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Surface dielectric barrier discharge (SDBD), which is widely used to control turbulence in aerodynamics, has a significant effect on the radar cross-section (RCS). A four-way linearly synthesized SDBD air plasma actuator is designed to bolster the plasma effects on electromagnetic waves. The diffraction angle is calculated to predict the RCS because of the periodic structure of staggered electrodes. The simplified plasma modeling is utilized to calculate the inhomogeneous surface plasma distribution. Monostatic RCS shows the diffraction in the plane perpendicular to the electrode array and the notable distortion by plasma. In comparison, the overall pattern is maintained in the parallel plane with minor plasma effects. The trends also appear in the bistatic RCS, which has a significant difference in the observation plane perpendicular to the electrodes. The peaks by Bragg’s diffraction are shown, and the RCS is reduced by 10 dB in a certain range by the plasma effect. The diffraction caused by the actuator and the inhomogeneous air plasma should be considered in designing an SDBD actuator for a wide range of application.

EMP(Electromagnetic Pulse) 공격에 대한 피해를 방호하기 위해 정화조에 사용되는 배수관에는 별도의 금속 차폐 구조물의 추가 설치가 고려된다. 이러한 차폐 구조물은 EMP 공격을 막아주지만, 물에 함께 섞여 흘러오는 불순물이 차폐구조물을 통과하지 못해 배수관 본연의 역할을 잃게 하며, 이를 관리하기 위해 추가적인 유지보수 인력을 필요로 한다. 위의 문제점들을 해결하기 위해 본 논문에서는 차폐 구조물 없이 물의 감쇠 특성을 고려한 배수관 구조를 제안하였다. 배수관 직경을 100 mm로 고정한 채로 물에 잠기는 깊이를 400 mm부터 800 mm까지 변화시켰을 때, 각각의 차폐 효과는 2 GHz 주변에서 70 dB부터 100 dB까지 증가됨을 확인하였다. 검증 과정을 통해 추가적인 차폐 구조물 없이 배수관 본연의 기능을 유지하고, EMP 공격을 차폐할 수 있는 효율적인 설계의 가이드라인을 제안하였다.

In this paper, a gas sensor using a modified hybrid coupler structure with conducting polymer which operates at 2.4 GHz is represented. Conducting polymers are used to the gas sensing material in proposed sensors. The conducting polymer varies its electrical property, such as work function and conductivity corresponding to the certain gas. To verify this variation of electrical property of conducting polymer at microwave frequencies, the conducting polymer is incorporated with the hybrid coupler structure, and this proposed sensor operates as reflection type variable attenuator and variable phase shifter. The conducting polymer is employed as impedence-variable transmission lines that cause a impedance mismatching between the general transmission line and conducting polymer. The experiment was conducted with 100 ppm ethanol gas at temperature of and relative humidity of 85 %. As a result, the amplitude deviation of is 0.13 dB and the frequency satisfying ${\angle}S_{21}

This paper presents a characteristic evaluation of commercial gallium nitride (GaN) transistors having two different gate-lengths of 0.4μm and 0.25-μm in the design of a class-S power amplifier (PA). Class-S PA is operated by a random pulse-width input signal from band-pass delta-sigma modulation and has to deal with harmonics that consider quantization noise. Although a transistor having a short gate-length has an advantage of efficient operation at higher frequency for harmonics of the pulse signal, several problems can arise, such as the cost and export license of a 0.25-μm transistor. The possibility of using a 0.4-μm transistor on a class-S PA at 955 MHz is evaluated by comparing the frequency characteristics of GaN transistors having two different gate-lengths and extracting the intrinsic parameters as a shape of the simplified switch-based model. In addition, the effectiveness of the switch model is evaluated by currentmode class-D (CMCD) simulation. Finally, device characteristics are compared in terms of current-mode class-S PA. The analyses of the CMCD PA reveal that although the efficiency of 0.4-μm transistor decreases more as the operating frequency increases from 955 MHz to 3,500 MHz due to the efficiency limitation at the higher frequency region, it shows similar power and efficiency of 41.6 dBm and 49%, respectively, at 955 MHz when compared to the 0.25-μm transistor.

In determining interaction between plasma and electromagnetic wave, plasma frequency and collision frequency are two key para-meters. They are derived from electron density and temperature, which vary in an extremely wide range, depending on a plasma gene-rator. Because the parameters are usually unknown, traditional researches have utilized simplified electron density model and constant electron temperature approximation. Introduction of plasma fluid model to electromagnetics is suggested to utilize relatively precise time dependent variables for given generator. Dielectric barrier discharge(DBD) generator is selected due to its simple geometry which allows us to use one dimensional analysis. Time dependent property is analyzed when microwave is launched toward parallel plate DBD plasma. Afterwards, attenuation tendency with the change of electron density and temperature is demonstrated.Key words: Plasma Fluid Model, Dispersion Relation, DBD Plasma, Atmospheric Pressure Plasma, Microwave Attenuation {O

In this paper, economic loss due to high power electromagnetic pulse is estimated and the methodology used for calculating its impacts is suggested using a macro approach. In order to investigate the most critical infrastructure for the high power electromagnetic pulse assault, the vulnerability assessment that provides information on the threats of concern is conducted. As a result, this study concentrates on the electric power networks. The presented assessment model is considered with gross domestic product (GDP) and energy consumption when the electric power networks are damaged due to high power electromagnetic pulse. In addition, economic losses are calculated by the extent of damages considering different types of the high power electromagnetic pulse assault generated by nuclear and man-made weapon. Through the estimation of these damages, the resulted economic loss will be compared with the protection cost. Consequently, protection of the vulnerable infrastructures can be prepared against electromagnetic pulse attack.Key words: High Power Electromagnetic Pulse, Economic Loss, Electric Power Network, Macro Approach Ik lf [lX(Department of Electrical and Electronics Engineering, Yonsei University) *Ik lfa m Revised June 17, 2014 ; Accepted July 7, 2014. (ID No. 20140506-041)Corresponding Author: Jong-Gwan Yook (e-mail: jgyook@yonsei.ac.kr)

In this paper, a TVS diode which is commonly used as a ESD protector in wireless communication devices could cause antenna wireless sensitivity to decrease has been analyzed. When a smartphone doesn't have enough space to place many components, there would be its speaker near antenna area. In order to protect ESD coming through the speaker there also could be a TVS within antenna GND area. Digital audio signal which was sent to speaker and CDMA RF communication signal coupled from antenna was mixed by TVS. And this leakage current running through TVS resulted in decrease of antenna wireless sensitivity. The results of various experiments can be explained using circuit simulation. Following works will give us some insights that can reduce unwanted summation of digital and RF signal due to nonlinearity of ESD protectors. Key words : ESD, TVS Diode, Antenna Wireless Sensitivity, Digital Signal, Communication RF Signal  {|(}~b >}(School of Electrical and Electronic Engineering, Yonsei University) *LGb (LG Electronics)Manuscript received June 21, 2013 ; Revised August 29, 2013 ; Accepted September 2, 2013. (ID No. 20130621-058)Corresponding Author : Jong-Gwan Yook (e-mail : jgyook@yonsei.ac.kr)

This paper expands a previously proposed optimized higher order (2, 4) finite-difference time-domain scheme (H(2, 4) scheme) for use with lossy material. A low dispersion error is obtained by introducing a weighting factor and two scaling factors. The weighting factor creates isotropic dispersion, and the two scaling factors dramatically reduce the numerical dispersion error at an operating frequency. In addition, the results confirm that the proposed scheme performs better than the H(2, 4) scheme for wideband analysis. Lastly, the validity of the proposed scheme is verified by calculating a scattering problem of a lossy circular dielectric cylinder.

In this paper, a formulation for obliquely incident electromagnetic wave has been presented for an analysis of highpower electromagnetic pulse penetration into multilayered dispersive media. Based on generalized models of measured dielectric constants and propagation channels reflecting the Earth`s general features, the propagation phenomenon of the obliquely incident early-time(E1) high altitude electromagnetic pulse(HEMP) is analyzed. In addition, the polarization and critical angle are also considered. It is found that the total reflection occurs at an incident angle of about 38 degrees at the soil-rock interface, and that the parallel-polarized E1 HEMP penetrates better than the perpendicular-polarized one. The peak level of the penetrating electric field is found to be 5.6 kV/m at normal incidence, regardless of the type of polarization, and E1 HEMP is greatly reduced near the critical angle. Moreover, the penetrating E1 HEMP is analyzed as a variation of moisture content and depth of materials, resulting E1 HEMP could be useful in determining the levels of shielding required for buried facilities.

This paper deals with the near-field to far-field calculation for far-field characteristics of antenna and electromagnetic compatibility(EMC) testing. Since the conventional EMC testing process is inefficient such as measurements of the wide band signals and mega structures, Stratton-Chu formula is used to predict the far-field emission by simple and direct process. The usefulness of Stratton-Chu formula is verified by comparing to the analytic solution of the uniform distri-bution aperture in free-space. In order to inspect the far-fields and to get the near-field values, full-wave simulation solver is utilized. Through the full-wave simulation about the patch antenna, calculated far-field results from Stratton- Chu formula are proven. The predicted magnitudes of the far-field are in error by less than 6 %.Key words : Near-Field to Far-Field Transformation, Stratton-Chu Formula 「본연구는방위사업청과국방과학연구소의지원으로수행되었음.」 연세대학교전기전자공학과(Department of Electrical & Electronic Engineering, Yonsei University) ․Manuscript received November 30, 2012 ; Revised February 19, 2013 ; Accepted February 20, 2013. (ID No. 20121130-07S)․Corresponding Author : Jong-Gwan Yook (e-mail : jgyook@yonsei.ac.kr)

In this paper, plasma modeling is achieved using fluid dynamics, thereby electron density is derived. The way proposes the key to overcoming the limitations of conventional researches which adopt simplified plasma model. The result is coupled with Maxwell-Boltzmann system in order to calculate scattering waves in various incident angle. The first part is dedicated to perform plasma modeling in dielectric barrier discharge(DBD) structure. Suzen-Huang model is adopted among various models due to the fact that it uses time independent variables to calculated potential and electron distribution in static system. The second part deals with finite difference time domain(FDTD) scheme which computes the scattered waves when the modulated Gaussian pulse is incident. Founded on it, radar cross section(RCS) is observed. Consequently, RCS is decreased by 1~2 dB with DBD plasma. The result is analogous to the RCS measurement in other researches.

In this paper, to the aim of wideband SSN(Simultaneous Switching Noise) suppression characteristic, investigation of spiral resonator are used in conjunction with bead which is commonly used for noise suppression method. Bead works effectively to suppress the power noise up to the first harmonic of fundamental frequency, 0.8 GHz, and spiral resonator suppress noise well in the frequency range of SRF(Self Resonance Frequency) which is inversely proportional to the length of spiral. Thus, when bead used in conjunction with a spiral the noise suppression characteristic is determined by the one of higher impedance element of the two in the frequency range and achieves more broadband filtering characteristic. The case for using 22 nH bead turns out 4.8, 2.0, 0, and, 0.6 dB, and the case for using 22 nH bead in conjunction with 3-turns spiral achieves more wideband characteristic of 9.5, 8.3, 6.1, and 9.9 dB power noise suppression performances at the first, second, third, and fourth harmonics, respectively. The peak-to-peak voltage levels decrease from 76 mV to 56 mV using 22 nH bead, and the level decrease rapidly to 34 mV when using in conjunction with bead and 3-turn spiral. Thus more wideband SSN suppression characteristic can be achieved using bead with spiral.

This paper describes a novel and compact biosensing platform using an RF active system. The proposed sensing system is based on the oscillation frequency deviation due to the biomolecular binding mechanism on a resonator. The impedance variation of the resonator, which is caused by a specific biomolecular interaction results in a corresponding change in the oscillation frequency of the oscillator so that this change is used for the discrimination of the biomolecular binding, along with concentration variation. Also, a Surface Acoustic Wave (SAW) filter is utilized in order to enhance the biosensing performance of our system. Because the oscillator operates at the skirt frequency range of the SAW filter, a small amount of oscillation frequency deviation is transformed into a large variation in the output amplitude. Next, a power detector is used to detect the amplitude variation and convert it to DC voltage. It was also found that the frequency response of the biosensing system changes linearly with three streptavidin concentrations. Therefore, we expect that the proposed RF biosensing system can be applied to bio/medical applications capable of detecting a nano-sized biomolecular interaction.

This paper presents a single-pole eight-throw switch, based on an eight-way power divider, using substrate integrate waveguide(SIW) technology. Eight sectorial-lines are formed by inserting radial slot-lines on the top plate of SIW power divider. Each sectorial-line can be controlled independently with high level of isolation. The switching is accomplished by altering the capacitance of the varactor on the line, which causes different input impedances to be seen at a central probe to each sectorial line. The proposed structure works as a switching circuit and an eight-way power divider depending on the bias condition. The change in resonant frequency and input impedance are estimated by adapting a tapered transmission line model. The detailed design, fabrication, and measurement are discussed.

In this paper, the effects of a metal plane on the performance of a meandered slot RFID antenna are evaluated in a real environment, and 3 metal plane cases are considered (the most likely scenarios in which metal conductive materials are placed near the tag antenna). The metal plane effects can be categorized as matching degradation and antenna gain variation. First, matching degradation due to the antenna’s induced mutual impedance is experimentally investigated. In addition, the gain variation is investigated to figure out the change in the radiation characteristics. With the derived antenna parameters, the read range is calculated with the Friis transmission equation and measured to analyze the effects of a metal plane on RFID system performance. The calculated and measured read range varies from 9.3 m to 19.1 m as the distance between the RFID antenna and the metal plane changes.

In this paper, reinforced concrete structures are modeled and analyzed. Reinforced concrete has been an essential element in the construction and one that is provided for shielding effectiveness at particular frequencies by rebar placed as a set up in the form of a grid. Using commercial 3-dimensional electromagnetic(3D EM) tool to analyze the reinforced concrete structure, the procedure of analysis for reinforced concrete is computed by dividing concrete, rebar and entire reinforced concrete. The spacing of rebar is bigger, transmission coefficient is higher and the diameter of rebar is bigger, transmission coefficient is lower. Also, in case of two layers is analyzed by gap of layers. Using single layer rebar that thickness of rebar given by 10, 20 and 30 mm have transmission coefficient of -1.89, -2.73 and -4.76 dB/10 cm at 500 MHz. Also, two layers rebar obtain -1.89, -2.73 and -4.76 dB/10 cm for same conditions.

This paper gives a electromagnetic coupling mechanism of the high altitude electromagnetic pulse (HEMP) into large- scale underground multilayer structures using analytic and numerical methods. The modeling methods are firstly addressed to the HEMP source which can be generated by intentional nuclear explosion. The instantaneous and intense electromagnetic pulse of the HEMP source is concerned from DC to 100 MHz band, because the power spectrum of the HEMP is rapidly decreased under -30 dB over the 100 MHz band. Through this range, a penetrated electric field distribution is computed within the large-scale underground multilayer structures. As a result, the penetrated electric field intensities at 0.1 and 1 MHz are about 10 and 5 kV/m, respectively. Therefore, additional shielding techniques are introduced to protect buried structures within the large-scale underground structures such as high-lossy material and filtering structures (wire screen).

This paper describes a compact and novel wireless vital sign sensor at 2.4 GHz that can detect heartbeat and respiration signals. The oscillator circuit incorporates a planar resonator, which functions as a series feedback element as well as a near-field radiator. The periodic movement of a human body during aerobic exercise could cause an input impedance variation of the radiator within near-field range. This variation results in a corresponding change in the oscillation frequency and this change has been utilized for the sensing of human vital signs. In addition, a surface acoustic wave (SAW) filter and power detector have been used to increase the system sensitivity and to transform the frequency variation into a voltage waveform. The experimental results show that the proposed sensor placed 20 mm away from a human body can detect the vital signs very accurately.