• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.2
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• pp.266-269
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• 2012

This paper introduces a signal processing technique for discrimination of ballistic missile's warhead. An interceptor missile to destroy the enemy's ballistic missile requires an information on the location of missile's warhead. In order to detect and locate the missile's warhead, a seeker radar in the interceptor missile makes use of chirp waveform to generate high resolution range profiles(HRRPs). We applied one of the well known spectral estimation technique called ESPRIT (Estimation of Signal Parameters by Rotational Invariance Technique) to these HRRPs to estimate scattering centers on the target. Using the information on the one-dimensional(1-D) scattering centers, we can find the location of the warhead by estimating the length of the missile, Simulation results show that the proposed signal processing technique is efficient in discriminating the warhead of an ballistic missile.

• The Journal of the Korea institute of electronic communication sciences
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• v.6 no.3
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• pp.343-348
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• 2011

With the rapid and wide-spread use of mobile communications much attention has been focussed on propagation in the urban area crowed with buildings. It is often surrounded by hills, forests, and mountains. The importance of surface scattering interference between transmitters and receivers on the rough surfaces has been interested and investigated. Therefore, a prediction method is necessary to estimate the influence of rough surfaces on microwave radio propagation. Moreover, most of the mobile communications are performed based on the digital communication system rather than the analog one. In this case, we must pay more careful attention to the signal delay caused by the phase delay due to the multi-path propagation. In this paper we have analyzed numerically scattering of electromagnetic waves from Composite structures by using FVTD (Finite Volume Time Domain) method. We consider two different types of rough surfaces such as periodic and composite structures.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.54 no.8
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• pp.384-389
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• 2005

The Resonance Scattering Theory(RST) provides the physical explanation of the scattered field that appears in the vicinity of the resonance frequency. The theory suggests that the amplitude of each Partial-wave mode can be divided into two components : resonance and non-resonant background. The long-standing difficulty in the application of RST is that it always requires background components. We have applied the RST to the electromagnetic scattering problems by a penetrable spherical scatterer and a cavity. In this paper, we show some numerical results, and validate background coefficients.

• Journal of electromagnetic engineering and science
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• v.17 no.4
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• pp.169-177
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• 2017

The role of electromagnetic (EM) waves in magnetic fusion plasma-ranging from radio frequency (RF) to microwaves-has been extremely important, and understanding of EM wave propagation and related technology in this field has significantly advanced magnetic fusion plasma research. Auxiliary heating and current drive systems, aided by various forms of high-power RF and microwave sources, have contributed to achieving the required steady-state operation of plasmas with high temperatures (i.e., up to approximately 10 keV; 1 eV=10000 K) that are suitable for future fusion reactors. Here, various resonance values and cut-off characteristics of wave propagation in plasmas with a nonuniform magnetic field are used to optimize the efficiency of heating and current drive systems. In diagnostic applications, passive emissions and active sources in this frequency range are used to measure plasma parameters and dynamics; in particular, measurements of electron cyclotron emissions (ECEs) provide profile information regarding electron temperature. Recent developments in state-of-the-art 2D microwave imaging systems that measure fluctuations in electron temperature and density are largely based on ECE. The scattering process, phase delays, reflection/diffraction, and the polarization of actively launched EM waves provide us with the physics of magnetohydrodynamic instabilities and transport physics.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.10 no.3
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• pp.440-448
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• 1999

This paper describes a full wave analysis of the scattering from electromagnetic absorbers which can be approximated as infinite periodic structure using hybrid finite element method. By introducing fictitious boundaries, equivalent finite region is defined and proper boundary conditions of each boundary are obtained by Floquet theorem. Since higher-order Floquet modes are employed, the method presented in this paper can be readily applied to the periodic structure haying a relatively long period. To reduce difficulty in evaluating the surface integral, the normal component to the surface were represented with the tangential component to the surface. Comparisons of calculated results with analytical or published ones show the validation of the method.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.3
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• pp.324-330
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• 2013

This paper presented measurement results of scattering characteristics of dielectric barrier discharge (DBD) plasma at atmospheric pressure. In this paper, plasma actuator is fabricated by parallel connecting of basic configuration of DBD plasma actuator, then plasma could be generated by applying 14 kV, 4 kHz of high voltage generator. In order to measure the scattering characteristics of DBD plasma, in this paper, two horn antennas and vector network analyzer are used to compare the S-parameter. Because of the structure of fabricated plasma generator, different result is obtained as antenna polarization changes. When antenna polarization is parallel to electrodes of plasma generator, the scattered field is reduced by 2 dB in maximum. In addition, for parallel polarization case, PEC is set up behind the plasma generator to measure backward scattered field. When the observation angles are $40^{\circ}C$ and $60^{\circ}C$, the amount of reduced scattered field is 2 dB in maximum at 5 GHz.

• Proceedings of the KIEE Conference
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• 2007.11a
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• pp.136-137
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• 2007

The emission of external incident field or near device field is important factor of EMI and EMC. In this paper, we apply MOM, using the RWG basis function, to analysis the induced current distribution on the PEC and dielectric plates. The volume and surface integral equations are presented for the electromagnetic wave scattering from plate structures composed of dielectric and conducting objects.

• Proceedings of the KAIS Fall Conference
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• 2004.06a
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• pp.247-249
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• 2004

본 논문에서는 격자구조의 유전체에 수직으로 입사된 전자기파의 산란, 투과 특성을 얇은 위상 막 근사화 이론을 이용하여 분석하였다. 위상 막 근사화 이론은 격자구조가 입사되는 전자기파의 위상 변화만을 주는 것으로 간주하는 것으로 이를 이용하여 격자구조를 통과한 직후인 근거리 필드 분포를 TE 모드에서 계산하였다. 기존의 제시된 이론에 비해 비교적 간단하고 빠르게 산란 필드를 분석할 수 있다.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.51 no.11
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• pp.551-558
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• 2002

A time-domain combined field integral equation (CFIE) is presented to obtain the transient scattering response from arbitrarily shaped three-dimensional conducting bodies. This formulation is based on a linear combination of the time-domain electric field integral equation (EFIE) with the magnetic field integral equation (MFIE). The time derivative of the magnetic vector potential in EFIE is approximated using a central finite difference approximation and the scalar potential is averaged over time. The time-domain CFIE approach produces results that are accurate and stable when solving for transient scattering responses from conducting objects. The incident spectrum of the field may contain frequency components, which correspond to the internal resonance of the structure. For the numerical solution, we consider both the explicit and implicit scheme and use two different kinds of Gaussian pulses, which may contain frequencies corresponding to the internal resonance. Numerical results for the EFIE, MFIE, and CFIE are presented and compared with those obtained from the inverse discrete Fourier transform (IDFT) of the frequency-domain CFIE solution.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.3B
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• pp.244-250
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• 2002

In this paper, rile scattered field from a random rough perfectly conducting surface by method of moment(MoM) was computed. A one-dimensional random rough surface predetermined statistical properties was generated by a digital computer. The number of surface realization for the computed field and the width of surface realization are set to be 100, 80 λ, respectively. To eliminate the scattering from the ends of the surface, the Gaussian taper function is used. Using Monte Carlo technique, we calculated hi-static scattering and back scattering coefficient. In order to verify the result by MoM we compare the MoM results with those of Kirchhoff approximations, which show good agreement between them.