• Proceedings of the KIPE Conference
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• 2001.07a
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• pp.118-123
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• 2001

For multi-carrier communication system, power amplifier generate intermodulation products caused by their nonlinear characteristics. Intermodulation products arised around the carrier frequency cannot be filtered out, operate as noise source for tile adjacent channel and thus degrades the quality of communication. In this paper, the 1850MHz-band RF linear power amplifier has been designed and fabricated with feedforward loop. The error signal loop consists of several key components such as phase shifter and attenuator, subtracter. The proposed Linearizer was tested with two-tone signals separated 10MHz apart at the center frequency of 1850MHz. The experimental results show C/I improvement by 14.5${\~}$20dB over 15dB dynamic range(33${\~}$47.8dBm) which gave IMD of 53.25${\~}$59dBc for the designed LPA.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.9
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• pp.1023-1029
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• 2010

In this paper, we proposed the broadband polarization diversity antenna operating in the PCS, WCDMA and WiBro band for mobile base station. We designed the antenna using the dipole antenna of the square loop type and microstrip feeding structure. Additionally, we used the choke box to remove the distortion of radiation patterns by the reflector structure when operating broadband. The simulation was performed using MWS in a commercial tool of CST company and the antenna was fabricated on a teflon substrate with 3.33 of the relative permittivity. The proposed antenna has the bandwidth of 640 MHz(from 1.75 to 2.39 GHz) when VSWR is below 1.5. At the operating bands, the interisolation between the cross-pair radiators is less than -25 dB and the maximum gains for PCS, WCDMA and WiBro band are 8.9, 8.2 and 8.6 dBi, respectively.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.11
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• pp.1233-1239
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• 2008

In this paper we proposed a novel broadband printed monopole antenna for PCS/IMT-2000/WLAN terminals by widening current flow To compensate narrow bandwidth characteristics which is one of disadvantages of general printed monopole antenna, we add the patch of diamond shape and induce the current in various directions for acquiring broadband characteristics. And frequency characteristics is optimized with Various design parameters. The bandwidth of the realized antenna is $1.66{\sim}3.04\;GHz$(58.72 %) below the return loss of -10 dB which contain the required band-width of PCS/IMT-2000/WLAN band.

• Journal of information and communication convergence engineering
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• v.6 no.2
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• pp.169-171
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• 2008

An internal antenna for small mobile systems is proposed to support the DVB-H system. It consists of two antenna elements, which are a folded planar monopole for DVB-H and PIFA for GSM/DCS/PCS, and a meander line and RF cable are used to increase the ground plane. Experimental results of the antenna are presented.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.10 s.113
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• pp.993-999
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• 2006

This paper presents the design simulation, implementation, and measurement of a miniaturized DCS, PCS / Satellite DMB dual-band stacked chip antenna with double coupled line for mobile communication terminals. A stacked meander is realized by using a via hole with height of 0.8 mm and a diameter of 0.35 mm to connect upper- and lower-layer meander sections for a reduction of the dimensions of the antenna. In addition the stacked meander chip antenna is extended by a double coupled-line to achieve two different radiation modes. A ratio of the first frequency and second frequency vary with the geometrical parameter of coupled lines. The fabricated antenna used FR-4 substrate with relative permittivity of 4.2. And its dimensions are $15.2{\times}7{\times}0.8mm^3$. The measured impedance bandwidth(VSRW<2) are 244 and 120 MHz at the operating frequency, respectively.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.44 no.1
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• pp.155-161
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• 2007

This paper presents the design simulation, implementation, and measurement of a miniaturized PCS / Satellite DMB dual-band stacked mompole antenna with a parasitic patch for mobile communication terminals. A stacked helix is realized by using a via hole with height of 0.4 mm and a diameter of 0.35 mm to connect upper- and lower-layer helix sections for a reduction of the dimensions of the antenna. In addition the stacked helix chip antenna is interleaved with a parasitic patch to achieve two different radiation modes. The ratio of the first frequency and the second frequency vary with the geometrical parameter of the parasitic patch. The fabricated antenna uses FR-4 substrate with a relative permittivity of 4.2. Its dimensions are $15.5{\times}7.6{\times}0.4 mm^3$. The measured impedance bandwidths (VSWR<2) are 240 and 250 MHz at the operating frequencies, respectively.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.11
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• pp.1287-1293
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• 2008

Antenna switch module(ASM) for quad-band was developed. This module was integrated by RFIPD(RF integrated passive device) and transistor switch instead of LTCC-type device using low pass filters, diodes and passive elements in RF front end module for cellular phone. This module leads to low cost and miniaturization(The area is $5{\times}5\;mm$ and the thickness is 0.8 mm). The insertion loss and the return loss of each band were averagely measured as 1.0 dB(insertion loss), 15.1 dB(GSM/EGSM return loss) and 19 dB(DCS/PCS return loss), respectively.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.4
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• pp.477-483
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• 2008

The paper introduces mobile handset multi-band chip antenna to be used on meander line PIFA structure and parasite patch. The proposed antenna uses an FR-4 substrate. The top layer is consist of meander lines PIFA structure to implement GSM900 and is connected with each rad and meander line on the via-hole for maximize space efficiency. The middle layer is designed with the signal line and gap to implement a DCS and PCS bands, the bottom layer which is added to a parasite patch on the ground can be show an adjust of frequency and impedance character by the connection of the radiators of middle layer and coupling. The fabricated antenna with the dimension of $28{\times}6{\times}4\;mm^3$. The ground plane a dimension of $45{\times}90\;mm$, designed by a commercial software CST simulator. The experimental results show that the bandwidth for(VSWR<3) is 90($875{\sim}965$) MHz in GSM900 band operation and 380($1,670{\sim}2,050$) MHz in DCS, PCS band operation. The maximum gains of antenna are 0.25 dBi, 3.65 dBi and 3.3 dBi at resonance frequencies and it has omni-directional pattern practically.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.39 no.2
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• pp.108-116
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• 2002

In this paper, to improve bandwidth of microstrip antenna, we discussed the patch structure using dual patch and probe feed. To provide PCS service and IMT-2000 service simultaneous, a microstrip patch antenna needs impedance bandwidth of 22%. We propose wide-band microstrip path antenna without complexity. To analyze characteristics of microstrip patch antenna, we used Ensemble of commercial software. The microstrip patch antenna was designed, fabricated, and tuned. The result was that 500 ㎒(25.5%) of impedance bandwidth for VSWR 2,430 ㎒(21.9%) of impedance bandwidth for VSWR 1.5. The microstrip patch antenna has side lobe of -14 dB. The front to back ratio is 20 dB overall. The measured gain of the microstrip patch antenna is 5.2 dBi.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.5
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• pp.552-559
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• 2011

In this paper, the frequency reconfigurable antenna is proposed and designed. The proposed antenna is designed using the vertically stacked dipole structures and have the operating band for Cellular, PCS/WCDMA/Wibro/WiFi and WiMAX. The operating frequency band is selected by three pair of PIN diodes using the voltage difference between each dipole antenna and feeding transmission lines. The proposed antenna meets the required operating bandwidth and the maximum gain for each frequency band are measured as 6.3 dBi, 5.4 dBi and 5.8 dBi, respectively. The proposed antenna in this paper can be applied for the future mobile small base station or repeater antenna because this antenna can provide the small size and high gain features.