiment completed in the East China Sea. The new MHF radar is designed to simultaneously work at four different frequencies at most between 7.5 MHz and 25 MHz. In this paper, we particularly focus on wave measurements, which were obtained both from MHF radar and wave buoy. A comparison of the two measurements is made, and the final result points out a potential and practical way to improve the performance of HF radar wave measuring. It is suggested that, when the fusion algorithm of multi-frequency data is robust enough, MHF radar can be widely used for ocean remote sensing. [ABSTRACT FROM AUTHOR]

In this paper, we propose a computational global optimization method based on differential evolution (DE) algorithm for synthesizing large multiple concentric rings arrays to generate a pencil beam with minimum peak side lobe level (PSLL) and constrained first null beam width (FNBW). The synthesis is performed with a differential evolution technique to optimize the ring spacing, the number of the elements in each ring as well as the amplitude distribution. Simulated results of the designed synthesis illustrate the efficiency and reliability of our proposed method. [ABSTRACT FROM AUTHOR]

In this paper, a compact ultra-wideband (UWB) antenna with a WLAN band-notched characteristic is presented. The design technique is based on a novel self-adaptive Differential Evolution (DE) algorithm namely ISADE (improved self-adaptive Differential Evolution algorithm). In order to evaluate the algorithm's performance, we tested it on nine most commonly used benchmark functions. Experimental results have shown that the proposed algorithm outperforms the classical DE and at least is comparable to some other adaptive DE algorithms. The optimized UWB antenna has a compact size of 14 mm × 30 mm and is fabricated and measured. Measured results have shown that the antenna has approximately omnidirectional radiation patterns with a good band-notched performance in the WLAN band. Therefore, the results indicate the advantages of this approach and the applicability of the proposed algorithm to other optimization problems in electromagnetics. [ABSTRACT FROM AUTHOR]

In this paper, a new, simple and accurate expression for the resonant length in calculating resonant frequency of H-shaped compact microstrip antennas at UHF frequencies applications is presented. H-shaped compact microstrip antennas with a range of different physical dimensions built on various substrates are numerically simulated with a software package based on finitedifference time domain method. A closed-form expression for the resonant length is constructed with the aid of both the artificial bee colony algorithm and the simulation data. The resonant frequency is then calculated by means of this resonant length expression. The average percentage error is found to be less than 0.79% for 216 simulated antennas. Experimental and simulated results reported elsewhere have been employed to illustrate the validity and accuracy of the present formulation. [ABSTRACT FROM AUTHOR]

This paper discusses an implementation of bistatic polar format algorithm (PFA) using chirp scaling (CS). The new algorithm applies CS in the range direction to realize the range resampling, which involves only complex multiplications and FFTs. The dechirped and the chirped signals are treated separately. The new approach obtains comparable results compared with the original algorithm, however improves the efficiency significantly. Point target simulation validates the new algorithm. [ABSTRACT FROM AUTHOR]

Novel dual band-notched monopole antenna is proposed in this paper, which is designed by an improved particle swarm optimization algorithm linked with HFSS. By etching a one order Minkowski fractal slot on the radiating patch and introducing a semi-octagon-shaped resonator on the back plane, excellent dual notched frequency bands characteristics of the proposed antenna are achieved. The antenna satisfies the VSWR requirement of less than 2.0 in the frequency band between 2.87 and 12 GHz, except two frequency stop-bands of 3.2–4.01 GHz and 5.55–6.1 GHz. The effects of the key parameters on the dual notched bands are also analyzed. A fairly stable radiation pattern over the frequency range of interest can be obtained. Moreover, measured group delay and transmission characteristics indicate that the antenna has good pulse handling capabilities. [ABSTRACT FROM AUTHOR]

The particle swarm optimization (PSO), now widely used in the electromagnetics community, is a robust evolutionary method based on the property of swarm intelligence. This paper focuses on the random variable effect in the PSO algorithm, and two random distribution functions, namely, the uniform distribution and Gaussian distribution, are studied and compared in details. It is revealed through the statistic analysis that the Gaussian distributed random variables increase the efficiency of the PSO algorithm as compared to the widely used uniformly distributed random variables. This conclusion has been demonstrated through both a mathematical benchmark function and an antenna array optimization. [ABSTRACT FROM AUTHOR]

In this paper, we present a new method for direction-of-arrival (DOA) estimation in the presence of unknown nonuniform white noise whose covariance is an arbitrary diagonal matrix. This new method can estimate the noise covariance matrix effectively based on the structure of array covariance matrix of the received data. The negative effect of the unknown nonuniform white noise on the DOA estimation can be eliminated by subtracting the noise covariance matrix from the array covariance matrix, then the conventional Multiple Signal Classification (MUSIC) algorithm can be applied. Computer simulations are conducted to show the validity and advantage of this method. [ABSTRACT FROM AUTHOR]

In this paper, a joint estimation of carrier frequency offset and sampling frequency offset is suggested for multi-band ultra-wideband orthogonal frequency division multiplexing (UWB-OFDM) systems. The basic idea of our approach is based on the fact that two adjacent OFDM symbols carry the identical information in the UWB-OFDM system, thus removing the need of pilot symbols. The system performance of using our algorithm is demonstrated in terms of mean square error and bit error rate. [ABSTRACT FROM AUTHOR]

A novel cost function is proposed for the design of cross coupled resonator filters in this paper. The cost function formulated depends on a minimum set of characteristics that can completely describe the desired response. An analytical gradient is also derived for the error function enhancing the efficiency of the optimization process. The proposed algorithm is less vulnerable to local minima and proves more robust compared to other optimization techniques. Examples demonstrating the efficiency of the proposed algorithm are provided. [ABSTRACT FROM AUTHOR]

A popular time evolution algorithm for solving Maxwell's equations for electromagnetic problems is the Yee's finite difference time domain (FDTD) algorithm. This algorithm introduces a non physical algorithmic anisotropic dispersion error and limited stability range. A new improved algorithm with isotropic dispersion error, better stability and faster execution is introduced in this paper. In this study, we compared the results of our improved isotropic algorithm, for simple and well-known problems, to that of the exact solution and that of the Yee algorithm. These comparisons show more accurate results for our improved isotropic algorithm compared to that for the Yee Algorithm. For practical application problems where solutions are too complicated to be solved analytically, we compared our algorithm to that of Yee and found that our algorithm simulate such problems faster and with smaller error. [ABSTRACT FROM AUTHOR]

In the bearings-only tracking problem, usually the uncertainty of process model is small compared with the uncertainty of measurement and this will lead to severe sample impoverishment when using particle filter (PF). In this paper, we proposed a novel roughening algorithm and its hardware architecture to solve this problem. The reasonable distribution of the roughening jitter is calculated from the innovations related to the survived particles. Simulation results indicate that for the bearings-only tracking problem, the PF with the proposed roughening algorithm outperforms the general PF and the PF with the typical roughening algorithm. Experimental study indicates that this roughening algorithm can be efficiently implemented in hardware and can effectively solve the bearings-only tracking problem with fast processing rate and low complexity. [ABSTRACT FROM AUTHOR]

In this paper, Conventional Beamforming algorithm is applied to the estimation of the time delay in impulse radio UWB (Ultra-Wide-Band) systems. The performance of the proposed algorithm is evaluated in indoor UWB channel model (CM1, CM2, CM3, and CM4) with dense multi-path. The simulation results show that the performance of the proposed algorithm is better than that of the correlation-based time delay estimation method. RMS error is used as a performance criterion. [ABSTRACT FROM AUTHOR]

Recently, thanks to the development of wireless communications, radio propagation plays an important role in the research of electromagnetic wave. Furthermore, signal-to-noise ratio (SNR) and Doppler shift of radio propagations receive many attentions due to their comprehensive use in adaptive reception. Hence with the help of double sampling rate (DSR) technique, this paper presents a new estimator to estimate the above two parameters together. We verify our algorithm by computer simulation, and the results have shown a good performance in a wide range of velocities and SNRs. [ABSTRACT FROM AUTHOR]

An improvement for the generic particle filter (PF) is to add a roughening step in resampling. This paper studied the reentry vehicle tracking problem using PF with roughening. A novel algorithm to calculate the reasonable standard deviation of the roughening jitter is proposed. For comparison, the Unscented Kalman filter, the generic PF and the PF with the typical roughening are used to gauge the estimation performance, and the results favor the PF with the proposed roughening method. The generic PF and the PF with the typical roughening have low probabilities of success under conditions of comparatively large initialization bias and accurate radar measurement. The proposed PF can handle these cases efficiently and give better performance. [ABSTRACT FROM AUTHOR]

In ordinary communication systems, modulation signal is identical in the beam. But this paper presents a new technique of multiple beam modulation to transmit data and azimuth information, so that the receiver with only an antenna can perform communication and direction-finding from demodulating signals. In addition, the transmit systems have a matching networks to dispel the mutual coupling among antenna elements. An algorithm of estimation azimuth angle was also developed on the basis of the multiple value resolution. The performances of the bit error rate and direction-finding in a Gaussian channel were investigated. [ABSTRACT FROM AUTHOR]