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Cheng D.,Communication University of China | Cheng D.,Tianjin University of Technology and Education | Yin H.-C.,Science and Technology on Electromagnetic Scattering Laboratory | Zheng H.-X.,Tianjin University of Technology and Education
Journal of Electromagnetic Waves and Applications | Year: 2012

A new defected microstrip structure is proposed in this paper. By etching a simple U-shaped slot in the center of microstrip line, a very good bandstop characteristic is exhibited. Its resonant frequency is extracted by transmission line network analysis. At the same time, an accurate method of adjusting the resonant frequency is proposed to match the designed resonant frequency exactly. As advantages of this structure, the lower insertion loss in the passband, higher rejection level, and more simply integrated structure have been mentioned. The applications have been verified in the design of both microstrip dual-band bandstop and bandpass filters by experiment. © 2012 Taylor & Francis. Source

Zhang M.,Xidian University | Chen H.,Xidian University | Yin H.-C.,Science and Technology on Electromagnetic Scattering Laboratory
IEEE Transactions on Geoscience and Remote Sensing | Year: 2011

This paper is aimed at developing an applicable and feasible facet model, which formulation should be tractable and time saving for personal computers to take charge of the efficient evaluation on the complex reflective function of large-scope 2-D oceans, either in the monostatic or bistatic case. The sea surface is envisaged as a two-scale profile on which the long waves are locally approximated by planar facets. The microscopic profile within a facet is assumed to be represented by a set of sinusoidal ripple patches. The complex reflective function of each modified facet is evaluated by a modified formula of the original Bass and Fuks' two-scale model, in which the phase factor of each facet is with the capillary wave modification. Several examples with application to the frozen or time-evolving case are given to prove the implementation. © 2011 IEEE. Source

Jiang W.-Q.,Xidian University | Zhang M.,Xidian University | Wei P.-B.,Xidian University | Yuan X.-F.,Science and Technology on Electromagnetic Scattering Laboratory
IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing | Year: 2014

The small slop approximation (SSA) is an accurate method to calculate the electromagnetic (EM) scattering properties of rough surfaces. However, its computational complexity restricts its application to smaller domains and there is always the need for speedup in very large cases using pure central processing units (CPUs) hardware. With the development of graphics processing units (GPUs), more processors are dedicated to perform independent calculations. In addition, NVIDIA introduced a parallel computing platform, compute unified device architecture (CUDA), which provides researchers an easy way to use processors on GPU. To calculate EM scattering properties on GPU, we reformulate the SSA method with CUDA to take advantage of GPU threads. Because each thread executes synchronously and deals with a corresponding point data of rough surface, the CUDA-based SSA method calculates faster than the pure-CPU equivalent. To overcome memory limitations, the data of large rough surface are stored on hard disk. Moreover, a subsidiary thread is used to deal with the process of data transmission between the memory and the hard disk and reduce transmitting time further. The factors, block size, data transfers, and register, are also discussed in the optimization of the CUDA application. Test cases running on a NVIDIA GTX 460 GPU indicate that two orders of magnitude speedup, including file input and output, is obtained with our new formulation. © 2008-2012 IEEE. Source

Chen H.,Xidian University | Zhang M.,Xidian University | Yin H.,Science and Technology on Electromagnetic Scattering Laboratory
Progress in Electromagnetics Research | Year: 2012

A feasible simulator, of which formulation and mechanism should be simple and time saving, is developed in this paper to overcome the diffculties of prediction on the EM scattering from three- dimensional (3-D) electrically very large ship-sea models. The work in this paper is twofold. First, the sea surfaces are supposed to be a combination of many locally-tilted slightly rough facets with two-scale profiles. The radar return from each local facet is associated to a semi- deterministic scheme which is established by combining the geometric optics limit of Kirchho® Approximation (KA-GO) with the Bragg components of Bass-Fuks' two-scale model (BFTSM). Furthermore, we associate the complex reflective function of the respective facet by a so-called Phase-modified Facet Model (PMFM), in which the facet's phase is treated approximately as a combination of inherent part that follows a homogeneous random distribution and coherent part associated with the relative path-delay. Second, in companion with the semi-deterministic treatment of the sea scattering model, a hybrid approximate algorithm is proposed to deal with the composite scattering of electrically large ship-sea model, which is entirely evolved through facets (for the sea surface) and wedges (for the ship target). The method of equivalent currents (MEC) and a hybrid frame which combines the four path model (FPM) with the quasi-image method (QIM) are employed to calculate the scattering characteristics of the ship-like target and ship-sea interactions, respectively. The entire simulator is of comparatively significant computational effciency, and suitable for providing a preliminary prediction on the instantaneous complex reflective functions and normalized radar cross sections (NRCS) mean levels for electrically very large ship-sea model. Source

Zhu Z.,Nanjing University of Aeronautics and Astronautics | Sun X.,Science and Technology on Electromagnetic Scattering Laboratory | Xue H.,Nanjing University of Aeronautics and Astronautics | Guo H.,Nanjing University of Aeronautics and Astronautics | And 3 more authors.
Journal of Materials Chemistry C | Year: 2014

Graphene is a highly desirable material for efficient electromagnetic wave absorption due to its strong dielectric loss and low density. However, the main drawbacks in pristine graphene, such as high dielectric constant and low permeability, inevitably limit its performance due to the poor impedance matching. In this paper, reduced graphene oxide-spherical carbonyl iron composites (RGO-SCI) have been successfully fabricated through a facile wet chemical method. As expected, an apparent improvement of impedance matching in electromagnetic wave absorption could be found through the combination of RGO and SCI. A carbon-bridge effect was adopted to explain the electromagnetic wave absorbing process, which is closely related to a cross-linked framework structure of as-synthesized composites. Besides, in the range of 7.79-11.98 GHz with the thickness of 3.0 mm, the RGO-SCI composites exhibited efficient electromagnetic wave absorption characteristics (RL < 10 dB) with a minimum reflection loss of -52.46 dB. This journal is © the Partner Organisations 2014. Source

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