• Journal of Advanced Navigation Technology
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• v.20 no.1
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• pp.59-64
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• 2016

This paper presents a high dividing ratio unequal dualband divider using coplanar waveguide (CPW) and shunt connected open stub transmission lines. In order to implement transmission lines for a dualband divider using design equations, the low impedance lines of divider can be realized a shunt connected open stub transmission line. Also, the high impedance lines are realized by CPW transmission lines. To certify the validity of an unequal dualband divider using CPW and shunt connected open stub transmission lines, the 10:1 unequal dualband divider is implemented at operating frequency of 1 and 2 GHz. Good experimental performance at each frequency are obtained, which are in good agreement with the simulated results.

• Journal of electromagnetic engineering and science
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• v.10 no.1
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• pp.6-12
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• 2010

In this paper, highly efficient class-F power amplifiers(PAs) with harmonic-controlling transmission lines(TLs) were built for cellular and WLAN applications at 840 MHz and 2.4 GHz each. Also, based on these single-band PAs, a dualband class-F PA was designed after a careful investigation into the harmonics of the two frequencies. The harmonic-controlling TL was designed for the class-F operation at dualband by switching the length of the shunt $\lambda$/4 TL part, while the series $\lambda$/4 TL is optimized for both frequencies. To verify the performance, two class-F PAs optimized at each frequency and a dualband class-F PA at the corresponding frequencies were built with the secondand the third-harmonic control circuits at each frequencies. As a result, the PA#1 at 840 MHz has a peak drain efficiency of 81.2 % with an output power of 24.4 dBm, while the PA#2 at 2.35 GHz shows a drain efficiency of 94.5 % with an output of 22.8 dBm. Finally, the dualband class-F PA#3 showed 60.5 % and 50.9 % drain efficiencies at 840 MHz and 2.4 GHz, with powers of 23.8 dBm and 19.62 dBm, respectively.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.6
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• pp.550-557
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• 2003

In this paper, two dualband internal antennas for GPS/PCS handset are proposed. At first, the monopole antenna with parasitic dipole element is designed to print PCB of handset directly. At second, the antenna with bended loop structure is designed to bend to use internal space of handset maximumly. The proposed dualband internal antennas provide a 2:1 VSWR bandwidth of over 19.1 % which are possible to cover two bands at once. the antennas have a gain between -0.4 and 3.33 ㏈i at all bands and they have almost omni-directional patterns.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.6
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• pp.1227-1232
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• 2011

Using the notch and isolation, we investigated the insertion loss and isolation characterics of the fabricated dielectric duplexers and bandpass filters for CDMA and W-CDMA dualband. Insertion loss(Tx band) and isolation(between Tx and Rx) of duplxer were about -2.1708dB and 45dB at CDMA band, respectively. Also, in the case of W-CDMA, the insertion loss(Tx band) and isolation(between Tx and Rx) showed about -2.6946 and 100dB, respectively. Summering the aboved results, fabricated the dielectric duplexers and bandpass filters will be contributed the increase of atttenuation and the decrease of interference at CDMA and W-CDMA dualband.

• Proceedings of the IEEK Conference
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• 2005.11a
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• pp.277-280
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• 2005

In this paper, we propose a frequency synthesizer for dualband repeater. The dual-band RF technology for applications to the wireless repeater for CDMA and WCDMA mobile communications has been developed in this paper. The dualband PLL module consisted of dual-band VCO and one PLL IC has been developed. The main technological efforts for the dual-band PLL module is to suppress the intermodulation distortion by applying the miniature ceramic filter using the slow wave characteristics. The dual-band miniature RF module including dual-band PLL module and one MCU controller is very attractive for applications to the miniature dual-band RF mobile repeaters.

• 한국ITS학회:학술대회논문집
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• 2003.11a
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• pp.217-220
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• 2003

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.25 no.12
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• pp.949-954
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• 2012

The K-PCS and W-CDMA dual band dielectric duplexer and bandpass filters have been designed and fabricated. The dual band duplexer consists of the separate monoblock K-PCS and W-CDMA duplexers using common antenna port. The coupling capacitance and I/O impedance matching have been designed to minimize the cross interference between the bands. Isolations of crosspoint between Tx and Rx in K-PCS and W-CDMA dualband were about 47 dB and 100 dB, respectively. On the other hand, isolations of Tx and Rx in K-PCS and W-CDMA were about 66 dB and 65 dB, respectively. The difference between 47 dB and 100 dB originated from the different center frequencies in Tx and Rx of K-PCS and W-CDMA bands. The coupling capacitance of the bandwidth, I/O capacitance of I/O matching and impedance matching, and various capacitances were important role to fabricate the dielectric duplexer and bandpass filters.

• Journal of Electrical Engineering and Technology
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• v.10 no.2
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• pp.634-640
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• 2015

This paper deals with the design of a microstrip line feed toppled T shaped microstrip patch antenna that gives dualband characteristics at 4 GHz and 6.73 GHz respectively. The simulation of proposed antenna geometry has been performed using method of moment based IE3D simulation software. A radial basis function neural network (RBFNN) is used for the estimation of bandwidth for dualband at 4 GHz and 6.73 GHz respectively. In RBFNN model, antenna parameters such as dielectric constant, height of substrate, and width are used as input and bandwidth of first and second band is considered as output of the network. To validate the RBFNN output, an antenna has been physically fabricated on glass epoxy substrate. The fabricated antenna can be utilized in S and C bands applications. RBFNN results are found in close agreement with simulated and experimental results.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.2
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• pp.265-271
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• 2015

In this paper, Dualband meander microstrip antenna is proposed for Wireless Body Area Network application. Designed antenna is mounted on the phantom to maintain a constant distance of the substrate, and studied the characteristics related to change in several meaningful parameters to improve performance. Characteristics of antenna, returnloss, radiation pattern, gain, bandwidth, are analyzed using Computer Simulation Technologes(CST) software. The proposed antenna operates at 4.33Ghz and 6.09GHz ~ 9.88GHz for UWB. The antenna showed that returnloss and -10dB bandwidth are -42.30dB and 410Mhz at 4.33GHz, maximum -29.11dB and 3.75GHz at 6.1GHz ~ 9.8GHz.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.9 no.7
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• pp.1541-1547
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• 2005

In this paper, Dualband internal antenna for GSM/DSC handset is proposed. The antenna has a size of about $38mm{\times}90mm{\times}1mm$, giving a total mobile phone PCB for support and fold type patch of about $30mm{\times}8mm{\times}3.2mm$. This antenna characteriatic facilitates the fine-tuning of the two operating frequencies of 909MHz and 1762MHz in the dualband design. The measured radiation pattern in the E-plane and H-plane for operating frequencies of 909MHz and 1762MHz is compared and analyzed. The designed and fabricated two band internal antenna for GSM/DSC handset have a gain between 0dBi and 2.0dBi at all bands. Also, the electric firld distribution and directivity on human head caused by portable phone is analyzed. An analysis model is composed of a human head model and the antenna mounted on the same ground plane as portable telephone size.