• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.9 no.4
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• pp.491-498
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• 1998

Based on FDTD(Finite-Difference Time-Domain) method the human head absorbed power radiated from a 1.8 GHz portable phone is computed. For this computation the 7 layered media for the human head modeling and the monopole antenna attached to metallic box for the portable phone are used. To reflect the real circumstances typical sizes of human heads and portable phones are considered in the calculation. The length of monopole antenna is 4.5 cm. Under the predetermined model the distribution of SAR over the human head are calculated, and from which the place of maximum SAR is near the head skin surface, not deep places far into the head. The computation shows the maximum SAR to be 1.4 mWg somewhat less than the internationally adopted value of 1.6 mW/g.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.2 s.117
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• pp.136-142
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• 2007

We present two effects of the case currents of a mobile phone on changing the radiation pattern of a PIFA and on enhancing the bandwidth of the monopole antenna. In order to change the radiation pattern, a modification of the ground plane is suggested to suppress the back radiation. The resulting gain is higher than that of a conventional PIFA by 0.5 dB. For enhancing the bandwidth, two parasitic metallic lines are added in the direction orthogonal to the monopole to induce double resonances. The impedance bandwidth of the proposed structure is 341 MHz, which is nearly twice of that of the conventional monopole.

• Journal of Satellite, Information and Communications
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• v.9 no.1
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• pp.102-106
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• 2014

In this paper, we investigate the realistic environment influence on the Hearing-Aid Compatibility(HAC) of the body-held device mock-up with a dual-band antenna. In detail, first, a dual-band internal antenna is designed considering the neighboring objects essential to a real attachable mobile device. This comes to reality by making its mock-up version. Second, the HAC of this device is simulated and measured for 'stand alone', and 'hand-held' cases. Particularly, the electromagnetic simulation of the designed antenna in the real device is verified by the standard measurement. Finally, the evaluated HAC is analyzed in terms of the relations with the bands, the mock-up environment and the hand effect.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.5
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• pp.493-500
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• 2008

This paper describes a design of internal frequency modulation(FM) radio antenna fur mobile terminal. In order to control of impedance at an operating frequency of the designed antenna, the lumped constant elements of R and L chip components are used. Patch and stubs located at antenna backside are added to control an exact resonance frequency and miniaturization. A fabricated antenna sire, the measured return loss, impedance, bandwidth, and gain are $40{\times}70{\times}1$ mm, -23 dB at 99 MHz, $55-j7{\Omega}$, 22 MHz($88{\sim}110$ MHz) below -10 dB, and -15 dBi, respectively. These measured results show a good agreement with simulated results. Especially, the measured gain of fabricated antenna is similar with value of a conventional ear-phone antenna in the designed frequency band. The measured radiation pattern agrees well with the calculated omni-directional pattern.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.12 no.3
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• pp.352-359
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• 2001

We propose the row method that is able to consider the SAR compliance test from the very beginning step of developing the mobile phone. The reason this new method is plausible is that we adopt the certified FDTD for the reliability of calculation, utilizing 1 mm high resolution model that is to model the phantom and the mobile phone almost identically to the reality. In this paper we introduce the process that will apply the proposed method in order to reduce the SAR of the mobile phone that has been problematic in satisfying the SAR compliance test. It results in dropping in the SAR that we keep the mobile phone or its antenna while we use it. Therefore here we make a claim as fellows. When we develop the new mobile phone, we should use the computer simulation combining the CAD design and radiation pattern rather than make a prototype and then use the trial and error method. Moreover the former way leads us to boost up the developing efficiency and reduce the cost.

• 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.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.10 no.7
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• pp.985-997
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• 1999

In this paper, the detection of 1 g and 10 g averaged SAR on human head caused by PCS handheld phones is analyzed and discussed. Conventional monopole antenna and planar structured PIFA are used in the computational model to apply to the antennas mounted on handheld phone. These antennas are designed to operate in the near of frequency 1.8 GHz, human head model is sampled to have cell size 1.5 mm and sloped to front direction by 30$^{\circ}$. It is found that, when monopole antenna is applied, 1 g averaged SAR is 1.4 W/kg, 10 g averaged SAR is 0.7 W/kg, when PIFA is applied, for each case, SARs are 1.143 W/kg, 0.4866 W/kg. While the radiation pattern of the monopole antenna is symmetrical, that of planar structured antenna is asymmetrical and SAR caused by PIFA is less than SAR by the monopole antenna. The radiation efficiency of PIFA is 62.6%, which is higher than that of monopole, 53%.

• Journal of Korea Multimedia Society
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• v.14 no.3
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• pp.414-422
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• 2011

The paper is for top and bottom symmetrical phase controlled loop antenna using for multi-media devices. We developed a top and bottom phase control loop pattern arrangement methods for loop antenna in mobile devices like as a cell phone and PCS, WCDMA. In the loop antenna pattern, arrange close adhesive the loop antenna pattern $180^{\circ}$ cycle in wave length, the radiated electro-magnetic wave from close adhesive loop pattern in $180^{\circ}$ become to coherent wave than the phase controlled loop antenna has high efficiency and high radiation gain. To acquire a wide band width on phase controlled loop antenna, we arrange a top and bottom symmetrical architecture loop pattern that bas a $180^{\circ}$ wave length in each layer. Top and bottom each layer bas a U form pattern separated $90^{\circ}$ wave length each other. This architecture cause a well balanced electro-magnetic flow control that acquired wide bandwidth resonance response in loop pattern antenna. In experiment, we designed a WCDMA mobile multi-media antenna in $40mm{\times}6mm$ area thickness 0.2mm, in that passive experiment the radiation efficiency is over 50% and over 0dBi radiation average gain was acquired, in the active experiment in real multi-media device we acquired -4dBi average gain and 43% transmit/receive efficiency.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.9 no.4
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• pp.526-534
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• 1998

The electric near-fields from a cellular phone's antenna are calculated using TLM method. The cellular phones is assumed to be a conductive box and the frequency is set to be 900 [MHz] and the radiated power is set to be 0.6 [W]. The near-fields and far-field patterns are obtained for wire antennas of 1/4 and 1/2 wavelengths. For the same radiation power, (0.6 [W]), it is found out the near-field for antennal length of λ/2 is much weaker than that for λ/4 antenna. The maximum SAR calculated in a simple head model becomes 1.4[W/kg].

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.16 no.5 s.96
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• pp.534-540
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• 2005

This paper analyzes the correlations between the impedance matching of the antenna and the radiation characteristics of the mobile handset body. Using two kinds of mobile handset which has retractable and fixed antenna the impedance and radiation pattern is measured under totally 16 conditions. By measured results, it has been identified that the radiation energy into human head can be reduced by attaining the better impedance matching when the radiation pattern out of the mobile handset is like the ideal monopole antenna.