472 research outputs found

    2008 Index IEEE Transactions on Control Systems Technology Vol. 16

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    This index covers all technical items - papers, correspondence, reviews, etc. - that appeared in this periodical during the year, and items from previous years that were commented upon or corrected in this year. Departments and other items may also be covered if they have been judged to have archival value. The Author Index contains the primary entry for each item, listed under the first author\u27s name. The primary entry includes the coauthors\u27 names, the title of the paper or other item, and its location, specified by the publication abbreviation, year, month, and inclusive pagination. The Subject Index contains entries describing the item under all appropriate subject headings, plus the first author\u27s name, the publication abbreviation, month, and year, and inclusive pages. Note that the item title is found only under the primary entry in the Author Index

    2009 Index IEEE Antennas and Wireless Propagation Letters Vol. 8

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    This index covers all technical items - papers, correspondence, reviews, etc. - that appeared in this periodical during the year, and items from previous years that were commented upon or corrected in this year. Departments and other items may also be covered if they have been judged to have archival value. The Author Index contains the primary entry for each item, listed under the first author\u27s name. The primary entry includes the coauthors\u27 names, the title of the paper or other item, and its location, specified by the publication abbreviation, year, month, and inclusive pagination. The Subject Index contains entries describing the item under all appropriate subject headings, plus the first author\u27s name, the publication abbreviation, month, and year, and inclusive pages. Note that the item title is found only under the primary entry in the Author Index

    Design of Sievenpiper HIS for use in planar broadband antennas by means of effective medium theory

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    The claim for multistandard operating handsets of small physical size as well as the ever increasing demand for higher data rates require new broadband operating antennas. Because of the widespread use of especially planar broadband antennas a lot of factors influencing the characteristic antenna parameters have to be regarded. Furthermore, aspects regarding the electromagnetic compatibility inside the handheld as well as the protection of biological systems, e.g. the user of a mobilephone, have to be payed attention to. An electromagnetic structure which allows for protection by means of shielding as well as enhances the antennas efficiency by providing unique electromagnetic properties are the so called Sievenpiper High Impedance Surfaces (HIS) invented by Sievenpiper (1999). This paper will present the theory and the well known design equations for those structures. An investigation by means of simulation tools and measurement setups will be done to approve the accuracy of the theoretical results. Here measurement results of the impedance and radiation properties of a planar log.-per. fourarm antenna equiped in conjunction with a fabricated prototype Sievenpiper HIS will be presented

    Design and Implementation of High Gain 60 GHz Antennas for Imaging/Detection Systems

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    Recently, millimeter wave (MMW) imaging detection systems are drawing attention for their relative safety and detection of concealed objects. Such systems use safe non-ionizing radiation and have great potential to be used in several applications such as security scanning and medical screening. Antenna probes, which enhance system performance and increase image resolution contrast, are primarily used in MMW imaging sensors. The unlicensed 60 GHz band is a promising band, due to its wide bandwidth, about 7 GHz (57 - 64 GHz), and lack of cost. However, at 60 GHz the propagation loss is relatively high, creating design challenges for operating this band in MMW screening. A high gain, low profile, affordable, and efficient probe is essential for such applications at 60 GHz. This thesis’s focus is on design and implementation of high gain MMW probes to optimize the performance of detection/imaging systems. First, single-element broadside radiation microstrip antennas and novel probes of endfire tapered slot high efficient antennas are presented. Second, a 57-64 GHz, 1 × 16-element beam steering antenna array with a low-cost piezoelectric transducer controlled phase shifter is presented. Then, a mechanical scanner is designed specifically to test proposed antenna probes utilizing low-power 60 GHz active monostatic transceivers. The results for utilizing proposed 60 GHz probes show success in detecting and identifying concealed weapons and explosives in liquids or plastics. As part of the first research theme, a 60 GHz circular patch-fed high gain dielectric lens antenna is presented, where the prototype’s measured impedance bandwidth reaches 3 GHz and a gain of 20 dB. A low cost, 60 GHz printed Yagi antenna array was designed, optimized, fabricated and tested. New models of the antipodal Fermi tapered slot antenna (AFTSA) with a novel sine corrugated (SC) shape are designed, and their measured results are validated with simulated ones. The AFTSA-SC produces a broadband and high efficiency pattern with the capacity for high directivity for all ISM-band. Another new contribution is a novel dual-polarized design for AFTSA-CS, using a single feed with a pair of linearly polarized antennas aligned orthogonally in a cross-shape. Furthermore, a novel 60 GHz single feed circularly polarized (CP) AFTSA-SC is modeled to radiate in the right-hand circularly polarized antenna (RHCP). A RHCP axial ratio bandwidth of < 3dB is maintained from 59 to 63 GHz. In addition, a high gain, low cost 60 GHz Multi Sin-Corrugations AFTSA loaded with a grooved spherical lens and in the form of three elements to operate as the beam steering antenna is presented. These probes show a return loss reduction and sidelobes and backlobe suppression and are optimized for a 20 dB or higher gain and radiation efficiency of ~90% at 60 GHz. The second research theme is implementing a 1 × 16-element beam steering antenna array with a low-cost piezoelectric transducer (PET) controlled phase shifter. A power divider with a triangular feed which reduces discontinuity from feed lines corners is introduced. A 1 × 16-element array is fabricated using 60 GHz AFTSA-SC antenna elements and showed symmetric E-plane and H-plane radiation patterns. The feed network design is surrounded by electromagnetic band-gap (EBG) structures to reduce surface waves and coupling between feed lines. The design of a circularly polarized 1 × 16-element beam steering phased array with and without EBG structures also investigated. A target detection investigation was carried out utilizing the proposed 60GHz antennas and their detection results are compared to those of V-band standard gain horn (SGH). System setup and signal pre-processing principle are introduced. The multi-corrugated MCAFTSA-SC probe is evaluated with the imaging/detection system for weapons and liquids concealed by clothing, plywood, and plastics. Results show that these items are detectable in clear 2D image resolution. It is believed that the 60 GHz imaging/detection system results using the developed probes show potential of detecting threatening objects through screening of materials and public

    Design and realization for radar cross section reduction of patch antennas using shorted stubs metamaterial absorbers

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    This thesis is devoted to analyzing of the Radar Cross Section (RCS) of rectangular patch antenna using Metamaterial Absorber (MMA) and the analysis of its reducing techniques. The addressed theme has a great complexity and it covers various areas that include designing and optimization of target geometrical model of rectangular patch antenna structures and making it compatible with respect to metamaterial geometry. Analyses have been made to optimize and validate the structure performances that include numerical methods for electromagnetic field computation, MMA behavior, characterization, extraction of parameters, antenna radiation performance analyses, simulation, fabrication, testing, and optimization with back validating the designs. The MMA structure finds its applications in antenna designing for the reduction of Monostatic and Bistatic RCS in stealth platform for lower detectable objects. However, there is still more emphasis needed to devote for in-band frequency response for low RCS of the antenna. Therefore, making these assumptions, we have been proposing novel designs of single-band, dual-band, and triple-band MMA structures. These structures provide significant scattering characteristics and offering flexibility to the designer to control and tune the resonant frequency, based on the specific applications as compared to that of the other MMAs in the microwave regime of the Electromagnetic (EM) spectrum. To explore the research scope, a three dimensional Frequency Selective Surface (FSS) structure has been analyzed and its simulation responses with respect to parametric analyses have been made. The research investigation further extended to Electronic Band Gap (EBG) Structure and Defected Ground Structure (DGS). A hybrid structure of patch antenna is proposed and designed for an inset feed rectangular microstrip patch antenna operating at 2.45 GHz in the Industrial, Scientific, and Medical (ISM) band. This hybrid structure claims the size reduction, bandwidth, and gains enhancement. The main focus of this research work is limited to determine the potential and practical feasibility of MMA’s to enhance the stealth performance of rectangular patch antennas. For this purpose, Monostatic and Bistatic RCS simulation and measurements are carried out in an anechoic chamber and practical methods for Radar Cross Section reduction are discussed and analyzed

    Advanced Circularly Polarised Microstrip Patch Antennas

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    The thesis describes outcomes of research on advanced circularly polarised antennas. The proposed designs are intended for integration into small mobile devices, therefore low profile and easy manufacturability are key parameters, along with good CP radiation properties. The designs were validated by simulation and measurement, and are also backed by theory and design guidelines. The primary focus is on the development of planar omnidirectional circularly polarised antennas, which are fabricated using multilayer PCB techniques and thus are lightweight and cost-efficient. Unlike in classical microstrip patch antenna designs, the groundplane of the proposed antenna was substantially reduced. This helps to achieve an omnidirectional circular polarisation pattern and miniaturize the antenna, however at the cost of increased feed circuit complexity. The basic design, its advantages and disadvantages are discussed in Section 3. In the next step, the omnidirectional circularly polarised antenna was extended with additional, advanced features. A miniaturized version is investigated, which offers a 20% footprint reduction by folding parts of the patch underneath itself. Further miniaturization is possible by increasing the dielectric constant of the substrate. A method to adjust the omnidirectional circularly polarised antenna performance by trimming four lumped capacitors is also investigated. Manufacturing inaccuracy in large scale production may cause some of the units to radiate outside of the desired frequencies. By integrating four trimmed capacitors into the antenna it can be precisely tuned to the desired band. Simulated results demonstrate this property by trimming the antenna between GPS L1 band (centre frequency at 1.575 GHz) and Galileo/Beidou-2 E2 band (1.561 GHz). Furthermore, a dual-band omnidirectional circularly polarised antenna is presented, which employs slots and capacitor loading to steer the current path of the first and second resonant mode. The design offers a small frequency ratio of 1.182. The methods to obtain a planar omnidirectional circularly polarised antenna have been further advanced to propose a reconfigurable antenna. The beam reconfiguration is capable of rotating it dipole-like radiation pattern around an axis, thus allowing reception or transmission from any spherical angle. The switching method is simple and does not require any semiconductor devices. Finally, a dual circularly polarised antenna is presented, which achieves dual-polarisation by employing even and odd modes in a coplanar waveguide. This technique allows greater flexibility and size reduction of the feed network, as two signals can be transmitted by a single multi-mode transmission line. Simulated results demonstrate this property by trimming the antenna between GPS L1 band (centre frequency at 1.575 GHz) and Galileo/Beidou-2 E2 band (1.561 GHz). Furthermore, a dual-band omnidirectional circularly polarised antenna is presented, which employs slots and capacitor loading to steer the current path of the first and second resonant mode. The design offers a small frequency ratio of 1.182. The methods to obtain a planar omnidirectional circularly polarised antenna have been further advanced to propose a reconfigurable antenna. The beam reconfiguration is capable of rotating it dipole-like radiation pattern around an axis, thus allowing reception or transmission from any spherical angle. The switching method is simple and does not require any semiconductor devices. Finally, a dual circularly polarised antenna is presented, which achieves dual-polarisation by employing even and odd modes in a coplanar waveguide. This technique allows greater flexibility and size reduction of the feed network, as two signals can be transmitted by a single multi-mode transmission line

    Wavelength-selective metamaterial absorber and emitter

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    Electromagnetic absorbers and emitters have been attracting interest in lots of fields, which are significantly revitalized because of the novel properties brought by the development of the metamaterials, the artificially designed materials. Metamaterials broadens the approaches to design the electromagnetic absorbers and emitters, making it possible to obtain the perfect absorption or emission at the wavelengths covering a wide range. Metamaterial absorbers and emitters are promising for various applications, including solar thermal-photovoltaics and thermal-photovoltaics for energy harvesting, chemical and biomedical sensors, nanoscale imaging and color printing. This work focuses on three aspects (materials, structures and design methods) to improve the experiment realizations of visible and infrared absorbers and emitters. Firstly, this work investigates simple structures based on aluminum and tungsten materials for the metamaterial absorber and emitter, which results in the realization of the all-metal visible color printing with square resonators and wavelength selective mid-infrared absorber (emitter) with cross resonators, respectively. Secondly, we explore the thermal emission properties of the quasi-periodic metal-dielectric multilayer metamaterials, which show the ability of engineering emissivity by different lattice structures. Finally, this work demonstrates the use of micro-genetic algorithm to realize efficient design and optimization for broadband metasurface absorbers, as well as wavelength-selective metasurfaces with giant circular dichroism. This work is believed to facilitate the development and application of metamaterial absorbers and emitters --Abstract, page iv

    Wideband two-dimensional and multiple beam phased arrays and microwave applications using piezoelectric transducers

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    Modern satellite, wireless communication, and radar systems often demand wideband performance for multi-channel operation and the ability to steer multiple beams for multiple moving targets. This dissertation covers a variety of topics to design low-cost and wideband antenna systems. The main areas of study are microwave devices controlled piezoelectric transducers (PETs) and wideband baluns and balanced microwave circuits using parallel-strip lines. Some focus has also been given to the design of Rotman lens for multiple beam generation and Vivaldi antenna arrays for wideband two-dimensional scanning. The dielectric perturbation technique controlled by PET is introduced to design a wideband phase shifter and a QPSK modulator, and to tune the resonant frequency of a slot dipole. The designed PET-controlled phase shifters are used for beam steering in a dual beam phased array using a bidirectional feeding scheme and a five-beam phased array using a microstrip Rotman lens. Vivaldi-type antennas are commonly used to achieve wideband performance. Very wideband performance can be achieved using an antipodal tapered slot antenna because of its inherent simple wideband transition from microstrip line to parallel-strip line. An antipodal tapered slot antenna and a phased array are designed to span 10 to 35 GHz. In addition, a 4??4 two-dimensional antenna array is designed using wideband antipodal tapered slot antennas, and two sets of PET-controlled phase shifters for E- and H-plane scanning are fabricated to steer the beam. As a microwave system using wideband antenna array, a new low-cost and wideband phased array radar is developed using a modulated pulse over 8 to 20 GHz band. The double-sided parallel-strip line as a balanced line is presented. The parallelstrip line offers much flexibility for microwave circuit designs. This transmission line makes it possible to realize a low impedance line and allows the design of a compact wideband balun and junction. Wideband transitions (or baluns) from parallel-strip line to microstrip line, a typical unbalanced transmission line, are realized to cover several octave bandwidth. Balanced microwave filters and a hybrid coupler are developed using the parallel-strip line

    Synthesis Technique of Thickness-Customizable Multilayered Frequency Selective Surface for Plasma-Based Electromagnetic Structures

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    This dissertation provides a synthesis technique for the design of thickness-customizable high-order (N ≥ 2) bandpass frequency selective surface (FSS) and its application in realizing versatile multi-layered FSS and absorbers. Admittance inverters layers are used to synthesize the transfer response of the filter given desired characteristics such as filter type, center frequency, and bandwidth. These inverter layers are essentially electromagnetic coupling interlayers that can be adjusted to customize the thickness of multilayered FSS without degrading the desired filter performance. A generalized equivalent circuit model is used to provide physical insights of the proposed design. This synthesis technique is adopted to deliver a versatile implementation capability of high-order FSS filters using various dielectric spacers with arbitrary thicknesses. Such technique enables the realization of spatial filters with variable size, while maintaining the desired filter response. To highlight the significance of the proposed synthesis technique, its concept is applied to two practical problems including the design of compact switchable FSS and adaptive/tunable microwave absorbers as it may allow simpler integration of active components that require specific physical dimensions. In the first practical problem, the feasibility of deploying plasma switchable compact spatial filter in harsh electromagnetic radiation environments is investigated. The proposed FSS integrates contained plasma (plasma-shells) as active tuning elements. These ceramic, gas-encapsulating shells are ideal for high-power microwave and electromagnetic pulse protection because they are rugged, hermetic, operable at extreme temperatures, and insensitive to ionizing radiation. A 2D periodic second-order switchable spatial filter is implemented. It is composed of electrically small Jerusalem cross structures embedded with discrete plasma shells strategically located to effectively switch the transfer function of the filter. This technique is used to realize compact low profile second order band pass spatial filter operating at S-band. It also has the ability to switch its transfer function within 20 to 100 ns while enabling in-band shielding protection for aerospace or terrestrial electromagnetic systems subjected to high power microwave energy (HPME) and high electromagnetic pulse (HEMP) in harsh space environment. Experimental results are shown to be in good agreement with simulation results. The second practical problem is addressed by deploying a large-scale adaptable compressed Jaumann absorber for harsh and dynamic electromagnetic environments. The multilayered conductor-backed absorbers are realized by integrating ceramic gas-encapsulating shells and a closely coupled resonant layer that also serves as a biasing electrode to sustain the plasma. These active frequency selective absorbers are analyzed using a transmission line approach to provide the working principle and its frequency tuning capability. By varying the voltage of the sustainer, the plasma can be modeled as a lossy, variable, frequency-power-dependent inductor, providing a dynamic tuning response of the absorption spectral band. To study the power handling capability of the tunable absorber, dielectric and air breakdowns within the device are numerically emulated using electromagnetic simulation by quantifying the maximum field enhancement factor (MFEF). Furthermore, a comprehensive thermal analysis using a simulation method that couples electromagnetics and heat transfer is performed for the absorber under high power continuous microwave excitations. The maximum power level handling capability of the microwave absorber has been numerically predicted and validated experimentally
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