• The Journal of Korean Institute of Communications and Information Sciences
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• v.42 no.4
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• pp.798-805
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• 2017

This paper presents a low profile multi circular ring with different radius, patch antenna with modified feed line and slotted ground. The size of the antenna is $15{\times}12mm^2$, having electrical dimensions of $0.14{\lambda}{\times}0.12{\lambda}$ (at lower initial frequency) and footprints of $180mm^2$. The proposed antenna covers 3.1 to 12.3 GHz, reflection coefficient up to -38 dB with Bandwidth ratio of 4.13:1 and fractional Bandwidth of 122%. Bandwidth dimension ratio has been calculated (which is 6246) as a proof for compact size. Thin slots introduced on the feed line provide good impedance matching for whole frequency band. Numerical simulations of the proposed antenna are reported in terms of reflection coefficient ${\leq}-10dB$, vswr 2:1, radiation pattern and group delay (ns). The proposed antenna has advantage of very small size along with better impedance match that provides a practical approach to realize it for BW enhancement and UWB applications.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.9
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• pp.1015-1022
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• 2007

In this paper, we proposed a wideband design of planar inverted-F antenna(PIFA) using two-layer, patches and modified ground structure. The antenna consists of two layer patches with common feed and modified ground plane to control resonance frequency and antenna input impedance. The measured bandwidth is 1,492 MHz(BW: 67.7 %, 1,457${\sim}2,949$ MHz) for VSWR<2, and 1,170 MHz(BW: 21 %, 4,970${\sim}$6,140 MHz) for VSWR<2.5. It covers service bands of DCS1800, DCS1900, UMTS(WCDMA), WiBro, WLAN(IEEE 802.11b), satellite DMB. WLAN(IEEE 802.11a) in Korea and radiation patterns shows constant figure with frequency change.

• Journal of Electrical Engineering and Technology
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• v.12 no.4
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• pp.1556-1565
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• 2017

This paper depicts the design, implementation and analysis of efficient resonant based wireless power transfer (WPT) technique using three magnetic coupled coils. This work is suitable for mid ranged device due to small form factor while minimizing the loading effect. A multi turned loop size resonator is exploited for both the transmitter and receiver for longer distance. In this paper, class-E power amplifier (class-E PA) is introduced with an optimum power tracking mechanism of WPT system to enhance the power capability at mid-range with a flat gain. A robust method of finding optimum distance is derived with an experimental analysis of the designed system. In this method, the load sensitive issue of WPT is resolved by tuning coupling coefficient at considerable distances. Our designed PA with a drain efficiency of 77.8% for a maximum output of 5W is used with adopted tuning technique that improves the overall WPT system performance by 3 dB at various operating points.

• Proceedings of the KIEE Conference
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• 2004.11a
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• pp.281-284
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• 2004

In Recent, it became necessary to envelope the technology about electrodeless fluorescent lamp according to demand of the electrodeless fluorescent lamp system that used higher efficiency and advantage of long-lifetime. Especially, in the electrodeless fluorescent lamp which used H-mode, efficiency of lamp is decided from matching parameter of antena and inverter So it is of the utmost importance to design antena and inverter. Therefore, this paper used a transformer principle for efficiency rising of electrodeless fluorescent lamp and interpreted an equivalent circuit, used an impedance analyzer in order to confirm a performance enhancement of lamp along design of antenna, and confirmed parameter characteristic of R, L, C, Z, Phase, Q-factor along a change of magnetic flux density. Also, this paper confirmed a luminance characteristic of electrodeless lamp along parameter change with measuring optical characteristic along a change of magnetic flux density.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.11a
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• pp.531-534
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• 2004

In Recent, it became necessary to develope the technology about electrodeless fluorescent lamp according to demand of the electodeless fluorescent lamp system that used higher efficiency and advantage of long-lifetime. Especially, in the electordeless fluorescent lamp which used H-mode, efficiency of lamp is decided from matching parameter of antena and inverter. So it is of the utmost importance to design antena and inverter Therefore, this paper used a transformer principle for efficiency rising of electrodeless fluorescent lamp and interpreted an equivalent circuit, used an impedance analyzer in order to confirm a performance enhancement of lamp along design of antenna, and confirmed parameter characteristic of R, L, C, Z, Q-factor along a change of magnetic flux density. Also, this paper confirmed a luminance characteristic of electordeless lamp along parameter change with measuring optical characteristic along a change of magnetic flux density

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.28 no.4
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• pp.351-354
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• 2017

In this paper, a compact MIMO(Multiple Input Multiple Output) antenna for smart glasses is proposed. The proposed MIMO antenna is designed using T-shaped isolator inserted between two closely located Inverted-F Antenna(IFA) and using two slots located in the ground for isolation enhancement and impedance matching characteristic. The proposed antenna has only the overall dimensions of $35mm{\times}9mm{\times}0.8mm$ and operates in the 2.4 GHz industrial, scientific, and medical(ISM) band. To verify human body effect, the phantom is used for antenna performance. The measured specific absorption rate(SAR) value is 1.38 W/kg with an input power of 18 dBm. The performance of the proposed antenna is compared with that of previous works for verification.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.4
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• pp.1908-1914
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• 2013

In this paper, we introduce a design method for a broadband planar quasi-Yagi antenna (QYA) for terrestrial digital television (DTV) reception. The coplanar strip line which feeds the driver dipole is connected to a microstrip line and is terminated by short circuit. By appending a wide strip-type rectangular director at a location close to the driver dipole, broadband impedance matching and gain enhancement in a high frequency region are obtained. The gain characteristics in a low frequency region are improved by adding a reflector formed by a truncated ground plane. To reduce the antenna size, the strip-type dipole and reflector are modified to half bow-tie (V)-shaped elements. The effects of various parameters on the antenna characteristics are examined. An antenna, as a design example for the proposed antenna, is designed for the operation in the frequency band of 470-806 MHz for terrestrial DTV. The optimized antenna is fabricated on an FR4 substrate and the experimental results show that the antenna has a good performance such as a frequency band of 450-848 MHz for a VSWR < 2, gain > 4.1 dBi, and front-to-back ratio > 10.4 dB.