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Dissertations / Theses on the topic 'Antennas - Bandwidth'
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Shahpari, Morteza. "Fundamental Limitations of Small Antennas." Thesis, Griffith University, 2015. http://hdl.handle.net/10072/365747.
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The physical size and material properties of antennas are major limiting factors of the antennas performance. These limitations are usually manifested through parameters such as bandwidth, quality factor and efficiency. The presented research examines these fundamental limitations with specific focus on electrically small antennas, and a new bound for antenna efficiency is developed.<br>Thesis (PhD Doctorate)<br>Doctor of Philosophy (PhD)<br>Griffith School of Engineering<br>Science, Environment, Engineering and Technology<br>Full Text
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Chiu, Chi Yuk. "Impedance bandwidth broadening techniques for small patch antennas /." access full-text access abstract and table of contents, 2005. http://libweb.cityu.edu.hk/cgi-bin/ezdb/thesis.pl?phd-ee-b19887796a.pdf.
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Thesis (Ph.D.)--City University of Hong Kong, 2005.<br>"Submitted to Department of Electronic Engineering in partial fulfillment of the requirements for the degree of Doctor of Philosophy" Includes bibliographical references (leaves 152-162)
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Hee, Ta Wei. "Wide bandwidth conformal array antennas." Thesis, University of Birmingham, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.521971.
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Cummings, Nathan Patrick. "Active Antenna Bandwidth Control Using Reconfigurable Antenna Elements." Diss., Virginia Tech, 2003. http://hdl.handle.net/10919/29990.
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Reconfigurable antennas represent a recent innovation in antenna
design that changes from classical fixed-form, fixed-function antennas
to modifiable structures that can be adapted to fit the requirements
of a time varying system. Advances in microwave semiconductor
processing technologies have enabled the use of compact, ultra-high
quality RF and microwave switches in novel aspects of antenna design.
This dissertation introduces the concept of reconfigurable antenna
bandwidth control and how advances in switch technology have made
these designs realizable. Specifically, it details the development of
three new antennas capable of reconfigurable bandwidth control. The
newly developed antennas include the reconfigurable ring patch, the
reconfigurable planar inverted-F and the reconfigurable parasitic
folded dipole. The relevant background work to these designs is
described and then design details along with computer simulations and
measured experimental results are given.<br>Ph. D.
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Castillo, Solis Maria De los angeles. "Dielectric resonator antennas and bandwidth enhancement techniques." Thesis, University of Manchester, 2015. https://www.research.manchester.ac.uk/portal/en/theses/dielectric-resonator-antennas-and-bandwidth-enhancement-techniques(44b64ce4-dc73-496a-b656-dc4b9c910291).html.
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In this thesis a technique that is being used in another area of technology to optimize light reception in a photographic camera was also applied to the dielectric resonator antenna. The technique consisting of the use of thin film to couple the media and camera impedances resulted in a dielectric resonator antenna bandwidth enhancement technique. The bandwidth enhancement technique was found when thin film dielectric layer structure was used to couple the dielectric resonator and its feed mechanism. Remarkable good performance was detected with a coplanar waveguide fed cylindrical dielectric resonator antenna which resulted in an improvement to its fractional bandwidth from 7.41% to 50.85%. Extensive experimental work was undertaken in order to explore the extent offered in bandwidth performance by using thin film dielectric layer structure in the dielectric resonator antenna performance. The experimental tasks were designed in order to investigate the influence of the thin film dielectric layer structure in relation to its size, shape, thickness, position and direction. Experimental results were supported with simulation work with the computer simulation technology microwave studio. The pieces of the material used for undertaking this experimental work were manually handcrafted. Four different dielectric resonator antenna designs were used in order to carry out the experimental work including the coplanar waveguide fed cylindrical dielectric resonator antenna. The other three dielectric resonator antennas were implemented using the same microstrip feed mechanism. Improved performance in bandwidth was achieved for all the designs. Optimization of the incoming signal was observed when a piece of thin film dielectric layer structure was placed in position between the feed mechanism and the dielectric resonator antenna. The optimization was observed as an enhancement in both the return loss level and the bandwidth of work. Different unexpected operational modes from were activated, such modes being called perturbed modes. Two different shapes were used in this project. Cylindrical dielectric resonator antenna (ɛr = 37) from a commercial provider and two novel rectangular dielectric resonator antennas. The novel rectangular dielectric resonator antennas were created with the methodology presented in this thesis. The rectangular dielectric resonator antennas were elaborated with transparent ceramic material (ɛr = 7) and TMM10i (ɛr = 9.8) from the Rogers Corporation company. The bandwidth enhancement technique was tested in novel embedded dielectric resonator antennas. A coplanar waveguide fed embedded cylindrical dielectric resonator antenna achieved a maximum bandwidth enhancement of 156.77% around f = 3.79 GHz with a thin film dielectric layer structure modified rectangular piece on one edge. Escalation to dielectric resonator antenna design at millimeter wave frequencies was achieved by using thin film dielectric layer structure bandwidth enhancement technique and a handcrafted printed circuit board millimeter wave feed mechanism. The millimeter wave feed mechanisms were achieved using a low cost alternative technique conceived as part of this project. Millimeter wave dielectric resonator antennas were implemented using thin film dielectric layers structure. The antennas deliver an adequate performance in bandwidth. The work presented in this thesis demonstrates dielectric resonator antenna simpler geometry, simple couple schemes, small size, low profile, light weight, and ease of excitation and orientation. Other parameters have also been investigated covering reduced complexity, high degree of flexibility, ease of fabrication and the use of low cost technology to escalate to millimeter wave frequencies.
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Komulainen, M. (Mikko). "Bandwidth enhanced antennas for mobile terminals and multilayer ceramic packages." Doctoral thesis, University of Oulu, 2009. http://urn.fi/urn:isbn:9789514290879.
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Abstract
In this thesis, bandwidth (BW) enhanced antennas for mobile terminals and multilayer ceramic packages are presented. The thesis is divided into two parts. In the first part, electrically frequency-tunable mobile terminal antennas have been studied. The first three antennas presented were of a dual-band planar inverted-F type (PIFA) and were tuned to operate in frequency bands appropriate to the GSM850 (824–894 MHz), GSM900 (880–960 MHz), GSM1800 (1710–1880 MHz), GSM1900 (1850–1990 MHz) and UMTS (1920–2170 MHz) cellular telecommunication standards with RF PIN diode switches. The first antenna utilized a frequency-tuning method developed in this thesis. The method was based on an integration of the tuning circuitry into the antenna. The tuning of the second antenna was based on a switchable parasitic antenna element. By combining the two frequency-tuning approaches, a third PIFA could be switched to operate in eight frequency bands.
The planar monopole antennas researched were varactor-tunable for digital television signal reception (470–702 MHz) and RF PIN diode switchable dual-band antenna for operation at four cellular bands. The key advantage of the former antenna was a compact size (0.7 cm3), while for the latter one, a tuning circuit was implemented without using separate DC wiring for controlling the switch component.
The second part of the thesis is devoted to multilayer ceramic package integrated microwave antennas. In the beginning, the use of a laser micro-machined embedded air cavity was proposed to enable antenna size to impedance bandwidth (BW) trade-off for a microwave microstrip in a multilayer monolithic ceramic media. It was shown that the BW of a 10 GHz antenna fabricated on a low temperature co-fired ceramic (LTCC) substrate could be doubled with this technique. Next, the implementation of a compact surface mountable LTCC antenna package operating near 10 GHz was described. The package was composed of a BW optimized stacked patch microstrip antenna and a wide-band vertical ball grid array (BGA)-via interconnection. Along with the electrical performance optimization, an accurate circuit model describing the antenna structure was presented. Finally, the use of low-sintering temperature non-linear dielectric Barium Strontium Titanate (BST) thick films was demonstrated in a folded slot antenna operating at 3 GHz and frequency-tuned with an integrated BST varactor.
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Evans, Huw. "Increased bandwidth microstrip antennas for road tolling applications." Thesis, Northumbria University, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.416056.
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Zilevu, Kojo Sitsofe. "A Nonlinear Technique for Bandwidth Improvement in Narrowband Antennas." Thesis, Virginia Tech, 2012. http://hdl.handle.net/10919/76984.
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Electrically small, low profile antennas have become the new frontier in wireless communication research. With the pressure to miniaturize wireless communication devices, engineers are turning to small low profile antennas as a way to reduce their antennas and hence their devices.
Ideally, one would also like to at least maintain antenna bandwidth and efficiency while reducing size. However, in theory, antenna performance degrades when it is miniaturized—impedance bandwidth decreases with the reduction in antenna size.
This thesis investigates the possibility of increasing the input impedance bandwidth without enlarging the volume of the antenna. This thesis attempts to break the fundamental tradeoff between antenna size and bandwidth by loading it with a nonlinear element. First, a brief summary of antenna background definitions is presented. Next, the analytical framework of the thesis is presented using a model of a narrowband antenna.
A literature review of various narrowband electrically small antennas is studied, including the pros and cons of the Inverted-F antenna (IFA), Inverted-L antenna (ILA), and the Planar Inverted-F antenna (PIFA).Next, the analysis and the methodology leading to results are discussed and simulated results are presented. Simulated results show that the PIFA is able to achieve a higher bandwidth with a loaded nonlinear element. However, it is difficult to sustain the efficiency of the antenna due to harmonics generated by nonlinearity in the antenna. Results indicate that an increase in nonlinearity tends to generate harmonics which leads to losses in the antenna.<br>Master of Science
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Kanesan, Manimaran. "RFID Antennas for Difficult Environments." Thesis, Griffith University, 2016. http://hdl.handle.net/10072/365462.
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The research work explored the fundamental ideas and techniques required to design an antenna placed on different common target objects for radio frequency identification. This was achieved by studying the effect of antenna conductivity in a wide range and the substrate relative permittivity from 1 to 10. The effect on wire meander antenna properties are different to that for a straight linear dipole antenna; the increase in wire radius of the meander antenna increases the resonant frequency but increases in wire radius of a straight dipole antenna decreases the resonant frequency. This study concluded that the approximate antenna bandwidth needed for common target object materials is 28.5%. A genetic algorithm GA code was written to optimize the meander antenna structure to obtain a larger bandwidth. The GA optimized each vertical element and horizontal element for radius and length. The optimized antenna has 14.5% bandwidth which covers the entire UHF RFID frequency.
As conductivity is not changed further, the properties of antennas on ungrounded substrates with different permittivity and thickness were investigated. The solution for this problem involved transforming a circular cross section wire antenna structure to a planar strip antenna structure. A number of theoretical approaches were assessed to solve for the effective permittivity when the substrate material is thin. Surface impedance and slab waveguide propagation techniques were compared to a capacitive solution and an insulated wire antenna. The insulated wire method gives most accurate results (< 3.5% error) and was verified using numerical modelling and experimental work. Measurements on a planar straight dipole on FR4 (fc = 1.50GHz) compare favourably with the antenna modelled without the substrate and scaled using the insulated wire technique at (fc = 1.49GHz).<br>Thesis (PhD Doctorate)<br>Doctor of Philosophy (PhD)<br>Griffith School of Engineering<br>Science, Environment, Engineering and Technology<br>Full Text
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Zou, Xinlei. "Bandwidth enhancement techniques for probe-fed microstrip patch antennas." Thesis, University of Ottawa (Canada), 2005. http://hdl.handle.net/10393/27106.
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Many bandwidth enhancement techniques for microstrip patch antennas have been developed since the 1970's. Except for an IEEE collection of reprints which appeared in 1995, relatively little work has been done to review and categorize these techniques. As a result, the published research and design of broadband microstrip antennas has become somewhat unsystematic. In this thesis, papers on broadband microstrip antennas have been reviewed. Using full-wave electromagnetic simulation, the important performance parameters such as the bandwidth, realized gain, antenna efficiency, radiation efficiency and radiation patterns of broadband microstrip patch antennas have been considered. Based on these results, bandwidth enhancement techniques have been categorized in two broad classes, namely those applicable when electrically-thick low-permittivity substrates are used, and those applicable to electrically-thin high-permittivity substrates. These broad classes have been sub-divided into several sub-classes in a structured manner that aids the understanding of the bandwidth enhancement methods. A summary of these techniques, linked to a comparison of resulting microstrip patch antenna performance obtained from full-wave analysis of the sub-classes, is provided. It is also shown, through a specific example, how the increased understanding afforded by this categorization can lead to the development of new broad bandwidth geometries that can offer some advantages over existing ones.
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Zhu, Ning. "Advances in Non-Foster Circuit Augmented, Broad Bandwidth, Metamaterial-Inspired, Electrically Small Antennas." International Foundation for Telemetering, 2012. http://hdl.handle.net/10150/581683.
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ITC/USA 2012 Conference Proceedings / The Forty-Eighth Annual International Telemetering Conference and Technical Exhibition / October 22-25, 2012 / Town and Country Resort & Convention Center, San Diego, California<br>There are always some intrinsic tradeoffs among the performance characteristics: radiation efficiency, directivity, and bandwidth, of electrically small antennas (ESAs). A non-Foster enhanced, broad bandwidth, metamaterial-inspired, electrically small, Egyptian axe dipole (EAD) antenna has been successfully designed and measured to overcome two of these restrictions. By incorporating a non-Foster circuit internally in the near-field resonant parasitic (NFRP) element, the bandwidth of the resulting electrically small antenna was enhanced significantly. The measured results show that the 10 dB bandwidth (BW10dB) of the non-Foster circuit-augmented EAD antenna is more than 6 times the original BW10dB value of the corresponding passive EAD antenna.
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LIU, BOSUI. "VERTICALLY INTERCONNECTED WIDE-BANDWIDTH MONOLITHIC PLANAR ANTENNAS FOR 3D-IC." University of Cincinnati / OhioLINK, 2002. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1040154281.
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Cutshall, Ryan T. "Achieving wide bandwidth electrically small antennas using internal non-foster elements." Thesis, The University of Arizona, 2013. http://pqdtopen.proquest.com/#viewpdf?dispub=1544745.
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<p> Electromagnetic equations pertaining to electrically small dipole antennas and electrically small monopole antennas with small circular ground planes are reviewed. Two electrically small antenna designs are analyzed numerically and the results are compared. The first is a frequency agile version of the two-dimensional (2D) planar Egyptian axe dipole (EAD) antenna. The second is its three-dimensional (3D) counterpart. The frequency agile performance characteristics of both the 2D and 3D EAD designs are studied and compared. The potential for non-Foster augmentation to achieve large instantaneous fractional impedance bandwidths is detailed for each antenna. In addition, details are given on how to run frequency agile simulations in both ANSYS HFSS and Agilent's ADS. Details are also provided on how to generate an antenna's non-Foster |S<sub>11</sub>| and radiation efficiency curves using HFSS, and how to generate an antenna's non-Foster |S<sub>11</sub>| curve using ADS. </p>
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Cutshall, Ryan Thomas. "Achieving Wide Bandwidth Electrically Small Antennas Using Internal Non-Foster Elements." Thesis, The University of Arizona, 2013. http://hdl.handle.net/10150/305873.
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Electromagnetic equations pertaining to electrically small dipole antennas and electrically small monopole antennas with small circular ground planes are reviewed. Two electrically small antenna designs are analyzed numerically and the results are compared. The first is a frequency agile version of the two-dimensional (2D) planar Egyptian axe dipole (EAD) antenna. The second is its three-dimensional (3D) counterpart. The frequency agile performance characteristics of both the 2D and 3D EAD designs are studied and compared. The potential for non-Foster augmentation to achieve large instantaneous fractional impedance bandwidths is detailed for each antenna. In addition, details are given on how to run frequency agile simulations in both ANSYS HFSS and Agilent's ADS. Details are also provided on how to generate an antenna's non-Foster |S₁₁| and radiation efficiency curves using HFSS, and how to generate an antenna's non-Foster |S₁₁| curve using ADS.
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McCann, John Forrest. "On the design of large bandwidth arrays of slot elements with wide scan angle capabilities." Connect to resource, 2006. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1209590321.
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DeJean, Gerald Reuben. "Design of Compact Antennas in Multilayer Technology for Wireless Communications / WLAN Applications." Thesis, Georgia Institute of Technology, 2005. http://hdl.handle.net/1853/6977.
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Various compact and packaging-adaptive antennas have been designed for practical wireless communications systems such as global system of mobile communications (GSM), Bluetooth Industrial-Scientific-Medical (ISM) devices, IEEE802.11a WLAN, and Local Multipoint Distribution Systems (LMDS) applications. First, compact stacked patch antennas using LTCC multilayer technology have been presented. A set of design rules is established for the purpose of designing optimized bandwidth compact antennas on LTCC multilayer substrates. To verify its effectiveness, the proposed design rules are applied to three emerging wireless bands. The return loss and the impedance bandwidth are optimized for all three bands. A maximum bandwidth of 7% can be achieved for an antenna operating in the LMDS band. Furthermore,
folded shorted patch antennas (SPAs) are designed to significantly reduce the resonant frequency of a standard patch antenna. The design methodology of this structure starts with a conventional half-wave and through a series of procedures, evolves into a smaller, lambda/8 wavelength resonant length structure. Upon varying the height of the lower patch, the resonant length can be reduced to lambda/16. A comparison between a folded SPA and a standard SPA validates the folding technique proposed in this document. The folded SPA is applied to the 2.4 GHz ISM band. The measured results are in good agreement with simulated results. This antenna can be implemented into 3D packages using multilayer laminates such as LTCC or LCP.
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Basat, Sabri S. "Design and Characterization of RFID Modules in Multilayer Configurations." Thesis, Georgia Institute of Technology, 2007. http://hdl.handle.net/1853/14070.
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Radio Frequency IDentification (RFID) Tags have become quite widespread in many services in the industry such as access control, parcel and document tracking, distribution logistics, automotive systems, and livestock or pet tracking. In these applications, a wireless communication link is provided between a remote transponder (antenna and integrated circuit (IC)) and an interrogator or reader. A suitable antenna for these tags must have low cost, low profile and especially small size whereas the bandwidth requirement (few kilohertz to megahertz) is less critical.
In this document, methods to reduce tag size, the performance optimization of the tag by using novel antenna matching techniques for increased operational bandwidth and gain/radiation pattern/radiation efficiency improvement are introduced for 13.56 MHz HF and 915 MHz UHF RFID tags.In addition, an evaluation of an active 915 MHz UHF RFID field study for container tracking at the port of Savannah, GA is also presented.
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Dutta, Chaudhury Nandan. "An investigation on the possibility for bandwidth improvement of dielectric antennas via modification of their geometry." Thesis, KTH, Skolan för elektroteknik och datavetenskap (EECS), 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-285571.
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The dielectric antenna is an interesting alternative to a metallic antenna. This is mainlydue to its low manufacturing cost and the possibility to fabricate complex antennageometry with the aid of additive manufacturing (AM). Sophisticated AM technologyprovides new degrees of freedom in shaping the outer and inner geometry of antennas.This feature can be utilized to optimize various properties of antenna, such as itsbandwidth, radiation pattern etc, while maintaining a compact geometry.This master thesis investigates the possibility of improving the bandwidth of acompact dielectric antenna by modifying its geometry. Specifically, dielectricresonator antennas (DRAs) have been considered here. In this connection, twoembedded cylindrical DRAs operating within 8 GHz-17 GHz frequency band havebeen designed and simulated using Ansys HFSS. For the first design (Design-1), abandwidth (corresponding to reflection coefficient ≤ -10dB) of approximately 63%has been obtained and the second design (Design-2) has a bandwidth (correspondingto reflection coefficient ≤ -10dB) of about 57%. However, in terms of radiationcharacteristics, the performance of Design-2 has been found to be superior comparedto Design-1, mainly due to its symmetrical geometry. Furthermore, the two designshave been compared to an existing compact rectangular embedded DRA. It has beenfound that both Design-1 and Design-2 have comparatively wider bandwidth. Withrespect to the radiation characteristics, the performance of the reference antenna andDesign-2 are similar. While, the radiation performance of the reference antenna isfound to be better than Design-1.<br>Dielektriska antenner är ett intressant alternativ till metalliska diton. Detta beror delspå lägre tillverkningskostnader men också, tack vare additiva tillverkningsmetoder,på grund av möjligheten att använda komplexa geometrier. De senaste årens framsteginom additiv tillverkning har öppnat upp nya möjligheter vid designen av den externaoch den inre geometrin hos dielektriska antenner. Detta kan utnyttjas till att optimeraolika aspekter hos antennen, exempelvis bandbredd och strålningsmönster, utan attpåverka de yttre måtten.Denna avhandling studerar möjligheten att förbättra bandbredden hos dielektriskaresonansantenner (DRA) genom att modifiera deras inre. Två cylindriska DRA:er,verksamma inom 8-17 GHz, har designats och simulerats i Ansys HFSS. Bandbredderom 63 % för Design-1, samt 57 % för Design-2, erhölls. Trots den första designensstörre bandbredd uppvisar Design-2 bättre strålningsegenskaper, främst avseendeantennens strålningsmönster. De simulerade antennerna har också visat sig hastörre bandbredd jämfört med en redan existerande kompakt, inbäddad DRA. Sett tillstrålningsegenskaper är prestandan hos Design-2 jämförbar med referensantennen,medan design ett uppvisar sämre prestanda.
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Garcia, Pardo Concepción. "Experimental characterization of the radio channel for systems of large bandwidth and multiple antennas." Thesis, Lille 1, 2012. http://www.theses.fr/2012LIL10014/document.
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La généralisation des nouvelles applications des communications sans fil nécessitera dans un avenir proche des communications très haut débit qui avoisineront 1Gb/s. Une des solutions proposées pour répondre à cette demande est basée sur l’utilisation de réseaux d’antennes à l’émission et à la réception connue sous la terminologie Multiple-Input Multiple-Output (MIMO). Plus récemment, les techniques ultra large bande (ULB) ont connu un regain d’intérêt grâce aux débits très élevés qu’offre sa grande bande passante et les faibles puissances d’émission mises en jeux. Si on envisage l’association de ces deux techniques au sein même d’un système, il est nécessaire, lors de l’optimisation de la chaîne de communication, de connaître au préalable les caractéristiques du canal radio. L’objectif de cette thèse porte sur la caractérisation expérimentale multidimensionnelle (MD) du canal radio pour des communications en milieux confinés. L’intérieur des bâtiments et le tunnel ferroviaire seront deux exemples traités dans cette étude. Précisons que la demande de haut débit en tunnel ferroviaire concerne les communications multimédia pour des applications de vidéo surveillance et de contrôle commande. Les travaux originaux menés au cours de cette thèse ont porté sur :- Le développement d’un sondeur de canal MIMO large bande permettant une caractérisation directe dans le domaine temporel. - La caractérisation (MD) en polarisation croisée du canal de propagation à l’intérieur d’un bâtiment et en tunnel. - l’analyse phénoménologique de la technique de retournement temporel et des diversités de polarisation, fréquentielle et d’espace appliquées aux communications en tunnel<br>Recent and future wireless applications require large data rates. Multiple-Input Multiple-Output (MIMO) systems were proposed as one solution to achieve higher spectral efficiency. More recently Ultra-Wideband (UWB) systems, have gained interest owing its extremely high data rates. However, precise knowledge of the radio channel is an essential issue to design the global system and, thus to reach such improvement in the performances of wireless communications. This thesis is mainly focused on the experimental characterization of the radio channel for systems with large bandwidth and MIMO. In general, most of the research on MIMO and UWB are performed in indoor environments. However, there are other scenarios where reliable communications are also needed, for example, in tunnels. In this special environment, there is an increasing necessity of developing and implementing control/command equipment, in order to develop safe and efficient trains and infrastructures. Thus, the objectives pursued in this thesis are:- Improve an existing frequency-domain MIMO channel sounder to achieve more enhanced capabilities.- Develop a wideband time-domain MIMO channel sounder in order to perform measurements directly in the time-domain.- Characterize the MIMO-UWB radio channel in office environment by means of measurements carried out in the underground level of the Universidad Politécnica de Cartagena. Multi dimensional channel parameters have been deduced from numerous measurement campaigns.- Study the propagation in tunnels and give physical interpretation of the performances of space, frequency and polarization diversity, and of time reversal techniques
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Blanco, Moro Rodrigo. "A novel technique for phased array receivers based on an economic sampling scheme." Thesis, Virginia Tech, 2013. http://hdl.handle.net/10919/23753.
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Phased array systems present desirable antenna features like beam steering and high gain. However, due to their high cost, civilian applications cannot generally afford them, restricting their usage to military. Hardware involved in phased array systems is expensive and the number of devices is high, since there is usually one device of each kind (filter, amplifier, shifter..) for each individual antenna. Alternative techniques, mainly based on TDMA, have been developed looking for lowering the number of elements in the system. However, these approaches increase the system bandwidth, multiplying it by a factor of $N$ (Number of antennas), as they use redundant information.
In this thesis, a novel phased receiver, based on an economic sampling scheme is proposed. All the elements in an array receive a common information (signal amplitude) and a unique information (relative delay between elements). The idea is to sample only the information required to reconstruct the transmitted signal and discard the redundant one. This idea is achieved by sampling just one antenna during each RF cycle and then gathering all the information taking in account the relative delay between different antenna elements.
The proposed technique is mathematically proved and validated by simulation. As a first approach, the equation for the received signal in the frequency domain is derived for a linear array. The radiation pattern and the received signals are simulated for equally spaced planar and linear arrays. Bandwidth signal transmission is demonstrated and tapering effects are shown. After that, the proposed technique is expanded for arbitrary structures and the resulting system bandwidth is enhanced by using different sampling order sequences.<br>Master of Science
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Tang, Ming-Chun, Ting Shi, and Richard W. Ziolkowski. "Electrically Small, Broadside Radiating Huygens Source Antenna Augmented With Internal Non-Foster Elements to Increase Its Bandwidth." IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2017. http://hdl.handle.net/10150/623616.
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A broadside radiating, linearly polarized, electrically small Huygens source antenna system that has a large impedance bandwidth is reported. The bandwidth performance is facilitated by embedding non-Foster components into the near-field resonant parasitic elements of this metamaterial-inspired antenna. High-quality and stable radiation performance characteristics are achieved over the entire operational bandwidth. When the ideal non-Foster components are introduced, the simulated impedance bandwidth witnesses approximately a 17-fold enhancement over the passive case. Within this -10-dB bandwidth, its maximum realized gain, radiation efficiency, and front-to-back ratio (FTBR) are, respectively, 4.00 dB, 88%, and 26.95 dB. When the anticipated actual negative impedance convertor circuits are incorporated, the impedance bandwidth still sustains more than a 10-fold enhancement. The peak realized gain, radiation efficiency, and FTBR values are, respectively, 3.74 dB, 80%, and 28.01 dB, which are very comparable to the ideal values.
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Doane, Jonathan P. "Wideband Low-Profile Antenna Arrays: Fundamental Limits and Practical Implementations." The Ohio State University, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=osu1366123876.
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Panayi, Petros K. "Design and comparative performance evaluation of novel mobile handset antennas and their radiative effects on users." Thesis, University of South Wales, 2000. https://pure.southwales.ac.uk/en/studentthesis/design-and-comparative-performance-evaluation-of-novel-mobile-handset-antennas-and-their-radiative-effects-on-users(f084a72c-b06d-47a6-8546-8ada0844c981).html.
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The beginning of the 21 st century is characterised, among others, by the evolution in telecommunications. The rapid growth of mobile communications and the variety of applications proposed for the third generation (3G) systems require long operation time, low weight and cost for terminals, as well as improved link quality. For this reason a good efficiency and low profile antennas with low absorption losses by the user are desirable. The Planar Inverted-F Antenna (PIFA) is shown to result into low SAR values and high efficiency when operating in the proximity of the user. Despite these advantages, PIFA is also characterised by narrow bandwidth that limits its practical use. The first part of this work is dedicated to the measurements and evaluation of the radiation characteristics of the PIFA and other wire antennas both in the near and far fields. In addition, novel methods of PIFA tuning are presented. These include the repositioning of the shorting pin and modification of its capacitance. By using these techniques, the effective bandwidth of the PIFA can be increased to satisfy the GSM900 and DCS 1800 system bandwidth requirements. Dual-band and electronically tuned PIFA prototypes are also included. The effects of the handset size on the mass averaged Specific Absorption Rate (SAR), and antenna efficiency are investigated. The appropriate choice of handset can result in up to 30%-reduced peak SAR. The computed SAR values from PIFA are compared with those resulting from the use of a handset equipped with quarter wavelength monopole antenna. A new measure referred to as the 3dB SAR volume is proposed. This measure provides better understanding of the absorbed power distribution in the operator's head. Results obtained in the course of study show that low profile handset antennas, such as the PIFA, present in addition to dual resonance and low reflection losses, reduced SAR values, high efficiency and low 3dB SAR volume. Finally, SAR and 3dB SAR volume values from simulations on 5- and 10- years old child head models are compared with their equivalents for adult models from which appropriate conclusions are drawn.
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DeJean, Gerald Reuben. "Design, Modeling, and Optimization of Compact Broadband and Multiband 3D System-On-Package (SOP) Antenna Architectures for Wireless Communications and Millimeter-Wave Applications." Diss., Georgia Institute of Technology, 2007. http://hdl.handle.net/1853/14630.
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In recent years, the miniaturization of cell phones and computers has led to a requirement for antennas to be small and lightweight. Antennas, desired to operate in the WLAN frequency range, often possess physical sizes that are too large for integration with radio-frequency (RF) devices. When integrating antennas into three-dimensional (3D) system-on-package (SOP) transceivers, the maintenance of a compact size also provides isolation from other devices, hence, surface wave propagation or high dielectric constant materials such as low temperature cofired ceramics (LTCC) does not affect nearby components of the transceiver such as filters, baluns, and other embedded passives. Therefore, the application of design methods is necessary for realizing compact antennas in the wireless community that can be integrated to RF packages. Furthermore, it is essential that these compact antennas maintain acceptable performance characteristics, such as impedance bandwidth, low cross-polarization, and high efficiency. In addition, the analysis of circuit modeling techniques that could be used to obtain a better understanding of the physical phenomena of the antenna is quite necessary as modules become more and more complex. Based on these requirements, the focus of this research is to improve the design of compact antennas for wireless communications, wireless local area networks (WLAN), and millimeter-wave applications by using time-domain electromagnetic and circuit modeling techniques and optimizations. These compact antenna designs are applied to practical wireless communications systems such as global system of mobile communications (GSM), Bluetooth Industrial-Scientific-Medical (ISM) devices, IEEE802.11a WLAN, and Local Multipoint Distribution Systems (LMDS) applications. Parametric analyses are conducted to study critical parameters that may affect the antenna designs. Moreover, optimizations are performed to optimize the structures, and measured results are presented to validate design techniques.
25
Irci, Erdinc. "Low-Profile Wideband Antennas Based on Tightly Coupled Dipole and Patch Elements." The Ohio State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=osu1316456337.
Full text
26
Morales, Cesar A. "Magneto-Dielectric Polymer Nanocomposite Engineered Substrate for RF and Microwave Antennas." Scholar Commons, 2011. http://scholarcommons.usf.edu/etd/3255.
Full textAbstract:
This dissertation presents the first reported systematic investigation on the implementation of multilayer patch antennas over Fe3O4-based polymer nanocomposite (PNC) magneto-dielectric substrates. The PNC substrate is created by the monodispersion of Fe3O4 nanopthesiss, with mean size of 7.5nm, in a polymeric matrix of Polydimethylsiloxane (PDMS).
Recently, magneto-dielectric substrates have been proposed by several researchers as a means for decreasing the size and increasing the bandwidth of planar antennas. Nevertheless, factors such as high loss and diminished control over magnetic and dielectric properties have hindered the optimal performance of antennas. In addition, the incompatibility and elevated complexity prevents integration of conventional magnetic materials with antennas and standard fabrication processes at printed circuit boards (PCBs) and wafer levels. Additionally, the low hysteresis losses exhibited by uniformly embedded superparamagnetic nanopthesiss complemented by the ease of integration of polymer nanocomposites in standard fabrication processes, offer promising solutions to resolve any of the complications and concerns foresaid.
Towards this dissertation work, one multilayer antenna was constructed over a molded PDMS substrate along with three similar antennas built on PDMS-Fe3O4 PNC substrates with different Fe3O4 nanopthesis loading concentrations in the PDMS matrix of 80%, 50% and 30% by weight. This pioneering work in the experimental implementation and characterization of magneto-dielectric PNC antennas has not only resulted in antennas with different operational frequencies in the 3-5GHz band, but also expanded our knowledge base by correlating the concentration of magnetic nanopthesiss to key antenna performance metrics such as antenna bandwidth, antenna efficiency and miniaturization factors.
Among the most significant results a magneto-dielectric antenna with maximum miniaturization factor of 57%, and a 58% increase in bandwidth, whilst retaining an acceptable antenna gain of 2.12dBi, was successfully demonstrated through the deployment of molded PDMS-Fe3O4 PNC substrate under external DC bias magnetic fields.
This dissertation also presents a versatile process for constructing flexible and multilayer antennas by the seamless incorporation of a variety of materials such as PDMS, Liquid Crystal Polymer (LCP) laminates, metal clads and molded magneto-dielectric polymer nanocomposites with evenly embedded magnetic nanopthesiss.
27
Bukilic, Nino. "Wide bandwidth focal plane array receiver for radio astronomy." Thesis, Curtin University, 2010. http://hdl.handle.net/20.500.11937/2331.
Full textAbstract:
Reflective antennas equipped with phase array feeds (PAFs) have been proposed as part of the Square Kilometre Array reference design, since they offer a wide Field of View (FoV) and large collecting area. To achieve a contiguous FoV, and to cancel spill-over radiation, the Focal Plane Array (FPA) must sample the focal field of the reflector at least every half-wavelength at the upper operating frequency. Low-noise operation over a wide bandwidth requires appropriate impedance matching to the low-noise amplifiers, and this is a challenging research problem since the input impedance of the FPA elements can vary strongly with frequency.Advanced broadband design techniques for antenna arrays have resulted in antenna shapes getting more complex. Modelling of these antennas can only be carried out using numerical computational electromagnetic methods (CEM), and accurate modelling of complex antennas demand the full-wave analysis with fields and currents that vary in three dimensional space. The Frequency Domain Integral Equation model is adopted in this study and used via the Method of Moments (MoM) technique for simulation and modelling of the FPA. The "MoM Antenna Development Toolbox" (MoMADT), 64 bit version of the modelling software, is specifically developed in this study for designing, building and modelling of complex antenna and electromagnetic structures. MoMADT utilizes surface and volume integral equations and provides functions for generating precise meshes and accurate method of moments solutions. MoMADT enables structures to be assembled in an array formation to consist of conductive or dielectric materials, or a combination of both.Study of the wide bandwidth FPA receiver was achieved through analysis of broadband planar antenna structures. This research investigates a unique design solution for a FPA utilizing the diamond planar strip antenna elements arranged to provide three vectors of polarization (triple-polarized FPA). The most promising FPA identified is the 77 Hexagonal Diamond Tripole (HDT) array. This array yields an operating frequency range of 550 to 2100 MHz, providing bandwidth ratio of 3.8:1. It is shown that adequate impedance match can be achieved across the indicated frequency range with desired directivity and gain. In addition, the 77 HDT array offers optimized efficiency and allows the polarization to be distinguished at any angle about the axis normal to the antenna plane to within a theoretical uncertainty of ± 2.2°. This is also true for any function of the FoV allowed by the surface area of the FPA.
28
Elmegri, Fauzi O. M. "Model and design of small compact dielectric resonator and printed antennas for wireless communications applications : model and simulation of dialectric resonator (DR) and printed antennas for wireless applications : investigations of dual band and wideband responses including antenna radiation performance and antenna design optimization using parametric studies." Thesis, University of Bradford, 2015. http://hdl.handle.net/10454/14742.
Full textAbstract:
Dielectric resonator antenna (DRA) technologies are applicable to a wide variety of mobile wireless communication systems. The principal energy loss mechanism for this type of antenna is the dielectric loss, and then using modern ceramic materials, this may be very low. These antennas are typically of small size, with a high radiation efficiency, often above 95%; they deliver wide bandwidths, and possess a high power handling capability. The principal objectives of this thesis are to investigate and design DRA for low profile personal and nomadic communications applications for a wide variety of spectrum requirements: including DCS, PCS, UMTS, WLAN, UWB applications. X-band and part of Ku band applications are also considered. General and specific techniques for bandwidth expansion, diversity performance and balanced operation have been investigated through detailed simulation models, and physical prototyping. The first major design to be realized is a new broadband DRA operating from 1.15GHz to 6GHz, which has the potential to cover most of the existing mobile service bands. This antenna design employs a printed crescent shaped monopole, and a defected cylindrical DRA. The broad impedance bandwidth of this antenna is achieved by loading the crescent shaped radiator of the monopole with a ceramic material with a permittivity of 81. The antenna volume is 57.0 37.5 5.8 mm3, which in conjunction with the general performance parameters makes this antenna a potential candidate for mobile handset applications. The next class of antenna to be discussed is a novel offset slot-fed broadband DRA assembly. The optimised structure consists of two asymmetrically located cylindrical DRA, with a rectangular slot feed mechanism. Initially, designed for the frequency range from 9GHz to 12GHz, it was found that further spectral improvements were possible, leading to coverage from 8.5GHz to 17GHz. Finally, a new low cost dual-segmented S-slot coupled dielectric resonator antenna design is proposed for wideband applications in the X-band region, covering 7.66GHz to 11.2GHz bandwidth. The effective antenna volume is 30.0 x 25.0 x 0.8 mm3. The DR segments may be located on the same side, or on opposite sides, of the substrate. The end of these configurations results in an improved diversity performance.
29
Elmegri, Fauzi. "Model and design of small compact dielectric resonator and printed antennas for wireless communications applications. Model and simulation of dialectric resonator (DR) and printed antennas for wireless applications; investigations of dual band and wideband responses including antenna radiation performance and antenna design optimization using parametric studies." Thesis, University of Bradford, 2015. http://hdl.handle.net/10454/14742.
Full textAbstract:
Dielectric resonator antenna (DRA) technologies are applicable to a wide variety of
mobile wireless communication systems. The principal energy loss mechanism for this
type of antenna is the dielectric loss, and then using modern ceramic materials, this
may be very low. These antennas are typically of small size, with a high radiation
efficiency, often above 95%; they deliver wide bandwidths, and possess a high power
handling capability.
The principal objectives of this thesis are to investigate and design DRA for low profile
personal and nomadic communications applications for a wide variety of spectrum
requirements: including DCS, PCS, UMTS, WLAN, UWB applications. X-band and part
of Ku band applications are also considered. General and specific techniques for
bandwidth expansion, diversity performance and balanced operation have been
investigated through detailed simulation models, and physical prototyping.
The first major design to be realized is a new broadband DRA operating from 1.15GHz
to 6GHz, which has the potential to cover most of the existing mobile service bands.
This antenna design employs a printed crescent shaped monopole, and a defected
cylindrical DRA. The broad impedance bandwidth of this antenna is achieved by
loading the crescent shaped radiator of the monopole with a ceramic material with a
permittivity of 81. The antenna volume is 57.0 37.5 5.8 mm3, which in conjunction
with the general performance parameters makes this antenna a potential candidate for
mobile handset applications.
The next class of antenna to be discussed is a novel offset slot-fed broadband DRA
assembly. The optimised structure consists of two asymmetrically located cylindrical
DRA, with a rectangular slot feed mechanism. Initially, designed for the frequency
range from 9GHz to 12GHz, it was found that further spectral improvements were
possible, leading to coverage from 8.5GHz to 17GHz.
Finally, a new low cost dual-segmented S-slot coupled dielectric resonator antenna
design is proposed for wideband applications in the X-band region, covering 7.66GHz
to 11.2GHz bandwidth. The effective antenna volume is 30.0 x 25.0 x 0.8 mm3. The DR
segments may be located on the same side, or on opposite sides, of the substrate. The
end of these configurations results in an improved diversity performance.<br>General Secretariat of Education and Scientific Research Libya
30
Maia, Anamaria Sena. "Estudo do comportamento dos parâmetros de antenas de microfita utilizando diferentes configurações de arranjos de estruturas EBG/PBG." Universidade Federal Rural do Semi-Árido, 2016. http://bdtd.ufersa.edu.br:80/tede/handle/tede/716.
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Previous issue date: 2016-05-19<br>Coordenação de Aperfeiçoamento de Pessoal de Nível Superior<br>Communication systems it has excelled in the development, social, economic and
cultural society. Every time there are new technologies seeking to offer the fastest, easy and
reliable access to various communications services. In this context, the microstrip antennas
stand out by having compact size and reduced cost. However, it presents some limitations
related to narrow bandwidth and low gain. A significant advance to minimize these losses
came to the use of structures EBG (Electromagnetic Band Gap) and PBG (Photonic Band
Gap) in the components of the antennas. This paper proposes the study and analysis of the
behavior of microstrip antennas properties designed with EBG/PBG structures in the substrate
and the ground plane. So that the structures are arranged just under the patch and are
developed with variations in radius, cylinder height and positioning in the ground plane. For
the resonance frequency 5.85 GHz, and substrates of different permittivity. In computer
modeling was used ANSYS HFFS® software. After analyzing the simulated results seven
devices were built, through a vector network analyzer, the measurements of the main
parameters were performed. Ultimately simulation are compared and measured values, so that
the results presented in most configurations a concord in the pattern of graphics, although the
frequency displacement. Also noted that antennas with the EBG/PBG structures presented
multiband, enabling the application specific frequency bands as well as, an increase in the
value of total gain, bandwidth and reduction of surface currents<br>Os sistemas de comunicação assumiram papéis fundamentais para o desenvolvimento,
social, econômico e cultural na sociedade. A cada momento, surgem novas tecnologias
procurando oferecer o acesso mais rápido, fácil e confiável aos diversos serviços de
comunicações. Nesse contexto, as antenas de microfita se destacam por possuírem
características como, tamanho compacto e custo reduzido. No entanto, apresentam algumas
limitações relacionadas a largura de banda estreita e ganho reduzido. Um avanço significativo
para minimizar essas perdas, proveio com a utilização de estruturas de bandas proibidas (EBG
– Eletromagnetic Band Gap e PBG – Photonic Band Gap) nos componentes das antenas. Este
trabalho propõe o estudo e análise do comportamento das propriedades de antenas de
microfita projetadas com configurações de estruturas EBG/PBG no substrato e no plano de
terra. De modo que as estruturas estão arranjadas apenas sob o patch e, são desenvolvidas
com variações no raio, altura do cilindro e posicionamento no plano de terra. Para a
frequência de ressonância de 5,85 GHz, e substratos de diferentes permissividades. Na
modelagem computacional foi utilizado o software ANSYS HFFS®, e com a análise dos
resultados simulados foram fabricados sete dispositivos, onde através de um analisador de
redes vetoriais, foram realizadas as medições dos principais parâmetros. Por fim são
comparados os valores simulados e medidos, de modo que que os resultados apresentaram na
maioria das configurações uma concordância no padrão de seus gráficos, apesar dos
deslocamentos de frequência. Também foi observado que as antenas com as estruturas
EBG/PBG apresentaram comportamento de multibandas, possibilitando a aplicação em faixas
de frequências específicas, assim como, ocorreu um aumento nos valores de ganho total,
largura de banda e a redução das correntes de superfície<br>2017-05-24
31
Rocha, HÃlio Henrique Barbosa. "Ressoadores e guias dielÃtricos cilÃndricos operando em micro-ondas e Ãptica: antenas dielÃtricas e acopladores refletores de Bragg a fibra." Universidade Federal do CearÃ, 2010. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=7068.
Full textAbstract:
FundaÃÃo Cearense de Apoio ao Desenvolvimento Cientifico e TecnolÃgico<br>CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel Superior<br>Duas contribuiÃÃes caracteristicamente distintas, nÃo obstante correlacionÃveis num mesmo sistema de telecomunicaÃÃo, sÃo apresentadas. A primeira versa sobre antenas ressoadoras constituÃdas por novas cerÃmicas dielÃtricas à base de Fe2O3. Os materiais desenvolvidos foram caracterizados na faixa de micro-ondas. Tratam-se de dielÃtricos com baixa permissividade relativa, baixa tangente de perda, e, no caso das amostras monofÃsicas, com coeficiente de temperatura na frequÃncia de ressonÃncia negativo. Posteriormente, as antenas ressoadoras dielÃtricas de geometria cilÃndrica (CDRAs) suportadas em plano de terra retangular e alimentadas por sonda monopolar sÃo analisadas segundo critÃrios de desempenho de irradiaÃÃo, quais sejam: frequÃncia de ressonÃncia, impedÃncia de entrada, largura de banda e padrÃes de irradiaÃÃo. AlÃm de experimentaÃÃo, o seu estudo envolveu procedimento computacional, no que foi promovida a comparaÃÃo de resultados. O mÃtodo dos elementos finitos, no qual està baseado o programa comercial empregado, foi utilizado para anÃlise destas antenas. Resulta que para maiores valores de permissividade relativa de uma amostra, menores sÃo a frequÃncia em que a mesma ressoa e a sua largura de banda. Ainda, foi observado satisfatÃrio casamento de impedÃncia e padrÃes de irradiaÃÃo "broadside", o que candidata os novos materiais desenvolvidos a esta importante aplicaÃÃo. Adicionalmente, mediante empilhamento dos protÃtipos monofÃsicos examinados, foi verificada a remodelagem da largura de banda em relaÃÃo Ãs contrapartidas individuais, provavelmente devido à excitaÃÃo de modos de ordem elevada das CDRAs. A segunda contribuiÃÃo està enfocada no contexto dos guias de ondas dielÃtricos operando em frequÃncias Ãpticas. Neste cenÃrio, sÃo investigados acopladores refletores de Bragg a fibra (FBGCs), estruturas resultantes da combinaÃÃo de dois dispositivos reconhecidamente versÃteis e de ampla aplicaÃÃo: redes de Bragg e acopladores direcionais. Foram apreciados dois estudos de caso numÃricos nos quais se fez promover a interaÃÃo de sinais Ãpticos com as estruturas propostas. Na medida em que descreve com satisfatÃria precisÃo as propriedades Ãpticas dos dispositivos de interesse, o modelo matemÃtico empregado à baseado na teoria dos modos acoplados. O tratamento numÃrico à realizado mediante codificaÃÃo, em linguagem de programaÃÃo FORTRAN, de um algoritmo preditivo-corretor. Considerando regimes pulsados em termos da potÃncia operacional, o problema foi analisado no domÃnio da frequÃncia e, sobretudo, no domÃnio do tempo. Em condiÃÃes especÃficas, a possibilidade de realizaÃÃo da extraÃÃo, reconfiguraÃÃo e comutaÃÃo de pulsos, exemplos de funÃÃes essenciais ao processamento totalmente Ãptico, reforÃam a importÃncia de tais estruturas hÃbridas.<br>Two heterogeneous contributions to modern communication systems â although fully possible to be correlated â are presented. The first one deals with resonant antennas consisting of new dielectric ceramics based on Fe2O3. These materials characterized at microwave frequency range possess low relative permittivity, low loss tangent and, concerned with the monophasic samples, negative temperature coefficient of resonant frequency. Subsequently, the cylindrical dielectric resonator antennas (CDRAs) supported on rectangular ground plane and fed by monopole are analyzed according to the following radiation performance criteria: resonant frequency, input impedance, bandwidth and radiation patterns. Besides experimentation, the study involved computational procedure, so that the results of both can be compared. A commercial software based on the finite element method was employed to examine the CDRAs. It follows that as higher is the permittivity of a material, the lower are the frequency at which it resonates as well as its bandwidth. Satisfactory impedance matching and broadside radiation patterns are observed, what enables the materials investigated to this relevant application. Additionally, the stacking of the monophasic CDRAs prototypes resulted in bandwidth enhancement, presumably due to their excited high order modes. The second contribution focuses on dielectric waveguides operating at optical frequencies, being fiber Bragg grating couplers (FBGCs) investigated in this scenario. Indeed, they result from a combination of two versatile and widely applied devices: fiber Bragg gratings and directional couplers. Two numerical case studies related to the interaction between optical signals and structures were performed. The theoretical model observed is based on the coupled mode theory since it provides a satisfactorily accurate description of the devices optical properties. By the way, the theoretical model is coded in FORTRAN programming language according to a predictor-corrector algorithm. In terms of operational power levels, analyses are carried out in frequency and (mainly) time domains. Under specific conditions, the capability of the extraction, reshaping and switching of pulses â examples of essential functions for all-optical processing â reinforces the importance of such hybrid structures.
32
Alves, George Dennes Fernandes. "Antenas planares multicamadas com materiais supercondutores e fot?nico para comunica??es m?veis." Universidade Federal do Rio Grande do Norte, 2006. http://repositorio.ufrn.br:8080/jspui/handle/123456789/15280.
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Previous issue date: 2006-08-04<br>Recently, planar antennas have been studied due to their characteristics as well as the advantages that they offers when compared with another types of antennas. In the mobile communications area, the need for this kind of antennas have became each time bigger due to the intense increase of the mobile communications this sector. That needs of antennas which operate in multifrequency and wide bandwidth. The microstrip antennas presents narrow bandwidth due the loss in the dielectric generated by radiation. Another limitation is the radiation pattern degradation due the generation of surface waves in the substrate. In this work some used techniques to minimize the disadvantages (previously mentioned) of the use of microstrip antennas are presented, those are: substrates with PBG material - Photonic Bandgap, multilayer antennas and with stacked patches. The developed analysis in this work used the TTL - Transverse Transmission Line method in the domain of Fourier transform, that uses a component of propagation in the y direction (transverse to the direction real of propagation z), treating the general equations of electric and magnetic field as functions of Ey and Hy. One of the advantages of this method is the simplification of the field equations. therefore the amount of equations lesser must the fields in directions x and z be in function of components Ey and Hy. It will be presented an brief study of the main theories that explain the superconductivity phenomenon. The BCS theory. London Equations and Two Fluids model will be the theories that will give support the application of the superconductors in the microfita antennas. The inclusion of the superconductor patch is made using the resistive complex contour condition. This work has as objective the application of the TTL method to microstrip structures with single and multilayers of rectangular patches, to obtaining the resonance frequency and radiation pattern of each structure<br>Recentemente as antenas planares t?m despertado interesses devido ?s suas caracter?sticas, assim como pelas vantagens que oferecem quando comparadas com os demais tipos de antenas. Na ?rea de comunica??es m?veis a necessidade de antenas desse tipo tem-se tornado cada vez maior devido ao intenso crescimento desse setor, necessitando de antenas que operem em multifreq??ncia e em banda larga. As antenas de microfita apresentam largura de banda estreita devido ?s perdas no diel?trico geradas pela irradia??o. Outra limita??o ? a degrada??o do diagrama de irradia??o devido ? gera??o de ondas de superf?cie no substrato. Neste trabalho s?o apresentadas algumas t?cnicas usadas para tentar minimizar as desvantagens (citadas acima) do uso de antenas de microfita, sendo elas: substratos com material PBG - Photonic Bandgap, antenas em multicamadas e a utiliza??o de patches fabricados de materiais supercondutores. As an?lises desenvolvidas neste trabalho foram realizadas com a utiliza??o do m?todo LTT - Linha de Transmiss?o Transversa no dom?nio da transformada de Fourier, que utiliza uma componente de propaga??o na dire??o y (transversa ? dire??o real de propaga??o z), tratando assim as equa??es gerais dos campos el?tricos e magn?ticos em fun??es de Ey e Hy. Uma das vantagens desse m?todo ? a simplifica??o das equa??es de campo, pois a quantidade de equa??es ? menor devido os campos nas dire??es x e z ficarem em fun??o das componentes Ey e Hy. Ser? apresentado um breve estudo das principais teorias que explicam o fen?meno da supercondutividade. As teorias BCS, Equa??es de London e modelo dos Dois Fluidos ser?o as teorias que dar?o suporte a aplica??o dos supercondutores nas antenas microfita. A inclus?o do patch supercondutor ? feita utilizando-se a condi??o de contorno complexa resistiva. Este trabalho tem como objetivo a aplica??o do m?todo LTT ?s estruturas de microfita
33
Alhaddad, Abdolrauf Gawad. "Balanced antennas for mobile handset applications : simulation and measurement of balanced antennas for mobile handsets, investigating specific absorption rate when operated near the human body, and a coplanar waveguide alternative to the balanced feed." Thesis, University of Bradford, 2012. http://hdl.handle.net/10454/5512.
Full textAbstract:
The main objectives of this research are to investigate and design low profile antennas for mobile handsets applications using the balanced concept. These antennas are considered to cover a wide range of wireless standards such as: DCS (1710-1880 MHz), PCS (1850-1990 MHz), UMTS (1920-2170 MHz), WLAN (2400-2500 MHz and 5000-5800 MHz) and UWB frequency bands. Various antennas are implemented based on built-in planar dipole with a folded arm structure. The performance of several designed antennas in terms of input return loss, radiation patterns, radiation efficiency and power gain are presented and several remarkable results are obtained. The measurements confirm the theoretical design concept and show reasonable agreement with computations. The stability performance of the proposed antenna is also evaluated by analysing the current distribution on the mobile phone ground plane. The specific absorption rate (SAR) performance of the antenna is also studied experimentally by measuring antenna near field exposure. The measurement results are correlated with the calculated ones. A new dual-band balanced antenna using coplanar waveguide structure is also proposed, discussed and tested; this is intended to eliminate the balanced feed network. The predicted and measured results show good agreement, confirming good impedance bandwidth characteristics and excellent dual-band performance. In addition, a hybrid method to model the human body interaction with a dual band balanced antenna structure covering the 2.4 GHz and 5.2 GHz bands is presented. Results for several test cases of antenna locations on the body are presented and discussed. The near and far fields were incorporated to provide a full understanding of the impact on human tissue. The cumulative distribution function of the radiation efficiency and absorbed power are also evaluated.
34
Alhaddad, A. G. "Balanced antennas for mobile handset applications. Simulation and Measurement of Balanced Antennas for Mobile Handsets, investigating Specific Absorption Rate when operated near the human body, and a Coplanar Waveguide alternative to the Balanced Feed." Thesis, University of Bradford, 2012. http://hdl.handle.net/10454/5512.
Full textAbstract:
The main objectives of this research are to investigate and design low profile antennas
for mobile handsets applications using the balanced concept. These antennas are
considered to cover a wide range of wireless standards such as: DCS (1710¿1880 MHz),
PCS (1850¿1990 MHz), UMTS (1920¿2170 MHz), WLAN (2400¿2500 MHz and 5000
¿ 5800 MHz) and UWB frequency bands. Various antennas are implemented based on
built-in planar dipole with a folded arm structure.
The performance of several designed antennas in terms of input return loss, radiation
patterns, radiation efficiency and power gain are presented and several remarkable
results are obtained. The measurements confirm the theoretical design concept and show
reasonable agreement with computations. The stability performance of the proposed
antenna is also evaluated by analysing the current distribution on the mobile phone
ground plane. The specific absorption rate (SAR) performance of the antenna is also
studied experimentally by measuring antenna near field exposure. The measurement
results are correlated with the calculated ones.
A new dual-band balanced antenna using coplanar waveguide structure is also proposed,
discussed and tested; this is intended to eliminate the balanced feed network. The
predicted and measured results show good agreement, confirming good impedance
bandwidth characteristics and excellent dual-band performance.
In addition, a hybrid method to model the human body interaction with a dual band
balanced antenna structure covering the 2.4 GHz and 5.2 GHz bands is presented.
Results for several test cases of antenna locations on the body are presented and
discussed. The near and far fields were incorporated to provide a full understanding of
the impact on human tissue. The cumulative distribution function of the radiation
efficiency and absorbed power are also evaluated.<br>UK Engineering and Physical Sciences Research Council (EPSRC)
35
Silva, Bruna Alice Lima da. "Antenas monopolo planar com patch em anel circular para sistemas UWB." Universidade Federal do Rio Grande do Norte, 2010. http://repositorio.ufrn.br:8080/jspui/handle/123456789/15320.
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Previous issue date: 2010-06-14<br>Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior<br>The microstrip antennas are largely used in wireless communication systems due to their low cost, weight, less complex construction and manufacturing, in addition to its
versatility. UWB systems have emerged as an alternative to wireless communications over short distances because they offer of higher capacity and lower multipath distortion than
other systems with the same purpose. Combining the advantages of microstrip antennas to the characteristics of UWB, it is possible to develop more and more smaller devices, with diverse geometries to operate satisfactorily in these systems. This paper aims to propose alternatives to microstrip antennas for UWB systems operate in the range between 3.1 and 10.6 GHz, with a patch on circular ring. Some techniques are analyzed and employed to increase the bandwidth of proposed antenna: the insertion of a parasitic elements and a rectangular slit in the displaced ground plane. For this, key issues are presented as the basic principles of UWB systems, the fundamental theory of antennas and microstrip antennas. The simulations and experimental characterization of constructed antennas are presented, as well as analysis of
parameters such as bandwidth and radiation pattern<br>As antenas de microfita s?o amplamente utilizadas nos sistemas de comunica??o sem fio devido ?s suas caracter?sticas de baixo custo, peso, menor complexidade de constru??o e fabrica??o, al?m de sua versatilidade. Os sistemas UWB surgiram como uma alternativa ?s comunica??es sem fio de curtas dist?ncias por oferecerem maior capacidade e menor distor??o por multipercurso que outros sistemas com a mesma finalidade. Aliando as vantagens das antenas de microfita ?s caracter?sticas do UWB ? poss?vel desenvolver dispositivos cada vez menores e com geometrias diversificadas para operar satisfatoriamente nesses sistemas. Este trabalho tem como objetivo propor alternativas de antenas de microfita para operar em sistemas UWB, na faixa entre 3,1 e 10,6 GHz, com patch em anel circular. S?o empregadas e analisadas algumas t?cnicas para aumentar a largura de banda das antenas propostas: a inser??o de elementos parasitas e de uma fenda retangular no plano terra deslocado. Para isto, s?o apresentados temas fundamentais como os princ?pios b?sicos dos sistemas UWB, a teoria fundamental de antenas e antenas de microfita. S?o apresentadas as simula??es e caracteriza??es experimentais das antenas constru?das, bem como uma an?lise de par?metros como a largura de banda e o diagrama de radia??o
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Téllez, Garzón Johan Leandro. "Desenvolvimento e implementação de antena planar para aparelhos celulares." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2013. http://hdl.handle.net/10183/76164.
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Neste trabalho é apresentado o projeto de uma antena planar de formato de F-invertido (PIFA) com ranhura-T para aplicação nos sistemas de comunicações sem fio GSM/UMTS/WCDMA. As larguras de banda da antena são aumentadas em função do aproveitamento dos modos ressonantes implícitos no plano de terra. Uma análise paramétrica é feita visando a obtenção de desempenho equilibrado na antena. As diversas simulações do desempenho da antena são realizadas com o software SEMCAD, que utiliza o método das diferenças finitas no domínio do tempo (FDTD). No trabalho é avaliada a diferença de desempenho da antena com e sem a presença do aparelho celular e também próximo à cabeça do usuário. Deste modo, é observada uma influência negativa sobre o desempenho da antena causada pela presença da cabeça do usuário. Adicionalmente, boa concordância é observada entre os dados do modelo simulado e os resultados medidos do protótipo.<br>This work presents the design and implementation of a planar inverted F-type antenna (PIFA) slot-T for wireless mobile communications GSM/UMTS/WCDMA. The excitation of the ground plane modes is used to increase the antenna bandwidth. A parametric analysis is done to obtain a balanced performance of the antenna. The several antenna performance simulations are performed with the SEMCAD software, which use the finite difference time domain (FDTD) method. In addition the differences in performance of the antenna are evaluated with and without the presence of the cell phone housing and the user's head, thus, negative influence on the antenna performance caused by the presence of the user's head is observed. Finally a prototype is implemented to get an idea of the real behavior of the proposed antenna. Good agreement is observed between data of the simulated model and measured results of the prototype.
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Hategekimana, Bayezi. "A Wideband Stacked Microstrip Patch Antenna for Telemetry Applications." International Foundation for Telemetering, 2010. http://hdl.handle.net/10150/604303.
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ITC/USA 2010 Conference Proceedings / The Forty-Sixth Annual International Telemetering Conference and Technical Exhibition / October 25-28, 2010 / Town and Country Resort & Convention Center, San Diego, California<br>This research article reports a design of a wide band multilayer microstrip patch antenna (MSPA). Positions of a coaxial probe feed to main patch of the multilayer MSPA, widths and lengths of main and parasitic patches, and height of a Rohacell foam layer in the multilayer MSPA were optimized to achieve desired performance in L-band. The work also reports a design of a two-by-two array of multilayer MSPA. We present results on antenna radiation patterns and return loss obtained with full wave finite element simulations with Ansoft HFSS software and measurements with a vector network analyzer.
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Chang, Li-Chung T. "Constant beamwidth ultrawide bandwidth linearly and dual polarized antenna design." Connect to resource, 1996. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1227214253.
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Uribeetxeberria, Roberto. "Adaptive space diversity and ring coding for multicarrier CDMA over mobile radio channels." Thesis, Staffordshire University, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.343385.
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Nithianandam, Jeyasingh. "L-Band Coplanar Slot Loop Antenna for iNET Applications." International Foundation for Telemetering, 2010. http://hdl.handle.net/10150/605925.
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ITC/USA 2010 Conference Proceedings / The Forty-Sixth Annual International Telemetering Conference and Technical Exhibition / October 25-28, 2010 / Town and Country Resort & Convention Center, San Diego, California<br>In this article we present a design of an L-band slot loop antenna with a dielectric loaded conductor backed coplanar waveguide (CBCPW) feed. The coplanar slot loop antenna has a transmission line resonator in series. We used full wave electromagnetic simulations with Ansoft's high frequency structure simulator (HFSS) software in the design of the coplanar slot loop antenna. The series transmission line resonator helps to tune the coplanar slot loop antenna and reduce its size. We present here results on return loss and radiations patterns of coplanar slot loop antenna obtained from HFSS simulations.
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Deng, Meiling. "The cloverleaf antenna : a compact wide-bandwidth dual-polarization feed for CHIME." Thesis, University of British Columbia, 2014. http://hdl.handle.net/2429/50288.
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A compact, wide-bandwidth, dual-polarization cloverleaf-shaped antenna has been developed to feed the CHIME radio telescope. The antenna has been tuned using a commercial antenna simulation program, CST, to have a very good impedance match to our amplifiers. Specifically, the return loss is smaller than -10dB for over an octave of bandwidth, covering the full CHIME band from 400MHz to 800MHz and this performance has been confirmed by measurement. The antennas are made of conventional low-loss circuit boards and can be mass produced economically, which is important because CHIME requires 1280 feeds. They are compact enough to be placed 30cm apart in a linear array at any azimuthal rotation. 128 of these feeds have now been built, tested and deployed on CHIME pathfinder.<br>Science, Faculty of<br>Physics and Astronomy, Department of<br>Graduate
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COOK, JAMES H. JR, and A. RENEE KOSTER. "A NEW EXTENDED BANDWIDTH ESCAN L-BAND & S-BAND TRACKING ANTENNA." International Foundation for Telemetering, 1990. http://hdl.handle.net/10150/613430.
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International Telemetering Conference Proceedings / October 29-November 02, 1990 / Riviera Hotel and Convention Center, Las Vegas, Nevada<br>The design and performance of a 1435 MHZ to 2600 MHZ ESCAN1 feed will be discussed. The radiation characteristics of a very small (<10 wavelengths) reflector antenna will be presented. The ESCAN tracking concept offers a significant improvement in the effective gain, sidelobes and tracking performance for broadband telemetry trackers over previous, low-cost approaches. The tradeoffs associated with the optimization of the ESCAN antenna’s radiation performance will be presented along with a comparison of conical scan and single channel monopulse performance. The tradeoffs will include an analysis of the limitations in performance due to central blockage, aperture illumination, spillover, and coma effects of an “effective” off-axis feed for a small, paraboloidal reflector antenna.
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Ojaroudi, Parchin Naser, J. Zhang, Raed A. Abd-Alhameed, G. F. Pedersen, and S. Zhang. "A planar dual-polarized phased array with broad bandwidth and quasi end-fire radiation for 5G mobile handsets." IEEE, 2021. http://hdl.handle.net/10454/18466.
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Yes<br>A planar dual-polarized phased array is proposed for 5G cellular communications. The array has the properties of dual-polarization, wideband and quasi end-fire radiation, which is printed on one side of a single-layer substrate. The design contains two 8-element sub-arrays including horizontally polarized end-fire dipole antennas and vertically polarized end-fire periodic slot antennas, employed on the PCB ground plane of the 5G mobile platform. Both sub-arrays provide wide bandwidth to cover 28 and 38 GHz (promising 5G candidate bands). The -10 dB impedance bandwidth of the proposed CPW-fed dipole and slot antennas are 26.5-39.5 GHz and 27.1-45.5 GHz, respectively. Moreover, for -6 dB impedance bandwidth, these values could be more than 20 GHz (24.4-46.4 GHz for the dipole antenna) and 70 GHz (22.3-95 GHz for the slot antenna). The fundamental characteristics of the proposed dual-polarized 5G antenna array in terms of the impedance bandwidth, realized gain, polarization, radiation pattern, and beam steering are investigated and good results are obtained. The clearance of the proposed dual-polarized 5G antenna array is less than 4.5 mm which is sufficient for cellular applications.<br>This work is partially supported by the InnovationsFonden project of Reconfigurable Arrays for Next Generation Efficiency (RANGE), AAU Young Talent Program, and European Union’s Horizon 2020 research and innovation programme under grant agreement H2020-MSCA-ITN-2016SECRET-722424.
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Wallace, Matthew J. "Mutual Elements and Substrate Effect Analysis on Patch Antenna Arrays." Scholar Commons, 2010. http://scholarcommons.usf.edu/etd/3702.
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There have been many different technology advancements with the invention of solid state electronics, leading to the digital era which has changed the way users employ electronic circuits. Antennas are no different; however, they are still analog devices. With the advancements in technology, antennas are being fabricated on much higher frequencies and with greater bandwidths, all while trying to keep size and weight to a minimum. Centimeter and millimeter wave technologies have evolved for many different radio frequency (RF) applications. Microstrip patch antennas have been developed, as wire and tubular antenna elements are difficult to fabricate with the tolerances required at micro-wavelengths. Microstrip patch antennas are continuously being improved. These types of antennas are great for embedded or conformal applications where size and weight are of the essence and the ease of manufacturing elements to tight tolerances is important. One of the greatest benefits of patch antennas is the ease in creating an array. Many simulation programs have been created to assist in the design of patch antennas and arrays. However, there are still discrepancies between simulated results and actual measurements.
This research will focus on these differences. It begins with a literature research of patch antenna design, followed by an assessment of simulation programs used for patch antenna design. The resulting antenna design was realized by the fabrication of an antenna from the Genesys software. Laboratory measurements of the real-world antenna are then compared to the theoretical antenna characteristics. This process is used to
illustrate deficiencies in the software models and likely improvements that need to be made.
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Karlsson, Magnus. "Ultra-wideband Antenna and Radio Front-end Systems." Doctoral thesis, Linköpings universitet, Institutionen för teknik och naturvetenskap, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-10338.
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The number of wireless communication applications increase steadily, leading to the competition for currently allocated frequency bands. Pressure on authorities around the world to permit communications in higher and wider frequency ranges to achieve higher wireless capacity than those existed in the past has resulted in several new specifications. The federal communication commission (FCC) in USA has unleashed the band 3.1-10.6 GHz for ultra-wideband radio (UWB) communications. The release has triggered a worldwide interest for UWB. Other regulatory instances throughout the world have issued use of UWB techniques as well. Capacity issues in form of data rate and latency have always been a bottleneck for broadened wireless-communication usages. New communication systems like UWB require larger bandwidth than what is normally utilized with traditional antenna techniques. The interest for compact consumer electronics is growing in the meantime, creating a demand on efficient and low profile antennas which can be integrated on a printed circuit board. In this thesis, some methods to extend the bandwidth and other antenna parameters associated with wideband usages are studied. Furthermore, methods on how to enhance the performance when one antenna-element is not enough are studied as well. The principle of antenna parallelism is demonstrated using both microstrip patch antennas and inverted-F antennas. Several techniques to combine the antennas in parallel have been evaluated. Firstly, a solution using power-splitters to form sub-arrays that covers one 500-MHz multi-band orthogonal frequency division multiplexing (OFDM) UWB is shown in Paper I. It is then proposed that the sub-bands are selected with a switching network. A more convenient method is to use the later developed frequency multiplexing technique as described in Paper V and VIII. Using the frequency multiplexing technique, selective connection of any number of antennas to a common junction is possible. The characteristic impedance is chosen freely, typically using a 50-Ω feed-line. Secondly, in Paper VIII a frequency-triplexed inverted-F antenna system is investigated to cover the Mode 1 multi-band UWB bandwidth 3.1-4.8 GHz. The antenna system is composed of three inverted-F antennas and a frequency triplexer including three 5th order bandpass filters. In Paper VI a printed circuit board integrated-triplexer for multi-band UWB radio is presented. The triplexer utilizes a microstrip network and three combined broadside- and edge-coupled filters. The triplexer is fully integrated in a four metal-layer printed circuit board with the minimum requirement on process tolerances. Furthermore, the system is built completely with distributed microstrips, i.e., no discrete components. Using the proposed solution an equal performance between the sub-bands is obtained. Finally suitable monopoles and dipoles are discussed and evaluated for UWB. In Paper X circular monopole and dipole antennas for UWB utilizing the flex-rigid concept are proposed. The flex-rigid concept combines flexible polyimide materials with the regular printed circuit board material. The antennas are placed entirely on the flexible part while the antenna ground plane and the dipole antenna balun are placed in the rigid part.
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Testa, Paolo Valerio, Bernhard Klein, Ronny Hahnel, Dirk Plettemeier, Corrado Carta, and Frank Ellinger. "On-Chip Integrated Distributed Amplifier and Antenna Systems in SiGe BiCMOS for Transceivers with Ultra-Large Bandwidth." De Gruyter, 2017. https://tud.qucosa.de/id/qucosa%3A38555.
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This paper presents an overview of the research work currently being performed within the frame of project DAAB and its successor DAAB-TX towards the integration of ultra-wideband transceivers operating at mm-wave frequencies and capable of data rates up to 100 Gbits–¹. Two basic systemarchitectures are being considered: integrating a broadband antenna with a distributed amplifier and integrate antennas centered at adjacent frequencies with broadband active combiners or dividers. The paper discusses in detail the design of such systems and their components, fromthe distributed amplifiers and combiners, to the broadband silicon antennas and their single-chip integration. All components are designed for fabrication in a commercially available SiGe:C BiCMOS technology. The presented results represent the state of the art in their respective areas: 170 GHz is the highest reported bandwidth for distributed amplifiers integrated in Silicon; 89 GHz is the widest reported bandwidth for integrated-system antennas; the simulated performance of the two antenna integrated receiver spans 105 GHz centered at 148GHz, which would improve the state of the art by a factor in excess of 4 even against III-V implementations, if confirmed by measurements.
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Papantonis, Dimitrios Papantonis. "Tightly-Coupled Arrays with Reconfigurable Bandwidth." The Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1503046689468305.
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Alibakhshikenari, M., B. S. Virdee, P. Shukla, et al. "Impedance Bandwidth Improvement of a Planar Antenna Based on Metamaterial-Inspired T-Matching Network." IEEE, 2021. http://hdl.handle.net/10454/18486.
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yes<br>In this paper a metamaterial-inspired T-matching network is directly imbedded inside the feedline of a microstrip antenna to realize optimum power transfer between the front-end of an RF wireless transceiver and the antenna. The proposed T-matching network, which is composed of an arrangement of series capacitor, shunt inductor, series capacitor, exhibits left-handed metamaterial characteristics. The matching network is first theoretically modelled to gain insight of its limitations. It was then implemented directly in the 50-Ω feedline to a standard circular patch antenna, which is an unconventional methodology. The antenna’s performance was verified through measurements. With the proposed technique there is 2.7 dBi improvement in the antenna’s radiation gain and 12% increase in the efficiency at the center frequency, and this is achieved over a significantly wider frequency range by a factor of approximately twenty. Moreover, there is good correlation between the theoretical model, method of moments simulation, and the measurement results.
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Liu, Chia-Wei. "Development of Automatic Design Optimization Method for Ultrawide Bandwidth (UWB) Multi-Layer Dielectric Rod Antenna." The Ohio State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=osu1306512723.
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Ghorbani, A., M. Ansarizadeh, and Raed A. Abd-Alhameed. "Bandwidth Limitations on Linearly Polarized Microstrip Antennas." 2010. http://hdl.handle.net/10454/5986.
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The Bode-Fano integral can be used as an objective tool for assessing the bandwidth of antennas, and especially schemes for bandwidth improvement. Results for U-slot and E-slot dual resonant patch antennas suggest that the Fano integral is invariantly related to the overall volume. The Bode-Fano and Youla theories of broadband matching have been applied to the narrowband and wideband lumped equivalent circuit of microstrip antennas to calculate the maximum achievable return loss-bandwidth product of linearly polarized microstrip antennas. Curves are presented showing the relation between the antenna bandwidth, maximum achievable return loss, and parameters of the equivalent circuit. It has been shown that creating parallel slots on the patch despite all potential advantages, may reduce the potential bandwidth of patch antennas.