Mobile Terminal Applications Research Articles

A novel compact dual-frequency monopole antenna for quad-band mobile terminal application

A novel compact dual-frequency monopole antenna with a parasitic radiating strip is presented. The antenna with a height of only 6.5 mm, printed on the upper board and side board, is vertically placed at the upper-left corner of the main board to reduce the occupied area of the main board. A parasitic strip with meandered structure is added into the antenna, and hence, the dual-frequency characteristic is achieved to broaden the bandwidth. The measured −10 dB impedance bandwidth is 960 MHz (1920–2880 MHz), covering the UMTS (1920–2170 MHz), WiBro (2300–2400 MHz), WLAN (2400–2483 MHz), and WiMAX (2500–2690 MHz) bands. Thus, the proposed antenna is suitable for multisystem mobile terminal applications. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:1743–1746, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26876

An Electrically Small Planar Loop Antenna with High Efficiency for Mobile Terminal Applications

An electrically small loop antenna with complete planar configuration is proposed. The radiator is directly connected with a 50-Ohm coaxial line when it is coupled-fed by a tiny feeding loop. The interdigital capacitor loaded loop has a size of only 0.116λ 0, where λ 0 is its operating wavelength, and the measured results show that it can have good radiation efficiency and gain. As the loop is placed coplanar with the ground plane, it has higher radiation efficiency and the impedance bandwidth is nearly doubled compared to its vertical counterpart. Other characteristics of such an electrically small loop like the reduced current on the ground plane, the tunable operating frequency, and potential pattern diversity for MIMO applications implies its promising use in mobile terminal applications. The working mechanism of the antenna is illustrated, with the help of an equivalent circuit and some key parameter study is also given.

Small Antennas: Miniaturization Techniques and Applications

The paper presents research results in the field of small antennas obtained at the Department of Wireless Communications, Faculty of Electrical Engineering and Computing, University of Zagreb. A study comparing the application of several miniaturization techniques on a shorted patch antenna is presented. Single and dual band shorted patch antennas with notches and/or slot are introduced. A PIFA designed for application in mobile GSM terminals is described. The application of stacked shorted patches as array elements for a mobile communication base station as well as for electromagnetic field sensor is presented. The design of single and dual band folded monopoles is described. Prototypes of the presented antennas have been manufactured and their characteristics were verified by measurements.

Design of Simple Multiband Patch Antenna for Mobile Communication Applications Using New E-Shape Fractal

In this study, a probe fed E-shape fractal patch antenna (EFPA) for heptads' band LTE/WWAN (GSM850/900/1800/1900/UMTS/LTE2300/2500) operation is proposed. Various iterations of this fractal antenna are compared, and an optimized design is presented. Exploitation of E-shape fractal notion in antenna design makes the patch antenna flexible in terms of generating resonances and bandwidth as an iteration order of the fractal is increased. Several properties of the antenna such as impedance bandwidth, radiation patterns, radiation efficiency, electric current distributions on the patch, and gain have been demonstrated numerically and empirically in detail. Experimental results have authorized the design procedure and confirm the gratification of the requirements for multistandard mobile terminal applications.

Theoretical and Experimental Investigation of the Modulated Scattering Antenna Array for Mobile Terminal Applications

The performance of the modulated scattering antenna array (MSAA) for mobile terminals is investigated in this paper. The electromagnetic scattering of the modulated scattering elements (MSEs) loaded with Schottky diode is analyzed by using the Volterra series method in conjunction with the method of moments, which rigorously includes the mutual couplings among the MSAA elements. By virtue of closed-form analytical expression of Volterra analysis, useful physical insights and guidelines are provided to find optimum parameters of the MSEs in order to improve the performance of the MSAA for wireless communications. Parametrical studies are carried out for the purpose of enhancing the scattered power level of the second-order intermodulation caused by the nonlinear load in the MSEs. Both numerical simulations and experiments validate the proposed theoretical analysis.

Closely-Located MIMO Antennas of Tri-Band for WLAN Mobile Terminal Applications

A closely-located MIMO antennas of tri-band with an inter-PIFA (Planner Inverted-F Antenna) spacing of only 20 mm is proposed for WLAN mobile terminal applications. Two L-shaped slots etched on each PIFA are introduced appropriately to achieve high isolation at higher frequencies and tri-band property. The MIMO antenna can operate in the bands of 2.4–2.4812 GHz, 5.07–5.4 GHz and 5.64–6.61 GHz, and the mutual couplings are less than −16.5 dB, −27 dB and −23 dB, respectively. Radiation pattern, gain and efficiency are also measured. Our designed antenna has the advantages of closely-located structure, tri-band, high isolation, small variation of gain and high efficiency.

A wideband circular polarization antenna for portable INMARSAT BGAN terminal applications

AbstractA low profile, wideband, and portable antenna has been designed and fabricated for Inmarsat broadband global area network (BGAN) land mobile terminal applications. The purpose of the antenna was to provide a low‐cost and easy‐fabricated solution with wide bandwidth and high performance. The proposed antenna is composed of the stacked corner‐truncated patches with sequential rotation oblique feed and a serial feeding network. Good antenna characteristics are achieved over the BGAN operating bands. The measurement results for return loss, gain, axial ratio, and radiation pattern confirm the integrity of the simulation results. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 2354–2357, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24643

Dynamic bias circuit of CMOS power amplifier sensing dissipated signals

A dynamic bias technology is proposed to meet the linearity standards at high-power levels and simultaneously reduce power consumption at low-power levels for mobile WiMAX terminal application. The dynamic bias circuit makes the bias operate the power amplifier (PA) dynamically as the output power level is increased. The fabricated PA complies with the spurious emission of WiMAX standards up to 20 dBm with improvement in average power usage efficiency by a factor of 5.21 over a fixed bias PA.

VARACTOR LOADED TUNABLE PRINTED PIFA

Varactor tuned printed planar inverted-F antennas (PIFA) are investigated. The low-proflle printed antennas are fabricated together with the layouts of its DC control circuits and other RF/base- band circuit footprints. A surface mounted (SMT) varactor is applied as a frequency-tuning element at the middle of the long radiating arm in PIFA. Passive lumped DC bias circuits are implemented with good isolation. Both single and dual-band varactor tuned PIFA antennas are investigated. For a single-band PIFA, prototype designs show the in-band frequency (return loss is <10dB) is tunable from 1.6GHz to 2.3GHz when the bias voltage varies from 0V to 9.5V. Measured results show about 70»75% e-ciency and 2»3dB maximum gain. For a dual band PIFA with two varactor loadings, both the 800»900MHz and 1.7»2.2GHz bands are tuned individually by a varactor. By varying low-band capacitance, the operation frequency is tuned from 780MHz to 1020MHz, with little change on the higher frequency band. By varying high-band capacitance, the operation frequency is tuned from 1700MHz to 2140MHz, with little change on the lower frequency. Measurement shows antenna radiation e-ciencies within operation bands are about 55% at the low band and about 45% at the high band. The proposed frequency reconflgurable antennas could be useful for personal mobile terminal applications.

Comparison of dual‐band printed dipoles for WLAN mobile communication devices

AbstractA research activity is described in this article, which is devoted to the design and characterization of dual‐band printed dipoles working in the wireless local area network (WLAN) frequency bands at 2.415–2.485 GHz and 5.15–5.35 GHz. In particular, four different prototypes have been designed and compared to check the effectiveness of the design procedure through comparisons between simulations and measurements. Attention is focused on the performance of the different printed dipoles for their application in WLAN mobile terminals. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 81–87, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23000

A new programming environment for software defined radio applications

AbstractThe mobile communication market is confronted with an increasing number of communication standards and a corresponding complexity of the mobile terminal applications. To cope with this complexity, the Software Defined Radio (SDR) approach gains more and more attractiveness. Hardware platforms for SDR must meet the conflicting goals of flexibility, that is support for different protocols, and low power consumption. Therefore, upcoming platforms deploy parallelism, which complicates software development and requires specific knowledge about the hardware architecture. To simplify the development process, we suggest to separate the application development process into two steps, such that developers only need experience in either the software or the hardware area. In the first step, the application is specified in a hardware‐independent way, and in the second step, the hardware‐specific implementation is done by application‐independent tools. We developed a new programming environment called Virtual Radio Engine (VRE) that supports this approach. This paper describes the VRE tool chain. Copyright © 2007 John Wiley &amp; Sons, Ltd.

Microstrip fractal antennas for multistandard terminals

A novel microstrip patch antenna with a Koch prefractal edge and a U-shaped slot is proposed for multi-standard use in GSM1800, UMTS, and HiperLAN2. Making use of an inverted-F antenna (PIFA) structure, an interesting size reduction is achieved. The multi-band behavior has been obtained by broadening the lower frequency resonance of the fractal patch to cover GSM1800 and UMTS, and inserting a U-slot dimensioned for the HiperLAN2 band. The effect of the small ground plane has been taken into account. Experimental results have validated the design procedure and confirm the fulfillment of the requirements for multistandard mobile terminal applications.

SiGe W-CDMA transmitter for mobile terminal application

This paper presents the design considerations and experimental results of a transmitter integrated circuit (IC) for wide-band code division multiple access (W-CDMA) mobile terminal application based on a superheterodyne architecture. Implemented by utilizing IBM's 0.5-μm SiGe BiCMOS technology, the transmitter IC consumes approximately 270 mW with a 3.0-V power supply. The radio-frequency IC features a third-order output intercept point (OIP3) of +25.0 dBm, a 95-dB dynamic range, and 6.3% error vector magnitude.

Transceiver architectures for W-CDMA mobile terminal applications

Eligible transceiver architectures for third-generation Wide-Band Code Division Multiple Access (W-CDMA) mobile terminal application are presented. The heterodyne, homodyne, and low-IF architecture are discussed in detail with respect to their specific properties regarding W-CDMA. The considered issues include topics like system requirements, technical performance parameters, integration level possibilities as well as general topics like system cost and development effort.

Collaborative context determination to support mobile terminal applications

Mobile devices, together with their users, are constantly moving from one situation to another. To adapt applications to these changing contexts, the devices must have ways to recognize the contexts. There are various sources for context information: sensors, tags, positioning systems, to name a few. The raw signals from these sources are translated into higher-level interpretations of the situation. Unfortunately, such data is often unreliable and constantly changing. We seek to improve the reliability of context recognition through an analogy to human behavior. Where multiple devices are around, they can jointly negotiate on a suitable context and behave accordingly. This approach is becoming particularly attractive with the multitude of personal devices on the market. We present a collaborative context determination scheme, suggest examples of potential applications of such collaborative behavior, and raise issues of context recognition, context communication, and network requirements.

RF microelectronics for W-CDMA mobile communication systems

Third generation (3G) mobile communication systems are now just starting to be introduced. With a maximum data rate of 2 Mbit/s they will make wireless access to broadband data services like the Internet or video applications feasible. Most of the different physical layer technologies summarised under the acronym 3G are based on wideband-CDMA (W-CDMA), in contrast to existing second generation systems, which mostly use TDMA and FDMA. This has severe consequences for the design of the transceiver front-ends. During standardisation these were assumed to have an adequate RF performance yet they still present a performance bottleneck for the system. Starting with a short introduction to UMTS (Universal Mobile Telecommunications System)-the 3G standard to be deployed in Europe and already operating in Japan-this paper describes by way of example some of the test cases specified for UMTS and their impact on the analogue front-end. It is shown that accurate simulation of all the analogue and digital signal processing is necessary in order to predict the RF performance needed of today's commercial RFICs. The paper then presents and reviews some actual design examples. Finally, possible technologies and techniques for application in future mobile terminals are discussed.

A digital signal processor with programmable correlator array architecture for third generation wireless communication system

A digital signal processor (DSP) with programmable correlator array architecture is presented for third generation wireless communication system. The programmable correlator array can be reconfigured. as a chip match filter, code group detector, scrambling code detector, and RAKE receiver with low power consideration. The architecture and instruction set of the proposed DSP are specially designed for several key operations of wireless communications, such as channel estimation for RAKE combining, Viterbi algorithm and finite-impulse response filtering. The proposed DSP outperforms other previously presented communication digital signal processors in terms of several crucial operations of wireless applications. A chip of the proposed DSP was implemented using hybrid design method where the timing critical components were full-custom designed and the other parts were cell-based designed under TSMC 0.35-/spl mu/m CMOS 1P4M technology. We believe that the proposed system architecture would be useful for upcoming 3G mobile terminal applications.

Low‐cost antennas for direct broadcast satellite radio

AbstractTwo omnidirectional and circularly polarized low‐gain antennas (the crossed drooping dipole and the TM21‐mode circular patch antenna) are developed for direct broadcast satellite radio (DBSR) outdoor mobile terminal applications. Two medium‐gain circularly polarized microstrip patch arrays [one uses the conventional circular polarization (CP) feed and the other uses the sequentially arranged CP feed techniques] are also developed to provide at least 12–dBic peak gain for DBSR indoor fixed terminal applications. The sequentially arranged CP fed array has a better CP performance over a broader bandwidth than the conventionally fed array. All the antennas are small in size/mass and inexpensive in fabrication cost. The patch antennas also have a low profile. © 1994 John Wiley &amp; Sons, Inc.