• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.14 no.2
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• pp.127-134
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• 2014

This paper presents a study on the radiation characteristics of low-VHF band electrically small antenna for direction finding. Firstly, it is simulated the antenna for mounting on flat ground and tank model(in 40MHz), and measured for mounting 1/10 scaled model(in 400 MHz). In case of flat ground feed at ${\phi}=0^{\circ}$, $180^{\circ}$(xz-plane), yz-plane $E_{\phi}$ (H-plane) and xz-plane $E_{\theta}$ (E-plane) radiation patterns are hemispheric omni-direction due to effect of narrow ground side. Then, in case of tank model, it is shown equally in case of the flat ground, yz-plane $E_{\phi}$ (H-plane) and xz-plane $E_{\theta}$ (E-plane) radiation patterns are hemispheric omni-direction nearly without effect of mounting position. Therefore, the suggested electrically small antenna for direction finding, in case of mounting on ground narrow side xz-plane(E-plane), is shown more stable radiation patterns as direction finding antenna.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.46 no.12
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• pp.52-58
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• 2009

We propose a folded monopole antenna with loads, and analyze the roles of design parameters which affect the return loss of the proposed antenna. VSWR < 3 bandwidth of the antenna is 30 ~ 2000 MHz, ranging from the HF/VHF/UHF bands. For operating travelling antenna, we connect six loads at the end of the antenna. The reflected wave is drastically reduced due to the six loads. For improved return loss properties, we use Klopfenstein tape that determine positions and values of six loads. The propose antenna has omni-directional radiational patterns like that of conventional monopole antennas. For wideband impedance transformation, we use the balun which operating frequency region is 10 ~ 1900 MHz. We expect the proposed antenna has important role for the wideband and multi-rold multi-functional communication systems.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.17 no.5
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• pp.91-96
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• 2017

In this paper, we proposed a meander sleeve monopole antenna for low earth orbit satellite communications. The antenna has broadband property with the planar monopole and ground of meander sleeve. Monopole and ground conductors of the antenna are on the same plane, and exited through coaxial cable feeding. In order to confirm the property of antenna parameters, it was used a commercial software, HFSS, For the antenna fabrication, a FR4 dielectric substrate has a dielectric constant of 4.4 was used. The size of the antenna was $600mm{\times}20mm{\times}1.6mm$. Frequency band of the fabricated antenna was 130MHz~151MHz, and the bandwidth was 20MHz. Measurement results of the fabricated antenna, the return loss is more than -10dB return loss in the band could be obtained. Radiation pattern has a maximum gain of 2.64dBi value.

• ETRI Journal
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• v.34 no.3
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• pp.454-457
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• 2012

A miniaturized planar digital video broadcasting terrestrial (DVB-T) antenna, which is composed of a patterned helical line, an open stub, and an impedance matching circuit on an FR4 (${\varepsilon}_r$=4.4) substrate for portable media player applications, is presented in this letter. The antenna has monopole-like, omni-directional radiation characteristics and a wide impedance bandwidth (VSWR<3) in the DVB-T band from 174 MHz to 230 MHz at the VHF band.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.7
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• pp.1450-1456
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• 2015

The received signal strengths according to the propagation distance between a transmitting shore station with a 53 m antenna hight and a receiving ship station with about 6m antenna hight from 700 m upto about 20 km are measured at ship's moving velocity of $5{\pm}1m/s$ using a single carrier signal at 150.0625MHz. In this paper, the path loss exponents at the propagation distance from 700 m to 20km are estimated via minimum-mean-square-error method using the measurements of the received signal strength, and the mean of the estimated path loss exponent become 3.79. The estimated propagation path loss exponents is similar to that calculated based on the field-strength values from 2 km to 20 km in Annex 2 of ITU-R P.1546-4, which is measuring results at maritime VHF at 100 MHz carrier frequency. Therefore, the estimated propagation path loss exponent shall be used as the expected path loss exponents for summer in costal area of South Sea of Korea.

• The Journal of the Korea institute of electronic communication sciences
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• v.11 no.11
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• pp.1039-1046
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• 2016

To study a habit and life patten of a wild animal, this paper do a research on the location tracing system of wild animal by yagi-antenna low pass filter, angle tracking technology. Commonly, VHF Radio Telemetry is used for the location tracing system of wild animal. Considering movement, Previous yagi-antenna has 4-element and has advantage of portability but the other advantages are small and preference is weak. To make the advantage of yagi-antenna higher than previous one, Supposed technology adapt to 6-element and make out Narrow space yagi-antenna technology. Also, It supposes that AOA (:Angle of arrival) technology is applied to detecting technology for a close direction from received signal. Based on this study suggest that position tracing technology is so as to figure out a life patten and habit of a wild animal which live in a certain area.

• Proceedings of the KIEE Conference
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• 2001.11a
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• pp.219-223
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• 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 Transactions of the Korean Institute of Electrical Engineers C
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• v.55 no.11
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• pp.527-531
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• 2006

Since 1996, KEPCO has been operating a wide range lightning detection system, LPATS, and been accumulating relative application techniques and statistical analysis skills. So, KEPRI already has its own basis to develope more accurate advanced detection technology and references to do comparative study. For three-dimensional imaging of lightning channels, UHF/VHF antenna systems were installed at 2 sites. The distance between two sites is about 30 km. These systems were used the AOA(Angle of Arrival) methods for lightning detection. In this paper, we would like to introduce about our system and its results.

• Journal of the Korea Institute of Military Science and Technology
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• v.10 no.3
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• pp.129-138
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• 2007

Recently, Direction Finding(DF) System is using switching DF algorithm to reduce system-weight by eliminating RF cable as much as possible. Also, Correlation Vector Direction Finding(CVDF) algorithms is being used for Fast Direction finding in tactical environment. In this paper, I will give you burst error elimination algorithms and compare the performance in case we use switching CVDF algorithm. Although antenna array is not working, we will successfully perform direction finding when we use this burst error elimination algorithms. Also, we will be completely capable of DF mission despite of meeting the unwanted situation that the monitoring signal disappear in case we use Switching Direction Finding algorithms. That situation frequently occurs under the Frequency Hopping signal circumstances.

• Proceedings of the Korean Magnestics Society Conference
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• 2005.06a
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• pp.190-190
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• 2005