• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.19 no.9
• /
• pp.1037-1044
• /
• 2008

Radiation efficiency and antenna gain, in this paper, can be increased by the slot on EMI shield painted on the mobile phone back cover. When the EMI slot which has proper dimension and location is located on the EMI paining area in the phone, the increment of antenna current density due to mutual coupling between the antenna and slot derives increment of antenna efficiency. For the verification of EMI slot effect, we apply the EMI slot to the mobile phone which is operating on GSM/DCS/USPCS/WCDMA quad band, and measure $S_{11}$ and antenna efficiency. It's shown that resonant frequency is not changed and radiation efficiencies to frequency channels by EMI slot are increased from 0.21 % to 8.96 %.

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

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.14 no.3
• /
• pp.290-295
• /
• 2003

In this study, we investigated the effect of particle size of Mn-Zn ferrite which is used as a material of electromagnetic wave absorber on electromagnetic wave properties. With increasing the particle size, the matching frequency is shifted toward lower frequency and the absorption ability of electromagnetic wave is decreased. We suggest that a sheet-type ferrite absorber composed of Mn-Zn ferrite with large particle is useful to compare with it composed of small particle size for mobile phone.

• The Korean Journal of Community Living Science
• /
• v.13 no.2
• /
• pp.1-11
• /
• 2002

This study was conducted to estimate the amounts of the electromagnetic wave penetrating from a cellular phone in a pocket of dress shirt, as well as to test how different the penetration amounts were under the conditions of wearing. It was also investigated the possibilities that the amounts of the electromagnetic wave penetrating could be decreased by using twofold pocket or electromagnetic wave free fabric. The amounts of the electromagnetic wave penetrating were measured in the following five cases; one-layered pocket with 10 different fabrics as dress shirt, a pocket adding a layer of knitted cotton, two-layered pocket with same fabric as dress shirt, two-layered pocket adding a layer of knitted cotton, and one-layered pocket adding a layer of electromagnetic wave free fabric. Each of these five cases were measured using the front and back sides of a cellular phone facing to the body. The results were as follows; 1) The amounts of the electromagnetic wave penetrating were not significantly different in 10 different fabrics and were all above the caution range (0.02mW/$cm^2$). 2) The amounts of the electromagnetic wave penetrating in cases of the back side of the cellular phone to the body, were more than in cases of the front side. 3) There is a significantly differences in part on adding a knitted under wear to one and two layers of the pocket in the case of penetration amount under the wearing conditions. 4) The amounts of the electromagnetic wave penetrating in cases of adding a layer of electromagnetic wave free fabric, were close to the safe standard value of it. The above results suggested that facing the front side of cellular phone to the body and using extra layering with some electromagnetic wave free fabrics might have some protective effects again to the penetration amounts.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.19 no.4
• /
• pp.470-476
• /
• 2008

In this paper, we describe the cause of TDMA noise and distinction method of TDMA noise source in a GSM mobile phone. The causes of TDMA noise are composed of RF(Radio Frequency) energy coupling and low frequency energy coupling by burst ripple. We propose the distinction method of TDMA noise source from output(TDMA noise measurement) and frequency response of a system(audio path). Especially we propose a method of insertion loss($S_{21}$) analysis and the improvement method for RF energy coupling. Capacitor(40 pF) is a solution to reduce RF energy coupling and therefore TDMA noise was reduced by 10 dB.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.15 no.12 s.91
• /
• pp.1190-1198
• /
• 2004

In this paper, meander-line planar monopole antenna mounted on PCS/IMT-2000/WLAN handset for SAR reduction is designed. Frequency characteristics and SAR value optimized with various design parameters are analyzed and designed. Designed internal monopole antenna mounted on the handset is simulated. The 1 g and 10 g peak average SARs of internal monopole antenna are 0.656 and 0.387 W/kg respectively. And internal monopole antenna and external monopole antenna attached on the handset are tested. As a result, internal monopole antenna 1 g and 10 g peak average SARs are 0.686 and 0.356 W/kg. And external monopole antenna's results are 1.33 and 0.812 W/kg, respectively. So internal monopole antenna has a about $50\%$ SAR reduction in comparison with external monopole antenna.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.19 no.12
• /
• pp.1455-1461
• /
• 2008

We implemented a subminiature internal antenna that is around 1 cc volume for the mobile phone. The fundamental type of studied antenna is IFA(Inverted F Antenna), and this antenna is designed to be improved efficiency and gain due to minimum current cancellation by the avoidance of multiple bending pattern. For the implementation of multiple band, helix is applied to compensate for short antenna length for low frequency band, and a 3 dimensional pattern is used for high frequency band. We made two kinds of 3D structure antenna. One is a 1 cc volume antenna for GSM/DCS band on the bare board set, and the other is a 1.5 cc volume for the GSM/USPCS mobile phone set. Measurements showed good gain performance that average gain of two antenna on each band are $-3.46{\sim}-0.45\;dBi$ and $-4.80{\sim}-3.29\;dBi$ respectively.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.22 no.7
• /
• pp.737-743
• /
• 2011

In this paper, we designed and implemented a Monopole+IFA(Inverted F Antenna) hybrid antenna using the coupled feeding structure for the all band mobile phone. Studied antenna has wide band characteristics by the simultaneous operation both monopole and IFA under the coupled feeding structure. An antenna has designed PCB embedded type without antenna carrier component for the low in cost. Implemented antenna has within 2.5:1 for VSWR under LTE/CDMA/GSM900/DCS/USPCS/WCDMA/WiBro/WiFi in all band for the mobile services Measured average gains and efficiencies were -3.98~-0.09 dBi and 40.03~97.99 % for the LTE, CDMA, GSM900 band, and -3.90~-1.01 dBi and 40.70~79.31 % for the DCS, USPCS, WCDMA, WiBro, WiFi band. It's shown that studied antenna can be applied to all band mobile phone antenna including LTE.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
• /
• 2001.11a
• /
• pp.315-318
• /
• 2001

We are proposing a new mobile phone antenna, which has a specially manufactured Mn-Zn cylindrical ferrite bead inside of the helical coil of the antenna. The extended antenna radiation patters and the spatial peak SAR averaged over 1 gram simulated tissue with and without the ferrite bead insertion were measured at 824 MHz. The results show that the ferrite bead resulted in SAR reduction about 20 %, and reflection coefficient increase about 7 % for the extended antenna. The applicability of this scheme to the antenna mass production is quite feasible.

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