• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.16 no.7 s.98
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• pp.720-731
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• 2005

In this paper, radiation patterns of electrically small inverted-F antennas(IFAs) on an electrically large cylindrical conducting body like a satellite launcher are experimentally studied. First, radiation patterns are obtained by using method of moment and a commercial software tool, HFSS(High Frequency Structure Simulator) and the results are compared and analyzed with experimental ones. Especially, when the size of a cylindrical conducting body is electrically large, the effects of the size of a cylindrical conducting body on radiation patterns are studied by considering only the partial ground in vicinity of antennas. And then, when one and two inverted-F antennas are on the cylindrical conducting body, radiation patterns are simulated and investigated by using method of moment and HFSS. Good agreements are observed among the results by method of moment, HFSS, and experiments.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.12
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• pp.1140-1147
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• 2013

In this paper, The path loss model of Air Traffic Control(ATC) telecommunication radio channel has been studied at the Incheon International Airport(IIA) Cargo Terminal. We measured one frequency among VHF channel bands. The transmitting site was located at different locations with different heights. The transmitting site radiated the Continuous Wave(CW). The propagation measurement was taken using the moving vehicle equipped with receiver and antenna. The transmitting power, frequency and antenna height are the same as the current operating condition. The path loss exponent and intercept parameters were extracted by the basic path loss model and hata model. The path loss exponent at IIA Cargo terminal area were 3.67 and 3.39 respectively in first and second transmitting sites. The deviation of prediction error is 14.42 and 10.38. The new path loss equation at the IIA Cargo terminal area was also developed using the derived path loss parameters. The new path loss was compared with other models. This result will be helpful for the ATC site selection and service quality evaluation.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.1
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• pp.67-75
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• 2011

This paper investigates the radiated emission from the enclosure aperture, when the enclosure contains a 4-layer PCB and the PCB is driven by a pulse train additive with the switching noise from an active device. Radiated emission characteristics with and without switch noise cases, respectively, are analyzed by changing the PCB location and the slot direction. The equivalent circuit of a DC-DC converter is used to simulate the switching noise of active device. Also, MWS simulation results are directly connected to the ADS simulator as a 2-port block. The simulated results are compared with the measured ones.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.2
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• pp.220-227
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• 2011

With the rapid development of mobile communication technology, the technologies based on the diverse digital modulation schemes have been used for the frequency range of over 800 MHz. The only radiation immunity has been tested using only AM signal based on IEC 61000-4-3 without any consideration of the influence of electromagnetic radiation in Korea. However, it has not been tested by wideband digital modulation signals such as cdmaone(IS-95), WCDMA and PM signal. The purpose of this study was to review the standards. In addition, the input signals were analyzed and tested considering the environments in Korea. The results showed that the devices were influenced by digital modulation signal or PM signal more than by AM signal.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.3
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• pp.273-279
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• 2009

In this paper, an antenna which has dipole-like radiation pattern and low profile is proposed. The antenna is composed of four elements slot array based on L-shaped 0.43 $\lambda_g$ slot element. It presents a omni-directional radiation patter in the azimuth plane and has a null toward broad-side direction. In the design, a small mono-pole antenna which acts as a large capacitance element, combined with the partially removed ground plane by four L-shaped slots. As a result, these structure act as a LC resonator for radiation. The measured result shows, the impedance bandwidth(VSWR$\leq$2) of the proposed antenna is 60 MHz(2.35$\sim$2.41 GHz). The measured maximum radiation gain and efficiency of proposed antenna is 0.02 dBi, 56.7 % at center frequency 2.38 GHz, respectively. The proposed antenna can be applied to wireless tan access point system.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.2
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• pp.263-270
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• 2008

In this paper, we investigated EMI(electromagnetic interference) reduction by conductor connection, which was used for fixing and electrical grounding between frames. Conductor connects two frames and then it provides the decrease of return path of signal current. To prove the effect of conductor, we measured/simulated the RE(radiated emission) with/without conductors between the two frames. From the measured/simulated results, we observed that EMI decreased about 1$\sim$10 dB at the frequency range of 30 MHz to 1 GHz. VNA(vector network analyzer) was used to measure the S parameters and the RE was measured in a 3 m anechoic chamber. The simulated and measured results are compared and discussed.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.8 no.1
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• pp.9-18
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• 2008

Recently according to the development of an information society the information technology equipments which a clock frequency has the facility over a number giga hertz have been developed much. And we have research which leakage electromagnetic signals can use at the communication security and tapping. In this paper, we restored leakage electromagnetic signals of the monitors. And we proposed efficient recovery technique to restore the screen of the monitor. First of all, we understand a screen characteristic of the monitor. And then we restored a monitor screen from leakage electromagnetic signals from the monitor. For also we tried to use a Wavelet transform and filters to remove the noise for better performance. In the result of the experiment, we used leakage electromagnetic signals and confirmed the possibility of a monitor screen of the recovery. And we improve the performance with Wavelet transform and filters.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.6
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• pp.509-515
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• 2009

In this paper, we analyzed and evaluated noise suppression characteristic of EM wave absorber. We fabricated several absorber samples in different ratios of Sendust and Amorphous with CPE(Chlorinated Ploy-ethylene) as binder and calculated material constants by measured S-parameter. Then, we confirmed that the noise suppression characteristic of EM wave absorbers using microstrip line. A microstrip line with EM wave absorber placed on its top was used to evaluate the conduction noise suppression. As a result, noise suppression effect show different charateristic by changing relative permeability. Therefore, EM wave absorber using Sendust show excellent characteristic. In particular the maximum power absorption over 90 % in 1.7 GHz to over 6 GHz has obtained when composition of Sendust:CPE=80:20wt.%.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.9 s.112
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• pp.895-899
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• 2006

A compact representation of Green function is proposed by applying the discrete wavelet concept in the k-domain, which can be used for the acceleration of scattered field calculations in integral equation methods. Since the representation of Green function is very compact in the joint spatio-spectral domain, it can be effectively utilized in the fast computation of radiation integral of electromagnetic problems. A mathematical expression of Green function based on the discrete wavelet concept is derived and its characteristics are discussed.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2017.10a
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• pp.57-58
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• 2017

In this paper, we have studied electromagnetic susceptibility tests of the battery protection circuit module of a lithium ion battery. Electromagnetic susceptibility tests can be divided into conducted susceptibility for electromagnetic waves flowing through power lines, input / output lines, antenna ports, and radiated susceptibility for spatially radiated electromagnetic waves. A lithium ion battery of S company was used as an experimental sample, and conducted susceptibility tests were conducted on Surge (IEC 61000-4-5), Ring wave (IEC 61000-4-12), and Damped oscillatory wave(IEC 61000-4-18). Radiated susceptibility tests were performed according to IEC 61000-4-3.