Showing papers in "Radioengineering in 2009"

SPICE Model of Memristor with Nonlinear Dopant Drift

Abstract: A mathematical model of the prototype of memristor, manufactured in 2008 in Hewlett-Packard Labs, is described in the paper. It is shown that the hitherto published approaches to the modeling of boundary conditions need not conform with the requirements for the behavior of a practical circuit element. The described SPICE model of the memristor is thus constructed as an open model, enabling additional modifications of non-linear boundary conditions. Its functionality is illustrated on computer simulations.

Current and Future Research Trends in Substrate Integrated Waveguide Technology

Abstract: Substrate Integrated Waveguide (SIW) tech- nology is the most promising candidate for the implemen- tation of millimeter-wave (mm-wave) integrated circuits and systems for the next decade. Based on planar dielectric substrates with top and bottom metal layers perforated with metalized holes, SIW structures offer a compact, low loss, flexible, and cost-effective solution for integrating active circuits, passive components and radiating elements on the same substrate. This paper presents an overview of the current status and future trends of academic and in- dustrial research on SIW technology. The historical devel- opment of SIW components and circuits is briefly outlined, and the current research topics are discussed: they include the development of numerical techniques for the modeling and design of SIW components, the investigation of novel compact and broadband interconnects, the determination of design solutions for loss minimization. Future research trends are also discussed: they mainly aim at the imple- mentation of SIW components at higher frequency (60-350 GHz) and the integration of complete Systems-on-Substrate (SoS).

3D-Spiral Small Antenna Design and Realization for Biomedical Telemetry in the MICS band

Abstract: This work presents the design and realization procedure of small implantable antenna for biotelemetry applications. The radiator occupies a volume smaller than 3 cm(3) (without its biocompatible insulation), is well matched within the Medical Implanted Communications System band and shows an adequate gain (-28.5 dB) while introduced in the appropriate equivalent body medium. The latter is a homogeneous phantom with muscle dielectric properties. A prototype has been manufactured and measurements agree with theoretical predictions. Particular attention is paid to the building requirements such as the presence of glue. Specific Absorption Rate (SAR) distribution has been computed evaluating the maximum power deliverable to the antenna in order to respect the regulated SAR limitation.

A High-Capacity Image Data Hiding Scheme Using Adaptive LSB Substitution

Abstract: Many existing steganographic methods hide more secret data into edged areas than smooth areas in the host image, which does not differentiate textures from edges and causes serious degradation in actual edge areas. To avoid abrupt changes in image edge areas, as well as to achieve better quality of the stego-image, a novel image data hiding technique by adaptive Least Significant Bits (LSBs) substitution is proposed in this paper. The scheme exploits the brightness, edges, and texture masking of the host image to estimate the number k of LSBs for data hiding. Pixels in the noise non-sensitive regions are em- bedded by a k-bit LSB substitution with a lager value of k than that of the pixels in noise sensitive regions. Moreover, an optimal pixel adjustment process is used to enhance stego-image visual quality obtained by simple LSB substi- tution method. To ensure that the adaptive number k of LSBs remains unchanged after pixel modification, the LSBs number is computed by the high-order bits rather than all the bits of the image pixel value. The theoretical analyses and experiment results show that the proposed method achieves higher embedding capacity and better stego- image quality compared with some existing LSB methods.

Traction Permanent Magnet Synchronous Motor Torque Control with Flux Weakening

Abstract: The paper deals with analysis of dynamic behavior of a feedback flux weakening control of PMSM traction drive for light vehicles. The PMSM flux weakening is very important for traction drives. Two torque control structures were analyzed - pure feedback control and feedback control with prediction of the field producing current component. The principles, control structures, simulation and experimental results are given.

Equivalent Circuit Model for Designing of Jerusalem Cross-Based Artificial Magnetic Conductors

Abstract: This paper introduces an equivalent circuit model to estimate the resonant frequency and reflection phase of Jerusalem cross-based artificial magnetic conductor (JC-AMC) structures for waves normally incident on the structure. The JC-AMC structure is composed of an array of Jerusalem cross-shaped frequency selective surfaces (JC-FSSs) printed on a metal-backed dielectric slab without vias. This approach is based on the coupled microstrip lines and transmission line theories. Analytical expressions for the resonant frequency and reflection phase resulting from our model are thoroughly verified by full-wave simulations for different samples reported in the open literature. A comprehensive parametric study of the design parameters of JC-AMC structure and the influence of these parameters on the reflection phase properties are presented. This model can easily be extended to complexshaped AMCs.

Directive Emission Obtained by Mu and Epsilon-Near-Zero Metamaterials

Abstract: In this work, we use Mu and Epsilon-Near-Zero (MENZ) metamaterials to realize the substrates that can modify the emission of an embedded line source. Simulation results show that the cylindrical waves emitted from the line source can be perfectly converted to plane wave through the MENZ metamaterial slab with planar exit face. Hence the line source together with the metamaterial slab constructs a high directive slab antenna. The directive radiation pattern of the MENZ metamaterial-assisted slab antenna is independent on the thickness of the slab, the position of the line source, and the shape of the entrance face of the slab, but the slab with grooved entrance side will result in stronger far-field intensity. We also show that the MENZ metamaterials can be applied to the design of antenna array. Moreover, compared with the high directive slab antenna obtained by coordinate transformation approach, the MENZ metamaterial-assisted antenna is more preferable.

Radiation efficiency improvement of zeroth-order resonator antenna

Abstract: The radiation as well as antenna efficiency of very thin profile zeroth-order resonator (ZOR) antenna, implemented in negative phase velocity (NPV) microstrip transmission line (TL) structure, has been solved by the method of moment simulator IE3D. The radiation is inves- tigated using individual portions of the ZOR antenna that shows significant values of the surface current density. Dominantly radiating parts have been identified, geometri- cally emphasized by means of the increase in the antenna height over the ground plane from 1/105 to 1/8 λ0. The measured parameters of the improved antenna prototype have been enhanced so they reached the following values (compared to original ones): gain 5.0 dBi (-3.0 dBi), an- tenna efficiency 97.7 % (9.5 %).

Design of a Multimode MIMO Antenna Using the Theory of Characteristic Modes

Abstract: In this communication, the design procedure of a multimode Multiple-Input Multiple-Output (MIMO) antenna is presented. The antenna consists of a metallic ring antenna operating with different orthogonal modes, whose performance in a MIMO system is similar to traditional antenna arrays. Thus, a compact MIMO antenna is obtained, which is very suitable for mobile terminals. A modal analysis of the antenna is carried out first by means of the Theory of Characteristic Modes, in order to identify the different radiating modes of the antenna. Then a set of feeding configurations is proposed so as to excite these modes. As the modes must operate in the same frequency band, a loading technique is used in the antenna in order to shift the resonance frequency of the modes to the proper band.

A simple signal shaper for GMSK/GFSK and MSK modulator based on sigma-delta look-up table

Abstract: Due to wide power spectrums of rectangular data streams, it is important for base-band signals to be heavily band limited before modulation. That can be achieved by pulse shaping of rectangular bits. Some of the most common are a half-sine pulse shaper and a Gaussian pulse shaper which are used in Minimum Shift Keying (MSK), Gaussian Minimum Shift Keying (GMSK) and Gaussian Frequency Shift Keying (GFSK) modulations, respectively. The most common solutions of such shapers use PCM based look-up-table (LUT), which requires an n-bit D/A converter. We proposed the use of a 1-bit Sigma Delta Modulation (SDM) LUT, which results in smaller ROM capacity, a 1-bit wide output word, and a simple1-bit D/A converter realized as an out-of-chip first-order low-pass RC filter, or an in-chip charge pump. This article describes a simple, but efficient SDM LUT-based half-sine and Gaussian shaper that can be used for generation of MSK and GMSK/GFSK modulated signals. Oscillograms and power spectrums are measured on SDM LUT realized in FLEX AlteraTM PLD, for a 10-bit pseudo-noise sequence test input signal.

Axial Vircator for Electronic Warfare Applications

Abstract: This paper deals with a high power microwave generator with virtual cathode – vircator in axial release for electronic warfare applications. The classification of directed energy weapons microwave (DEWM) is introduced together with basic block diagrams of a particular class of DEWM. In the paper, methods for designing vircator pulsed power supply, axial vircator structure, measurement methods and experimental results are presented. The vircator in electromagnetic ammunition is powered by magneto-cumulative generator and in weapons for defense of objects (WDO), it is powered by Marx generator. The possible applications of a vircator in the DEWM area are discussed.

Performances of hybrid Amplitude Shape Modulation for UWB communications systems over AWGN channel in a single and multi-user environment

Abstract: This paper analyzes the performance of the hybrid Amplitude Shape Modulation (h-ASM) scheme for the time-hopping ultra-wideband (TH-UWB) communica- tion systems in the single and multi-user environment. h-ASM is the combination of Pulse Amplitude Modulation (PAM) and Pulse Shape Modulation (PSM) based on modified Hermite pulses (MHP). This scheme is suitable for high rate data transmission applications because b = log2(MN) bits can be mapped with one waveform. The channel capacity and error probability over AWGN chan- nel are derived and compared with other modulation schemes.

Utilization of Birefringent Fiber as Sensor of Temperature Field Disturbance

Abstract: The paper deals with utilization of induced bi- refringence sensitivity to temperature field in birefringent optical fibers. The propagating optical wave and optical fibers are described by means of coherency and Jones matrices, which are decomposed into unitary matrix and spin matrices. The development of polarization caused by temperature field is interpreted on the Poincare sphere by means of MATLAB® environment. The temperature sensi- tivity of Panda and bow-tie fiber has been measured for circular polarization excitation. Curves of intensity fluc- tuation caused by the temperature dependence are pre- sented.

Embedded Platform for Automatic Testing and Optimizing of FPGA Based Cryptographic True Random Number Generators

Abstract: This paper deals with an evaluation platform for cryptographic True Random Number Generators (TRNGs) based on the hardware implementation of statistical tests for FPGAs. It was developed in order to provide an automatic tool that helps to speed up the TRNG design process and can provide new insights on the TRNG behavior as it will be shown on a particular example in the paper. It enables to test sufficient statistical properties of various TRNG designs under various working conditions on the fly. Moreover, the tests are suitable to be embedded into cryptographic hard- ware products in order to recognize TRNG output of weak quality and thus increase its robustness and reliability. Tests are fully compatible with the FIPS 140 standard and are im- plemented by the VHDL language as an IP-Core for ven- dor independent FPGAs. A recent Flash based Actel Fu- sion FPGA was chosen for preliminary experiments. The Actel version of the tests possesses an interface to the Ac- tel's CoreMP7 softcore processor that is fully compatible with the industry standard ARM7TDMI. Moreover, identi- cal tests suite was implemented to the Xilinx Virtex 2 and 5 in order to compare the performance of the proposed solu- tion with the performance of already published one based on the same FPGAs. It was achieved 25% and 65% greater clock frequency respectively while consuming almost equal resources of the Xilinx FPGAs. On the top of it, the proposed FIPS 140 architecture is capable of processing one random bit per one clock cycle which results in 311.5 Mbps through- put for Virtex 5 FPGA.

Study of a Miniaturized Quasi-Self-Complementary UWB Antenna in Frequency and Time Domain

Abstract: A compact antenna for UWB communication systems has been realized by employing a quasi-self- complementary structure together with a triangular notch on microstrip feed line in this paper. The optimal design of this type of antenna can offer an ultra wide return loss bandwidth with reasonable radiation properties. It features a quite small physical dimension of 16 mm×25 mm, corre- sponding to an electrically size of 0.24 λ. A good agree- ment is achieved between the simulated and the measured antenna characteristics. The major parameters that influ- ence the performance of the antenna are investigated numerically to gain an insight into the antenna operation. Time domain performance of the antenna is also examined in order to assess its suitability for impulse radio applications.

Experimental Characterization of System Parameters for Ranging in IEEE 802.15.4a using Energy Detectors

Abstract: The IEEE 802.15.4a standard for impulse ra- dio ultrawide band (IR-UWB) communication systems de- fines a ranging scheme which relies on the measurement of the round-trip propagation time of electromagnetic pulses. Accuracy is strongly dependent on the estimation of the time- of-arrival (TOA) of the pulse that is spread in time due to multipath propagation. The major concern therefore is the proper detection of the leading edge. In this work, the rang- ing capabilities of the standard are analyzed for an energy detector receiver. Emphasis is put on the influence of trans- mitter and receiver parameters, which are evaluated for a set of measured scenarios. It is shown that sub-meter ranging accuracy can be achieved with fixed parameter settings.

Antenna-User Interaction in MIMO-Enabled Laptops

Abstract: The operation of wireless personal communication terminals very close to the user inherently faces the problem of electromagnetic (EM) coupling between the device and the biological tissues. In this paper the effects of the electromagnetic antenna-human interaction is studied for a laptop MIMO antenna system, where four integrated antenna elements can operate simultaneously. Two points of view are considered: antenna performance and EM dosimetry. The first one addresses not only the degradation of the antenna performance but includes also the effect of the human proximity on the antenna characteristics, namely scattering matrix, Total Active Reflection Coefficient (TARC), radiation efficiency and envelope correlation between port signals. The exposure of the human tissues to EM radiation is expressed in terms of Specific Absorption Rate (SAR). These characteristics are evaluated as a function of the array excitation scheme (including phased array approach and MIMO-like signaling) and compared to simple scenarios where all the power is radiated only by one antenna element.

Channel Capacity Enhancement by Pattern Controlled Handset Antenna

Abstract: This paper presents a radiation pattern con- trolled antenna for handset terminals to reduce the cor- relation coefficient between antennas and enhance the channel capacity in MIMO applications. A pair of small inverted-F shaped antennas combined by a phase shifter provides a single port with controlled pattern. To enhance the channel capacity, the phase difference for the IFA array is optimized using the evaluation parameter of re- ception level, correlation coefficient and mean effective gain of the proposed array geometry. The channel capacity enhancement is verified by assuming Croneker scattering under Nakagami-Rice propagation model.

Distribution of Video-on-Demand Service over Cable Television Networks

Abstract: The paper deals with investigations carried out to increase the effectiveness of video-on-demand (VoD) systems when cable television networks are used. A comparative analysis of the existing VoD architectures is made with respect to the equipment cost and the traffic load over the central transport network. Through statistical studies the main characteristics of a particular hybrid VoD are determined (such as twenty-four-hour distribution of the video traffic, average inter-arrival time of the VoD requests, average duration of video streams demanded, movies distribution according to the subscribers’ preferences). An algorithm for the videocontent flexible distribution among the distribution hubs is suggested. Thus a higher effectiveness of the system is achieved without significantly increasing the equipment cost.

Using Digital Filtration for Hurst Parameter Estimation

Abstract: We present a new method to estimate the Hurst parameter. The method exploits the form of the autocorrelation function for second-order self-similar processes and is based on one-pass digital filtration. We compare the performance and properties of the new method with that of the most common methods.

Two-Element PIFA Array Structure for Polarization Diversity in UMTS Mobile Phones

Abstract: In this paper, we demonstrate the possibility to strongly modify the radiated fields of a UMTS handset by using a phased two-element PIFA array. The structure is composed of a 100x40 mm 2 metallic ground plane acting as the Printed Circuit Board (PCB) of the mobile phone. Two UMTS PIFAs are located at the top edge of this PCB. They are fed by a double Quasi-Lumped Coupler able to provide a 360° phase difference between its two outputs. By properly choosing the DC bias of the double Quasi- Lumped Coupler, we can set a specific phase difference between the two PIFAs. In this way the two-element array is able to radiate different electromagnetic fields. Simulated and measured radiation patterns in the two main planes of the chassis are presented for different phase differences. It is especially revealed that the novel two- antenna structure is able to radiate vertically-polarized electric fields in the azimuthal plane of the phone and horizontally-polarized electric fields in the same plane when changing the phase shift between the antennas from 0° to 180°. Potential applications are polarization-diver- sity techniques and Specific Absorption Rate reduction for handsets.

An efficient CS-CPWL Based Predistorter

Abstract: Fil: Bruno, Marcelo Javier. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Conicet - Bahia Blanca. Instituto de Investigaciones en Ingenieria Electrica "Alfredo Desages". Universidad Nacional del Sur. Departamento de Ingenieria Electrica y de Computadoras. Instituto de Investigaciones en Ingenieria Electrica "Alfredo Desages"; Argentina

Efficient Procedure for the Calculation of Electric and Magnetic Energies in Vacuum

Abstract: New expressions are derived to calculate the reactive energy stored in the electromagnetic field surrounding an electromagnetic device. The resulting expressions are 1. very simple to interpret, 2. general, 3. rigorous in terms of the currents flowing on the device, and 4. fast since they involve integrals solely over the device generating the field. The new technique is very feasible to be used in cases where the electric and magnetic reactive energies are important in practice, for example in the case of resonators, or in the case of radiating structures. Used there, they allow to study in a rigorous way the effect of the shape of the device on the amount of reactive energy, and thus for example on the Q of the device. The implementation of the new expressions in numerical CAD tools is extremely simple and straight- forward. In this paper, the expressions are derived for sources in the homogeneous medium vacuum, but this is not a fundamental restriction.