Aurora Andujar

Bio: Aurora Andujar is an academic researcher from Ramon Llull University. The author has contributed to research in topics: Ground plane & Antenna (radio). The author has an hindex of 17, co-authored 87 publications receiving 1145 citations.

Advances in Antenna Technology for Wireless Handheld Devices

Abstract: The constant evolution of wireless handheld devices together with the apparition of multiple wireless communication systems fosters the antenna community to design new radiating and measurements systems capable of satisfying the market demands. It is an object of the present paper to provide an overview of the evolution that wireless handheld technology has experienced in the last years. In this sense, a description of the evolution of wireless handheld devices, regulations, challenges in today’s smartphones, and handset characterization is reviewed. Finally, recent advances in antenna technology for wireless handheld or portable devices are presented.

Ground Plane Boosters as a Compact Antenna Technology for Wireless Handheld Devices

Abstract: The increasing demand for multifunctional wireless devices has fostered the need to reduce the space devoted to the antenna in order to favor the integration of multiple and new functionalities. This fact becomes a challenge for the handset antenna designers who have to develop antennas capable of providing multi-band operation constrained by physical limitations. This proposal consists in a radiating system capable of providing multi-band operation without the need of an antenna element, by properly exciting the efficient radiation modes associated to the ground plane structure. In this sense, the typical volume devoted to a handset antenna is reduced by a factor of 20. The electrical model approximation of the radiating structure leads to the radiofrequency system design able to provide multi-band operation. The feasibility of the proposal has been tested by electromagnetic simulations as well as by experimental measurements regarding the main antenna parameters: reflection coefficient, efficiency, and radiation patterns. Furthermore, the human head interaction concerning biological compatibility in terms of SAR (Specific absorption rate) has been measured and a solution for its reduction is presented. As a result, a promising standard solution for a radiating system capable to operate in the main communication standards GSM850, GSM900, DCS, PCS and UMTS is provided with a volume reduction factor around 20.

A miniaturized metamaterial slot antenna for wireless applications

Abstract: A novel miniaturized five band metamaterial inspired slot antenna is reported. The proposed design consists of a ring monopole and metamaterial Rectangular Complementary Split Ring Resonator (RCSRR) as the radiating part, two L and one T–shaped slot as the ground plane, respectively. Miniaturization in the proposed design is accomplished by metamaterial RCSRR, and also, it helps the antenna to operate at 2.9 and 5.2 GHz frequency bands. The aforementioned miniaturization process leads to about 46.8% reduction in volume of the proposed design, as compared to the conventional antenna. The pass band characteristics of the metamaterial RCSRR through waveguide medium are discussed in detail. In order to enhance the operating abilities of the miniaturized antenna, slots are etched out in the ground plane, thereby making the miniaturized antenna further operate at 2.4, 5.6 and 8.8 GHz, respectively. The proposed design has an active patch area of only , with dB bandwidth of about 4.16% (2.35–2.45 GHz), 5.71% (2.63–2.76 GHz), 10.25% (4.44–4.92 GHz), 6.25% (5.42–5.77 GHz) and 2.39% (8.68–8.89 GHz) in simulation, and about 6.86% (2.25–2.41 GHz), 5.01% (2.55–2.7 GHz), 9.16% (4.58–5.02 GHz), 5.38% (5.79–6.11 GHz) and 5.42% (8.44–8.91 GHz) in measurement. The antenna has good impedance matching, acceptable gain and stable radiation characteristics across the operational bandwidths.

Multiband and Small Coplanar Antenna System for Wireless Handheld Devices

Abstract: Multiband and small antennas are strongly demanded in current wireless handheld or portable devices that require multiband operation. Nowadays, trends are focused on exciting ground plane radiation modes in order to reduce as much as possible the volume devoted to the antenna element. This paper studies different geometries for determining which one better excites a ground plane radiation mode at different frequency regions. The results demonstrate that a non-resonant pad element attains the best tradeoff between performance and geometry complexity. A multiband antenna system featuring small coplanar pad elements is proposed for providing operation at the communication standards LTE700 (698-787 MHz), GSM850 (824-894 MHz), GSM900 (880-960 MHz), GSM1800 (1710-1880 MHz), GSM1900 (1850-1990 MHz), UMTS (1920-2170 MHz), LTE2100 (1920-2170 MHz), LTE2300 (2300-2400 MHz), LTE2500 (2500-2690 MHz) as well as at the satellite positioning systems GPS (1575 MHz), Galileo L1 (1559-1591 MHz), Glonass (1592-1609 MHz). A radiofrequency system comprising broadband matching networks is included to provide the required impedance bandwidth. Numerical results give physical insight into the behavior of the proposed planar element. A prototype is built to demonstrate the feasibility of the proposal. The proposed radiating system is appealing for the new wireless handheld devices due to its small size (153 ), planar profile, and multiband performance.

Coupled monopole antenna design for multiband handset devices

Abstract: A low profile planar antenna, comprising a driven element coupled with one or more parasitic elements is proposed. The design is suitable to be used into a handheld device due to the antenna reduced dimensions (33 × 15 × 1 mm3). To facilitate the integration of other components, such as cameras or speakers, a ground plane area at the right side of the antenna is provided. The study carried out reveals the relevance of the arms location over the performance of the antenna. The theoretic analysis is reinforced using a network model and a parametric study. The coupling between elements controls the behavior of the antenna. In this sense, a weak coupling between the driven element and at least one parasitic element enhances the bandwidth, whereas a multiband behavior is achieved by a tight coupling. Finally, the PCB (Printed Circuit Board) influence has also been analyzed. ©2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 359–364, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24893

I and i

Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

About Authors

Abstract: Catherine Durnell Cramton (\"The Mutual Knowledge Prob- conditions, the impact of organizational change on subsequent lem and Its Consequences for Dispersed Collaboration\") is Asso- performance and survival, and the consequences of organizational ciate Professor in the School of Management at George Mason structures and dynamics for employees\' careers and the compo- University. She recieved her Ph.D. in organizational behavior from sition of organizations\' work forces. She serves on the editorial Yale University. Her research explores the contemporary chal- boards of Organization Science, Administrative Science Quar- lenges of collaboration and leadership, including distributed work, terly, and the American Sociological Review. Address: Columbia interorganizational collaboration, project team leadership, and the University, Graduate School of Business, 706 Uris Hall, New impact of technology on collaboration. Address: School of Man- York, NY 10027-6902; telephone: (212) 854-4424; e-mail: agement, Mail Stop 5F5, George Mason University, Fairfax, VA hah15@columbia.edu . 22030-4444; telephone: (703) 993-1814; fax: (202) 318-4319; John C. Henderson (\"Understanding `Strategic Learning\': e-mail: ccramton@som.gmu.edu . Linking Organizational Learning, Knowledge Management, and Sue R. Faerman (\"Understanding Interorganizational Cooper- Sensemaking\") is the Richard C. Shipley Professor of Manage- ation: Private-Public Collaboration in Regulating Financial Market ment, Chairperson of the Information Systems Department, and Innovation\") is Professor of Public Administration and Organiza- Director of the Institute for Leading in a Dynamic Economy at tional Studies and Dean of Undergraduate Studies at the University Boston University\'s School of Management. He is a noted at Albany, State University of New York. Her research focuses on researcher, consultant, and executive educator with papers appear- the paradoxical nature of leadership and organizational perfor- ing in many refereed journals. His coauthored book, Knowledge mance. She received her Ph.D. in public administration from the Engine, examines leveraging a firm\'s knowledge assets. His University at Albany, State University of New York. Address: research interests include: managing strategic partnerships, impact Office of Undergraduate Studies-LC30, University at Albany, of the mobile Internet on markets and organizations, and knowl- State University of New York, 1400 Washington Avenue, Albany, edge management. Address: Boston University School of Man- NY 12222; telephone: (518) 442-3950; fax: (518) 442-4959; e-mail: agement, 595 Commonwealth Avenue, Room 546H, Boston, MA sfaerman@uamail.albany.edu . 02215; telephone: (617) 353-6142; fax: (617) 353-1695; e-mail: James F. Fairbank (\"Emulation in Academia: Balancing Struc- jchender@bu.edu . ture and Identity\") received his Ph.D. in management and organi- Giuseppe (Joe) Labianca (\"Emulation in Academia: Balancing zation, The Pennsylvania State University and is an assistant pro- Structure and Identity\") received his Ph.D. in management and or- fessor of management in the College of Business and Economics ganization, The Pennsylvania State University, and is an assistant at West Virginia University in Morgantown, WV. His current re- professor of organization and management at Emory University\'s search interests are strategic decision making and the management Goizueta Business School in Atlanta, GA. His primary interests are of information technology. Address: College of Business and Eco- in network and cognition research at the intra- and interorganiza- nomics, P.O. Box 6025, Morgantown, WV 26506-6025; telephone: tional levels. Recent projects have investigated the antecedents and (304) 293-7937; fax: (304) 293-5652; e-mail: ifairban@wvu.edu . consequences of disliking others in one\'s social networks at work, Dennis A. Gioia (\"Emulation in Academia: Balancing Structure as well as investigating the process of emulation between organ- and Identity\") is Professor of Organizational Behavior, Department zations. He conducts both quantitative and qualitative research, and of Management and Organization, Smeal College of Business Ad- has published in the Academy of Management Journal and Orga- ministration at The Pennsylvania State University. His current nization Science. He is currently serving on the editorial review research and writing interests focus primarily on the cognitive board of the Academy of Management Journal. Address: Goizueta processes of organization members, especially the ways in which Business School, 1300 Clifton Road, Emory University, Atlanta, identity, image, and reputation are involved in organizational GA 30322; telephone: (404) 727-7662; fax: (404) 727-6663; e-mail: sensemaking, sensegiving, and change. His work has appeared joe_labianca@bus.emory.edu . in many of the top journals in the field and he has coedited two David P. McCaffrey (\"Understanding Interorganizational Co- volumes of original contributions: The Thinking Organization operation: Private-Public Collaboration in Regulating Financial and Creative Action in Organizations. Address: Smeal College of Market Innovation\") is Professor of Public Administration, Public Business, Penn State University, 403 Beam BAB, University Park, Policy, and Organizational Studies at the University at Albany, PA 16802; telephone: (814) 865-6370; fax: (814) 863-7261; e-mail: State University of New York. His research focuses on the orga- dag4@psu.edu . nizational dynamics of regulatory systems. He received his Ph.D. Heather A. Haveman (\"Organizational Environments in Flux: in sociology from the State University of New York at Stony The Impact of Regulatory Punctuations on Organizational Do- Brook. Address: Department of Public Administration and Policy, mains, CEO Succession, and Performance\") is Professor of Man- University at Albany, State University of New York, 135 Western agement at the Graduate School of Business, Columbia University. Avenue, Albany, NY 12222; e-mail: d.mccaffrey@albany.edu . She received her Ph.D. in organizational behavior and industrial Alan D. Meyer (\"Organizational Environments in Flux: The relations from the Haas School of Business Administration at the Impact of Regulatory Punctuations on Organizational Domains, University of California at Berkeley in 1990. Her research inves- CEO Succession, and Performance\") is the Charles H. Lundquist tigates organizations\' responses to shifting internal and external Professor of Entrepreneurial Management at the University of

A Comprehensive Survey on “Various Decoupling Mechanisms With Focus on Metamaterial and Metasurface Principles Applicable to SAR and MIMO Antenna Systems”

Abstract: Nowadays synthetic aperture radar (SAR) and multiple-input-multiple-output (MIMO) antenna systems with the capability to radiate waves in more than one pattern and polarization are playing a key role in modern telecommunication and radar systems. This is possible with the use of antenna arrays as they offer advantages of high gain and beamforming capability, which can be utilized for controlling radiation pattern for electromagnetic (EM) interference immunity in wireless systems. However, with the growing demand for compact array antennas, the physical footprint of the arrays needs to be smaller and the consequent of this is severe degradation in the performance of the array resulting from strong mutual-coupling and crosstalk effects between adjacent radiating elements. This review presents a detailed systematic and theoretical study of various mutual-coupling suppression (decoupling) techniques with a strong focus on metamaterial (MTM) and metasurface (MTS) approaches. While the performance of systems employing antenna arrays can be enhanced by calibrating out the interferences digitally, however it is more efficient to apply decoupling techniques at the antenna itself. Previously various simple and cost-effective approaches have been demonstrated to effectively suppress unwanted mutual-coupling in arrays. Such techniques include the use of defected ground structure (DGS), parasitic or slot element, dielectric resonator antenna (DRA), complementary split-ring resonators (CSRR), decoupling networks, P.I.N or varactor diodes, electromagnetic bandgap (EBG) structures, etc. In this review, it is shown that the mutual-coupling reduction methods inspired By MTM and MTS concepts can provide a higher level of isolation between neighbouring radiating elements using easily realizable and cost-effective decoupling configurations that have negligible consequence on the array’s characteristics such as bandwidth, gain and radiation efficiency, and physical footprint.

A Comprehensive Survey of “Metamaterial Transmission-Line Based Antennas: Design, Challenges, and Applications”

Abstract: In this review paper, a comprehensive study on the concept, theory, and applications of composite right/left-handed transmission lines (CRLH-TLs) by considering their use in antenna system designs have been provided. It is shown that CRLH-TLs with negative permittivity (e <; 0) and negative permeability (μ <; 0) have unique properties that do not occur naturally. Therefore, they are referred to as artificial structures called “metamaterials”. These artificial structures include series left-handed (LH) capacitances (C L ), shunt LH inductances (L L ), series right-handed (RH) inductances (LR), and shunt RH capacitances (CR) that are realized by slots or interdigital capacitors, stubs or via-holes, unwanted current flowing on the surface, and gap distance between the surface and ground-plane, respectively. In the most cases, it is also shown that structures based on CRLH metamaterial-TLs are superior than their conventional alternatives, since they have smaller dimensions, lower-profile, wider bandwidth, better radiation patterns, higher gain and efficiency, which make them easier and more cost-effective to manufacture and mass produce. Hence, a broad range of metamaterial-based design possibilities are introduced to highlight the improvement of the performance parameters that are rare and not often discussed in available literature. Therefore, this survey provides a wide overview of key early-stage concepts of metematerial-based designs as a thorough reference for specialist antennas and microwave circuits designers. To analyze the critical features of metamaterial theory and concept, several examples are used. Comparisons on the basis of physical size, bandwidth, materials, gain, efficiency, and radiation patterns are made for all the examples that are based on CRLH metamaterialTLs. As revealed in all the metematerial design examples, foot-print area decrement is an important issue of study that have a strong impact for the enlargement of the next generation wireless communication systems.

A Dual-Loop Antenna Design for Hepta-Band WWAN/LTE Metal-Rimmed Smartphone Applications

Abstract: A simple direct-fed dual-loop antenna capable of providing hepta-band WWAN/LTE operation under surroundings of an unbroken metal rim in smartphone applications is proposed. The greatest highlight of this proposed antenna is that it provides a simple and effective multiband antenna solution for an unbroken metal-rimmed smartphone. The unbroken metal rim with 5 mm in height embraces the system circuit board of 130 $\, \times \,$ 70 mm $^{2}$ . Two no-ground portions of 10 $\, \times \,$ 70 mm $^{2}$ and 5 $\, \times \,$ 70 mm $^{2}$ are set on the top and bottom edge of the system circuit board, respectively. In-between the two separate no-ground portions, there is a system ground of 115 $\, \times \,$ 70 mm $^{2}$ connected with the unbroken metal rim via a small grounded patch which divides the unbroken metal rim into two strips. Finally, a dual-loop antenna is formed by combining the inner system ground and two strips. This proposed dual-loop antenna is capable of covering GSM850/900/DCS/PCS/UMTS2100/LTE 2300/2500 operating bands. Detailed design considerations of the proposed antenna are described and both experimental and simulation results are also presented and discussed.