112 research outputs found
Wideband and UWB antennas for wireless applications. A comprehensive review
A comprehensive review concerning the geometry, the manufacturing technologies, the materials, and the numerical techniques, adopted for the analysis and design of wideband and ultrawideband (UWB) antennas for wireless applications, is presented. Planar, printed, dielectric, and wearable antennas, achievable on laminate (rigid and flexible), and textile dielectric substrates are taken into account. The performances of small, low-profile, and dielectric resonator antennas are illustrated paying particular attention to the application areas concerning portable devices (mobile phones, tablets, glasses, laptops, wearable computers, etc.) and radio base stations. This information provides a guidance to the selection of the different antenna geometries in terms of bandwidth, gain, field polarization, time-domain response, dimensions, and materials useful for their realization and integration in modern communication systems
Antenna Study and Design for Ultra Wideband Communication Applications
PhDSince the release by the Federal Communications Commission (FCC) of a bandwidth of
7.5GHz (from 3.1GHz to 10.6GHz) for ultra wideband (UWB) wireless communications,
UWB is rapidly advancing as a high data rate wireless communication technology.
As is the case in conventional wireless communication systems, an antenna also plays
a very crucial role in UWB systems. However, there are more challenges in designing
a UWB antenna than a narrow band one. A suitable UWB antenna should be capable
of operating over an ultra wide bandwidth as allocated by the FCC. At the same
time, satisfactory radiation properties over the entire frequency range are also necessary.
Another primary requirement of the UWB antenna is a good time domain performance,
i. e. a good impulse response with minimal distortion.
This thesis focuses on UWB antenna design and analysis. Studies have been undertaken
covering the areas of UWB fundamentals and antenna theory. Extensive investigations
were also carried out on two different types of UWB antennas.
The first type of antenna studied in this thesis is circular disc monopole antenna. The
vertical disc monopole originates from conventional straight wire monopole by replacing
the wire element with a disc plate to enhance the operating bandwidth substantially.
Based on the understanding of vertical disc monopole, two more compact versions featuring
low-profile and compatibility to printed circuit board are proposed and studied.
Both of them are printed circular disc monopoles, one fed by a micro-strip line, while
the other fed by a co-planar waveguide (CPW).
The second type of UWB antenna is elliptical/circular slot antenna, which can also be
fed by either micro-strip line or CPW.
The performances and characteristics of UWB disc monopole and elliptical/circular slot
antenna are investigated in both frequency domain and time domain. The design parameters
for achieving optimal operation of the antennas are also analyzed extensively in
order to understand the antenna operations.
It has been demonstrated numerically and experimentally that both types of antennas
are suitable for UWB applications
Study and miniaturisation of antennas for ultra wideband communication systems
PhDWireless communications have been growing with an astonishing rate over the past
few years and wireless terminals for future applications are required to provide
diverse services. This rising demand prompts the needs for antennas able to cover
multiple bandwidths or an ultrawide bandwidth for various systems.
Since the release by the Federal Communications Commission (FCC) of a bandwidth
of 7.5 GHz (from 3.1 GHz to 10.6 GHz) for ultra wideband (UWB) wireless
communications, UWB has been rapidly evolving as a potential wireless technology
and UWB antennas have consequently drawn more and more attention from both
academia and industries worldwide.
Unlike traditional narrow band antennas, design and analysis of UWB antennas are
facing more challenges and difficulties. A competent UWB antenna should be
capable of operating over an ultra wide bandwidth as assigned by the FCC. At the
same time, a small and compact antenna size is highly desired, due to the integration
requirement of entire UWB systems. Another key requirement of UWB antennas is
the good time domain behaviour, i.e. a good impulse response with minimal
distortion.
This thesis focuses on UWB antenna miniaturisation and analysis. Studies have been
undertaken to cover the aspects of UWB fundamentals and antenna theory. Extensive
investigations are also conducted on three different types of miniaturised UWB
antennas.
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The first type of miniaturised UWB antenna studied in this thesis is the loaded
orthogonal half disc monopole antenna. An inductive load is introduced to broaden
the impedance bandwidth as well as the pattern bandwidth, in other words, an
equivalent size reduction is realised.
The second type of miniaturised UWB antenna is the printed half disc monopole
antenna. By simply halving the original antenna and tuning the width of the coplanar
ground plane, a significant more than 50% size reduction is achieved.
The third type of miniaturised UWB antenna is the printed quasi-self-complementary
antenna. By exploiting a quasi-self-complementary structure and a built-in matching
section, a small and compact antenna dimension is achieved.
The performances and characteristics of the three types of miniaturised UWB
antennas are studied both numerically and experimentally and the design parameters
for achieving optimal operation of the antennas are also analysed extensively in order
to understand the antenna operations.
Also, time domain performance of the Coplanar Waveguide (CPW)-fed disc
monopole antenna is examined in this thesis to demonstrate the importance of time
domain study on UWB antennas.
Over the past few years of my PhD study, I feel honoured and lucky to work with
some of the most prestigious researchers in the Department of Electronic
Engineering, Queen Mary, University of London. I would like to show my most
cordial gratitude to those who have been helping me during the past few years. There
would be no any progress without their generous and sincere support.
First of all, I would like to thank my supervisors Professor Clive Parini and Professor
Xiaodong Chen, for their kind supervision and encouragement. I am impressed by
their notable academic background and profound understanding of the subjects,
which have proved to be immense benefits to me. It has been my great pleasure and
honour to be under their supervision and work with them.
Second of all, I would like to thank Mr John Dupuy for his help in the fabrication
and measurement of antennas I have designed during my PhD study. Also, a special
acknowledgement goes to all of the staff for all the assistance throughout my
graduate program
Small Antenna Options for Ultra-Wideband (UWB) Applications
Ultra-Wideband (UWB) systems provide a means for short range high data rate wireless transmission between electronic devices. Portable devices and in particular, mobile handsets, have the potential to harness the unprecedented connectivity associated with UWBâs high speed, low power data transfer. Over the course of this work, a number of small antenna options for UWB mobile handset applications are presented. Two key subgroups of the 3.1 â10.6GHz UWB band are chosen and suitable antennas designed for both bands. At the upper end of the band, a ceramic planar inverted-F antenna is proposed to cover band groups 3 & 6 (6.3 â 9GHz). At the lower end of the band, a novel Dual-Band PIFA structure is presented and optimised to cover the band group 1 bands (3.1 â 4.8GHz). Design work is carried out using CST Microwave Studio simulation software, and all parameter sweeps of critical dimensions are presented, as well as an in-depth examination of E-fields, Surface Currents and Radiation Patterns for both antennas. Finally measurement prototypes are built up and measured to validate the simulation data. Correlation between measured and simulated results is observed and the performance of the antennas with respect to typical UWB antenna specifications is discussed
Ultra-wideband indoor communications using optical technology
La communication ultra large bande (UWB) a attirĂ© une Ă©norme quantitĂ© de recherches ces derniĂšres annĂ©es, surtout aprĂšs la prĂ©sentation du masque spectral de US Federal Communications Commission (FCC). Les impulsions ultra-courtes permettent de trĂšs hauts dĂ©bits de faible puissance tout en Ă©liminant les interfĂ©rences avec les systĂšmes existants Ă bande Ă©troite. La faible puissance, cependant, limite la portĂ©e de propagation des radios UWB Ă quelques mĂštres pour la transmission sans fil Ă lâintĂ©rieur dâune piĂšce. En outre, des signaux UWB reçu sont Ă©tendus dans le temps en raison de la propagation par trajet multiple qui rĂ©sulte en beaucoup dâinterfĂ©rence inter-symbole (ISI) Ă haut dĂ©bit. Le monocycle Gaussien, lâimpulsion la plus commune dans UWB, a une mauvaise couverture sous le masque de la FCC. Dans cette thĂšse, nous dĂ©montrons des transmet- teurs qui sont capables de gĂ©nĂ©rer des impulsions UWB avec une efficacitĂ© de puissance Ă©levĂ©e. Une impulsion efficace rĂ©sulte dans un rapport de signal Ă bruit (SNR) supĂ©rieur au rĂ©cepteur en utilisant plus de la puissance disponible sous le masque spectral de la FCC. On produit les impulsions dans le domaine optique et utilise la fibre optique pour les transporter sur plusieurs kilomĂštres pour la distribution dans un rĂ©seau optique pas- sif. La fibre optique est trĂšs fiable pour le transport des signaux radio avec une faible consommation de puissance. On utilise les Ă©lĂ©ments simples comme un modulateur Mach-Zehnder ou un rĂ©sonateur en anneau pour gĂ©nĂ©rer des impulsions, ce qui permet lâintĂ©gration dans le silicium. Compatible avec la technologie CMOS, la photonique sur silicium a un potentiel Ă©norme pour abaisser le coĂ»t et lâencombrement des systĂšmes optiques. La photodĂ©tection convertit les impulsions optiques en impulsions Ă©lectriques avant la transmission sur lâantenne du cĂŽtĂ© de lâutilisateur. La rĂ©ponse frĂ©quentielle de lâantenne dĂ©forme la forme dâonde de lâimpulsion UWB. Nous proposons une technique dâoptimisation non-linĂ©aire qui prend en compte la distorsion dâantenne pour trouver des impulsions qui maximisent la puissance transmise, en respectant le masque spectral de la FCC. Nous travaillons avec trois antennes et concevons une impulsion unique pour chacune dâentre elle. LâamĂ©lioration de lâĂ©nergie des impulsions UWB amĂ©liore directement la SNR au rĂ©cepteur. Les rĂ©sultats de simulation montrent que les impulsions optimisĂ©es amĂ©liorent considĂ©rablement le taux dâerreur (BER) par rapport au monocycle Gaussien sous propagation par trajet multiple. Notre autre contribution est lâĂ©valuation dâun filtre adaptĂ© pour recevoir efficacement des impulsions UWB. Le filtre adaptĂ© est synthĂ©tisĂ© et fabriquĂ© en technologie microstrip, en collaboration avec lâUniversitĂ© McGill comme un dispositif de bande interdite Ă©lectromagnĂ©tique. La rĂ©ponse frĂ©quentielle du filtre adaptĂ© montre une ex- cellente concordance avec le spectre ciblĂ© de lâimpulsion UWB. Les mesures de BER confirment la performance supĂ©rieure du filtre adaptĂ© par rapport Ă un rĂ©cepteur Ă conversion directe. Le canal UWB est trĂšs riche en trajet multiple conduisant Ă lâISI Ă haut dĂ©bit. Notre derniĂšre contribution est lâĂ©tude de performance des rĂ©cepteurs en simulant un systĂšme avec des conditions de canaux rĂ©alistes. Les rĂ©sultats de la simulation montrent que la performance dâun tel systĂšme se dĂ©grade de façon significative pour les hauts dĂ©bits. Afin de compenser la forte ISI dans les taux de transfert de donnĂ©es en Gb/s, nous Ă©tudions lâalgorithme de Viterbi (VA) avec un nombre limitĂ© dâĂ©tats et un Ă©galiseur DFE (decision feedback equalizer). Nous examinons le nombre dâĂ©tats requis dans le VA, et le nombre de coefficients du filtre dans le DFE pour une transmission fiable de UWB en Gb/s dans les canaux en ligne de vue. LâĂ©valuation par simulation de BER confirme que lâĂ©galisation amĂ©liore considĂ©rablement les performances par rapport Ă la dĂ©tection de symbole. La DFE a une meilleure performance par rapport Ă la VA en utilisant une complexitĂ© comparable. La DFE peut couvrir une plus grande mĂ©moire de canal avec un niveau de complexitĂ© relativement rĂ©duit.Ultra-wideband (UWB) communication has attracted an enormous amount of research in recent years, especially after the introduction of the US Federal Communications Commission (FCC) spectral mask. Ultra-short pulses allow for very high bit-rates while low power eliminates interference with existing narrowband systems. Low power, however, limits the propagation range of UWB radios to a few meters for indoors wireless transmission. Furthermore, received UWB signals are spread in time because of multipath propagation which results in high intersymbol interference at high data rates. Gaussian monocycle, the most commonly employed UWB pulse, has poor coverage under the FCC mask. In this thesis we demonstrate transmitters capable of generating UWB pulses with high power efficiency at Gb/s bit-rates. An efficient pulse results in higher signal-to-noise ratio (SNR) at the receiver by utilizing most of the available power under the FCC spectral mask. We generate the pulses in the optical domain and use optical fiber to transport the pulses over several kilometers for distribution in a passive optical network. Optical fiber is very reliable for transporting radio signals with low power consumption. We use simple elements such as a Mach Zehnder modulator or a ring resonator for pulse shaping, allowing for integration in silicon. Being compatible with CMOS technology, silicon photonics has huge potential for lowering the cost and bulkiness of optical systems. Photodetection converts the pulses to the electrical domain before antenna transmission at the user side. The frequency response of UWB antennas distorts the UWB waveforms. We pro- pose a nonlinear optimization technique which takes into account antenna distortion to find pulses that maximize the transmitted power, while respecting the FCC spectral mask. We consider three antennas and design a unique pulse for each. The energy improvement in UWB pulses directly improves the receiver SNR. Simulation results show that optimized pulses have a significant bit error rate (BER) performance improvement compared to the Gaussian monocycle under multipath propagation. Our other contribution is evaluating a matched filter to receive efficiently designed UWB pulses. The matched filter is synthesized and fabricated in microstrip technology in collaboration with McGill University as an electromagnetic bandgap device. The frequency response of the matched filter shows close agreement with the target UWB pulse spectrum. BER measurements confirm superior performance of the matched filter compared to a direct conversion receiver. The UWB channel is very rich in multipath leading to ISI at high bit rates. Our last contribution is investigating the performance of receivers by simulating a system employing realistic channel conditions. Simulation results show that the performance of such system degrades significantly for high data rates. To compensate the severe ISI at gigabit rates, we investigate the Viterbi algorithm (VA) with a limited number of states and the decision feedback equalizer (DFE). We examine the required number of states in the VA, and the number of taps in the DFE for reliable Gb/s UWB trans- mission for line-of-sight channels. Non-line-of-sight channels were also investigated at lower speeds. BER simulations confirm that equalization considerably improves the performance compared to symbol detection. The DFE results in better performance compared to the VA when using comparable complexity as the DFE can cover greater channel memory with a relatively low complexity level
Novel ultra wideband antennas for wireless systems
This thesis focuses on Ultra Wideband (UWB) antenna designs and analysis. Studies have been undertaken covering the areas of UWB fundamentals and antenna theory. UWB wireless technology is being considered as the solution to overcome data rate bottlenecks in the wireless communications and applications. UWB is able to achieve high data transmission rates because it transmits data over a very large spectrum of frequencies from 3.1 GHz to 10.6 GHz (7.5 GHz). Consequently, it provides many challenges for design in the communications arena, including antenna design. The main objective of this thesis is to study, design, analyze and implement novel UWB low profile printed patch antennas that satisfy UWB technology requirements. Several techniques are used for optimal UWB bandwidth performance of the UWB antenna designs in this thesis. The undertaken thesis focuses on planar antennas printed on PCBs. Therefore, this research introduces novel five designs of microstrip-fed, small, low-profile, printed microstrip UWB antennas using different bandwidth-enhancement techniques to satisfy UWB bandwidth. According to their geometrical shapes, they can be classified into two types: the first types are stepped UWB antennas which are namely: a stepped-trapezoidal patch antenna and a trimmed notch-cut patch antenna. The second ones are beveled UWB antennas which are namely: an elliptical patch antenna, a double-beveled patch antenna, and a band-rejected elliptical patch antenna. It has been demonstrated numerically and experimentally that the proposed antennas are suitable for UWB systems. They can provide satisfactory frequency domain performance, including ultra-wide bandwidth with nearly omni-directional radiation patterns, relatively flat gain and very good radiation efficiency. These features make them very suitable for UWB communications and applications, such as wireless personal area networks (WPANs) application
TechNews digests: Jan - Nov 2006
TechNews is a technology, news and analysis service aimed at anyone in the education sector keen to stay informed about technology developments, trends and issues. TechNews focuses on emerging technologies and other technology news. TechNews service : digests september 2004 till May 2010 Analysis pieces and News combined publish every 2 to 3 month
Study, Design and Analysis of Antennas for Millimeter Waves and UWB Applications
Since the release by the Federal Communications Commission (FCC) of a license free UWB (Ultra-Wide Band) bands mainly offering bandwidth of 7.5 GHz (from 3.1 GHz to 10.6 GHz) and UWB at Millimetre(MM) wave frequency centred at 60 GHz (57 GHz to 64 GHz) for wireless communications, UWB is rapidly advancing as a high data rate wireless communication technology. As is the case in conventional wireless communication systems, antennas plays a very crucial role in UWB systems. However, there are more challenges in designing a UWB antenna than designing narrow band one. A suitable UWB antenna should be capable of operating over an UWB as allocated by the FCC. At the same time, satisfactory radiation properties over the entire frequency range with minimal distortion are also necessary. This thesis focuses on UWB antenna design and analysis for two different frequency bands, the first UWB antenna designed for frequency range from 3.1 GHz to 10.6 GHz and the second one is a MM wave UWB antenna which is centred around 60 GHz and ranges from 57 GHz to 64GHz. Studies have been undertaken covering the areas of UWB fundamentals and antenna theory. Extensive investigations and theoretical analysis were also carried out on proposed UWB antennas. In this work literature survey is carried out about different antenna structures used for UWB applications. To design antenna for UWB (3.1 GHz to 10.6 GHz), studies have been carried out and four Swastika-shaped slot antenna designs have been proposed. Both ground plane and radiating patch are modified in proposed antennas. In the first three antenna designs (antenna design 1, antenna design 2, antenna design 3) the radiating patch is modified with concentric circular slots of different dimensions while in antenna design 4, two inverted L-shaped slots on ground plane are used to achieve enhanced bandwidth and reduced return losses. All these proposed novel antennas are of compact size having dimensions of 24 mm x 24 mm and they almost cover entire UWB range (3.1GHz to 10.6 GHz). The antenna parameters like bandwidth, return loss, radiation pattern and impedance of these antennas are analysed and discussed in chapter 2
Emerging Communication Technologies (ECT) Phase 2 Report
The Emerging Communication Technology (ECT) project investigated three First Mile communication technologies in support of NASA s Second Generation Reusable Launch Vehicle (2nd Gen RLV), Orbital Space Plane, Advanced Range Technology Working Group (ARTWG) and the Advanced Spaceport Technology Working Group (ASTWG). These First Mile technologies have the purpose of interconnecting mobile users with existing Range Communication infrastructures. ECT was a continuation of the Range Information System Management (RISM) task started in 2002. RISM identified the three advance communication technologies investigated under ECT. These were Wireless Ethernet (Wi-Fi), Free Space Optics (FSO), and Ultra Wideband (UWB). Due to the report s size, it has been broken into three volumes: 1) Main Report 2) Appendices 3) UWB
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Measurement and characterization of ultra-wideband wireless interconnects within active computing systems
Ultra-wideband (UWB) radio has become an attractive alternative for wireless communications due to the robustness to multipath fading, low power transmission, mostly-digital implementation, and low cost. Furthermore, short-range, high data-rates applications are possible with UWB radios due to the wide spectral
allocations at 3.1 - 10.6 GHz.
This thesis presents experimental measurements of UWB wireless interconnects within an operational computer system chassis. The purpose of the thesis is to analyze and verify the implementation of high-bandwidth wireless communications using an impulse-radio ultra-wideband (IR-UWB) 3.1 - 5 GHz transceiver within an enclosed, heavy multipath, metallic environment such as a computer server chassis. Bit-error-rate (BER) and recovered clock jitter were measured at various positions within the computer chassis. The results show a 6X improvement in BER after applying the equalizer to the noisy channel while the motherboard is fully operating
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