# April 2008, Volume 17, Number 1

**N. Yannopoulou, P. Zimourtopoulos**
[references] [full-text]

S-Parameter Uncertainties in Network Analyzer Measurements with Application to Antenna Patterns

An analytical method was developed to estimate uncertainties in full two-port Vector Network Analyzer measurements, using total differentials of S-parameters. System error uncertainties were also estimated from total differentials involving two triples of standards, in the Direct Through connection case. Standard load uncertainties and measurement inaccuracies were represented by independent differentials. Complex uncertainty in any quantity, differentiably dependent on S-parameters, is estimated by the corresponding Differential Error Region. Real uncertainties, rectangular and polar, are estimated by the orthogonal parallelogram and annular sector circumscribed about the Differential Error Region, respectively. From the user\'s point of view, manufactures\' data may be used to set the independent differentials and apply the method. Demonstration results include: (1) System error differentials for Short, matching Load and Open pairs of opposite sex standards; (2) System error uncertainties for VNA extended by two lengthy transmission lines of opposite sex end-connectors; (3) High uncertainties in Z-parameters against frequency of an appropriately designed, DC resistive, T-Network; (4) Moderate uncertainties in amplitude and phase patterns of a designed UHF radial discone antenna (azimuthally rotated by a built positioner, under developed software control of a built hardware controller) polarization coupled with a constructed gain standard antenna (stationary) into an anechoic chamber.

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- YANNOPOULOU, N., ZIMOURTOPOULOS, P. Total differential errors in one-port network analyzer measurements with application to antenna impedance. Radioengineering, June 2007, vol. 16, no. 2, p. 1-8.
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Keywords: Microwave Measurements, Network Analyzer, Uncertainty, S-parameters, Z-parameters, Antenna Patterns

**Z. Elhadj**
[references] [full-text]

Analysis of a New Three-Dimensional Quadratic Chaotic System

This paper has reported the finding of a new simple three dimensional quadratic chaotic system with three nonlinearities obtained by adding a cross-product nonlinear term to the first equation of the Lu system. Basic properties of the system have been analyzed by means of Lyapunov exponent spectrum and bifurcation diagram of an associated Poincare map. This analysis shows that the system has complex dynamics with some interesting characteristics in which there are several periodic regions, but each of them has quite different periodic orbits. Shilnikov’s criterion is included and discussed.

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Keywords: New chaotic attractors, three quadratic nonlinearities, modified Lu system; Lyapunov exponent spectrum, bifurcation diagram, Poincare map

**R. Zajicek, L. Oppl, J. Vrba**
[references] [full-text]

Broadband Measurement of Complex Permittivity Using Reflection Method and Coaxial Probes

This paper describes and evaluates a method for determining complex permittivity, and presents results of permittivity measurement of some substances. Complex permittivity of a phantom of biological muscle tissue, of some industrial chemicals and dielectrics is found. A non-destructive and non-invasive method based on reflection coefficient measurement of an open-ended coaxial line attaching the material under test is used. Two coaxial probes are under investigation. Vector measurement of the reflection coefficient on the interface between probes and measured samples is performed with the aid of network analyzer in the frequency range from 300 kHz to 3 GHz. Numerical modeling (FDTD) is compared with measurement. The results indicate that using the coaxial probe with dimensions of N connector the method is suitable in the frequency range approximately from 30 MHz to 1 GHz and using the probe with dimensions of SMA connector in range approximately from 30 MHz to 3 GHz.

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- OPPL, L. Measurement of Dielectric Properties. Dissertation Thesis, CTU in Prague, Dept. of EM field, 2001. (in Czech)
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- HUDLICKA, M., HAZDRA, P. Finite Integration Technique. In: Modeling of Fields. IEEE Czechoslovak Section, 2006, p. 58-77.
- http://niremf.ifac.cnr.it/tissprop/ Dielectric properties of body tissues developed by C.Gabriel and colleagues.

Keywords: Complex permittivity measurement, vector reflection coefficient measurement, coaxial probes.

**R. Galuscak, M. Watanabe, P. Hazdra, S. Takeda, K. Seki, M. Prochazka, Y. Uchiyama**
[references] [full-text]

Design of Primary Feeds for 32m KDDI Antenna System IBA-4 in Cassegrain Configuration

Physically large dimensional dish antennas in Cassegrain configuration have played an important role in satellite communications during the past several decades. Recently, however, emerging new technologies have begun to displace these elegant antennas in professional telecommunication service due to their lower operating costs. A beneficial aspect of this transitional situation is that it has created opportunities for amateur radio enthusiasts to use these soon-to-be-retired dish antenna systems for limited experimental testing. Adaptation of these professionally designed antennas to bands allocated for amateur radio service presents excellent educational opportunities in using antenna engineering skills and the use of modern electromagnetic simulation software provides a novel perspective for these antenna design and transformation tasks.

- ICARA, Induced Current Analysis of Reflector Antennas-software, www.com.uvigo.es/ant/icara_english.htm
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- FEKO EM systems-Software & SS.A. (Pty) Ltd, www.feko.info
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- PROCHAZKA, M. Kelvin Sum software. Privately developed software program, 1999.
- BUI-HAI: Antennes Micro-Ondes, 08/01/1999 MASSON.
- Project BIG DISH, http:// 8N1EME.jp
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Keywords: Cassegrain antenna, EME communication, Primary feed, Circular polarization, Dish antenna, Project Big Dish, KDDI antenna

**M. Pokorny, J. Horak, Z. Raida**
[references] [full-text]

Planar Tri-Band Antenna Design

The paper briefly uncovers techniques used for a design of compact planar antennas in order to achieve the wideband and the multi-band capability. The main topic is aimed to the multi-objective optimization using genetic algorithms.

A quarter-wavelength planar inverted-F antenna (PIFA) using a slot and shorted parasitic patches is chosen to cover GSM900, GSM1800 and ISM2400 bands.

A global multi-objective optimization uses a binary genetic algorithm with a composite objective function to tune this antenna. The impedance match and the direction of maximum gain are desired parameters to improve.

- CIAIS, P., STARAJ, R., KOSSIAVAS, G., LUXEY, C. Design of an internal quad-band antenna for mobile phones. IEEE Microwave and Wireless Components Letters, April 2004, Vol. 14, no. 4, p. 148 - 150.
- KHOO, C. W. Multiband Antenna for Handheld Transceivers. Bachelor thesis. Ipswich: The University of Queensland, Online: http://innovexpo.itee.uq.edu.au/2002/projects/s4000751/thesis.pdf.
- RAIDA, Z. Optimization in Electrical Engineering. Online: http://www.urel.feec.vutbr.cz/~raida/optimalizace/index.htm.en
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- Arlon Product Datasheets. Rancho Cucamonga: Arlon-MED., 2006.
- HERAS, E., RAIDA, Z., LAMADRID, R. Quad-band U-slot antenna for mobile applications. Radioengineering, 2006, vol. 15, no. 2, p. 22 to 29.
- IE3D Reference Manual. Fremont: Zeland Software Inc., 2006.
- DEB, K. Multi-Objective Optimization using Evolutionary Algorithms. New York: John Wiley & Sons, 2001.

Keywords: Multi-objective optimization, multi-band antenna, planar antenna, genetic algorithm, GSM, ISM, Matlab, IE3D

**J. Jilkova, Z. Raida**
[references] [full-text]

Ultra-Wideband Coplanar-Fed Monopoles: A Comparative Study

The paper provides an experimental comparison of four types of ultra-wideband coplanar-fed planar monopole antennas. Parameters of the open stub completed by an L-shaped monopole and the cross monopole were adopted from the literature. The forked monopole and the coplanar monopole were fabricated and measured.

Monopoles were compared from the viewpoint of the impedance bandwidth, gain, directivity patterns and dimensions.

- KIM, J. I., JEE, Y. Design of ultra-wideband coplanar waveguide-fed LI-shape planar monopole antennas. Antennas and Wireless Propagation Letters. 2007, vol. 6, p. 383–387.
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- LIN, Y. F., LIN, C. H., CHEN, H., M., HALL, P. S. A miniature dielectric loaded monopole antenna for 2.4/5 GHz WLAN applications. Microwave and Wireless Components Letters. 2006, vol. 16, no. 11, p. 591–593.
- ZACHOU, V., CHRISTODOULOU, C. G., CHRYSSOMALLIS, M. T., ANAGNOSTOU, D., BARBIN, S. Planar monopole antenna with attached sleeves. IEEE Antennas and Wireless Propagation Letters. 2006, vol. 5, p. 286–289.
- KIM, J., YOON, T., JAEMOUNG, K., CHOI, J. Design of an ultra wide-band printed monopole antenna using FDTD and genetic algorithm. Microwave and Wireless Components Letters. 2005, vol. 15, no. 6, p. 395–397.
- LIU, W. C. Design of a multiband CPW-fed monopole antenna using a particle swarm optimization approach. IEEE Transactions on Antennas and Propagation. 2005, vol. 53, no. 10, p. 3273–3279.
- CHEN, H. D., CHEN, H. T. A CPW-fed dual-frequency monopole antenna. IEEE Transactions on Antennas and Propagation. 2004, vol. 52, no. 4, p. 978–982.
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Keywords: Ultra-wideband monopole antennas, coplanar feeding, planar antennas, numerical modeling

**J. Holis, P. Pechac**
[references] [full-text]

Provision of 3G Mobile Services in Sparsely Populated Areas Using High Altitude Platforms

This paper deals with the application of High Altitude Platforms for the provision of third generation mobile services in sparsely-populated areas or in developing countries. It focuses on the behavior of large cells provided via a multiple HAP deployment and shows the possibilities of using small cells located inside these large cells to serve hot-spot areas. The impact of the different types of HAP antenna masks and their adjustment on cell capacity and the quality of coverage is presented. The main parameter of the antenna radiation pattern under investigation is the power roll-off at the cell edge. Optimal values of this parameter are presented for different scenarios. Simulations of system level parameters were based on an iteration loops approach.

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Keywords: High Altitude Platforms (HAPs), UMTS, Antennas, 3G Mobile services

**K. Ulovec**
[references] [full-text]

Recognition of OFDM Modulation Method

This contribution deals with asynchronous noncoherent recognition of modulation types. The main aim is to recognize OFDM modulation method from some other single-carrier analog and digital modulation types in the presence of AWGN noise. The described solution of recognizer uses key features of the received signal. The signal amplitude is observed at the output of the quadrature intermediate-frequency stage. The properties of the recognizer are verified by simulations using Matlab.

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Keywords: Noncoherent asynchronous recognition, OFDM modulation method, AWGN noise, quadrature intermediate-frequency signal, signal key feature, correct recognition, false alarm, simulation

**M. Khelladi, O. Seddiki, F. T. Bendimerad**
[references] [full-text]

Time-Frequency Decomposition of an Ultrashort Pulse: Wavelet Decomposition

An efficient numerical algorithm is presented for the numerical modeling of the propagation of ultrashort pulses with arbitrary temporal and frequency characteristics through linear homogeneous dielectrics. The consequences of proper sampling of the spectral phase in pulse propagation and its influence on the efficiency of computation are discussed in detail. The numerical simulation presented here is capable of analyzing the pulse in the temporal-frequency domain. As an example, pulse propagation effects such as temporal and spectral shifts, pulse broadening effects, asymmetry and chirping in dispersive media are demonstrated for wavelet decomposition.

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Keywords: Refraction index, femtosecond pulse, chromatic dispersion, chirp, Fourier analysis, wavelet decomposition

**S. P. Maity, S. Maity**
[references] [full-text]

Wavelet Based Hilbert Transform with Digital Design and Application to QCM-SS Watermarking

In recent time, wavelet transforms are used extensively for efficient storage, transmission and representation of multimedia signals. Hilbert transform pairs of wavelets is the basic unit of many wavelet theories such as complex filter banks, complex wavelet and phaselet etc. Moreover, Hilbert transform finds various applications in communications and signal processing such as generation of single sideband (SSB) modulation, quadrature carrier multiplexing (QCM) and bandpass representation of a signal. Thus wavelet based discrete Hilbert transform design draws much attention of researchers for couple of years. This paper proposes an (i) algorithm for generation of low computation cost Hilbert transform pairs of symmetric filter coefficients using biorthogonal wavelets, (ii) approximation to its rational coefficients form for its efficient hardware realization and without much loss in signal representation, and finally (iii) development of QCM-SS (spread spectrum) image watermarking scheme for doubling the payload capacity. Simulation results show novelty of the proposed Hilbert transform design and its application to watermarking compared to existing algorithms.

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Keywords: Hilbert transform, wavelets, biorthogonal wavelets, hardware design, QCM-SS watermarking

**E. Chromy, I. Baronak**
[references] [full-text]

Common Virtual Path and Its Expedience for VBR Video Traffic

The paper deals with utilization of common Virtual Path (VP) for variable bit rate (VBR) video service. Video service is one of the main services for broadband networks. Research is oriented to statistical properties of common and separate VPs. Separate VP means that for each VBR traffic source one VP will be allocated. Common VP means that for multiple VBR sources one common VP is allocated. VBR video traffic source is modeled by discrete Markov chain.

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Keywords: NGN, ATM, Quality of Service, common Virtual Path, VBR video traffic, Markov model

**B. Tsankov, R. Pachamanov, D. Pachamanova**
[references] [full-text]

Resource Planning for Voice over Wireless Both-Way Transmission Media

The medium in IEEE 802.11- and IEEE 802.16-based networks for voice communications can be considered “both-way” - for transmission and reception. Therefore, the packet arrivals for voice dialogue services in such networks are not strictly independent. In this paper, we discuss the traffic capacity in the call (network) layer and suggest accounting for the impact of the correlated nature of two-way voice conversations on performance estimation. We present analytical results and numerical examples.

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Keywords: IEEE 802.11, IEEE 802.16, voice call capacity, WLAN, WMAN