• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07a
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• pp.523-526
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• 2002

We designed wideband HTS antennas which consists of two triangle-radiation patches using a YBa$_2$Cu$_3$O$\sub$7-x/ (YBCO) superconducting thin film. The major limitation of high-Tc superconducting (HTS) microstrip antennas is the narrow bandwidth due to the high Q and thin substrate. Defining bandwidth as the frequency range over which standing wave ratio (SWR) 2:1 or less, HTS antenna bandwidths are typically 0.85% to 1.1%. Thus considerable effort has been focused on developing antennas for broadband operation. To calculate input impedance and design of the broadband HTS antennas a moment method technique was used. The HTS antenna fabricated in this work was designed for K-band, which is useful band for satellite-to-satellite communications. The bandwidth obtained was a significant 6.7% and the other measured performance of our HTS antenna, including the bandwidth, radiation Pattern, efficiency, standing wave ratio (SWR) and return losses was reported.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.2 no.2
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• pp.197-205
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• 1998

The purpose of this paper is to analyze the electromagnetic field characteristics of array antenna with the finite difference-time domain algorithm. Finite difference equations of Maxwell's equations are defined in cylindrical coordinate systems. To simulate the unbounded problem like a free space, the Mur's absorbing boundary condition is also used. After modeling the array antenna with the grid structure, the transient response of the field distribution is depicted in the time domain.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.11a
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• pp.559-562
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• 2000

In this paper, coplanar waveguide fed antennas (CPWFAs) insetting two slits to boundary of the square microstrip patch are presented. These slits play roles in not only lowering a resonant frequency but also fine-tuning for the proposed antenna together with open stub of CPW feed line. The CPWFAs were designed and manufactured using microwave dielectrics (Al,Mg)TaO$_2$ having high dielectric-constant ($\varepsilon$r=20). The return loss and input impedance of the CPWFAs were investigated in terms of the slit length and open stub length of CPW feed line. It is shown that a resonant frequency decreases as the slit length increases.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.12
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• pp.1316-1324
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• 2009

In this paper, cross-aperture coupled microstrip circular polarization antenna is proposed for 5.8 GHz WLAN(Wireless Local Area Network). A single antenna consists of square patch and slots are located in series feed line with $\lambda_g$/4 phase different which make current direction maximum and minimum repeatedly to generate RHCP(Right Handed Circularly Polarization). We are proposed new structure that removed the section which intersected at a right angle and were composed to four separated slots. The proposed cross slots reduce back lobe of radiation pattern and improve antenna gain. Impedance bandwidth of the manufactured $2\times2$ array antenna is from 5.67 to 5.95 GHz and the maximum radiation gain is 10.59 dBi.

• Journal of Advanced Navigation Technology
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• v.22 no.6
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• pp.665-669
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• 2018

In this paper, we design an antenna for LTE / Wi-Fi communication that operates in 2.65 GHz and 5 GHz band for small-sized broadband communication antenna that can be used in the sea. Microstrip patch antennas were chosen to improve the bandwidth. The slot width, length, and transmission line width were calculated using the theoretical formula for each step. In addition, we designed a microstrip antenna using CST Microwave Studio 2014 program that can design 3D. Simulation results show that the reflection lossis -12.712 dB at 2.65 GHz and -16.583 dB at 5 GHz. The gain was 1.738 dBi at 2.65 GHz and 3.284 dBi at 5 GHz. In this paper, we propose a dual-band antenna for LTE / Wi-Fi, which can be used in maritime environments, which is worse than terrestrial communication, because of differences in communication speed and communication stability compared with those used on land.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 1999.07a
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• pp.185-190
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• 1999

대부분의 물질에 함유된 수분은 물질의 중요한 구성성분중의 하나이며 특히 농산물이나 식품 등에 함유된 수분은 각 품질을 평가하기 위한 중요한 인자중의 하나이다. 각종 농산물 및 식품가공공정 뿐만 아니라 저장단계에서 원료의 수분함량을 신속 정확하게 측정할 수 있는 시스템의 개발이 요구되고 있다. 이러한 원료의 수분함량을 간접적으로 측정하는 방법으로서 주로 전기저항, 고주파 정전용량, 근적외선, 마이크로파 등이 이용되고 있다. (중략)

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2003.05a
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• pp.530-533
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• 2003

본 논문에서는 2GHz의 패치폭과 그라운드면의 폭이 같은 QMSA의 구조를 설계 및 제작하였고, QMSA의 구조를 변형하여 용량을 장하한 QMSA와 기생소자를 갖는 QMSA를 제안하였다. QMSA의 구조는 한 쪽 끝이 전기적으로 단락된 λ/4의 구조로 설계하였으며, 용량을 갖는 QMSA는 상측 평행 평판과 하측 평행 평판 사이의 용량을 구성시킴으로써 리턴로스와 공진주파수의 변화를 비교 평가하였다. 또한, 기생소자를 갖는 QMSA의 구조는 상측 평행 평판위에 기생소자를 가변함으로써 안테나를 소형화할 수 있었다. QMSA는 2GHz의 중심주파수를 갖고 2%의 대역폭을 갖으며, 용량의 변화와 기생소자의 길이에 따라 공진주파수의 변화를 보였다.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2002.11a
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• pp.227-231
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• 2002

GPR은 건물의 크랙, 지중 매설물과 같은 정보를 수집하기 위해 좁은 펄스를 사용하므로 넓은 대역의 주파수 특성을 가진다. 본 논문에서는 광대역 특성을 가지는 안테나를 마이크로스트립을 이용하여 보우타이 형태로 설계하였다. 설계 기판으로는 $\varepsilon$$_{r}$=4.0, t=1.6 mm의 FR-4 유전체 기판을 사용하였다. 제작된 안테나는 S$_{11}$<-10 ㏈에서 10.62%의 대역폭을 가지고, 5.778GHz에서 -33.3 ㏈의 S$_{11}$과 1.04의 VSWR 값을 나타내었다.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.1
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• pp.1-10
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• 2013

In this paper, a broadband planar monopole antenna for multi-band services is proposed. The physical size of the proposed antenna is miniaturized by folding a rectangular loop. And a resonance point in the 3.9 GHz band is reduced by a coupling phenomenon with the central part of the T-shaped patch and the folded rectangular loop. In addition, the T-shaped patch is inserted to the rectangular shaped monopole antenna due to deriving the broadband frequency characteristics. The frequency characteristic is optimized by adjusting the gap and length of the folded rectangular loops and a transverse diameter of the T-shaped patch. The antenna dimensions including the ground plane are $40{\times}60{\times}1.6mm^3$. It is fabricated on the FR-4 substrate(${\epsilon}_r$=4.4) using a microstrip line of $50{\Omega}$ for impedance matching. In the measured result, the bandwidth corresponding to the VSWR of 2:1 is 162 MHz(815~977 MHz) and 2,530 MHz(1.43~3.96 GHz). For analyzing the human effect by the proposed antenna, 1 g and 10 g averaged SARs are simulated and measured. As the simulated results, 1 g-averaged SAR is 1.044 W/kg, and 10 g-averaged SAR is 0.718 W/kg. This result are satisfied by the SAR guidelines which are 1.6 W/kg(1 g-averaged) and 2.0 W/kg(10 g-averaged).

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.12
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• pp.1343-1351
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• 2010

In this paper, a novel patch antenna based on the metamaterial CRLH(Composite Right- and Left-Handed) structure is designed, implemented, and measured. Contrary to the standard microstrip patch's fundamental resonance mode of half-wavelength or its positive multiple, the proposed antenna shows the in-phase electric field over the entire antenna. The proposed antenna has a desired omni-directional field pattern which is typical characteristic of $\lambda/4$ monopole antenna, and also shows the merit of low profile. HFSS(High Frequency Structure Simulator) of Ansoft which is based on the FEM(Finite Element Method) is used to simulate the proposed antenna. FR-4 substrate of thickness 1.6 mm and relative permitivity 4.4 is used for the proposed antenna implementation. The implemented antenna showed VSWR (Voltage Standarding Wave Ratio)$\leq$2 for the frequency band from 2.63 GHz to 2.655 GHz which is used for S-DMB (Satellite-Digital Multimedia Broadcasting) service. And measured peak gain and efficiency are 2.65 dBi and 81.14 %, respectively.