• Journal of electromagnetic engineering and science
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• v.12 no.1
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• pp.85-93
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• 2012

We propose a new expression of the near-field gain correction to calculate the on-axis far-field gain from the onaxis near-field gain for a directive antenna. The new expression is represented by transversal vectorial transmitting characteristics of two antennas that are measured by planar near-field equipment. Due to the advantages of the photonic sensor, the utilization of the new expression realizes the measurements of the on-axis far-field gains for two kinds of double ridged waveguide horn antennas within 0.1 dB deviation from 1 GHz to 6 GHz without calibrating the photonic sensor system.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.45 no.7
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• pp.72-76
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• 2008

In this paper, the several printed square loop antennas which modified monopole antennas are proposed. The proposed antennas are reduced about 20% physical size of antenna and miniaturized reactance value of impedance due to fold center part of the loop. They obtained omni-directional radiation patterns with broad bandwidth and feed method used coplanar waveguide to composed single planar. The proposed antenna bandwidth is about 900MHz($2.63{\sim}3.56GHz]$) resonance frequency on $VSWR{\le}2$. it can be sufficiency of S-DMB band.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.5
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• pp.981-989
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• 1997

In this paper, the 5-element active phased array antennas coupled through slotline between elements are designed and fabricated. A recent studies on the active phased array antennas using the transmission line coupling which can be designed to provide strong coupling and the appropriate coupling phase. But this sturucture has limitation of expanding in two dimensions for planar active phased array antennas and distortion of the radiation pattern caused by coupling network. Thus our work proposes the slotline coupling structure asthe broadband coupling network for the active phased array antenna. In experiment, 5-elements active phased array antenas have steering range from -30.deg. to 20.deg. off broadside as the free-running frequencies of end elements are controlled. The overall results show that the proposed slotline coupling structure is suited for the coupling network in the actie phased array antenna system. And the proposed coupling structire solves the expansion problem and eliminates the distortion of the radiation pattern caused by the spurious radiation of the transmission line coupling network. Thus thiscan be expanded to two dimensional coupling network for the planar active phased array antenna system.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.43 no.4 s.346
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• pp.52-57
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• 2006

In this paper, the triple-band planar monopole antennas are designed for cellular communication, WiBro and WLAN(IEEE802.11b/g) communication and WLAN(IEEE802.11a) communication of 5GHz band to using filled mobile convergence subscriber unit. Various types of antennas are designed and examined experimentally as bended in the low and middle band radiation elements to decrease antennas size and increased the width of radiation elements to improve bandwidth The proposed antennas are reduced by 11% in antenna size with bended low-band radiation elements down and are extended by $30%{\sim}40%$ in bandwidth by increasing the width of the radiation element at 800MHz band.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2005.11a
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• pp.335-340
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• 2005

In this paper, the triple-band planar monopole antennas are designed for cellular communication, WiBro and WLAN(IEEE802.llb/g) communication and WLAN(IEEE802.lla) communication of 5GHz band. Various types of antennas are designed and examined experimentally as bended in the low and middle band radiation elements to decrease antennas size and increased radiation elements width to improve bandwidth. The proposed antennas are improved by 11% in antenna size with bended low-band radiation elements down and are extended by 30%$\sim$40% in bandwidth by increasing the width of the radiation element at 800MHz band.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.45 no.9
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• pp.60-66
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• 2008

In this paper, the CPW-fed Ultra-wideband antenna is designed and fabricated for UWB communications. To achieve ultra-wide bandwidth of the antenna, we propose the mutual coupling of two planar monopole antennas. The mutual coupling of monopole pair of the proposed antenna is optimized by adjusting the parameters, the widths of the planar monopoles and the space between two monopoles. Two UWB antennas with different horizontal sections of the CPW-fed monopole antenna are fabricated and measured to examine the mutual coupling effects on the monopole pair antenna. The measured result show that two antennas are satisfied with UWB communication band(3.1$\sim$10.6Ghz).

• Journal of electromagnetic engineering and science
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• v.3 no.1
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• pp.17-21
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• 2003

In this paper, we design an optimal planar array geometry for maximum side-lobe reduction. The concept of thinned array is applied to obtain an optimal two dimensional(2-D) planar array structure. First, a 2-D rectangular array with uniform spacing is used as an initial planar array structure. Next, we modify the initial planar array geometry with the aid of thinned array theory in order to reduce the maximum side-lobe level. This is implemented by a genetic algorithm under some constraint, minimizing the maximum side-lobe level of the 2-D planar array. It is shown that the optimized planar array structure can achieve low side-lobe level without optimizing the excitations of the array antennas.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.16 no.1 s.92
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• pp.40-48
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• 2005

In this paper, we explore the inductively coupled concept and propose a class of electrically small planar antennas. The antennas are optimized using NEC in conjunction with a Pareto GA. These antennas show good efficiency and bandwidth performance without any additional matching network. Several optimized designs are fabricated and measured. We explain the operating principle of these antennas using a simple lumped element circuit model. The proposed antennas are translated as printed lines on Duroid for RFID tag antennas.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.7 no.6
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• pp.1194-1199
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• 2006

In this paper, small printed antennas for MIMO applications are presented. The proposed antennas are based on PIFA structure which is a popular approach for miniaturization. The obtained antenna operates in IEEE802.11a band (5.15-5.35GHz) and has a planar structure which can be adopted for various potable applications. According to our simulation results, prototype antennas are manufactured and the isolation among the antenna elements are measured for MIMO applications. And we suggest a technique to improve isolation by adding a $\lambda$/4 slit between two antennas and investigate the results.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2005.11a
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• pp.205-210
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• 2005

In this paper, a planar half-circle shape ultra-wideband(UWB) antenna fed by CPW is designed, fabricated and measured for UWB communications. Within the UWB band(3.1 GHz $\sim$ 10.6 GHz), 5.15 GHz $\sim$ 5.825 GHz frequency band is used by IEEE 802.lla WLAN applications. It may be necessary to notch out this band to avoid interference with IEEE 802.lla WLAN. Therefore, we have proposed three kinds of UWB antennas having a notch function, such as a rectangular slot, a hat-shaped slot, a circle-shaped slot. The notch frequency of the proposed antenna can be adjusted by controlling the slot length or slot width. From the measured results, the proposed antennas show a good gain flatness except the IEEE 802.lla WLAN frequency band and have a reasonable agreement with simulated results.