• Journal of the Institute of Electronics Engineers of Korea TC
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• v.45 no.8
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• pp.8-14
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• 2008

In this paper, the effects of ground size on the characteristics such as input resistance, fractional bandwidth, and radiation efficiency of epsilon negative (ENG) zeroth order resonance (ZOR) antennas were investigated theoratically. Two types of ENG ZOR antennas were studied: mushroom ENG ZOR antenna with via and via-free defected ground structure (DGS) ENG ZOR antenna. It was confirmed that the ground size had more effects on the characteristics of a Via-free ZOR antenna than those of mushroom ZOR antenna with via. The via-free antenna could radiate properly with the required size of ground plane since the size of ground plane should exceed some critical value for DGS to suitably operate. As a height of substrate of mushroom ZOR antenna with via increased, the fractional bandwidth and radiation efficiency were improved. On the other hand, as a height of via-free ZOR antenna increased, the fractional bandwidth and radiation efficiency were degraded. Finally, a via-free ZOR antenna had an advantage of compactness even though its fractional bandwidth is narrow and its radiation efficiency is poor, compared with thoses of mushroom ZOR antenna with via.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.8
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• pp.920-926
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• 2008

In this paper, small epsilon negative(ENG) zeroth-order resonance(ZOR) antenna with improved bandwidth is presented. To reduce the size of ENG ZOR antenna without narrowing bandwidth, large shunt inductance is introduced by adding patterns on patch and meandered via. The effective permittivity of meandered via is less dependent of frequency than that of straight via in same size. Thus, ENG ZOR antenna with meandered via has broader bandwidth. As a result, the bandwidth of ENG ZOR antenna with meandered via is 1.38 times as broad as that of spiral ENG ZOR antenna with straight via. On the other hand, the area of ENG ZOR antenna is reduced by 64 % compared with that of conventional mushroom ZOR antenna.

• Journal of electromagnetic engineering and science
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• v.11 no.3
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• pp.201-206
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• 2011

This paper presents a miniaturized epsilon negative (ENG) zeroth-order resonance (ZOR) patch antenna with an improved bandwidth. The miniaturization and the broad bandwidth of the ENG ZOR patch antenna are achieved by using a meandered via and a high permeability substrate instead of a straight via and a dielectric substrate. The use of a meandered via allows miniaturization of the ENG ZOR patch antenna without narrowing the bandwidth. The use of a high permeability substrate allows further miniaturization of the ENG ZOR patch antenna and improvement of the bandwidth. A high permeability substrate consisting of a multi-layered substrate is designed to have a small material loss. The antenna (kr=0.32) has a 10 dB fractional bandwidth of ~1 %, which is 1.74 times as broad as that of an antenna with a dielectric substrate.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.8
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• pp.886-892
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• 2010

In this paper, the hybrid antenna utilizing epsilon negative zeroth-order resonance(ENG ZOR) and $TM_{010}$-mode is presented. The antenna has a directional radiation pattern and improved bandwidth. To obtain a ENG ZOR and $TM_{010}$-mode, the hybrid antenna employs the mushroom structure and the microstrip patch, respectively. Two antennas of the mushroom and the patch are coupled by gap and fed by one coaxial feed. The frequencies of ENG ZOR and of $TM_{010}$ resonance are designed to be 4 GHz and 3.9 GHz, respectively. Because two resonant frequencies are set to be close, the dual-resonance can be formed, resulting in the broader bandwidth. Even though the radiation pattern of an ENG ZOR antenna is omnidirectional, the directional radiation of a microstrip patch antenna compensates the null of omnidirectional pattern of an ENG ZOR antenna. Thus, the hybrid antenna has a directional radiation pattern. The antennas having 4, 3, and 2 unit cells of mushroom structure are designed and analyzed. The antennas have fractional bandwidths of 4.29~4.95 %, gains of 3.16~5.57 dBi, and radiation efficiencies of 62.4~94.2 %.

• International journal of advanced smart convergence
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• v.13 no.2
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• pp.1-6
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• 2024

Reconfiguration and miniaturization of antennas have become key attributes in modern wireless communication systems. Reconfiguration of radiation pattern can alleviate the problems encountered in modern wireless communication systems such as multi-path problems. Physical limitation of miniaturization also can be overcome by using a zeroth-order resonance (ZOR) antenna based on metamaterial. In order to achieve reconfiguration and miniaturization of antennas at the same time, we propose a new pattern reconfigurable zeroth-order resonance (ZOR) antenna that reconfigures the radiation patterns by varying the position and the number of unit cells comprising the antenna. The antenna is fabricated in an equilateral triangular shaped symmetrical structure to increase pattern variety. This structure can easily provide eight different radiation patterns (two omnidirectional and six monopole like patterns).

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.9
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• pp.997-1002
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• 2009

This Letter presents a wideband ENG(Epsilon Negative) ZOR(Zeroth-Order Resonant) antenna designed on a microstrip line. It has a mushroom structure and its size is only $7.65{\times}1.31{\times}2.37\;mm$(or $0.306{\times}0.053{\times}0.095\;{\lambda}_0$ at 12 GHz) owing to zeroth-order resonance. The design procedures with closed form solutions are provided using transmission line theory considering radiation loss. The measured antenna bandwidth is about 20.0 % at 9.2 GHz and antenna gain is 7.1 dBi despite the compact size.