• Journal of the Institute of Electronics Engineers of Korea TC
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• v.44 no.12
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• pp.73-78
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• 2007

In this paper, the CPW-fed triple-band internal planar monopole antenna which simultaneously meets the three bands such as Cellular, PCS and Wibro is designed. The size of the radiation elements can be reduced to about $\lambda/4$ by designing the CPW-fed monopole antenna and then we can miniaturize the antenna size by meandering the radiation elements. In addition, we design the planar antenna for the slim-type mobile phone. We can obtain the desired antenna properties by controlling the length of each radiation elements. The measured return loss of the antenna is less than -7 dB at the desired bandwidth. And the measured radiation patterns are similar to that of the monopole antenna. The designed antenna has the gains -5.2 dBi. -2 dBi, -0.4 dBi at each resonant frequencies respectively.

• Journal of information and communication convergence engineering
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• v.8 no.6
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• pp.630-634
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• 2010

In this paper, we designed and fabricated a multi-band folded monopole antenna for mobile handsets that can be used for multiple services. The proposed antenna, with a small size of $28.060{\times}12.665{\times}5.035mm^3$ can provide sufficient bandwidth to cover the GSM900 (Global System for Mobile Communications: 880-960 MHz), DCS (Digital Cellular System: 1710-1880 MHz), K-PCS (Korea-Personal Communication Service: 1750-1870 MHz), Wibro (2300-2390 MHz) and Bluetooth (2400-2483 MHz) bands.

• Journal of IKEEE
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• v.7 no.1 s.12
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• pp.88-96
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• 2003

In this paper, We designed and implemented a linear high-power amplifier which can be used for the commercial service in band of $1.9GHz(1.93{\sim}1.99GHz)$ at U.S.A. The output power of the implemented linear high power amplifier is 25W. In order to satisfy IMD characters decided by FCC, the Feedforward linearization techniques has been used. The used feedforward method has improved the IMD characteristics from 10.51dBc to 19.01dBc in each power level from 1W(30dBm) to 25W(44dBm). The IMD level of the final output shows from minimum 64.84dBc to maximum 68.17dBc. Because this good characteristics of IMD, the LPA is expected to use as a commercial product of PCS base station.

• Journal of Electrical Engineering and information Science
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• v.2 no.6
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• pp.202-207
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• 1997

Design and fabrication issues for an L-band GaAs Monolithic Microwave Integrated Circuit(MMIC) Voltage Controlled Oscillator(VCO) as a component of Personal Communications Systems(PCS) Radio Frequency(RF) transceiver are discussed. An ion-implanted GaAs MESFET tailored toward low current and low noise with 0.5mm gate length and 300mm gate width has been used as an active device, while an FET with the drain shorted to the source has been used as the voltage variable capacitor. The principal design was based on a self-biased FET with capacitive feedback. A tuning range of 140MHz and 58MHz has been obtained by 3V change for a 600mm and a 300mm devices, respectively. The oscillator output power was 6.5dBm wth 14mA DC current supply at 3.6V. The phase noise without any buffer or PLL was 93dB/1Hz at 100KHz offset. Harmonic balance analysis was used for the non-linear simulation after a linear simulation. All layout induced parasitics were incorporated into the simulation with EEFET2 non-linear FET model. The fabricated circuits were measured using a coplanar-type probe for bare chips and test jigs with ceramic packages.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.1
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• pp.78-81
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• 2015

This paper investigates the performance of phone case with different permittivities like plastic, urethane and silicone. Then, we put an electromagnetic band gap (EBG) structure in phone case to reduce the specific absorption rate (SAR). In order to design the phone case, a loop antenna for PCS 1900 band was used. The phone case consists of a hairpin-like EBG structure that is more compact than other EBG structures. The SEMCAD X fdtd simulation results showed that, this proposed phone case can reduce SAR by 13 - 30% at similar power that is radiated by the antenna. This phone case can be used in future to reduce the SAR from mobile phones.

• Journal of electromagnetic engineering and science
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• v.15 no.3
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• pp.185-193
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• 2015

In this paper, a hybrid multiple input multiple output (MIMO) antenna for eight-band mobile handsets is designed and implemented. For the MIMO antenna, two hybrid antennas are laid symmetrically and connected by an interconnection tie, thereby enabling complementary operation. The tie affects both the impedance and radiation characteristics of each antenna. Further, printed circuit board (PCB) embedded type is applied to the antenna design. To verify the results of this study, we designed eight bands-LTE class 12, 13, and 14, CDMA, GSM900, DCS1800, PCS, and WCDMA-and implemented them on a bare board the same size as the real board of a handset. The voltage standing wave ratio (VSWR) is within 3:1 over the entire design band. Antenna isolation is less than -15 dB at the lower band, and -12 dB at the WCDMA band. Envelope correlation coefficient (ECC) of 0.0002-0.05 is obtained for all bands. The average gain and efficiency are measured to range from -4.69 dBi to -2.88 dBi and 33.99% to 51.5% for antenna 1, and -4.74 dBi to -2.97 dBi and 33.45% to 50.49% for antenna 2, respectively.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.8
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• pp.899-905
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• 2008

In this paper, we propose a dual-spiral line loaded monopole antenna having a vertical ground plane for quadband applications. The antenna occupies a volume of $38{\times}12{\times}7\;mm^3$ with a $40{\times}92\;mm^2$ ground plane. The measured impedance bandwidths of the antenna based on $VSWR{\le}2$ are approximately of 11.7 % and 24.8 % in the first and second frequency band, respectively. The operating frequency can simultaneously cover Cellular($0.824{\sim}0.894\;GHz$), PCS($1.750{\sim}1.870\;MHz$), UMTS($1.920{\sim}2.170\;MHz$), and IMT-2000($1.885{\sim}2.200\;GHz$) bands. The maximum gains of the antenna are -0.99 dBi, 4.07 dBi, 2.72 dBi, and 4.33 dBi at the center frequencies of the Cellular, PCS, UMTS, and IMT-2000 bands, respectively. Good radiation patterns are experimentally obtained.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.12
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• pp.1391-1401
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• 2007

This paper proposed a novel broadband printed monopole antenna for PCS/IMT-2000/WLAN terminals. Frequency characteristics are optimized with various design parameters. Two Z-shaped patchs were utilized in order to improve the characteristics of a printed monopole antenna which usually has a narrow bandwidth. The bandwidth of the realized antenna is $1.590{\sim}2.614$ GHz(48.43 %) below the return loss of -10 dB which contain the required bandwidth of PCS/IMT-2000/WLAN band. The simulated and measured values of 1 g and 10 g averaged peak SAR on human head caused by the proposed antenna on folder-type phone were analyzed and discussed. As a result, the measured 1 g peak SAR value is 0.794 W/kg and 10 g peak SAR value is 0.368 W/kg at 1.8 GHz. The results are smaller than the reference SAR limit values that are respectively 1.6 W/kg and 2 W/kg on 1 g and 10 g averaged SAR values.

• International Journal of Internet, Broadcasting and Communication
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• v.12 no.1
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• pp.37-44
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• 2020

In this paper, we proposed a compact printed monopole antenna with an inverted L-shaped slot for dual-band operations. Two operating frequency bands are achieved with the use of an inverted L-shaped slot etched on the radiating strip for bandwidth enhancement and a defected ground structure for return loss improvement in the higher frequency band. The measured results showthat the proposed antenna has impedance bandwidths (S₁₁< -10 dB) of 270 MHz (1.81-2.08 GHz) and 340 MHz (2.36-2.70 GHz), covering the required bandwidths for PCS (1850.5-1989.5 MHz), CDMA 2000 (1850-1990 MHz), TD-SCDMA (1880-2025 MHz) and 2.4 GHz WLAN (2400-2484 MHz). The measured return loss of the proposed antenna has a good value of approximately 27.2 dB at 2.4 GHz WLAN. The antenna's peak gains also have a high value of 1.92 dBi at 2 GHz and 2.12 dBi at 2.45 GHz. The proposed antenna shows omnidirectional radiation patterns over the entire frequency range of interest.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.6
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• pp.1170-1174
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• 2009

Two frequency-reconfigurable antennas have been designed and combined in a space with limited volume, i.e., 40mm ${\times}$ 20mm ${\times}$ 6mm. Each antenna can be reconfigured to operate at different frequency bands depending on the state of an embedded switch, which is implemented using a PIN diode. The first antenna can be switched between 0.82GHz ${\sim}$ 0.96GHz band (GSM/ CDMA) and 1.7GHz ${\sim}$ 2.17GHz band (DCS/ PCS/ WCDMA), which are cellular bands. The second antenna can be switched between 3.4GHz ${\sim}$ 3.6GHz band (mWiMax) and 2.3GHz ${\sim}$ 2.5GHz, 5.15GHz ${\sim}$ 5.35GHz bands (WiBro/ WLAN 11a/b/g/n), which are connectivity bands. The proposed combined antenna operates both over cellular bands and connectivity bands concurrently. The choice of the operation bands is made independently by the states of the two switches.