Dual-band Mobile Phone Research Articles

Shielding Efficiency of a Fabric Based on Amorphous Glass-Covered Magnetic Microwires to Radiation Emitted by a Mobile Phone in 2G and 3G Communication Technologies

Abstract A dual band mobile phone model was used to check the shielding properties of an amorphous ferromagnetic textile against the radiation emitted by the handset. Two frequencies belonging to the 2nd and 3rd generation of mobile emission technologies were used, 897 MHz and 1950 MHz. The specific absorption rate (SAR) of energy deposition in a human head phantom was measured in standardized conditions. The textile contained micrometric-diameter wires of a ferromagnetic mixture embedded in a thin glass coat and weaved in a specific way. A set of fabric orientations and configurations (layering) were provided in the experiment in order to achieve a better shielding to the phone’s radiation. Compared with the non-shielded handset, SAR deposited in the head while using the fabric-covered phone could be decreased up to 30 % of its initial value – in case of 2G technology and up to 24 % – in case of 3G technology. This type of material shows one of the highest shielding efficiencies of the electric-field component in near-field exposure conditions reported until now. A cubic curve of SAR decrease in depth of the head was revealed in both uncovered and covered handset, the effect of shielding being larger at the higher frequency.

A Benchmark CAD Mobile Phone Model for Specific Absorption Rate Calculations

Specific absorption rate (SAR) calculation using a computer-aided design (CAD)-based mobile phone model is still a challenging task. Seven international laboratories participated in an interlaboratory comparison of SAR calculations using a CAD-based model of a commercially available dual-band mobile phone. Return loss and peak 10 g average SAR results obtained using six different electromagnetic solvers were compared. Considering the differences in the techniques implemented in the solvers-either time or frequency domain-used for the interlaboratory comparison, overall a good agreement is observed. Proposed as a benchmark, results of the measured return loss and peak 10 g average SAR using the actual mobile phone are also provided.

Radiation efficiency improvement for dual-mode mobile phone using a slot on a ground plane

A dual-band mobile phone antenna with dual feeders is proposed to improve antenna radiation efficiency in the CDMA band of 824–894 MHz and the GSM band of 880–960 MHz. The proposed antenna consists of two planar inverted-F antennas and a common ground plane with a slot. The electric fields are more confined on each radiating element region at each band in this configuration. Measured results show that radiation efficiencies of the proposed antenna are improved by up to 20% compared to those of the antenna without a slot.

Dual‐band antenna design using genetic algorithm‐generated topology

AbstractThis article represents an antenna topology selection for dual‐band mobile phone using an optimization technique that applies a genetic algorithm (GA) in the early stage of the design. Commercial software (CST MWS) is used to predict the performance of the antenna. Then, the fitness function is evaluated by integrating the CST with the GA using visual basic language. After the antenna topology was selected, a dual‐band antenna for GSM and DCS applications was designed by adding a parasitic line. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 1170–1174, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25141

헤릭스를 이용한 3차원 구조의 휴대폰 내장형 안테나

1.5 cc 이하의 안테나 체적을 갖는 소형 안테나의 이득을 향상시킬 수 있는 3차원 구조의 휴대폰 내장형 안테나를 설계하고 이를 제작하였다. 소형 안테나 경우, 공진을 위해서 안테나를 복잡하게 구부리게 된다. 이러한 구부림은 전류 상쇄 작용을 발생시킴으로써 결국 이득 감소를 초래한다. 본 연구에서는 안테나의 구부림을 최소화하여 전류 상쇄를 줄였다. 짧은 안테나 길이의 보상과 방사 소자로의 동시 역할을 위해 헤릭스 소자를 사용하였다. 타당성을 입증하기 위하여 1.5 cc 체적으로 설계한 안테나를 프레스 공법으로 제작하여 2중 대역 휴대폰에 적용하였다. 측정 결과, GSM/USPCS 대역에서 슬라이드 다운 및 업일 때 효율과 이득은 각각 최대 27.73 %, 46.84 % 및 0.29 dBi, 2.27 dBi로 소형임에도 불구하고 양호한 특성이 나타났다. 방사 패턴은 2대역 모두 H-면 전방향성 특성을 보였다. We designed and implemented a 3-dimensional structure internal antenna which has volume less than 1.5 cc for mobile phone to improve efficiency and gain. Multiple bending for the resonance of small internal antenna derives reduction of gain due to cancellation of antenna current. In this study, the current cancelation was reduced by the minimization of antenna bending. And the helix element was applied for the purpose both compensation of short antenna length and action of radiation element. For the verification of this study, a 1.5 cc volume 3D antenna which was fabricated by the press method applied to the dual band mobile phone. Measurement showed that efficiencies and gains under the slide down and up were 27.73 %, 0.29 dBi for the GSM band and 46.84 %, 2.27 dBi for the USPCS band, and had good performance under the small antenna volume. H-plane radiation pattern showed omnidirectional for the both band.

User's hand effects on EMC internal GSM/DCS dual-band mobile phone antenna

User's hand effects on an electromagnetic-compatible (EMC) internal dual-band mobile phone antenna for GSM/DCS operation are studied. The EMC internal antenna can be placed in direct contact with nearby conducting elements, without degradation in the antenna performances. Experimental and simulation studies are conducted to analyze the user's hand effects on this EMC antenna. Obtained results indicate that the user's hand affects not only the impedance matching of the antenna, but also the radiation characteristics including radiation patterns and efficiency. Effects of different positions of the user's hand holding the mobile phone are also analyzed and discussed. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 1563–1569, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21699

Study of specific absorption rate (SAR) induced in two child head models and in adult heads using mobile phones

This paper gives a first comparison of specific absorption rate (SAR) induced in a child-sized (CS) head and an adult head using a dual-band mobile phone. In the second study, the visible human head is considered and comparison of SAR induced in a CS or child-like (CL) head and an adult head using a dual-band mobile phone is given. All the peaks of average SAR over a mass of 10 and 1 g in the head and the power budget are determined in the two comparisons using the finite-difference time-domain method. The differences between the results for adult and CS or CL heads are given at 900 and 1800 MHz. No important differences are noted for the peak SAR averaged over 10 g (SAR10 g), between the two adult head models, as well as between the two child head models. The peak SAR10 g in the brain of the CS or CL head is slightly more significant than that for the adult one.

A miniaturized Hilbert PIFA for dual-band mobile wireless applications

A miniaturized planar inverted-F antenna (PIFA) is proposed for dual-band mobile phone application in the 900- and 1900-MHz bands. By employing a Hilbert geometry, an overall size reduction of 50% was achieved compared to a conventional rectangular PIFA. The proposed antenna can be easily printed on the inside surface of the plastic housing of a mobile phone or other wireless device. An experimental prototype of this miniature antenna was fabricated on 0.125 mm thick Duroid 5880 substrate. Measured results demonstrate dual-band characteristics with good radiation patterns.

PIFA with a meandered and folded patch for the dual-band mobile phone application

In this communication, a novel design of the planar inverted-F antenna (PIFA) is proposed for the dual-band mobile telephone application. To reduce the antenna size, the radiating patch is meandered and folded. The studies begin with a folded-patch PIFA that has two tunable resonant modes. Next, by loading three slits on the patch, the surface current path is meandered and the antenna length is reduced significantly. The IE3D simulation software is employed for optimizing the design parameters, and the simulation results in general agree with the measured data. Results also show that, the excitation of the 900 and 1800 MHz resonant modes can be achieved for the proposed antenna with a small volume of 24/spl times/10/spl times/7.2 mm/sup 3/. Radiation patterns for both resonances are measured and shown. The maximum antenna gain is estimated to be 2.5 dBi for both 900/1800 band operations.

Dual-band planar inverted F antenna for GSM/DCS mobile phones

A compact dual-band planar inverted F antenna suitable for the application as a global system for mobile communication/digital communication system (GSM/DCS) dual-band mobile phone internal antenna is proposed and implemented. The proposed antenna has three resonant elements, two meandered metallic strips of slightly different lengths and one nearly-rectangular patch, which are printed on a supporting FR4 substrate and arranged in a compact configuration. These three resonant elements share a common shorting pin, and for the GSM (890-960 MHz) operation, the proposed antenna is operated with the two meandered strips both resonated as a quarter-wavelength structure, leading to a wide bandwidth formed by two resonant modes. For the upper band of the proposed antenna, three resonant modes are generated, two from the second higher-order modes of the two meandered strips and one from the nearly-rectangular patch, leading to a wide bandwidth covering the DCS band (1710-1880 MHz). The antenna design and experimental results are presented.

Shorted, folded planar monopole antenna for dual-band mobile phone

A novel shorted, folded planar monopole antenna for application in GSM/DCS dual-band mobile phones is proposed. The antenna is easily fabricated from stamping a single metal plate, which is then folded onto a foam base of compact size 5×10×40 mm3. In addition, the proposed antenna shows a very low profile of 5 mm protruded from the top edge of the system ground plane, making it very promising to be employed within the casing of a mobile phone as an internal antenna.

Folded meandered‐patch monopole antenna for low‐profile GSM/DCS dual‐band mobile phone

AbstractA novel low‐profile monopole mobile phone antenna capable of GSM and DCS dual‐band operations is proposed. The monopole antenna is easily constructed by folding a planar meandered patch into a rectangular‐tube‐like structure, and has a compact size of 9 × 9 × 34 mm3 for achieving 900‐ and 1800‐MHz operations. Details of the proposed antenna design are described, and experimental results of a constructed prototype are presented and discussed. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 34: 84–86, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10380

An inverted‐L monopole antenna loaded with a meandered wire for GSM/DCS dual‐band mobile phones

AbstractA novel dual‐band monopole antenna, created by loading a meandered wire to an inverted‐L wire monopole, is proposed. The antenna is suitable for applications in GSM/DCS dual‐band mobile phones. Both the inverted‐L wire and the meandered wire operate as quarter‐wavelength structures, and generate a resonant mode at about 1800 and 900 MHz, respectively. The obtained impedance bandwidths cover the required bandwidths of the GSM band (890–960 MHz) and the DCS band (1710–1880 MHz). In addition, the proposed antenna has a low profile of only 14 mm (about 4.2% of the wavelength at 900 MHz). © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 33: 212–214, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10278