Pavel Hazdra

Bio: Pavel Hazdra is an academic researcher from Czech Technical University in Prague. The author has contributed to research in topics: Antenna (radio) & Dipole antenna. The author has an hindex of 14, co-authored 102 publications receiving 710 citations.

A Method for the Evaluation of Radiation Q Based on Modal Approach

Abstract: A new formula for the evaluation of the modal radiation Q factor is derived. The total Q of selected structures is to be calculated from the set of eigenmodes with associated eigen-energies and eigen-powers. Thanks to the analytical expression of these quantities, the procedure is highly accurate, respecting arbitrary current densities flowing along the radiating device. The electric field integral equation, Delaunay triangulation, method of moments, Rao-Wilton-Glisson basis function and the theory of characteristic modes constitute the underlying theoretical background. In terms of the modal radiation Q, all necessary relations are presented and the essential points of implementation are discussed. Calculation of the modal energies and Q factors enable us to study the effect of the radiating shape separately to the feeding. This approach can be very helpful in antenna design. A few examples are given, including a thin-strip dipole, two coupled dipoles a bowtie antenna and an electrically small meander folded dipole. Results are compared with prior estimates and some observations are discussed. Good agreement is observed for different methods.

A Method for Tracking Characteristic Numbers and Vectors

Abstract: A new method for tracking characteristic numbers and vectors appearing in the Characteristic Mode Theory is presented in this paper. The challenge here is that the spectral decomposition of the moment impedance-matrix doesn't always produce well ordered eigenmodes. This issue is addressed particularly to flnite numerical accuracy and slight nonsymmetry of the frequency- dependent matrix. At speciflc frequencies, the decomposition problem might be ill-posed and non-uniquely deflned as well. Hence an advanced tracking procedure has been developed to deal with noisy modes, non-continuous behavior of eigenvalues, mode swapping etc. Proposed method has been successfully implemented into our in-house Characteristic Mode software tool for the design of microstrip patch antennas and tested for some interesting examples.

The Measurable Q Factor and Observable Energies of Radiating Structures

Abstract: New expressions are derived to calculate the Q factor of a radiating device. The resulting relations link Q based on the frequency change of the input impedance at the input port (Qx, Qz) with expressions based solely on the current distribution on an radiating device. The question of which energies of a radiating system are observable is reviewed, and then the proposed Q factor as defined in this paper is physical. The derivation is based on potential theory rather than fields. This approach hence automatically eliminates all divergent integrals associated with electromagnetic energies in infinite space. The new formulas allow us to study the radiation Q factor for antennas without feeding (through e.g. Characteristic Modes) as well as fed by an arbitrary number of ports. The new technique can easily be implemented in any numerical software dealing with current densities. To present the merits of proposed technique, three canonical antennas are studied. Numerical examples show excellent agreement between the measurable Qz derived from input impedance and the new expressions.

The Measurable Q Factor and Observable Energies of Radiating Structures

Abstract: New expressions are derived to calculate the Q factor of a radiating device. The resulting relations link Q based on the frequency change of the input impedance at the input port (QX, QZ) with expressions based solely on the current distribution on an radiating device. The question of which energies of a radiating system are observable is reviewed, and then the proposed Q factor as defined in this paper is physical. The derivation is based on potential theory rather than fields. This approach hence automatically eliminates all divergent integrals associated with electromagnetic energies in infinite space. The new formulas allow us to study the radiation Q factor for antennas without feeding (through e.g., characteristic modes) as well as fed by an arbitrary number of ports. The new technique can easily be implemented in any numerical software dealing with current densities. To present the merits of proposed technique, three canonical antennas are studied. Numerical examples show excellent agreement between the measurable QZ derived from input impedance and the new expressions.

Radiation ${Q}$ -Factors of Thin-Wire Dipole Arrangements

Abstract: In this letter, we present an investigation of the radiation Q-factors of two coupled thin dipole antennas with sinusoidal current distribution. The approach is based on novel rigorous equations for radiated power and stored energies recently derived by Vandenbosch. First, we study the validity of the used thin-wire approximation with a reduced kernel. Good agreement between the assumed sinusoidal current distribution and the real cylindrical antenna modeled with the full-wave method of moments (MoM) is observed. Then, radiation Q-factors are evaluated for half-wave side-by-side coupled dipole antennas with different feeding configurations. It is found that every such combination of studied coupled dipoles presents minimum Q for specific feeding arrangement and separation distance.

Art of electronics

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A Review of Passive RFID Tag Antenna-Based Sensors and Systems for Structural Health Monitoring Applications

Abstract: In recent few years, the antenna and sensor communities have witnessed a considerable integration of radio frequency identification (RFID) tag antennas and sensors because of the impetus provided by internet of things (IoT) and cyber-physical systems (CPS). Such types of sensor can find potential applications in structural health monitoring (SHM) because of their passive, wireless, simple, compact size, and multimodal nature, particular in large scale infrastructures during their lifecycle. The big data from these ubiquitous sensors are expected to generate a big impact for intelligent monitoring. A remarkable number of scientific papers demonstrate the possibility that objects can be remotely tracked and intelligently monitored for their physical/chemical/mechanical properties and environment conditions. Most of the work focuses on antenna design, and significant information has been generated to demonstrate feasibilities. Further information is needed to gain deep understanding of the passive RFID antenna sensor systems in order to make them reliable and practical. Nevertheless, this information is scattered over much literature. This paper is to comprehensively summarize and clearly highlight the challenges and state-of-the-art methods of passive RFID antenna sensors and systems in terms of sensing and communication from system point of view. Future trends are also discussed. The future research and development in UK are suggested as well.

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