Current Issue : October - December Volume : 2014 Issue Number : 4 Articles : 5 Articles
The higher-order hierarchical Legendre basis functions combining the electrical field integral equations (EFIE) are developed to\nsolve the scattering problems from the rough surface.The hierarchical two-level spectral preconditioning method is developed for\nthe generalized minimal residual iterative method (GMRES). The hierarchical two-level spectral preconditioner is constructed by\ncombining the spectral preconditioner and sparse approximate inverse (SAI) preconditioner to speed up the convergence rate of\niterative methods.Themultilevel fastmultipole method (MLFMM) is employed to reduce memory requirement and computational\ncomplexity of the method of moments (MoM) solution. The accuracy and efficiency are confirmed with a couple of numerical\nexamples....
We consider the problem of tracking the direction of arrivals (DOA) of multiple moving targets in monostatic multiple-input\nmultiple-output (MIMO) radar. A low-complexity DOA tracking algorithm in monostatic MIMO radar is proposed. The proposed\nalgorithm obtains DOA estimation via the difference between previous and current covariance matrix of the reduced-dimension\ntransformation signal, and it reduces the computational complexity and realizes automatic association in DOA tracking. Error\nanalysis and Cram�´er-Rao lower bound (CRLB) of DOA tracking are derived in the paper. The proposed algorithm not only can\nbe regarded as an extension of array-signal-processing DOA tracking algorithm in (Zhang et al. (2008)), but also is an improved\nversion of the DOA tracking algorithm in (Zhang et al. (2008)). Furthermore, the proposed algorithm has better DOA tracking\nperformance than the DOA tracking algorithm in (Zhang et al. (2008)). The simulation results demonstrate effectiveness of the\nproposed algorithm. Our work provides the technical support for the practical application of MIMO radar....
This paper presents general approach to design a novel coaxial fed square ring microstrip patch antenna. Software based design and analysis has been done for a square ring patch antenna using different substrate materials. The effect of substrate permittivity on resonant frequency, bandwidth and gain was studied and analyzed for square ring patch antenna. A coaxial probe fed square ring microstrip patch antenna operating at C-band (4-8 GHz) was analyzed on different substrate materials like Rogers RT/duroid 5880, Rogers RT/duroid 5870, Neltec NX9240 and Arlon DiClad 527. The design was analyzed by finite element method (FEM) based HFSS™ EM simulator software. Return loss, VSWR plot, smith chart and radiation pattern plots are observed and plotted for all designed antennas....
Human is one kind of the most interesting targets in through-the-wall imaging. In high-resolution imaging applications, human is\nno longer a point target. Therefore, the previous signal models constructed by point target assumption cannot accurately describe\nreal characteristics of EM propagation. We construct the signal models based on extended target theory in this paper. Compared\nwith previous works, the main contributions are as follows. Firstly, human is considered as an extended target. The expressions\nof target scattering and wall reflections are derived. Secondly, target scattering is no longer isotropic in new model. A new kind\nof ghost problem which is caused by target obscuring in EM propagation is discovered and exploited. Thirdly, to improve image\nquality in moving target imaging, an efficient approach which adopts CFAR, clustering method, and spatial geometry relationship is\nproposed to remove the ghosts. The derived models are shown to agree with synthetic and experimental results. And the efficiency\nof proposed method is also validated,which illuminates that the ghosts are efficientlymitigated and the image quality is significantly\nimproved....
The use of a millimeter-wave band defined as a 30ââ?¬â??300 GHz range is significant element for improving performance of\n5th generation (5G) mobile communication systems. However, since the millimeter-wave signal has peculiar propagation\ncharacteristics especially toward non-line-of-sight regions, the system architecture and antenna structure for 5G mobile\ncommunications should be designed to overcome these propagation limitations. For realization of the 5G mobile communications,\nelectronics and telecommunications research institute (ETRI) is developing central network applying various massive antenna\nstructures with beamforming. In this paper, we have introduced the central network and evaluated the system coverage and capacity\nthrough C++ language-based simulations with real geospatial information....
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