• The Transactions of the Korean Institute of Electrical Engineers C
• /
• v.53 no.6
• /
• pp.330-336
• /
• 2004

In this work, in order to obtain the detailed information about lightning electromagnetic pulses, the electric fields radiated from multiple lightning return strokes were measured and analyzed statistically. The electric field measuring system consists of a hemisphere antenna of 30cm in diameter, integrator and data acquisition device, and its frequency bandwidth ranges from 200Hz to 1.56MHz, and the sensitivity is 0.96㎷/V/m. The electric field signals are digitized every 200ns with the transient signal analyzer having the resolution of 12-bit and the recording length of 5 kilowords and are registered at personal computer. As a result, the electric fields produced by the first return stroke begin with a slow initial part or front, which starts just after or during the last stepped leader. On the average the rise times of the electric fields for the positive first, second and third strokes are 4.21${\mu}\textrm{s}$, 3.94${\mu}\textrm{s}$ and 2.75${\mu}\textrm{s}$, respectively, and those for the negative first, second and third strokes are 3.46${\mu}\textrm{s}$, 3.15${\mu}\textrm{s}$ and 2.79${\mu}\textrm{s}$, respectively. The zero-crossing times of the electric fields for first return strokes range from about 10 to 80${\mu}\textrm{s}$. The mean zero-crossing times for subsequent return strokes are shorter than those for first lightning return strokes.

• Aerospace Engineering and Technology
• /
• v.10 no.2
• /
• pp.82-86
• /
• 2011

This paper presents an RF Electric field assessment at 2.290 [GHz] inside launcher PROTON M/Breeze M long fairings, produced by COMS TM. COMS intentional RE due to TM ON under fairing has been assessed considering PROTON M / BREEZE M fairing characteristics. As fairings of all launchers present similar sizes, a similar E-field level under fairing is expected for the other launchers. As a result, the RE level under faring is compliant with COMS RS limits, but is not compliant with RS requirements of the launcher PROTON M/Breeze M.

• Aerospace Engineering and Technology
• /
• v.6 no.1
• /
• pp.173-181
• /
• 2007

Radiated emission / susceptibility performance of the KSLV-I 2nd stage which are controlled from the unit level to the system level should be examined and managed all over the frequency ranges in order to ensure the normal operation of the SC, the 1st stage of the KSLV-I, ground support equipments which are installed at the space center, and other wireless communication networks. Not only unintentional electric field emissions from the KSLV-I system and its subsystems should be restricted to the levels less than the limits specified in the EMC requirements, but also proper test and evaluation method should be established, respectively. In this paper, radiated emission/susceptibility test limits, method, and test results of the KSLV-I 2nd stage engineering model are presented.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.11 no.7
• /
• pp.1121-1127
• /
• 2000

Among many EMI suppression techniques for radiated emissions from PCB traces, image technique is adapted in this paper. A model for the analysis of the effect of image plane on the radiation of a microstrip trace is presented. After a simulation was carried out by using the FEM(Finite Element Method), field strength was measured with electric probe. The radiated emission levels were measured for various image plane width, separation distances, and their results show that the measured data are very close to those of simulation result. It proves that a proper use of image planes on the PCBs is very effective means of reducing EMI emissions on the PCBs.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.16 no.4
• /
• pp.73-79
• /
• 2002

In this paper, electromagnetic waves radiated from discharge at three-type electrodes(needle-plane, plane-plane and sphere-plane electrode) using AC power source in air are measured and the peculiar patterns of their spectra are reported. The radiated electromagnetic waves were measured in bandwidth of VHF(30-230[MHz]) using a biconical antenna and a spectrum analyzer. When the discharge onset voltage range, high electric field intensity is shown in frequency band of 45, 70, 80[MHz] in case of needle-plane electrode configuration and 40[MHz] in case of plane-plane and sphere-plane electrodes configuration. However, when the breakdown voltage range, the frequency spectrum distribution of radiated electromagnetic waves appear different in the whole frequency range according to the shapes of electrode.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.39 no.3
• /
• pp.150-157
• /
• 2002

A nonlinear shaping method for a wire antenna is presented to improve the limited pulse radiation ability due to the frequency characteristics with nulls which are found in the conventional straight or V antennas. The developed scheme is based on the minimization of frequency-dependence of the radiated electric field intensity over wide band, hence giving the ripple-type frequency characteristics. It is shown that the synthesized shape has more advantage in the case of shorter pulse. That is, we found that for shorter pulse exciting, the radiated peak value of the synthesized antenna is larger than that of the conventional linear antenna. The inverse discrete Fourier transform based on the moment method is used for the transient analysis of current distribution and far field electric field.

• Proceedings of the KIEE Conference
• /
• 2001.11a
• /
• pp.219-223
• /
• 2001

In this paper, electromagnetic waves were measured in accordance with propagating the discharge when positive and negative DC high voltage was applied to needle-plane electrdes and plane-plane electrdes that solid dielectric was inserted between the electrodes. The radiated electromagnetic waves were investigated in bandwidth of VHF($30{\sim}230$[MHz]) using an biconical antenna. In needle-plane electrodes high electric field intensity is shown in both frequency band of 90(MHz) and 170[MHz], and gradually decreasing characteric is appeared at high frequency band. However high electric field intensity is shown in both 80[MHz] and 140[MHz] in case of plane-plane electrodes configuration. And over 150[MHz] frequency band, rapidly decreasing characteristic is shown. Moreover, electric field intensity of positive DC is about $5{\sim}10$[dB] higher than negative DC.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.9 no.4
• /
• pp.526-534
• /
• 1998

The electric near-fields from a cellular phone's antenna are calculated using TLM method. The cellular phones is assumed to be a conductive box and the frequency is set to be 900 [MHz] and the radiated power is set to be 0.6 [W]. The near-fields and far-field patterns are obtained for wire antennas of 1/4 and 1/2 wavelengths. For the same radiation power, (0.6 [W]), it is found out the near-field for antennal length of λ/2 is much weaker than that for λ/4 antenna. The maximum SAR calculated in a simple head model becomes 1.4[W/kg].

• 전기의세계
• /
• v.23 no.3
• /
• pp.67-69
• /
• 1974

The electric characteristics of all the instruments and materials used in atomic field is changed due to radiation damages by the effects of radio activities. In this study, when the condenser is radiated by Gamma-ray, variations in its electric properties have been investigated. The following results are obtained. (1) The capacitance in O.F paper condenser is exponentially increased as the quantity of irradiation by Gamma-ray is increased, but polyethylene, ceramic, chemical, neostyrene, mylar condenser are decreased. and in case of more than 10$^{7}$ of irradiation it has saturated state, (2) The breakdown voltage and the .delta. in condensers except the O.F paper condenser are exponentially increased as the quantity of irradiation by Gamma-ray is increased but in case of more than 10$^{7}$ .gamma. of irradiation it has decreased.

• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
• /
• v.6 no.4
• /
• pp.28-36
• /
• 1995

The use of image planes can reduce effectively the radiated emissions from a printed circuit board. This work deals with the influence of image planes on radiation from current trace. The configu- rations of one and two layers of image planes on both sides of current trace are proposed. The radiated emissions of those configurations have been calculated by solving a set of electric field integral equations by the method of moments. The induced current distributions on image planes and the radiation patterns are analyzed for different configurations of image planes, the distance between current trace and image planes, and the frequency of signal current.