• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.33 no.4
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• pp.231-244
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• 2015

The accuracy of reference point of VLBI antenna is mandatory to perform collocation of different space geodetic techniques. In this study, we evaluated the optimal methods for the 3D circle fitting to enhance the accuracy of the reference point of VLBI antenna. Two kinds of methodologies for the orthonormal coordinate system with translation of planar observation point and the unitary coordinate transforamation were suggested and their fitting accuracies were evaluated where the orthogonal distance was calculated by residual between observation point and fitting model and the recursive calculation was performed to improve the accuracy of 3D circle fitting. Finally, we found that the methodology for the unitary coordinate transformation is highly appropriate to determine the optimal equation for azimuth-axis and elevation-axis of VLBI antenna. Therefore, the reference point of VLBI antenna with high accuracy can be determined by the intersection of the above two axises (azimuth-axis and elevation-axis). This result is expected to be utilized for a variety of researches for connection between VLBI observation results and the national control point.

• Journal of Advanced Navigation Technology
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• v.15 no.6
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• pp.1008-1014
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• 2011

In this paper, multi-band fractal microstrip patch antenna which is possible for WLAN band and WiMax band is designed and made. For multi-resonance of developed antenna, resonance frequency, impedance matching, polarity and reflection pattern can mad perfectly, then to make satisfied multi-independent frequency three kind of half circle fractal patch is inserted. In the situation continuously happening half circle in designed structure, antennas one of half-circle band is shown.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.16 no.9 s.100
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• pp.932-940
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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${\~}$10.6 GHz), 5.15 GHz${\~}$5.825 GHz frequency band is used by IEEE 802.1la WLAN applications. It may be necessary to notch out this band to avoid interference with IEEE 802.1la 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 802.1la WLAN frequency band and have a reasonable agreement with simulated results.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.9B
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• pp.1676-1682
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• 1999

In this paper, the double circular array microstrip patch antenna was designed to minimize the side lobe in which a cooperate feeding network was used to supply the same amplitude and equi-phase to each antenna element. Eight microstirip patch antenna(MPA) elements were arrayed with $45^{\circ}$ interval in the inner circle and the outer circle respectively. The simulation results showed that when the radii of the inner circle and the outer circle were 0.7 $\lambda$0 and 1.45 $\lambda$0, the side lobes of beam pattern were minimized. As the results of the measurements, the return loss of the designed antenna was -14.5[dB] at 11.75[GHz] in the input terminal. When the level of the main lobe was normalized at 0[dB], those of the first and the second side lobe were -18[dB] and -26[dB] respectively. The radiation patterns agree well with the simulated patterns.

• 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.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2003.11a
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• pp.532-535
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• 2003

In this paper, we made study for plastic chip antenna, the plastic is Formax with the circle of PVC and its electric characteristics are dielectric constant 1.9, surface current $10{\Omega}$. The proposed antenna same as the conventional antenna are usually constructed with ceramic chip, which are not fragile in nature and don't tend to break easily. Therefore the proposed antenna with its advantage are attractive for application in mobile antenna. We study the dual-band plastic chip antenna resonated at 800Mhz and 1800Mhz. From this study results, we feel confident of application for mobile phone antenna.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.18 no.2
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• pp.130-135
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• 2005

In this papers, we made study for plastic chip antenna, the plastic is Foamex with the circle of PVC and its electric characteristics are dielectric constant 1.9, insulation intensity 112 KV/cm. The proposed antenna is same as the conventional antennas are usually constructed with ceramic chip, which are not fragile in nature and don't tend to break easily. Therefore the proposed antenna with its advantage is attractive for application in mobile antenna. In order to valid the proposed papers, it is implemented the antennas of four types and experimented. From the results, we conformed that the antennas are operated at the dual band which is cellular band and Korea-PCS band. And the gain of the antennas has about above -2 dB and the pattern is same as conventional antennas. From this papers, the realized antennas using Foamex material will be application for mobile phone antenna.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.7 s.110
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• pp.665-672
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• 2006

In this paper, we propose and fabricate the dual-band microstrip patch antenna with parasitic patch for S-DMB(Satellite-Digital Multimedia Broadcasting) and ITS (Intelligent Transport System) services. The measured - 10 dB bandwidth and the minimum return loss is 300 MHz and - 27 dB for S-DMB, 600 MHz and -17 dB for ITS, respectively. It is noticed that the measured and simulated results are agreed well. The S-DMB antenna has conical beam pattern in the vertical plane and has omni-directional beam pattern in the horizontal plane. The conical beam pattern has the maximum gain about 4.2 dBi when ${\theta}$ is $45^{\circ}$ at the center frequency of 2.6 GHz. The ITS antenna has directional beam pattern in the vertical plane that has maximum gain about 6.4 dBi when ${\theta}$ is $0^{\circ}$ at the center frequency of 5.8 GHz.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.7
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• pp.1509-1513
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• 2009

A semicircle antenna is presented for wideband communication system. The proposed antenna radiates linear polarized wave omnidirectionally in wide frequency band from 1.5 GHz to more than 5 GHz (110%). The frequency bands of the proposed antenna are investigated from the variable current path lengths by tilting angles. The overall radiation gain of the proposed antenna is 2-3 dBi.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.25 no.12
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• pp.1212-1218
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• 2014

This paper proposes a planar bow-tie UWB antenna by modifying the ground patch of a reference bowtie-monopole antenna satisfying low band of UWB. The proposed antenna was implemented with five-angled ground patch to be operated in whole UWB band, while the reference antenna had a ground patch of half circle type. The measured return loss satisfies less than -10 dB in 3.1~10.6 GHz, except 4.9~5.8 GHz rejection band. The measured radiation pattern is almost the same with that of the monopole antenna. The radiation gain reduction is about 8 dB at rejection band.