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Proceedings of Czech and Slovak Technical Universities

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June 2008, Volume 17, Number 2

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A. K. Skrivervik, J. F. Zurcher [references] [full-text]
Terminal Antenna Design

This paper introduces first some general considerations about antenna miniaturization and multi-band terminal antenna design. These general design principles are then illustrated on some practical applications.

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  7. SKRIVERVIK, A. K., ZURCHER, J-F., STAUB, O., MOSIG, J. R. PCS antenna design: the challenge of miniaturization. IEEE Anten-nas and Propagation Magazine, 2001, vol. 43, no. 4, p. 12–27.
  8. VENDELIN, G. D. Design of Amplifier and Oscillators by the S Parameter Method. Chapter 2. New-York: John Wiley and Sons, 1982.
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  10. LEE, G. Y., WONG, K. L. Very low profile bent planar monopole antenna for GSM/DCS dual-band mobile phone. Microwave and Optical Technology Letters, 2001, vol. 34, no. 6, p. 406–409.
  11. TENG, P. L., CHEN, H. T. Multi-frequency planar monopole antenna for GSM/DCS/PCS/WLAN operation. Microwave and Optical Technology Letters, 2003, vol. 36, no. 5, p. 350–352.
  12. KITCHENER, D., SMITH, M. S., POWER, D. K., ROBSON, J. G., LLEWELLYN, L.P., JOHNSTON, R. H. Multiband terminal and base station antennas for mobile communications. In IEE 11th International Conference on Antenna and Propagation (ICAP), 2001, p. 68–70.
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  14. ZURCHER, J-F., SKRIVERVIK, A., STAUB, O., VACCARO, S. A compact dual port, dual frequency printed antenna with high decoupling. Microwave and Optical Technology Letters, 1998, vol. 19, no. 2, p. 131–137.
  15. NUNEZ, F., LLORENS DEL RIO, D., ZURCHER, J-F., SKRIVER-VIK, A. K. Optimization of a tri-band mobile communication antenna using genetic algorithms. In Journees Internationales de Nice sur les antennes (JINA'02). Nice (France), 2002, vol. II, p. 65–68.
  16. NUNEZ, F., YING, Z., SKRIVERVIK, A. K. Design and optimization of a pentaband terminal antenna. In Proceedings of the 18th International Conference of Applied Electromagnetics and Communications, ICECom 2005. Dubrovnik (Croatia), 2005, p. 33–36.
  17. ZURCHER, J-F., STAUB, O., SKRIVERVIK, A. K., HERMANJAT, M. Accurate measurement of the maximum gain of electrically small antennas. Microwave and Optical Technology Letters, 1999, vol. 23, p. 328–331.

Keywords: Electrically small antenna, antenna design, multi-frequency antenna

M. Martinez-Vazquez, R. Serrano, J. Carlsson, A. K. Skrivervik [references] [full-text]
Terminal Antennas in ACE2

The ACE Network of Excellence was a European Commission funded Network of Excellence, which lasted from 2004 to 2007. One of the activities performed by this Network was in the frame of terminal antennas. In this activity, three aspects were covered in three projects: Small antenna technologies, small terminal antenna technologies and benchmarking of small terminal antennas measurement facilities. The overall aim was to identify the newest trends in antenna design and measurement for personal communications devices, and suggest novel solutions and design methodologies for various applications. The results of this work are presented in this paper.

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  4. JOFRE, L., CETINER, B. A., DE FLAVIIS, F. Miniature multi-element antenna for wireless communications. IEEE Transactions on Antennas and Propagation, 2002, vol. 50. p. 658–669.
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  9. CIAIS, P., STARAJ, R., KOSSIAVAS, G., LUXEY, C. Design of an internal quad-band antenna for mobile phones. IEEE Microwave and Wireless Components Letters, 2004, vol. 14, no. 4, p. 148–150.
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Keywords: Terminal antennas, small antenna measurement, antenna technology

J. Guterman, A. A. Moreira, C. Peixeiro, Y. Rahmat-Samii [references] [full-text]
User Interaction with Inverted-F Antennas Integrated into Laptop PCMCIA Cards

This paper evaluates the overall laptop integration effects on the performance of commercial 2.4 GHz Inverted-F antennas built into PCMCIA cards. A generic laptop model is used to represent the antenna housing effects while an anatomical shape homogenous human model is used to estimate the electromagnetic interaction between the antenna and the user. The antenna performance is evaluated for different card locations in terms of reflection coefficient, far-field gain pattern and radiation efficiency. The human exposure to EM radiation is analyzed in terms of Specific Absorption Rate.

  1. GUTERMAN, J., RAHMAT-SAMII, Y., MOREIRA, A. A., PEIXEIRO, C. Radiation from commercially viable antennas for PCMCIA cards housed in laptops. In Proc. IST Mobile and Wireless Communications Summit. Budapest (Hungary), 2007.
  2. GUTERMAN, J., RAHMAT-SAMII, Y., MOREIRA, A. A., PEIXEIRO, C. Radiation pattern of a 2.4/5.2GHz laptop internal antenna: near field spherical range measurements and full wave analysis. In Proc. International Workshop on Antenna Technology – IWAT. Cambridge (United Kingdom), 2007.
  3. JENSEN, M. A., RAHMAT-SAMII, Y. EM interaction of handset antennas and a human in personal communications. Proceedings of the IEEE, 1995. vol. 83, no. 1, p. 7–17.
  4. WANG, J., FUJIWARA, O. EM Interaction between a 5 GHz band antenna mounted PC and a realistic human body model. IEICE Transaction on Communications, 2005, vol. E88-B, no.6, p. 2604 to 2608.
  5. SORAS, C., KARABOIKIS, M., TSACHTSIRIS, G., MAKIOS, V. Analysis and design of an inverted-F antenna printed on a PCMCIA card for the 2.4 GHz ISM band. IEEE Antenna and Propagation Magazine, 2002, vol. 44, no. 1, p. 37–44.
  6. LIU, D., GAUCHER, B. P., FLINT, E. B., STUDWELL, T. W., USUI, H., BEUKEMA, T. J. Developing integrated antenna subsystems for laptop computers. IBM Journal of Research and Development, 2003, vol. 47, no. 2/3, p. 355–367.
  7. CENELEC, European Spec. ES 59005, Considerations for the evaluation of human exposure to electromagnetic fields (EMFs) from mobile telecommunication equipment (MTE) in the frequency range from 30 MHz - 6 GHz, Ref. n° ES 59005, 1998.
  8. GUTERMAN, J., PEIXEIRO, C., MOREIRA, A. A. Omnidirectional wrapped microstrip antenna: concept, integration and applications. Frequenz, 2007, vol. 61, no. 3-4, p. 78–83.

Keywords: Laptop antennas, inverted-F antennas, electromagnetic human interaction, wireless communications

N. Farahat, R. Mittra, K. Lugo, L. Ma, R. A. Gomez [references] [full-text]
Analysis of Highly Directive Cavity-Type Configurations Comprising of Low Profile Antennas Covered by Superstrates

In this paper we present a technique for designing antenna/superstrate composites to produce enhanced directivities. As a first step, we study the underlying mechanism that governs the performance of theses antennas by studying the canonical problem of a line source in a rectangular waveguide. The above problem is solved by constructing the Green’s function corresponding to the line source in the rectangular guide, one of whose walls is partially reflecting, that is can leak electromagnetic energy into the space external to the guide. The Green’s function for this problem can be constructed by aggregating the multiple reflections from the two walls. Although the above model is only two-dimensional, we show that it can be used to predict the performance of antenna/superstrate composites. We demonstrate this by modeling several highly directive antennas and show that indeed the required characteristics of this type of antennas can be determined from the analysis of the cutoff behavior of the rectangular guide.

  1. THEVENOT, M., CHEYPE, C., REINEIX, A., JECKO, B. Directive photonic-bandgap antennas. IEEE Transactions on Microwave Theory and Techniques, 1999, vol. 47, no. 11.
  2. LUGO, K., GOMEZ, R. A., LEE, Y., FARAHAT, N., MITTRA, R., HAO, Y. FDTD Analysis of an Antenna Covered by a Dielectric Woodpile EBG Superstrate. Accepted to AP-S08. San Diego (California), July 2008.
  3. LEE, Y. J., YEO, J., MITTRA, R., PARK, W. S. Design of a high-directivity electromagnetic band gap (EBG) resonator antenna using a frequency selective surface (FSS) superstrate. Microwave and Optical Technology Letters, 2004, vol. 43, no. 6, p. 462–467.
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  5. TAFLOVE, A., HAGNESS, S. C. Computational Electromagnetics: The Finite-Difference Time-Domain Method. 2nd ed. Boston, MA: Artech House, 2000, p. 552–558.
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  7. COLLIN, R. Field Theory of Guided Waves. Willey and IEEE Press p. 90–91.

Keywords: Highly directivity antennas, frequency selective surfaces

F. Caminita, A. Cucini, S. Maci [references] [full-text]
Fast Analysis of Stop-Band FSS Integrated with Phased Array Antennas

This paper presents a method for the efficient analysis of multilayer frequency selective surfaces (FSSs) integrated with phased array of open-ended waveguides. The method is based on the assumption that all the periodic surfaces are arranged on the same spatial lattice (of arbitrary shape). The whole structure is represented as an equivalent multi-mode transmission line network, where each interface is characterized by an equivalent Generalized Scattering Matrix (GSM), computed through a fullwave analysis. To reduce the computational effort of the analysis a fast adaptive interpolation algorithm for the scattering matrix entries is included.

  1. MITTRA, R., CHAN, C. H., CWIK, T. Techniques for analyzing frequency selective surfaces – A review. Proceedings of the IEEE, 1988, vol. 76, no. 12.
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  4. MOSCA, S., MERCANTI, B., FANI, A. A graphical method to design radiating elements for phased array antennas. In IEEE 12th International Conference on Antennas and Propagation, 2003.
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  7. TASCONE, R., ORTA, R. Frequency Selective Surfaces – Analysis and Design. Ch. 7, edited by J. C. Vardaxoglou, Research Studies Press Ltd., 1997.
  8. LEHMENSIEK, R., MEYER, P. Creating accurate multivariate rational interpolation models of microwave circuits by using efficient adaptive sampling to minimize the number of computational electromagnetic analyses. IEEE Transactions on Microwave Theory and Techniques, 2001, vol. 49, no. 8, p. 1419–1430.
  9. MUNK, B. A. Frequency Selective Surfaces. Ch. 8. John Wiley & Sons, Inc, 2000.
  10. MARCUVITZ, N. Waveguide Handbook. Boston Technical Publishers, Inc., p. 72–80, 1964.

Keywords: Frequency selective surface, generalized scattering matrix, open-ended waveguide arrays

V. Papamichael, M. Karaboikis, C. Soras, V. Makios [references] [full-text]
Diversity and MIMO Performance Evaluation of Common Phase Center Multi Element Antenna Systems

The diversity and Multiple Input Multiple Output (MIMO) performance provided by common phase center multi element antenna (CPCMEA) systems is evaluated using two practical methods which make use of the realized active element antenna patterns. These patterns include both the impact of the mutual coupling and the mismatch power loss at antenna ports. As a case study, two and four printed Inverted F Antenna (IFA) systems are evaluated by means of Effective Diversity Gain (EDG) and Capacity (C). EDG is measured in terms of the signal-to-noise ratio (SNR) enhancement at a specific outage probability and in terms of the SNR reduction for achieving a desired average bit error rate (BER). The concept of receive antenna selection in MIMO systems is also investigated and the simulation results show a 43% improvement in the 1% outage C of a reconfigurable 2x2 MIMO system over a fixed 2x2 one.

  1. LEE, G., CHEN, W., WONG, K. Planar-diversity folded-dipole antenna for 5-GHz WLAN operation. Microwave Optical Technology Letters, 2003, vol. 39, no. 5, p. 368–370.
  2. CHI, G., LI, B., QI, D. Dual-band printed diversity antenna for 2.4/5.2-GHz WLAN application. Microwave Optical Technology Letters, 2005, vol. 45, no. 6, p. 561–563.
  3. KARABOIKIS, M., SORAS, C., TSACHTSIRIS, G., PAPAMICHAEL, V., MAKIOS, V. Multi element antenna systems for diversity and MIMO terminal devices. In Proceedings of Progress in Electromagnetics Research Symposium. Pisa (Italy), 2004.
  4. KARABOIKIS, M., PAPAMICHAEL, V., TSACHTSIRIS, G., SORAS, C., MAKIOS, V. Integrating compact printed antennas onto small diversity/MIMO terminals. To appear in the IEEE Transactions on Antennas and Propagation.
  5. BROWNE, D., MANTEGHI, M., FITZ, M. P., RAHMAT-SAMII, Y. Experiments with compact antenna arrays for MIMO radio communications. IEEE Transactions on Antennas and Propagation, 2006, vol. 54, no. 11, p. 3239–3250.
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  7. KILDAL, P., ROSENGREN, K., BYUN, J., LEE, J. Definition of effective diversity gain and how to measure it in a reverberation chamber. Microwave Optical Technology Letters, 2002, vol. 34, no. 1, p. 56–59.
  8. TAKADA, J., OGAWA, K. Concept of diversity antenna gain. Paris, France, EURO-COST 273 TD (3) 142, 2003.
  9. ZWICK, T., FISCHER, C., WIESBECK, W. A stochastic multipath channel model including path directions for indoor environments. IEEE Journal on Selected Areas in Communications, 2002, vol. 20, no. 6, p.1178–1192.
  10. MOLISCH, A. A generic model for MIMO wireless propagation channels in macro- and microcells. IEEE Transactions on Signal Processing, 2004, vol. 52, no. 1, p. 61–71.
  11. KONANUR, A., GOSALIA, K., KRISHNAMURTHY, S., HUGHES, B., LAZZI, G. Increasing wireless channel capacity through MIMO systems employing co-located antennas. IEEE Transactions on Microwave Theory and Techniques, 2005, vol. 53, no. 6, p. 721–729.
  12. MIGLIORE, M. D., PINCHERA, D., SCHETTINO, F., Improving channel capacity using adaptive MIMO antennas. IEEE Transactions on Antennas and Propagation, 2006, vol. 54, no. 11, p. 3481–3489.
  13. OGAWA, K., TAKADA, J. An analysis of the effective performance of a handset diversity antenna influenced by head, hand, and shoulder effects-A proposal for a diversity antenna gain based on a signal bit error rate and analytical results for the PDC system. Electronics and Communications in Japan, Part 2, 2001, vol. 84, no. 6, p. 852 to 865.
  14. MOLISCH, A., WIN, M., CHOI, Y.-S., WINTERS, J.-H. Capacity of MIMO systems with antenna selection. IEEE Transactions on Wireless Communications, 2005, vol. 4, no. 4, p. 1759–1772.
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  17. TELATAR, I. E. Capacity of multiantenna Gaussian channels. European Transactions on Telecommunications, 1999, vol. 10, no. 6, p. 585–595.
  18. SORAS, C., KARABOIKIS, M., TSACHTSIRIS, G., MAKIOS, V. Analysis and design of an inverted F antenna printed on a PCMCIA card for the 2.4 GHz ISM band. IEEE Antennas and Propagation Magazine, 2002, vol. 44, no. 1, p.37–44.
  19. Zeland Software Inc. IE3D, http://www.zeland.com/.

Keywords: Antenna diversity, bit error rate, effective diversity gain, MIMO capacity, printed circuit antennas, receive antenna selection

S. Vergerio, J. P. Rossi, P. Sabouroux [references] [full-text]
MIMO Capacity Estimation at 2 GHz with a Ray Model in Urban Cellular Environment

MIMO technology promises a linear increase of capacity in function of the minimum antenna number at the transmitter and at the receiver. In order to test if these performances can be actually met in mobile communications, we propose here a study of MIMO (Multiple Input Multiple Output) capacity in urban cellular environment at 2 GHz with a help of an efficient ray propagation model. We have tested different types of base station antennas (vertically or ±45° polarized) and two different types of mobile. Capacity is found to significantly increase between SISO (Single Input Single Output) and MIMO systems, but less than usually expected. We show that return and coupling losses as low as 10% can also reduce significantly the capacity. On the other hand, we study the influence of the way to take into account received power level on the MIMO capacity estimation.

  1. FOSCHINI, G.J., GANS, M. J. On limit of wireless communications in a fading environment when using multiple antennas. Wireless Personal Communications, 1998, vol. 6, p. 331–335.
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  5. GESBERT, D., BOLCSKEI, H., GORE, D. A., PAULRAJ, A. J. Outdoor MIMO wireless channels: Models and performance prediction. IEEE Trans. Commun., 2002, vol. 50, no. 12.
  6. ZWICK, T., FISCHER, C., WIESBECK, W. A stochastic multipath channel model including path directions for indoor environments. IEEE J. Select. Areas Commun., 2002, vol. 20, p. 1178–1192.
  7. POLLARD, A., LISTER, D., DOWDS, M. System level evaluation of standard-compatible MIMO techniques for downlink. In IST Mobile Communications Summit, Sitges (Spain), 2001.
  8. KURPJUHN, T. P., JOHAM, M., UTSCHICK, W., NOSSEK, J.A. Experimental studies about eigenbeamforming in standardization MIMO channels. In IEEE 56th VTC’2002, 2002, vol. 1, p. 185–189.
  9. KERMOAL, J. P., SCHUMACHER, L., PEDERSEN, K. I., MORGENSEN, P. E., FREDERIKSEN, F. A stochastic MIMO radio channel model with experimental validation. IEEE Journal on Selected Areas in Communications, 2002, vol. 20, p. 1211.
  10. 3GPP, Spatial channel model for multiple input multiple output (MIMO) simulations. 3gpp tr 25.996 Technical Report, 2003, version 6.1.0, release 6.
  11. SWINDLEHURST, A. L., GERMAN, G., WALLACE, J., JENSEN, M. Experimental measurements of capacity for MIMO indoor wireless channels. In 3rd IEEE Signal Processing Workshop, Taïwan, 2001.
  12. OZCELIK, H., HERDIN, M., HOFSTETTER, H., BONEK, E. Capacity of different MIMO systems based on indoor measurements at 5.2 GHz, IEE, 2003.
  13. SKENTOS, N., KANATAS, A. G., PANTOS, G., CONSTANTINOU, P. Capacity results from short range fixed MIMO measurements at 5.2 GHz in urban propagation environment. IEEE, 2004.
  14. SULONEN, K., SUVIKUNNAS, P., VUOKKO, L., KIVINEN, J., VAINIKAINEN, P. Comparison of MIMO antenna configurations in picocell and microcell environments. IEEE J. on Select. Areas in Comm., 2003, vol. 21, no. 5.
  15. SABATIER, C. T-dipole arrays for mobile applications. IEEE Antennas and Propagation Magazine, 2003, vol. 45, no. 6, p. 9–26.
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Keywords: Capacity, cellular environment, diversity, directivity, losses, multiple antennas

A. M. Vegni, A. Di-Nepi, A. Neri, C. Vegni [references] [full-text]
Local Positioning Services on IEEE 802.11 Networks

This paper deals with localization services in IEEE 802.11 networks, for indoor environment. The proposed solution processes the Time Of Arrival of location packets sent by a Mobile Terminal, that makes access in a IEEE 802.11 network. A set of Location Supporting Nodes and a Location Support Server composes an indoor location services architecture. A fully compatible IEEE 802.11 Localization Services protocol supporting data exchange related to both TOA measurement and processing is reported. Simulation results show the method efficiency in both IEEE 802.11 PCF and DCF modes. Assessment of the maximum number of users for which location services can be provided is also reported. Since high localization accuracy requires large bandwidth, a broadband antenna for LSN and LSS was designed. The related results are reported in the second part of the paper. The antenna works at 5.0 GHz (centre frequency) in broadband mode and is matched on the wireless operating frequencies with a percentage more than 8% (1:1.5 VSWR).

  1. XUE, Y., LI, B., NAHRSTEDT, K. A Scalable Location Management Scheme in Mobile Ad-hoc Networks. In Proceeding of the 26th IEEE Annual Conference on Local Computer Networks 1, Tampa (Florida), 2001, p.102–111.
  2. KUPPER, A. Location-Based Services: Fundamentals and Operation. Hoboken: John Wiley & Sons, 2005.
  3. VENKATRAMAN, S., CAFFERY JR., J. Hybrid TOA/AOA techniques for mobile location in non-line-of-sight environments. In Proceeding of IEEE Wireless Communications and Networking Conference, WCNC 2004. Atlanta (Ga, USA), 2004, vol. 1, p. 274 to 278.
  4. BORKOWSKI, J., LEMPIAINEN, J. Practical network-based techniques for mobile positioning in UMTS. EURASIP Journal on Applied Signal Processing, 2006, article ID 12930, 15 pages.
  5. SOLIMAN, S. S., WHEATLEY, C. E. Geolocation technologies and applications for third generation wireless. Wireless Communications and Mobile Computing, 2002, vol. 2, no. 3, p. 229–251.
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Keywords: Indoor localization services, IEEE 802.11, TOA, antenna array

Y. Kadoya, M. Onuma, S. Yanagi, T. Ohkubo, N. Sato, J. Kitagawa [references] [full-text]
THz Wave Propagation on Strip Lines: Devices, Properties, and Applications

We report the propagation characteristics of THz pulses on micro-strip-lines and coplanar strip-lines, in which low permittivity polymer materials are used as the dielectric layer or the substrate. As a result of the low attenuation and small dispersion in the devices, the spectral width up to 3 THz can be achieved even after the 1 mm propagation. Spectroscopic characterizations of liquid or powder specimens are demonstrated using the devices. We also show a possibility of realizing a very low attenuation using a quadrupole mode in three strip coplanar lines on the polymer substrate.

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Keywords: Terahertz, strip-line, time-domain spectroscopy

S. E. Lauro, A. Toscano, L. Vegni [references] [full-text]
Enhanced Coupling Values in Coupled Microstrip Lines using Metamaterials

In this paper, we show how metamaterials can be used to enhance the coupling values of microstrip directional couplers. Coupling between regular coplanar microstrip lines, in fact, is limited, due to the small ratios between the characteristic impedances of even and odd TEM modes supported by the structure. The broadside configuration or the employment of an overlay are often utilized to overcome this limitation, leading, however, to more bulky components. On the other hand, the employment of metamaterials with a negative real part of the permittivity is able to increase the coupling values, while keeping the profile of the structure very low. A quasi-static model of the structure is developed and physical insights on the operation of the proposed component and on the role of the metamaterial loading are also given. Simple design formulae derived through a conformal mapping technique are presented and validated through proper full wave numerical simulations.

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Keywords: Coupled lines, microstrip lines, metamaterials

S. Radionov, I. Ivanchenko, A. Korolev, N. Popenko [references] [full-text]
Broadband SHF Direction-Finder

The original design of the compact broadband direction-finder is presented in this paper. The cylindrical monopole antenna serves as a primary source of the reflector- type antenna. \"Zero-amplitude\" technique is used for bearing the SHF sources. The model experiments with the proposed direction-finder prototype in the frequency band 6 GHz – 11 GHz have been carried out.

  1. ZOOGHBY, H., SOUTHALL, H. L., CHRISTODOULOU, C. G. Experimental validation of a neural network direction finder. In Proceedings of IEEE International Symposium on Antennas and Propagation, 1999, vol. 3, p. 1592–1595.
  2. PARSONS, A. C., GRADY, W. M., POWERS, E. J., SOWARD, J. C. A direction finder for power quality disturbances based upon disturbance power and energy. IEEE Transactions on Power Delivery, 2000, vol. 15, no. 3, p. 1081–1086.
  3. CHAN, Y. T., LEE, B. H., INKOL, R., YUAN, Q. Direction finding with a four-element Adcock-Butler matrix antenna array. IEEE Transactions on Aerospace and Electronic Systems, 2001, vol. 37, no. 4, p. 1155–1162.
  4. KUWAHARA, Y., MATSUMOTO, T. Experiments on direction finder using RBF neural network with post-processing. Electronics Letters, 2005, vol. 41, no. 10, p. 602–603.
  5. MUELLER, R., LORCH, R., MENZEL, W. A. UHF direction finding antenna with optimized radar cross section. In Proceedings of IEEE International Symposium on Antennas and Propagation, 2006, p. 3255–3258.
  6. KRAVETS, A., MORHART, C., BIEBL, E. Design of radio frequency direction finder for automotive locations. In Proceedings of 36th European Microwave Conference, 2006, p. 714–717.
  7. IVANCHENKO, I. V., KHRUSLOV, M. M., KOROLEV, A. M., PAZYNIN, V. L., POPENKO, N. A. Effect of finite screen and monopole’s height on radiation characteristics of monopole antenna. In Proceedings of 16th International Conference on Microwaves, Radar and Wireless Communications MIKON 2006. Krakow (Poland), 2006, p. 729–731.
  8. IVANCHENKO, I. V., IVANCHENKO, D. I., KOROLEV, A. M., POPENKO, N. A. Experimental studies of X-band leaky-wave antenna performances. Microwave and Optical Technology Letters, 2002, vol. 35, no. 4, p. 277–281.
  9. ANDRENKO, A. S., IVANCHENKO, I. V., IVANCHENKO, D. I., KARELIN, S. Y., KOROLEV, A. M., LAZ’KO, E. P., POPENKO, N. A. Active broad X-band circular patch antenna. IEEE Antennas and Wireless Propagation Letters, 2006, vol. 5, p. 529–533.

Keywords: Mobile communication, direction-finder, antenna measurement, antenna radiation pattern, \"zero-amplitude\" technique

E. Ugarte-Munoz, F. J. Herraiz-Martinez, V. Gonzalez-Posadas, D. Segovia-Vargas [references] [full-text]
Patch Antenna Based on Metamaterials for a RFID Transponder

In this paper a self-diplexed antenna is proposed for a RFID transponder application. The development cycle is divided into two stages: antenna design and filters design. The antenna is based on a square microstrip patch filled with metamaterial structures. The inclusion of these structures allows simultaneous operation over several frequencies, which can be arbitrarily chosen. The antenna working frequencies are chosen to be 2.45 GHz (receiver) and 1.45 GHz (transmitter). In addition, the antenna is fed through two orthogonal coupled microstrip lines, what provides higher isolation between both ports. Some filters based on metamaterial particles are coupled or connected to the antenna feeding microstrip lines to avoid undesired interferences. This approach avoids using of an external filter or diplexer, providing larger size reduction and a compact self-diplexed antenna.

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  5. ANTONIADES, M. A., ELEFTHERIADES, G. V. Compact linear lead/lag metamaterial phase shifters for broadband applications. IEEE Microwave and Wireless Propagation Letters, 2003, vol. 2, p. 103–106.
  6. SCHUSSLER, M., FREESE, J., JAKOBY, R. Design of compact planar antennas using LH transmission lines. In Proceedings of the IEEE MTT-S International Microwave Symposium, 2004, vol. 1, p. 209–212.
  7. QURESHI, F., ANTONIADES, M. A., ELEFTHERIADES, G. V. A compact and low-profile metamaterial ring antenna with vertical polarization. IEEE Microwave and Wireless Propagation Letters, 2005, vol. 4, p. 333–336.
  8. LEE, C. J., LEONG, K. M. K. H., ITOH, T. Composite right/lefthanded transmission line based compact resonant antennas for RF module integration. IEEE Transactions on Antennas and Propagation, 2006, vol. 54, no. 8, p. 2283–2291.
  9. GARCIA-GARCIA, J., MARTIN, F., FALCONE, F., BONACHE, J., BAENA, J. D., GIL, I. , AMAT, E., LOPETEGUI, T., LASO, M. A. G., MARCOTEGUI ITURMENDI, J. A. Microwave filters with improved stopband based on sub-wavelength resonators. IEEE Transactions on Microwave Theory and Techniques, 2005, vol. 53, no. 6, p. 1997–2006.
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  12. BAENA, J. D., BONACHE, J., MARTIN, F., MARQUES, R., FALCONE, F., LOPETEGUI, T., G. LASO, M. A., GARCIA, J., GIL, I., SOROLLA, M. Equivalent circuit models for split ring resonators and complementary split ring resonators coupled to planar transmission lines. IEEE Transactions on Microwave Theory and Techniques, 2005, vol. 53, p. 1451–1461.
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  14. HERRAIZ-MARTINEZ, F. J., GONZALEZ-POSADAS, V., SEGOVIA- VARGAS, D. A dual-band circularly polarized antenna based on a microstrip patch filled with left-handed structures. In EuCAP 2007, Edinburgh (UK), 2007.
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Keywords: Metamaterials, self-diplexed antennas, RFID, microstrip patch antennas

R. Chernobrovkin, I. Ivanchenko, L. P. Ligthart, A. Korolev, N. Popenko [references] [full-text]
Wide-Angle X-Band Antenna Array with Novel Radiating Elements

An antenna array with wide-angle beam steering is presented in this paper. The antenna consists of dielectrically filled open-ended waveguides with a new type of excitation as individual radiators. The characteristics of the radiator have been analyzed. The novel radiator has a wide beamwidth and the frequency band of around 21%. Following the computational modeling and experimental investigations the characteristics of the antenna array for scan angles up to 50° are discussed.

  1. HOLTER, H. Dual-polarized array antenna with BOR-elements, mechanical design and measurements. IEEE Transactions on Antennas and Propagation, 2007, vol. 55, no. 2, p. 305–312.
  2. LEE, J. J., LIVINGSTONE, S., KOENING, R., NAGATA, D., LAI, L. L. Compact light weight UHF arrays using long slot apertures. IEEE Transactions on Antennas and Propagation, 2006, vol. 54, no. 7, p. 2009–2015.
  3. THORS, B., STEYSKAL, H., HOLTER, H. Broadband fragmented aperture phased array element optimization using genetic algorism. IEEE Transactions on Antennas and Propagation, 2005, vol. 53, no. 10, p. 3280–3287.
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  5. ANDRENKO, A. S., IVANCHENKO, I. V., IVANCHENKO, D. I.,. KARELIN, S. Y., KOROLEV, A. M., LAZ’KO, E. P., POPENKO, N. A. Active broad X-band circular patch antenna. IEEE Antennas and Wireless Propagation Letters, 2006, vol. 5, p. 529–533.
  6. CHERNOBROVKIN R., IVANCHENKO I., POPENKO N. Novel V-band antenna for nondestructive testing techniques. Microwave and Optical Technology Letters, July 2007, vol. 49, no. 7, p 1732 to 1735.

Keywords: Antenna array, open-ended waveguide, near-field measurements,radiation pattern

D. Bonefacic, B. Rapinac [references] [full-text]
Small H-shaped Shorted Patch Antennas

Four H-shaped shorted patch antennas with reduced dimensions are developed by using several techniques for size reduction of patch antennas. Step-by-step approach shows the obtainable reduction in size. All antennas are designed for operation at 2 GHz. Calculation results for all antennas are compared with measurement results on antenna prototypes. Antenna input impedances, radiation patterns and gains are measured. Good agreement between calculated and measured values is obtained. Both calculated and measured results are used to compare the advantages and disadvantages of the applied miniaturization techniques.

  1. SKRIVERVIK, A. K., ZURCHER, J.-F., STAUB, O., MOSIG, J. R. PCS antenna design: The challenge of miniaturization. IEEE Antennas and Propagation Magazine, 2001, vol. 43, no. 4, p. 12–26.
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  3. WONG, K. L. Planar Antennas for Wireless Communications. Hoboken (New Jersey, USA): J. Wiley, 2003.
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  5. KAN, H. K., WATERHOUSE, R. B. Small printed-wing antenna suitable for wireless handset terminals. Microwave and Optical Technology Letters, 2001, vol. 30, no. 4, p. 226–229.
  6. CHAIR, R., LUK, K. M., LEE, K. F. Miniature multilayer shorted patch antenna. Electronics Letters, 2000, vol. 36, no. 1, p. 3–4.
  7. CHAIR, R., LUK, K. M., LEE, K. F. Miniature shorted dual-patch antenna. IEE Proceedings – Microwaves, Antennas and Propagation, 2000, vol. 147, no. 4, p. 273–276.
  8. KUO, J. S., WONG, K.-L. A low-cost microstrip-line-fed shortedpatch antenna for a PCS base station. Microwave and Optical Technology Letters, 2001, vol. 29, no. 3, p. 146–148.
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  10. HERSCOVICI, N., FUENTES OSORIO, M., PEIXEIRO, C. Minimization of a rectangular patch using genetic algorithms. In Proceedings of the 18th International Conference on Applied Electromagnetics and Communications (ICECom 2005). Dubrovnik (Croatia), 2005, p. 37–40.
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  12. SINGH, D., GARDENER, P., HALL, P. S. Miniaturized microstrip antenna for MMIC application. Electronics Letters, 1997, vol. 33, no. 22, p. 1830–1831.

Keywords: Microstrip antenna, small antenna, shorted patch antenna

B. Estebanez, J. Gutierrez-Rios, J. Vassallo-Saco, A. Tazon, J. Vassallo-Sanz [references] [full-text]
The Use of the Fluorescence to the Study of the Water Quality

We present a work proposal now in course that is based on the study of the fluorescence in cyanobacteria and toxicity, and the possibility of detecting their presence in freshwater environment, with a direct application in water assessment. The proposal is a consequence of a previous study about the fluorescence generated by hydrocarbon residue on the sea surface.
In the first part of this work we present a review of results obtained from the analysis of hydrocarbon samples from the \"prestige\" oil spill accident and other referential hydrocarbons. In the second part we show the capability of this technique for the development of probes to explore the water quality.

  1. ZIELINSKI, O., ANDREWS, R., GOBEL, J., HANSLIK, M., HUNSANGER, T. , REUTER, R. Operational airborne hydrographic laser fluorosensing. Report of the Bundesanstalt fur Gewasserkunde in Lidar Remote Sensing on Land and Sea. Rainer Reuter (Editor) EARSeL, Proceedings 1, 2001, p. 53–60.
  2. ESTEBANEZ, B., GUTIERREZ-RIOS, J., VASSAL’LO-SACO, J., TAZON, A., VASSAL’LO-SANZ, J. Nuevas tecnicas para el studio de la calidad del agua. In CONAMA8 Spanish Congress about the Environment. Madrid (Spain), 2006. RADIOENGINEERING, VOL. 17, NO. 2, JUNE 2008 87
  3. JUBERA, E., FERNANDEZ-MAZUECOS, M. , ESPI, A., LUNA, J., MORILLO, L., QUIROGA, A., RODRIGUEZ-POZO, M., TOLEDO, J., ORGAZ, D., ESTEBANEZ, B., VASSAL’LO, J. Caracterizacion de comunidades bentonicas de cianobacterias en el Arroyo Pozo Azul (Covanera, Burgos). In XVI Simposio Botanica Criptogamica. Leon, 2007.
  4. JUBERA, E., FERNANDEZ-MAZUECOS, M., ESPI, A., QUIROGA, A., LUNA, J., OLIVAS, A., ESTEBANEZ, B., VASSAL’LO, J. Comunidades de cianobacterias bentonicas en el enclave del Pozo Azul (karst de Burgos). In VIII Coloquio Internacional de Botanica Pirenaica. Leon, 2007.
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  6. GUTIERREZ-RIOS, J., VASSAL’LO-SACO, J., SOTO, I., GALLEGO, E., MARAVER, P., ESTEBAN, A., MEDRANO, A., VASSAL’ LO-SANZ, J. Tecnicas de teledeteccion inteligente de vertidos de hidrocarburos en medio marino (Report Fluorosensing). Final Report - Reference: TTIVHMM02_Final_2006 – Fundacion Arao – Xunta de Galicia, 2006.
  7. LAKOWICZ, J. R. Principles of Fluorescence Spectroscopy. Third Edition. Springer, 2006.
  8. LEE, R. E. Phycology.2nd ed. Cambridge University Press, 1989.
  9. BABICHENKO, S., DUDELZAK, A., LAPIMAA, J., LISIN, A., PORYVKINA, L., VOROBIEV, A. Locating water pollution and shore discharges in costal zone and inland waters with FLS lidar. European Association of Remote Sensing Laboratories: EARSeL eProceedings, 5 1/2006.
  10. ZIELINSKI, O., HENGSTERMANN, T., MACH, D., WAGNER, P. Multispectral information in operational marine pollution monitoring: A data fusion approach. In Fifth International Airborne Remote Sensing Conference, San Francisco, California, 2001.

Keywords: Fluorosensing, fluorometry, detection of contaminant substances

G. Sisul, B. Modlic, M. Cvitkovic [references] [full-text]
Simple and Low-Cost Realization of RDS Encoder

This paper presents a simple and easy way of realization of RDS encoder. Autonomous equipment which is capable to generate wanted data stream, modulate that data stream and mixed generated signal with stereo or mono FM composite multiplex signal is simulated and produced.
Parts of encoder are described, simulated and measured. The use of RDS makes FM receivers more user-friendly. With this simple and cheap RDS encoder, smaller FM broadcasters have a chance to improve business ability.

  1. DOMITROVIC, H., JAMBROSIC, K. Receivers. Available at http://www.zea.fer.hr/Predmeti/Prijamnici/prijamnici.htm
  2. RDS FORUM, RDS standards, IEC 62106. First edition 2001. Available at http://www.rds.org.uk/rds98/rds98.htm
  3. ATMEL CORPORATION, ATmega8 ATmega8L Summary, Available at http://www.atmel.com/dyn/resources/prod_documents/ 2486S.pdf
  4. MODLIC, B., MODLIC, I. Modulacije i modulatori. Zagreb: Skolska knjiga, 1995.

Keywords: FM, RDS, D/A Converter, ATmega8, MFB filter, DSB-SC

I. Lujo, P. Klokoc, T. Komljenovic, M. Bosiljevac, Z. Sipus [references] [full-text]
Fiber-Optic Vibration Sensor Based on Multimode Fiber

The purpose of this paper is to present a fiberoptic vibration sensor based on the monitoring of the mode distribution in a multimode optical fiber. Detection of vibrations and their parameters is possible through observation of the output speckle pattern from the multimode optical fiber. A working experimental model has been built in which all used components are widely available and cheap: a CCD camera (a simple web-cam), a multimode laser in visible range as a light source, a length of multimode optical fiber, and a computer for signal processing. Measurements have shown good agreement with the actual frequency of vibrations, and promising results were achieved with the amplitude measurements although they require some adaptation of the experimental model. Proposed sensor is cheap and lightweight and therefore presents an interesting alternative for monitoring large smart structures.

  1. LENG, J., ASUNDI, A. K. Fiber optic vibration sensor – based smart civil structures. In SPIE Conference on Advanced Photonic Sensors and Applications, 1999, p. 505–510.
  2. SALEH, B. E. A., TEICH, M. C. Fundamentals of Photonics. Wiley, 2007.
  3. SIPUS, Z. Optical Communication Systems. Lecture notes, Faculty of Electrical Engg. and Computing, University of Zagreb, 2008.
  4. SPILLMAN JR., W. B., KLINE, B. R., MAURICE, L. B. Statistical mode sensor for fiber optic vibration sensing uses. Applied Optics, 1989, vol. 28, no. 15, p. 3116.

Keywords: Optical sensors, vibration measurements, multimode fiber

J. Lacik, Z. Lukes, Z. Raida [references] [full-text]
On Using Ray-Launching Method for Modeling Rotational Spectrometer

In this paper the ray-launching method is developed and used for the modeling of a rotational spectrometer. Since the electrical size of the spectrometer is several thousands times longer compared to the wavelength, the presented approach is much suitable for the analysis of such huge devices than the classical numerical exact methods such as the fast integral methods.
The accuracy of the developed approach is verified on an analysis of a spectrometer component – a lens. Firstly, the lens is analyzed in CST Microwave Studio, and secondly, by the developed ray-launching method. Comparisons show that the accuracy of the developed approach is good.

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Keywords: Ray tracing, ray launching, rotational spectrometer, rotational spectroscopy

M. Bobula, K. Danek, A. Prokes [references] [full-text]
Simplified Frame and Symbol Synchronization for 4–CPFSK with h=0.25

This paper examines the problem of rapid frame and symbol synchronization techniques intended particularly for constant envelope modulation formats M–CPFSK with modulation index h=1/M which are used in strictly bandwidth limited narrowband industrial applications. The data aided and non data aided versions of the algorithm based on digital frequency discrimination are discussed and compared against the synchronization techniques found in literature. Sample wise pattern correlation technique for joint frame and symbol synchronization is also studied. With the focus on a practical digital implementation the advantages and disadvantages of the described approaches are discussed.

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Keywords: M–CPFSK, symbol timing recovery, frame based communication, synchronization

V. Ricny, P. Stancik [references] [full-text]
Contactless Area Measurement (Contactless Planimeter)

The paper describes the designed hardware and software systems (so-called planimeters) for contactless measurement of areas (eventually geometric distances between two selected points) of planar projections of various objects. These systems operate on the principle of processing the video signal scanned by a digital camera (or TV camera).

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Keywords: Measurement, area, dimension, video signal, camera, processing

J. Svihlik, P. Pata [references] [full-text]
Elimination of Thermally Generated Charge in Charged Coupled Devices Using Bayesian Estimator

This paper deals with advanced methods for elimination of thermally generated charge in astronomical images, which were acquired by a Charged Coupled Device (CCD) sensor. There exist a number of light images acquired by telescope, which were not corrected by dark frame. The reason is simple: the dark frame doesn’t exist, because it was not acquired. This situation may for instance come when sufficient memory space is not available. Correction methods based on the modeling of the light and dark image in the wavelet domain will be discussed. As the model for the dark frame image and for the light image the generalized Laplacian was chosen. The model parameters were estimated using moment method, whereas an extensive measurement on an astronomical camera was proposed and done. This measurement simplifies estimation of the dark frame model parameters. Finally a set of astronomical testing images was corrected and then the objective criteria for an image quality evaluation based on the aperture photometry were applied.

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Keywords: Dark frame correction, Bayesian estimator, discrete wavelet transform, generalized Laplacian

I. Peterlik, R. Jirik, N. Ruiter, J. Jan [references] [full-text]
Regularized Image Reconstruction for Ultrasound Attenuation Transmission Tomography

The paper is focused on ultrasonic transmission tomography as a potential medical imaging modality, namely for breast cancer diagnosis. Ultrasound attenuation coefficient is one of the tissue parameters which are related to the pathological tissue state. A technique to reconstruct images of attenuation distribution is presented. Furthermore, an alternative to the commonly used filtered backprojection or algebraic reconstruction techniques is proposed. It is based on regularization of the image reconstruction problem which imposes smoothness in the resulting images while preserving edges. The approach is analyzed on synthetic data sets. The results show that it stabilizes the image restoration by compensating for main sources of estimation errors in this imaging modality.

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Keywords: Ultrasound, transmission tomography, algebraic reconstruction techniques, regularization