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1
Kujiraoka, Scott R., e Vries James M. De. "REDUCED APERTURE MICROSTRIP ANTENNAS FOR AIRBORNE VEHICLES". International Foundation for Telemetering, 1998. http://hdl.handle.net/10150/607353.
Testo completoAbstract (sommario):
International Telemetering Conference Proceedings / October 26-29, 1998 / Town & Country Resort Hotel and Convention Center, San Diego, CaliforniaThe available space for the mounting of antennas on missiles and airborne targets is very limited. The vehicle integrator is constantly striving for smaller antenna apertures while requiring increased performance. Microstrip antennas with moderate dielectric loading have been successfully utilized in the past to meet these requirements. With the advent of high dielectric substrate materials, the designer now has the option of further reducing the size of the antenna while preserving the most desirable performance attributes. An example of the size reduction achievable with the new substrate materials is presented along with performance characteristics.
2
Zivanovic, Bojana. "Series-Fed Aperture-Coupled Microstrip Antennas and Arrays". Scholar Commons, 2012. http://scholarcommons.usf.edu/etd/4425.
Testo completoAbstract (sommario):
The focus of this dissertation is on the development and circuit modeling of planar series-fed, linear- and circular-polarized microstrip aperture-coupled antennas and N-element arrays operating in C-band. These arrays were designed to be used as part of airborne or land-based frequency-hopped communication systems. One of the main objectives of this work was to maintain a constant beam angle over the frequency band of operation. In order to achieve constant beam pointing versus frequency, an anti-symmetric series-fed approach using lumped-element circuit models was developed. This series feed architecture also balances the power radiated by each element in the N-element arrays.
The proposed series-fed approach was used in the development of four-element series-fed aperture-coupled arrays with 15% 10 dB impedance bandwidth centered at 5 GHz and a gain of 11.5 dB, to construct an omni-directional radiator. Omni-directional radiators with pattern frequency stability are desired in a multitude of applications; from defense in tactical communications, information gathering, and detection of signal of interest to being part of sensors in medical applications. A hexagonal assembly of six series-fed microstrip aperture-coupled four-element arrays was used to achieve the omni-directional radiation with 0.6 dB peak to peak difference across 360˚ broadside pattern and 0.6 dB gain variation at the specific azimuth angle across 15% impedance bandwidth. Given that each of these six arrays can be individually controlled, this configuration allows for individual pattern control and reconfiguration of the omni-directional pattern with increased gain at specific azimuth angles and the ability to form a directional pattern by employing a fewer number of arrays. Incorporating a beam-forming network or power distribution network is also possible.
Wide 3 dB circular polarization (CP) bandwidth was achieved without external couplers and via only a single feed with a unique Z-slot aperture-coupled microstrip antenna. A single RHCP Z-slot aperture-coupled antenna has ∼10% CP and 10 dB impedance bandwidth. The series-fed network consisting of lumped elements, open-circuited stubs and transmission lines was subsequently developed to maintain more than 5% CP and 10% 10 dB impedance bandwidth in the series-fed four-element Z-slot aperture-coupled CP array that could also be used for-omni-directional radiation.
3
Zhang, Tieren, University of Western Sydney, of Science Technology and Environment College e School of Engineering and Industrial Design. "Applications of microwave holography to the assessment of antennas and antenna arrays". THESIS_CSTE_EID_Zhang_T.xml, 2001. http://handle.uws.edu.au:8081/1959.7/770.
Testo completoAbstract (sommario):
Gabor's original holography, which is the basic theory of modern microwave holographic techniques, is introduced. By computer simulations, it is demonstrated that the conventional holographic approach can be used as a tool to reconstruct aperture field distributions of an antenna with some constraints. Computer simulations of the theory and technique of the improved microwave holographic approach originally introduced by Rahmat-Samii et al. are carried out. The results show that it can be used for surface distortion diagnosis of large reflector antennas. The physical optics integral formulation is derived by general solutions of the vector wave equations. The necessary theory , which is needed to reconstruct the aperture field from near-field measurements both in a rectangular coordinate system and in a cylindrical coordinate system is developed. It is based on the plane wave spectrum and the vector wave modal expansion of an electromagnetic field. By using a simple dipole and other well-defined antennas, computer simulations have been performed. The results show that the technique is rigorous and applicable. It is also demonstrated that the sampling intervals and the number of sampling points should be chosen carefully in order to obtain a satisfactory resolution of the reconstructed aperture field. Furthermore, the simulations carried out in this work reveal that the real aperture field distribution of a dipole antenna has a maximum point at each end of the antenna. This characteristic can only be obtained at a very close distance to the antenna. This study also reveals the significant contributions of the evanescent waves to the aperture reconstruction. A simple but effective method for examining the evanescent waves from the measured near-field is also presented. By using dipoles and other well known antennas and antenna arrays, the experiments were carried out. The experimental results provide reasonable good agreements with the simulations. The technique proposed is effective and accurate.Doctor of Philosophy (PhD)
4
Cheng, Chin-Yuan. "Numerical electromagnetic modeling of a small aperture helical-fed reflector antenna". Ohio : Ohio University, 1998. http://www.ohiolink.edu/etd/view.cgi?ohiou1176838193.
Testo completo
5
Zhang, Tieren. "Applications of microwave holography to the assessment of antennas and antenna arrays". Thesis, View thesis, 2001. http://handle.uws.edu.au:8081/1959.7/770.
Testo completoAbstract (sommario):
Gabor's original holography, which is the basic theory of modern microwave holographic techniques, is introduced. By computer simulations, it is demonstrated that the conventional holographic approach can be used as a tool to reconstruct aperture field distributions of an antenna with some constraints. Computer simulations of the theory and technique of the improved microwave holographic approach originally introduced by Rahmat-Samii et al. are carried out. The results show that it can be used for surface distortion diagnosis of large reflector antennas. The physical optics integral formulation is derived by general solutions of the vector wave equations. The necessary theory , which is needed to reconstruct the aperture field from near-field measurements both in a rectangular coordinate system and in a cylindrical coordinate system is developed. It is based on the plane wave spectrum and the vector wave modal expansion of an electromagnetic field. By using a simple dipole and other well-defined antennas, computer simulations have been performed. The results show that the technique is rigorous and applicable. It is also demonstrated that the sampling intervals and the number of sampling points should be chosen carefully in order to obtain a satisfactory resolution of the reconstructed aperture field. Furthermore, the simulations carried out in this work reveal that the real aperture field distribution of a dipole antenna has a maximum point at each end of the antenna. This characteristic can only be obtained at a very close distance to the antenna. This study also reveals the significant contributions of the evanescent waves to the aperture reconstruction. A simple but effective method for examining the evanescent waves from the measured near-field is also presented. By using dipoles and other well known antennas and antenna arrays, the experiments were carried out. The experimental results provide reasonable good agreements with the simulations. The technique proposed is effective and accurate.
6
Zhang, Tieren. "Applications of microwave holography to the assessment of antennas and antenna arrays". View thesis, 2001. http://library.uws.edu.au/adt-NUWS/public/adt-NUWS20040330.103805/index.html.
Testo completoAbstract (sommario):
Thesis (Ph.D.) -- University of Western Sydney, 2001."Submitted in fulfilment of requirements for the degree of Doctor of Philosophy, School of Engineering and Industrial Design, University of Western Sydney" Includes bibliography.
7
Arakaki, Dean Yasuo. "A reciprocity approach for analyzing radiation from aperture and nicrostrip antennas". Adobe Acrobat reader required to view the full dissertation, 2000. http://www.etda.libraries.psu.edu/theses/approved/WorldWideIndex/ETD-21/index.html.
Testo completo
8
Robinson, Bryan. "Mathematical modelling of aperture coupled patch antennas with multi-layered superstrates". Thesis, Northumbria University, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.245239.
Testo completo
9
Monkevich, James Matthew. "Analysis of Aperture Radiation Using Computer Visualization and Image-Processing Techniques". Thesis, Virginia Tech, 1998. http://hdl.handle.net/10919/36735.
Testo completoAbstract (sommario):
In order to accurately describe the behavior of an antenna, one needs to
understand the radiation mechanisms that govern its operation. One way to
gain such an insight is to view the fields and currents present on a
radiating structure. Unfortunately, in close proximity to an antenna
empirical techniques fail because the measurement probe alters the
operation of the radiating structure. Computational methods offer a solution
to this problem. By simulating the operation of an antenna, one can
obtain electromagnetic field data near (or even internal to) a radiating
structure. However, these computationally intense techniques often
generate extremely large data sets that cannot be adequately interpreted
using traditional graphical approaches.
A visualization capability is developed that allows an analysis of the above-mentioned data sets. With this technique, the data is viewed from a unique, global perspective. This format is well suited for analytical investigations as well as debugging during modeling and simulation. An illustrative example is provided in the context of a rectangular microstrip patch antenna. A comparison is performed between the visualized data and the theory of operation for the microstrip patch in order to demonstrate that radiation mechanisms can be obtained visually.
An additional analysis tool is developed using Gabor filters and image-processing
techniques. This tool allows one to detect and filter electromagnetic
waves propagating with different velocities (both speed and
direction). By doing so, each mode of an antenna can be analyzed
independently. The fields of a multi-moded, open-ended rectangular
waveguide are analyzed in order to demonstrate the effectiveness of these
techniques.
Master of Science
10
Ozdemir, Caner. "Synthetic aperture radar algorithms for imaging antenna-platform scattering /". Digital version accessible at:, 1998. http://wwwlib.umi.com/cr/utexas/main.
Testo completo
11
Teniou, Mounir. "Metasurface antennas for space applications". Thesis, Paris 6, 2017. http://www.theses.fr/2017PA066281/document.
Testo completoAbstract (sommario):
Dans ce rapport, une méthode pour l'implémentation de distributions de champ arbitraires utilisant des metasurfaces tensorielles est présentée. Les metasurfaces modulées sinusoïdalement sont utilisées afin de générer des ondes de fuite avec un contrôle de l'amplitude et de la phase. La distribution de phase du champ d'ouverture désirée est obtenue en utilisant une nouvelle formulation locale du principe de l'holographie. D'autre part, la distribution d'amplitude est contrôlée en faisant varier les indices de modulations ainsi que l'impédance moyenne en fonction de la position. Un contrôle indépendant de l'amplitude et de la phase est obtenu en modulant séparément les composantes du tenseur d'impédance. La formulation théorique est présentée en détails en prenant en compte la méthode d'implémentation ainsi que les contraintes d'adaptation. La méthode proposée est appliquée afin de générer plusieurs types de diagrammes de rayonnement aussi bien en champ lointain qu'en champ proche. La procédure de design a été validée numériquement avec des simulations pour une fréquence de travail de 20GHz. Les résultats obtenus sont en concordances avec les résultats théoriques attendus. Différentes metasurfaces ont ensuite été fabriquées et mesurées pour des fréquences de travail de 10GHz, 12.25GHz et 20GHz. Les résultats de mesures et de simulations démontrent qu'une large variété de distribution d'ouverture avec un contrôle d'amplitude et de phase peut être réalisée avec la méthode proposéeIn this thesis, a method for the implementation of arbitrary aperture field distributions using tensorial metasurfaces is introduced. Sinusoidally modulated metasurfaces are used in order to generate leaky waves with control on both phase and amplitude. The desired aperture phase distribution is obtained using a new local holography formulation. On the other hand, the amplitude distribution is controlled by varying modulation indices and average impedance depending on the position. A separate control of the aperture field components is achieved by modulating the impedance tensor elements independently. The theoretical formulation of the method is presented in details by taking into account the implementation method and antenna adaptation issues. The method is applied to design a wide range of radiation patterns examples both for far-field and near-field applications. The design procedure was first validated with simulations results for a working frequency of 20GHz giving a good agreement with the theoretical results. Several metasurfaces were then manufactured and measured for working frequencies of 10 GHz, 12.25 GHz and 20GHz. The consistency of the measurements and the simulation results proves that a good control of the aperture field phase and amplitude distributions is achieved using the proposed method
12
Biswas, Mahmud. "An Aperture Synthesis Technique for Cylindrical Printed Lens/Transmitarray Antennas with Shaped Beams". Thèse, Université d'Ottawa / University of Ottawa, 2013. http://hdl.handle.net/10393/24262.
Testo completoAbstract (sommario):
Printed lens antennas offer the possibility of realizing shaped beam patterns using no more complexity than is required for pencil beam patterns. Shaped beam patterns can be obtained by appropriately determining the complex transmission coefficient required for each cell (or element) of the printed lens, taking into account the varying feed field over the input surface of the lens. Certain ranges of transmission coefficient amplitude and phase are undesirable (eg. too low an amplitude implies a large reflection at the lens input surface). It would be preferable to constrain the range of values that the transmission coefficient can take as an integral part of the lens synthesis procedure, and thus the transmission coefficient itself needs to be the synthesis variable. In this thesis a synthesis technique for doing this is developed based on the method of generalized projections, modified to “operate” in the space of transmission coefficients. This makes it possible to immediately perceive what influence constraints on the actual transmission coefficients have on the possible radiation pattern performance. In addition, an approach that allows one to constrain the transmission coefficient to values that must be selected from an available database of transmission coefficients is incorporated into the synthesis technique.
13
Baek, Seung Hoon. "STUDY OF MULTI- AND BROAD-BAND INTERNAL ANTENNAS FOR MOBILE APPLICATIONS". OpenSIUC, 2011. https://opensiuc.lib.siu.edu/dissertations/424.
Testo completoAbstract (sommario):
The modified aperture coupled MicroStrip Antenna (MSA) and Planar Inverted F Antenna (PIFA) for mobile applications are studied and presented in this dissertation. The designed antennas are improved multi-band and broad-band characteristics by the modification of radiating elements and/or the ground plane. The novel modified aperture coupling annular-ring antenna fed by stripline is the hybrid structure of the aperture coupling feed MSA and the proximity feed MSA. The proximity feed enable to concentrate the field strength toward the direction of the radiating element and the modified aperture layer contributes to provide the maximum coupling to the radiating element. The measurement bandwidths of the Aperture Coupling Proximity Feed Hybrid MSA #1(ACPF-HMSA#1, design #1) and ACPF-HMSA #2 (design #2) are 185MHz (7%) and 105MHz (4.1%), VSWR in less than 2, respectively. Two layers Planar Inverted F Antenna (PIFA) with the modification of the ground and radiating element was studied. The inserted T-shaped or L-shaped ground and inserted a slot and slits on radiating elements help to adjust the resonant frequencies to the target applications. The result of PIFA #3 (design #3) is presented a significant board-band characteristic on the upper band by 910MHz (from 1.45GHz to 2.36GHz) with VSWR less than 2.5. It covers GPS, DCS, PCS, and UMTS bands. Novel internal loop planar inverted F antennas (L-PIFA) with Inserted Concentrated Annular Rings (ICAR) and Inserted Loop Inductors (ILI) are presented as design #4 (ICAR-L-PIFA #4) and design #5 (ILI-L-PIFA #5), respectively. The simple loop structure consists of a meandered line. It increases the capacitance between adjacent lines. The Inserted annular-rings and loop inductors provide inductance values to the main loop antennas. Therefore, the impedance bandwidth of the design #4 is 570MHz (from 1.69GHz to 2.26GHz) with VSWR less than 2.5. And, the impedance bandwidth of the design #5 is 275MHz (from 1.63GHz to 1.905GHz) and 465MHz (from 2.19GHz to 2.655GHz) with VSWR less than 2.5.
14
Cuiñas, Gómez Íñigo, Luis Landesa e Pino Marcos Rodríguez. "Using wavelets in applied electromagnetics : an algorithm for efficient pattern synthesis of linear aperture antennas". Pontificia Universidad Católica del Perú, 2014. http://repositorio.pucp.edu.pe/index/handle/123456789/97009.
Testo completoAbstract (sommario):
Pattern synthesis of linear aperture antennas is a classical problem in Applied Electromagnetics with a great number of resolving methods. In this paper, a new algorithm that uses wavelets to compute the solution is presented. The new method reaches a good approximation of the aperture field from the antenna radiation pattern, using the Haar wavelet basis. Results prove the performance of the proposed method.
15
Chim, Kwok Chi. "Investigating the impact of smart antenna on SAR /". View Abstract or Full-Text, 2002. http://library.ust.hk/cgi/db/thesis.pl?ELEC%202002%20CHIM.
Testo completoAbstract (sommario):
Thesis (M. Phil.)--Hong Kong University of Science and Technology, 2002.Includes bibliographical references (leaves 53-54). Also available in electronic version. Access restricted to campus users.
16
Iseri, Kadir. "Analysis Of Dual-polarized Aperture-coupled Microstrip Antennas With H-shaped Slots And Equivalent Circuit Modeling Of H-shaped Slots". Master's thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12614527/index.pdf.
Testo completoAbstract (sommario):
This thesis includes the design, production and measurement of a wideband dualpolarized
X-band aperture-coupled microstrip patch antenna. The wideband and
dual-polarized operation is achieved through the use of H-shaped coupling slots.
Therefore, the equivalent circuit modeling of a microstrip line fed H-shaped slot is
also studied in this thesis. A step-by-step procedure is followed during the design
process of the dual-polarized aperture-coupled microstrip antenna. First, an
aperture-coupled microstrip antenna with a single rectangular slot, that exhibits a
wideband characteristic for single polarization, is designed. Then, the design
procedure is repeated for an antenna with H-shaped slot in order to satisfy the same
specifications with a shorter slot. Finally, dual-polarized aperture-coupled
microstrip antenna is designed. At this configuration, two H-shaped slots are used
and they are placed orthogonal to each other. During the design process, the effects
of antenna parameters on the input impedance characteristics of the antenna are
investigated. These parametric analyses are done in CST Microwave Studio®. The v designed dual-polarized wideband aperture-coupled microstrip antenna is manufactured. Simulation results and measurement results are compared. During the equivalent circuit modeling of an H-shaped slot fed by a microstrip line, an approach based on the reciprocity theorem is utilized. The method was originally proposed for rectangular shaped slots, in this thesis it is generalized for arbitrarily shaped slots. Software codes are developed in MATLAB to calculate the equivalent impedance of the slot.
17
Charland, Shawn Carleton University Dissertation Engineering Electrical. "An investigation of the extent of the fresnel region of aperture antennas with attention to superdirectivity". Ottawa, 1985.
Cerca il testo completo
18
Abdel-Rahman, Mohamed A. "Numerical Reconstruction and Applications of Acoustic and Electromagnetic Ultra-Wideband Localized Pulses Generated by Dynamic Aperture Antennas". Diss., Virginia Tech, 1997. http://hdl.handle.net/10919/26335.
Testo completoAbstract (sommario):
A study is undertaken of the numerical reconstruction of acoustic and electromagnetic (EM) localized waves (LWs). The latter are carrier-free ultra-wideband pulses characterized by large focusing depths and extended ranges of localization. Special emphasis is placed on finite energy LWs that can be generated by dynamic aperture antennas with independently addressable elements. The reconstruction techniques are based on Huygens and Rayleigh-Sommerfeld integral I and II representations, both in the time and frequency domains. In contradistinction to the Weyl representation,they lend themselves to the physical realization of space-time aperture sources capable of generating localized wave solutions propagating away from the aperture plane. A detailed comparison of the three reconstruction techniques has been carried out in connection with LW solutions to the scalar wave equation, especially with respect to their handling of acausal components incorporated in the aperture excitation fields. In addition, a study is presented of the characteristic properties of LWs propagating through dispersive media modeled by the Klein-Gordon equation. It is demonstrated that contrary to expectation, the depletion of the spectral components of the LW Klein-Gordon field may be slower than that associated with the free space scalar field. Previous work by Power et al. [73] is extended by studying the acoustic bistatic scattering of a modified power spectrum (MPS) pulse from rigid and compressible spheres. The analysis allows the extraction of the radius of a sphere from the backscattered data. Finally, a special class of electromagnetic (EM) LWs, referred to as azimuthally polarized X waves (APXWs), is derived and their reconstruction is addressed, both in the time and frequency domains.Ph. D.
19
Okuducu, Yusuf. "Dual Band Microstrip Patch Antenna Structures". Master's thesis, METU, 2005. http://etd.lib.metu.edu.tr/upload/2/12606859/index.pdf.
Testo completoAbstract (sommario):
Wideband and dual band stacked microstrip patch antennas are investigated for the new wideband and dual band applications in the area of telecommunications. In this thesis, aperture-coupled stacked patch antennas are used to increase the bandwidth of the microstrip patch antenna. By this technique, antennas with 51% bandwidth at 6.1 GHz and 43% bandwidth at 8 GHz satisfying S11<-15 dB are designed, manufactured and measured. A dual-band aperture coupled stacked microstrip patch antenna operating at 1.8 GHz with 3.8% bandwidth and at 2.4 GHz with 1.6% bandwidth is designed, produced and measured for mobile phone and WLAN applications. In addition, an aperture coupled stacked microstrip patch antenna which operates at PCS frequencies in 1.7-1.95 GHz band is designed. Dual and circularly polarized stacked aperture coupled microstrip patch antennas are also investigated. A triple band dual polarized aperture coupled stacked microstrip patch antenna is designed to operate at 900 MHz, at 1.21 GHZ and at 2.15 GHz. Mutual coupling between aperture coupled stacked microstrip patch antennas are examined and compared with the coupling of aperture coupled microstrip patch antennas
20
Kwinana, Phumezo M. "A T-resonator technique for aperture plane admittance parameters of electrically short RF monopoles". Thesis, Stellenbosch : University of Stellenbosch, 2006. http://hdl.handle.net/10019.1/1501.
Testo completoAbstract (sommario):
Thesis (MScEng (Electrical and Electronic Engineering))--University of Stellenbosch, 2006.This thesis focuses on the coaxial-microstrip T-resonator measurement technique to determine the aperture plane capacitance and radiation resistance of electrically short monopoles above a finite ground plane at Radio Frequencies. The determination of these impedance parameters is of interest as they are needed in the Thévenin equivalent circuit of the monopole to establish the relationship between the monopole, the electromagnetic field within which it is immersed, and its surrounding medium properties. Electromagnetically short monopoles are used in various applications such as in permittivity and biomedical measurement techniques and near-field metrology. The coaxial-microstrip device allows the measurement of transmission coefficient nulls when connected to the network analyser. By measuring the frequency shift in transmission null points and analysing the results, the capacitance of short monopoles of various lengths can be obtained. The radiation resistance of the monopole can also be determined by comparing the depth of transmission coefficient nulls points at various resonant frequencies. Monopoles ranging from flush-mounted to various sizes of protruding centre conductors, both bare and insulated, are investigated in the frequencies ranging from 45 MHz to 3 GHz. The experimental results compare well with FEKO numerical predictions at the ranges where this technique is applicable. The technique is however not applicable near and beyond the resonant frequency of the monopole where it is considered to be electrically long. Measurements to obtain monopole impedance parameters were conducted by connecting the device to the HP 8510C Network Analyser. To enhance accuracy, the Network Analyser was calibrated using a high quality calibration kit with precisely defined standards. The technique used was found to accurately yield capacitances in the range of 0.0211 to 1 pF and radiation resistances in the range of 0.9245 to 12.1 Ohms. These results were obtained for monopoles of length 0.0062 < h/l < 0.24. Results from literature, viz. W.R Scott, R.W.P. King and L.J. Cooper, show radiation resistance in the ranges: 2.5 to 35 Ohms (0.079 < h/l < 0.22), 1.26 to 74.08 Ohms (0.026 < h/l < 0.28) and 5.59 to 74.98 Ohms (0.1 < 0.28) for electrically short monopoles. The results of this work are compared with those in the literature and show variations of less than 6%. A technique capable of accurately measuring capacitance and radiation resistance of the monopole at various lengths of protruding centre conductor has been developed. The capacitance for a flush probe compares very well (agreement is less than 6%) when compared with those obtained by the previous researchers. The technique is capable of yielding accurate results radio frequencies in the challenging low radiation resistance range around 1 Ohm.
21
Kacar, Merve. "Direct Digital Manufacturing of Multi-layer Wideband Ku-band Patch Antennas". Scholar Commons, 2017. https://scholarcommons.usf.edu/etd/7411.
Testo completoAbstract (sommario):
Design and performance of fully-printed Ku-band aperture coupled patch antennas fabricated by a direct digital manufacturing (DDM) approach that integrates fused deposition modeling (FDM) of acrylonitrile butadiene styrene (ABS) thermoplastic with in-situ micro-dispensing of conductive silver paste (CB028) are reported. Microstrip line characterizations are performed and demonstrate that misalignment of ABS substrate deposition direction with microstrip line micro-dispensing direction can degrade the effective conductivity up to 60% within the Ku-band, and must be taken into consideration in antenna array feed network designs. Specically, over 125 µm thick ABS substrate, RF loss of 0.052 dB/mm is obtained at 18 GHz, demonstrating the feasibility of additively manufactured RF devices within the Ku-band. By varying ABS inll ratios and resorting to multi-layer printing with custom substrate thicknesses, single and stacked patch antennas are designed, fabricated, and characterized with bandwidth performances up to 35%, and radiation efficiencies up to 90%. This extensive utilization of the design flexibilities provided by the direct digital manufacturing (i.e. customized substrate thicknesses, multiple substrates with varying infill ratios, and in-situ micro-dispensing of conductors) distinguishes the present work from the recently reported 3-D printed antennas. Compared to the existing work in literature, the antennas presented within this thesis stand out as being fully printed structures, operating in higher frequency range (i.e. Ku-band), and exhibiting high radiation efficiencies with wide bandwidth performances.
22
Gagnon, Nicolas. "Phase Shifting Surface (PSS) and Phase and Amplitude Shifting Surface (PASS) for Microwave Applications". Thesis, Université d'Ottawa / University of Ottawa, 2011. http://hdl.handle.net/10393/19826.
Testo completoAbstract (sommario):
This thesis describes an electrically thin surface used for electromagnetic applications in the microwave regime. The surface is free-standing and its primary purpose is to modify the phase distribution, or the phase and amplitude distribution of electromagnetic fields propagating through it: it is called phase shifting surface (PSS) in the first case, and phase and amplitude shifting surface (PASS) in the second case. For practical applications, the surface typically comprises three or four layers of metallic patterns spaced by dielectric layers. The patterns of the metallic layers are designed to locally alter the phase (and amplitude in the case of the PASS) of an incoming wave to a prescribed set of desired values for the outgoing wave. The PSS/PASS takes advantage of the reactive coupling by closely spacing of the metallic layers, which results in a larger phase shift range while keeping the structure significantly thin. The PSS concept is used to design components such as gratings and lens antennas which are presented in this document. The components are designed for an operating frequency of 30 GHz. The PSS phase grating gives high diffraction efficiency, even higher than a dielectric phase grating. Several types of lens antennas are also presented, which show comparable performance to that of a conventional dielectric plano-hyperbolic lens antenna with similar parameters. The PASS concept is used in a beam shaping application in which a flat-topped beam antenna is designed. This work demonstrates the potential for realising thin, lightweight and low-cost antennas at Ka band, in particular for substituting higher-gain antenna technologies such as conventional dielectric shaped lens antennas.
23
Jacmenovic, Dennis, e dennis_jacman@yahoo com au. "Optimisation of Active Microstrip Patch Antennas". RMIT University. Electrical and Computer Engineering, 2004. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20060307.144507.
Testo completoAbstract (sommario):
This thesis presents a study of impedance optimisation of active microstrip patch antennas to multiple frequency points. A single layered aperture coupled microstrip patch antenna has been optimised to match the source reflection coefficient of a transistor in designing an active antenna. The active aperture coupled microstrip patch antenna was optimised to satisfy Global Positioning System (GPS) frequency specifications. A rudimentary aperture coupled microstrip patch antenna consists of a rectangular antenna element etched on the top surface of two dielectric substrates. The substrates are separated by a ground plane and a microstrip feed is etched on the bottom surface. A rectangular aperture in the ground plane provides coupling between the feed and the antenna element. This type of antenna, which conveniently isolates any circuit at the feed from the antenna element, is suitable for integrated circuit design and is simple to fabricate. An active antenna design directly couples an antenna to an active device, therefore saving real estate and power. This thesis focuses on designing an aperture coupled patch antenna directly coupled to a low noise amplifier as part of the front end of a GPS receiver. In this work an in-house software package, dubbed ACP by its creator Dr Rod Waterhouse, for calculating aperture coupled microstrip patch antenna performance parameters was linked to HP-EEsof, a microwave computer aided design and simulation package by Hewlett-Packard. An ANSI C module in HP-EEsof was written to bind the two packages. This process affords the client the benefit of powerful analysis tools offered in HP-EEsof and the fast analysis of ACP for seamless system design. Moreover, the optimisation algorithms in HP-EEsof were employed to investigate which algorithms are best suited for optimising patch antennas. The active antenna design presented in this study evades an input matching network, which is accomplished by designing the antenna to represent the desired source termination of a transistor. It has been demonstrated that a dual-band microstrip patch antenna can be successfully designed to match the source reflection coefficient, avoiding the need to insert a matching network. Maximum power transfer in electrical circuits is accomplished by matching the impedance between entities, which is generally acheived with the use of a matching network. Passive matching networks employed in amplifier design generally consist of discrete components up to the low GHz frequency range or distributed elements at greater frequencies. The source termination for a low noise amplifier will greatly influence its noise, gain and linearity which is controlled by designing a suitable input matching network. Ten diverse search methods offered in HP-EEsof were used to optimise an active aperture coupled microstrip patch antenna. This study has shown that the algorithms based on the randomised search techniques and the Genetic algorithm provide the most robust performance. The optimisation results were used to design an active dual-band antenna.
24
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.
Testo completoAbstract (sommario):
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.
25
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.
Testo completoAbstract (sommario):
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.General Secretariat of Education and Scientific Research Libya
26
Goksu, Mesut. "Analysis Of Slot Coupled Patch Antennas Using Closed Form Green". Master's thesis, METU, 2009. http://etd.lib.metu.edu.tr/upload/12610996/index.pdf.
Testo completoAbstract (sommario):
In this thesis, an analysis technique for the slot coupled patch antennas using MoM in
conjunction with the closed form Green&rsquos functions is presented. Slot coupled patch antennas are fed by a microstrip open stub which is coupled to the patch through an electrically small slot. Current distributions over the microstrip line, slot line and the patch are represented by rooftop basis functions. First, a relatively simple structure, microstrip coupled slot line is investigated using the proposed technique. Then the method is extended to the slot coupled patch antenna geometry. By using the method, current distributions on the feedline and the patch are calculated for a generic slot coupled patch antenna. Then by using the distributions, return scattering parameters of the antenna is approximated with complex exponentials using Prony&rsquo
s method. A parametric study is carried out to observe the effect of each antenna component on the antenna performance. Current distributions and return loss calculations are repeated for modified antennas to observe and demonstrate the performance differences. All simulations are verified using HFSS®
software and the results available in the literature.
27
Alam, Muhammad Faiz, e Muhammad Faiz Alam. "Dielectric Resonator Antennas (DRA) for satellite and body area network applications". Phd thesis, Université Paris-Est, 2012. http://tel.archives-ouvertes.fr/tel-00795292.
Testo completoAbstract (sommario):
Technologies such as direct broad cast satellite system (DBSS), Geosynchronous Earth Orbit (GEO) and Low Earth Orbit (LEO) satellite communications , global positioning system (GPS), high accuracy airborne navigation system and a large variety of radar systems demand for high level of antenna performance. Similar is the requirement for upcoming land based wireless systems such as cellular and indoor communication systems that is needed some more specific and additional features added to the antenna to compensate for the deficiencies encountered in system's performance. Though metallic antennas are capable enough to fulfil all the operational requirements, however at very high frequencies and under hostile temperature conditions they are constrained to face certain limitations. To avoid these constraints the performance of Dielectric Resonator Antennas (DRAs) is evaluated and their new applications are proposed. In the thesis, two types of antenna applications are sought :-First is for tracking and satellite applications that needs a larger aperture coverage in elevation plane. This coverage is realized with a good CP purity by proposing two ports dual linearly polarized DRA working at X-band. The DRA is excited by two orthogonal H-shaped aperture slots yielding two orthogonal polarizations in the broadside direction. A common impedance bandwidth of 5.9% and input port isolation of -35 dB are obtained. The broadside radiation patterns are found to be highly symmetric and stable with cross polarization levels -15dB or better over the entire matching frequency band. The maximum measured gain is found to be 2.5dBi at 8.4 GHz.- The 2nd type of antenna is a dual pattern diversity antenna to be used in the Body Area Network (BAN) context. This antenna combines a slot loop and DRA yielding broadside and end-fire radiation patterns respectively. Based upon the feeding techniques, the DG antenna is further divided into two categories one with planar feeds and the other with non-planar feeds (slot loop excited by planar CPW but DRA excited by vertical monopole) .Both types are successfully designed and measured upon body when configured into different propagation scenarios. The non-planar feeds antenna allows wider common impedance bandwidths than the planar feeds (4.95% vs 1.5%).In both cases, a maximum value of DG=9.5dB was achieved when diversity performance tests were carried out in rich fading environments. This value is close to the one (10 dB) theoretically reached in a pure Rayleigh environment and was obtained with efficiencies of 70% and 85% for the slot loop and the DRA respectively. Therefore, we conclude that these antennas could be used on the shoulders or the chest of professional clothes (firemen, policemen, soldier) where full planar integration is not a key issue but where the communication must be efficient in harsh environments and for various gestures, positions and scenarios
28
Iliopoulos, Ioannis. "Engineering the near field of radiating systems at millimeter waves : from theory to applications". Thesis, Rennes 1, 2017. http://www.theses.fr/2017REN1S165.
Testo completoAbstract (sommario):
L'objectif général est de développer un nouvel outil numérique dédié à la focalisation en 3D de l'énergie en zone de champ très proche par un système antennaire. Cet outil permettra de définir la distribution spatiale complexe des champs dans l'ouverture rayonnante afin de focaliser l'énergie sur un volume quelconque en zone de champ réactif. L'hybridation de cet outil avec un code de calcul dédié à l'analyse rapide d‘antennes SIW par la méthode des moments permettra de synthétiser une antenne SIW ad-hoc. Les structures antennaires sélectionnées seront planaires comme par exemple les antennes RLSA (Radial Line Slot Array). Les dimensions de l'antenne (positions, dimensions et nombre de fentes) seront définies à l'aide des outils décrits ci-dessus. Les résultats numériques ainsi obtenus seront validés d'abord numériquement par analyse électromagnétique globale à l'aide de simulateurs commerciaux, puis expérimentalement en ondes millimétriques (mesure en zone de champ très proche). Pour atteindre ces objectifs, nous avons défini quatre tâches principales : Développement d'un outil de synthèse de champ dans l'ouverture rayonnante (formulation théorique couplée à une méthode dite des projections alternées) ; développement d'un outil de calcul rapide (sur la base de traitements par FFT) du champ électromagnétique rayonné en zone de champ proche par une ouverture rayonnante, et retro-propagation ; hybridation de ces algorithmes avec un code de calcul (méthode des moments) en cours de développement à l'IETR et dédié à l'analyse très rapide d'antennes en technologie SIW ; conception d'une preuve ou plusieurs preuves de concept, et validations numérique et expérimentale des concepts proposésWith the demand for near-field antennas continuously growing, the antenna engineer is charged with the development of new concepts and design procedures for this regime. From the microwave and up to terahertz frequencies, a vast number of applications, especially in the biomedical domain, are in need for focused or shaped fields in the antenna proximity. This work proposes new theoretical methods for near-field shaping based on different optimization schemes. Continuous radiating planar apertures are optimized to radiate a near field with required characteristics. In particular, a versatile optimization technique based on the alternating projection scheme is proposed. It is demonstrated that, based on this scheme, it is feasible to achieve 3-D control of focal spots generated by planar apertures. Additionally, with the same setup, also the vectorial problem (shaping the norm of the field) is addressed. Convex optimization is additionally introduced for near-field shaping of continuous aperture sources. The capabilities of this scheme are demonstrated in the context of different shaping scenarios. Additionally, the discussion is extended to shaping the field in lossy stratified media, based on a spectral Green's functions approach. Besides, the biomedical applications of wireless power transfer to implants and breast cancer imaging are addressed. For the latter, an extensive study is included here, which delivers an outstanding improvement on the penetration depth at higher frequencies. The thesis is completed by several prototypes used for validation. Four different antennas have been designed, based either on the radial line slot array topology or on metasurfaces. The prototypes have been manufactured and measured, validating the overall approach of the thesis
29
Alam, Muhammad Faiz. "Dielectric Resonator Antennas (DRA) for satellite and body area network applications". Thesis, Paris Est, 2012. http://www.theses.fr/2012PEST1057/document.
Testo completoAbstract (sommario):
Dans cette thèse, on vise deux types d'applications de l’antenne à résonateur diélectrique (DRA): 1) La réalisation d’un élément rayonnant pour un réseau phasé embarqué sur un véhicule terrestre ou un avion. Cet élément de base requiert une couverture en élévation supérieure à celle des éléments imprimés pour permettre une poursuite typique comprise entre ±70°. La couverture dans un cône large est assurée avec une bonne pureté de polarisation circulaire en alimentant l’antenne à travers deux ouvertures à fente en H orthogonales parfaitement découplées en bande X. 2) La deuxième structure est destinée à la diversité d’antennes dans le contexte des réseaux corporels embarqués ou Body Area Network (BAN). L’antenne à diversité combine une antenne fente en boucle avec un DRA ce qui permet dans un espace compact de réaliser des diagrammes de type “broadside” et “endfire” respectivement. Les alimentations considérées sont de 2 types; Soit purement planaire (microruban et coplanaire) soit mixte en combinant une alimentation coaxiale et une alimentation coplanaire. Caractéristiques principales des antennes à résonateur diélectrique (DRA): Pour répondre aux attentes des utilisateurs en termes de débit, les systèmes de communication sans fils se tournent vers des fréquences de plus en plus élevées. La conséquence de cette montée en fréquence est notamment l’augmentation des pertes au niveau des éléments conducteurs et donc une diminution de l’efficacité globale des systèmes de communication. Dans ces circonstances, les DRA offre de meilleurs résultats par rapport à d'autres familles d'antennes à base d’éléments métalliques. De plus, les DRA offrent des pertes diélectriques négligeables, elles sont peu sensibles aux variations de température et s’intègrent facilement sur des technologies de fabrication planairesTechnologies such as direct broad cast satellite system (DBSS), Geosynchronous Earth Orbit (GEO) and Low Earth Orbit (LEO) satellite communications , global positioning system (GPS), high accuracy airborne navigation system and a large variety of radar systems demand for high level of antenna performance. Similar is the requirement for upcoming land based wireless systems such as cellular and indoor communication systems that is needed some more specific and additional features added to the antenna to compensate for the deficiencies encountered in system's performance. Though metallic antennas are capable enough to fulfil all the operational requirements, however at very high frequencies and under hostile temperature conditions they are constrained to face certain limitations. To avoid these constraints the performance of Dielectric Resonator Antennas (DRAs) is evaluated and their new applications are proposed. In the thesis, two types of antenna applications are sought :-First is for tracking and satellite applications that needs a larger aperture coverage in elevation plane. This coverage is realized with a good CP purity by proposing two ports dual linearly polarized DRA working at X-band. The DRA is excited by two orthogonal H-shaped aperture slots yielding two orthogonal polarizations in the broadside direction. A common impedance bandwidth of 5.9% and input port isolation of -35 dB are obtained. The broadside radiation patterns are found to be highly symmetric and stable with cross polarization levels -15dB or better over the entire matching frequency band. The maximum measured gain is found to be 2.5dBi at 8.4 GHz.- The 2nd type of antenna is a dual pattern diversity antenna to be used in the Body Area Network (BAN) context. This antenna combines a slot loop and DRA yielding broadside and end-fire radiation patterns respectively. Based upon the feeding techniques, the DG antenna is further divided into two categories one with planar feeds and the other with non-planar feeds (slot loop excited by planar CPW but DRA excited by vertical monopole) .Both types are successfully designed and measured upon body when configured into different propagation scenarios. The non-planar feeds antenna allows wider common impedance bandwidths than the planar feeds (4.95% vs 1.5%).In both cases, a maximum value of DG=9.5dB was achieved when diversity performance tests were carried out in rich fading environments. This value is close to the one (10 dB) theoretically reached in a pure Rayleigh environment and was obtained with efficiencies of 70% and 85% for the slot loop and the DRA respectively. Therefore, we conclude that these antennas could be used on the shoulders or the chest of professional clothes (firemen, policemen, soldier) where full planar integration is not a key issue but where the communication must be efficient in harsh environments and for various gestures, positions and scenarios
30
Gosal, Gurpreet Singh. "The use of Inverse Neural Networks in the Fast Design of Printed Lens Antennas". Thesis, Université d'Ottawa / University of Ottawa, 2015. http://hdl.handle.net/10393/32249.
Testo completoAbstract (sommario):
In this thesis the major objective is the implementation of the inverse neural network concept in the design of printed lens (transmitarray) antenna. As it is computationally extensive to perform full-wave simulations for entire transmitarray structure and thereafter perform optimization, the idea is to generate a design database assuming that a unit cell of the transmitarray is situated inside a 2D infinite periodic structure. This way we generate a design database of transmission coefficient by varying the unit cell parameters. Since, for the actual design, we need dimensions for each cell on the transmitarray aperture and to do this we need to invert the design database.
The major contribution of this thesis is the proposal and the implementation of database inversion methodology namely inverse neural network modelling. We provide the algorithms for carrying out the inversion process as well as provide check results to demonstrate the reliability of the proposed methodology. Finally, we apply this approach to design a transmitarray antenna, and measure its performance.
31
Gardenier, Peter H. "Antenna aperture phase retrieval". Thesis, University of Canterbury. Electrical and Electronic Engineering, 1990. http://hdl.handle.net/10092/6028.
Testo completoAbstract (sommario):
Geometrical defects of a high gain reflector antenna can cause the radiation pattern of the antenna to fail to meet its specifications. These defects give rise to loss of gain, widening of the main beam and raising of sidelobes. The geometrical defects can be identified, and subsequently corrected, by utilizing information contained in the phase of the copolar aperture field distribution. For technical reasons, this phase can be difficult or inconvenient to measure directly. Therefore, indirect methods of deducing the phase are often preferred.
This thesis introduces an iterative algorithm, called the modified Gerchberg-Saxton algorithm, which has been developed for retrieving the copolar aperture field phase distribution from the far field copolar amplitude pattern. In order to aid convergence of this algorithm, it incorporates information concerning the design and any known aspect of the antenna. The modified Gerchberg-Saxton algorithm is based on the conventional Gerchberg-Saxton algorithm, originally developed for electron microscopy, but incorporates features of Fienup's phase retrieval algorithms.
This thesis reviews radio engineering theory with an emphasis on high gain reflector antennas. In particular, the Fourier transform relationship between the copolar aperture field distribution and the copolar radiation pattern is critically examined. The problem of retrieving the copolar aperture field distribution from the amplitude of its Fourier transform is called a Fourier phase problem. The Fourier phase problem, the uniqueness of its solutions and iterative algorithms for solving it are discussed. Other established methods for determining geometrical defects of an antenna are described and their relative advantages and disadvantages are assessed. The main advantage of the modified Gerchberg-Saxton algorithm is that it requires measurement of only a single copolar amplitude pattern.
The modified Gerchberg-Saxton algorithm is evaluated by applying it to computer simulated data and to measured amplitude patterns of an acoustic antenna. This evaluation illustrates the relationship between the accuracy of the data to which the algorithm is applied and the accuracy of the retrieved copolar aperture field phase distribution. The performance of the algorithm appears to be insensitive to the location and dimensions of the geometrical defects of the antenna. The optimum form of the algorithm seems to be versatile and robust enough to offer real hope of being able to retrieve, to a useful level of accuracy, the phase of the aperture field from a single measured radiation pattern amplitude (i.e. there is no need to measure the phase of the radiation pattern).
32
Ventas, Muñoz de Lucas Jesus. "Active- integrated aperture lens antenna". Thesis, KTH, Skolan för elektroteknik och datavetenskap (EECS), 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-303003.
Testo completoAbstract (sommario):
Luneburg lens antennas are gaining popularity in new communication systems, as increasingly higher frequencies are being used. Broadband fully- metallic implementations of Luneburg lenses, such as Rinehart- Luneburg lenses, constitute simple, cheap and efficient beamformers. However, Luneburg lenses need to have one amplifier per port, which constrains the maximum power that can be transmitted and increases the cost of the system. In this thesis, an investigation to integrate amplifiers within the aperture of Luneburg lenses is conducted. This concept allows for increasing the maximum transmitted power with reduced costs. Special attention has been paid to the design principles. Active integration without altering the Luneburg lens functionality has been a key task in this work. A design in Kaband (2640 GHz) has been also exemplified in order to show the feasibility of the concept. The final design includes transitions to a PCB in the aperture of the Luneburg lens, where amplifiers can be mounted. Good results were obtained in terms of directivity and side- lobe levels, and the antenna achieves a scanning range up to ±64° with reasonable scan losses.Luneburgs linsantenner blir alltmer populära i nya kommunikationssystem eftersom högre frekvenser används. Det finns bredbandiga Luneburg- linser som är helt metallicof, som Rinehart- Luneburg- linsen, vilket gör den till en enkel, billig och effektiv strålformare. Luneburg- linser måste dock ha en förstärkare per port, vilket begränsar den maximala sändningseffekten och ökar kostnaden för systemet. I den här avhandlingen undersöks hur man kan integrera förstärkare, monterade på ett PCB, i Luneburg- linsernas öppning. Detta tillvägagångssätt gör det möjligt att öka den maximala överförda effekten och minska kostnaderna. Särskild uppmärksamhet har ägnats åt konstruktionsprinciperna. Att hitta en geometri som gör det möjligt att integrera förstärkare inuti utan att ändra Luneburg- linsens strålningsegenskaper har varit en viktig uppgift i detta arbete. En specifik konstruktion för Ka- bandet (2640 GHz) har också utvecklats för att visa att konceptet är genomförbart. Den slutliga utformningen omfattar övergångar till ett kretskort i Luneburg- linsens öppning, där förstärkare kan monteras. Resultaten visar på rimliga värden för riktverkan och sidolobnivåer, och antennen har ett avläsningsområde på upp till ±64°.
Las lentes de Luneburg se están haciendo cada vez más populares en los nuevos sistemas de comunicaciones, debido al uso de frecuencias cada vez más altas. Existen implementaciones totalmente metálicas y de banda ancha de las lentes de Luneburg, como las lentes de Rinehart- Luneburg, lo que las convierte en conformadores de haz simples, baratos y eficientes. Sin embargo, las lentes de Luneburg necesitan tener un amplificador en cada uno de sus puertos, lo que limita la máxima potencia que se puede transmitir e incrementa el coste del sistema. En este trabajo de fin de Máster se lleva a cabo una investigación que busca la integración de amplificadores, montados en una PCB, dentro de la apertura de las lentes de Luneburg. Este enfoque permite transmitir potencias mayores y además reduce costes. Se ha puesto especial atención en los principios de diseño. Encontrar una geometría que permite integrar amplificadores dentro sin alterar las características de radiación de la lente de Luneburg ha sido uno de los puntos clave de este trabajo. También se ha desarrollado un diseño específico en banda Ka (2640 GHz) para mostrar la viabilidad de la idea. El diseño final incluye transiciones a un PCB en la apertura de la lente, donde se pueden incluir los amplificadores. Los resultados muestran valores razonables de directividad y lóbulos secundarios, y la antena permite un rango de escaneo de hasta ±64°.
33
Civerolo, Michael Paul. "Aperture Coupled Microstrip Antenna Design and Analysis". DigitalCommons@CalPoly, 2010. https://digitalcommons.calpoly.edu/theses/300.
Testo completoAbstract (sommario):
A linearly-polarized aperture coupled patch antenna design is characterized and optimized using HFSS antenna simulation software. This thesis focuses on the aperture coupled patch antenna due to the lack of fabrication and tuning documentation for the design of this antenna and its usefulness in arrays and orthogonally polarized communications. The goal of this thesis is to explore dimension effects on aperture coupled antenna performance, to develop a design and tuning procedure, and to describe performance effects through electromagnetic principles.
Antenna parameters examined in this study include the dimensions and locations of the substrates, feed line, ground plane coupling slot, and patch. The operating frequency, input VSWR, percent bandwidth, polarization ratio, and broadside gain are determined for each antenna configuration.
The substrate material is changed from RT Duroid (material in nominal HFSS design) to FR4 due to lower cost and availability. The operating frequency is changed from 2.3GHz (specified in nominal HFSS design) to 2.4GHz for wireless communication applications. Required dimensional adjustments when changing substrate materials and operating frequencies for this antenna are non-trivial and the new design procedure is used to tune the antenna.
The antenna is fabricated using 59mil thick double and single sided FR4 boards joined together with double sided 45mil thick acrylic tape. The antenna is characterized in an anechoic chamber and experimental results are compared to theoretical predictions. The results show that the new design procedure can be successfully applied to aperture coupled antenna design.
34
Ferland, Etienne. "Analysis and design of a synthetic aperture radar membrane antenna". Thesis, McGill University, 2005. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=95659.
Testo completoAbstract (sommario):
Use of a membrane antenna on remote sensing satellites is now possible because of new materials and manufacturing technologies. This would allow space organizations to cut cost and weight by a non-negligible factor. All possible failure modes must be fully analyzed before these are sent to space. With membrane antennas, a new type of failure mode must be looked at: wrinkling. The wrinkling of the emitting layer could greatly undermine the performance of the antenna by modifying the orientation of the radiating elements rendering the wrinkle-affected area useless. It has been anticipated that such wrinkling could occur under temperature variations in space. There is currently a lack of available analyses for predicting with confidence the behaviour of such stretched material in a space environment. This work develops and establishes a finite-element approach as a potential method for predicting wrinkle height and orientation under thermal loads. Some designs for controlling the wrinkles are introduced with the benefits of optimizing the antenna area. The influence of the variation of the parabolic edges and corner cut-offs on the required cable load has been studied. Dynamic behaviour poses a concern, especially with a larger and flexible membrane and has been studied to determine the natural frequencies and the response of the antenna to on-orbit micro-vibrations .L'utilisation d'une antenne membrane sur les satellites de télédétection est désormais possible par la fabrication de nouveaux matériaux et le développement de nouvelles techniques manufacturières. Une telle antenne permettrait aux organisations possédant de tels satellites d'en réduire le poids et du fait même le coût de lancement par un facteur important. Toutes les causes d'échec, de panne ou d'insuccès reliées à l'utilisation d'une antenne membrane doivent être pleinement étudiées avant qu'elle ne soit lancée. Avec l'émergence de cette nouvelle technologie, une nouvelle problématique s'ajoute: le plissement. Le plissement de la membrane émettrice pourrait affecter l'efficacité del'antenne et réduire ses performances électriques en modifiant l'orientation des éléments radiatifs de la membrane rendant ainsi inopérante la région affectée. Les variations de température présentes dans l'espace peuvent produire de tels plissements. Très peu d'analyses sont disponibles pour prédire en toute certitude le comportement d'une telle membrane en orbite. Cette étude propose l'étude d'une approche par éléments finis analysant la hauteur et l'orientation des plissements dues aux variations de température. Le contrôle des ridules par méthode passive a été également étudié permettant l'optimisation de l'aire et des dimensions de la membrane. L'influence de la forme parabolique des cotés de la membrane sur la force axiale du câble de tension a été étudiée et est présentée. Le comportement dynamique de la membrane est l'objet d'une attention particulière étant donné sa propension à amplifier les micro vibrations . fr
35
Baretela, Michael J. "Increasing prompt response from impulse radiating antenna by aperture shaping". Thesis, Monterey California. Naval Postgraduate School, 2002. http://hdl.handle.net/10945/6094.
Testo completoAbstract (sommario):
Approved for public release, distribution is unlimitedIn order to improve the prompt response from an impulse radiating antenna (IRA)number of studies have suggested controlling the spatial distribution of the aperture fields by changing the feed arm angle. Other work has suggested that proper shaping of the aperture can further enhance the radiated signal for a given feed structure. This paper shows how the radiated prompt response can be maximized for a given feed arm configuration by shaping the aperture to eliminate fields orientated in the wrong direction. The percent increase in the prompt radiated electric field for a 200 . IRA with a ideally shaped aperture compared to a standard circular aperture ranged from 0.42% to 39.94% depending on the input electrode angle. For the most common electrode angles of 45Ê» and 60Ê» the increases are 6.00% and 16.63% respectively.
36
Zubir, Farid. "Direct integration of push-pull amplifier and aperture coupled antenna". Thesis, University of Birmingham, 2016. http://etheses.bham.ac.uk//id/eprint/6454/.
Testo completoAbstract (sommario):
The work described in this thesis concerns the integration of push-pull class B amplifier and antenna modules. Push-pull class B is well-known with its fruitful advantages of using differential feeding technique, resulting in low distortion, reasonably high efficiency and high output power. Meanwhile, the antenna module in this work is adapted from the aperture-coupled antenna structure due to its degree of freedom to control the variables which provide the best possible topology that could be realised in system on chip or system in package. More generally, the variables allow good coverage of the Smith Chart so that a wide range of odd-mode matching requirements could be met, for different devices and bias condition of a given transistor. The approach also offers additional filtering up to 3rd harmonic in that it comprises identical harmonic traps on both sides of the aperture using resonant stubs to form bandstop filters, which reduce the ripples at the output waveforms, giving them a significant advantage of neat and tight integration of a push-pull transmitting amplifier.
37
Warrington, E. Michael. "Ionospheric radiowave propagation effects observed with a large aperture antenna array". Thesis, University of Leicester, 1986. http://hdl.handle.net/2381/35817.
Testo completoAbstract (sommario):
The wavefronts of high frequency (HF) radio waves received after reflection from the ionosphere exhibit both spatial non-linearities and temporal variations which limit the performance of large aperture receiving arrays. The first objective of this investigation was to measure the phase and amplitude of ionospherically propagated signals at several widely spaced antennas in order to relate these parameters to the reflection process. From the amplitudes and phases measured at pairs of spaced antennas, the direction of arrival (DOA) of the signal in both azimuth and elevation was determined. Furthermore. by combining the DOA and reflection height measurements the transmitter location can be estimated from a single receiving site. The second objective of this study was to investigate the ability of the system to determine DOA and transmitter locations correctly. Two seven element antenna arrays were employed with maximum apertures of 1526 m and 294 m respectively. The associated multi-channel receiving and data logging equipment is described together with a pulsed sounding system employed for mode identification. Signals received from several European transmitters exhibited widely differing behaviour and this was interpreted in terms of their modal content. For predominantly single moded signals the observations indicate that the diffracted components normally contribute less than 10% of the received power, moreover the DOA varies in both azimuth and elevation by approximately 1-2° over time periods of several minutes. The use of the smaller array for DF and SSL applications is discussed in detail. In particular, the performance of the system was severly affected by multi-moded propagation. Techniques were developed for recognising periods of single moded propagation, when accurate measurements are to be expected. Good position fixes were obtained when measurements were restricted to these periods provided accurate reflection height information was also available.
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Guadiana, Juan, Fil Macias e Chris Braun. "A Smarter Antenna". International Foundation for Telemetering, 2011. http://hdl.handle.net/10150/595731.
Testo completoAbstract (sommario):
ITC/USA 2011 Conference Proceedings / The Forty-Seventh Annual International Telemetering Conference and Technical Exhibition / October 24-27, 2011 / Bally's Las Vegas, Las Vegas, NevadaThe Isotropic radiator, a device capable of radiating energy evenly in all directions is an abstraction, itsʼ real counterpart is called an omnidirectional (omni) antenna. The omnidirectional antenna is found on many vehicles. Ideally, only one receiving system is ever needed to acquire an omni, no matter the vehicle orientation, given the range is not excessive. There are trade-offs with antenna efficiency, with gain typically around -15 dBi (95% coverage). This paper proposes abandoning this paradigm. If a vehicle knows where the ground is why radiate energy up into the sky, where there are no receiving stations. This can be achieved by integrating some instrumentation with a discrete antenna array so that it radiates only from selected elements. The accuracy required is modest, an inexpensive Inertial Measurement Unit (IMU) is sufficient to improve link margin by 10, 20dB or more. These numbers are credible, as outlandish as they are, and substantiated in this paper. Ironically, from the ground this non-isotropic antenna looks very isotropic. Of significant benefit, this Smarter Antenna concept enables spatial discrimination and with that comes spectrum efficiency gains beyond that achieved by other means including advanced modulation formats.
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Albornoz, Navarro Daniel Alejandro. "Diseño y fabricación de un arreglo de antenas metamaterial alimentado mediante acoplamiento por apertura a 5.8 GHz en sustrato FR4". Tesis, Universidad de Chile, 2019. http://repositorio.uchile.cl/handle/2250/170701.
Testo completoAbstract (sommario):
Memoria para optar al título de Ingeniero Civil EléctricoEn los últimos años ha existido un justificado interés en el desarrollo y aplicaciones de los metamateriales. Estos consisten en estructuras o materiales compuestos que pueden imitar respuestas de materiales conocidos o exhibir propiedades que no están disponibles en la naturaleza. Ser capaz modificar las propiedades de los metamateriales permite controlar su comportamiento a nivel electromagnético. En el diseño de antenas esto significa contar con herramientas adicionales para mejorar el desempeño, reducir el tamaño y abrir nuevas áreas de investigación. En esta memoria se muestra el diseño, fabricación y caracterización de arreglos ante- nas microstrip utilizando una superficie selectiva de frecuencia como elemento radiador, y acoplamiento por apertura como técnica de alimentación. El objetivo del presente trabajo es explorar el desempeño de un arreglo de antenas . Este diseño considera excitar cada antena del arreglo por separado y así tener aplicaciones con el sintetizador de haces en la banda 5.8 GHz ISM que posee el Laboratorio de Ondas Milimétricas. Se construyeron tres prototipos de arreglos. El prototipo final cuenta con 16 elementos distribuidos en un sustrato de dimensiones 129 x 129 mm y su desempeño se mide con las siguientes figuras de mérito. Ancho de banda fraccional medido varía entre 11,3% hasta 47.5% para los elementos del arreglo, con un promedio de 27,2%. Su beamwidth es de 23.5° a 5,81 GHz Lóbulos laterales en simulación tienen 15 dB menos que al haz principal. La Eficiencia de radiación simulada es de 80,57% en sustrato FR4 y 95,74% en sustrato Kappa 438.
ROGERS CORPORATION por la donación de sustrato RO4003C y KAPPA 438
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Rizzo, Carlo Anthony Edward. "Phase retrieval near-field/far-field measurement techniques for quasi-optical large apertures". Thesis, University of Sheffield, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.310888.
Testo completo
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Nafi, Kawser Wazed. "Application of Synthetic Aperture Radar with Wi-Fi for Indoor Localization". Thesis, Université d'Ottawa / University of Ottawa, 2016. http://hdl.handle.net/10393/34467.
Testo completoAbstract (sommario):
Indoor localization is the process of localizing people or objects inside a building in the same way GPS does in an outside environment. In recent years, researchers have successfully achieved improvement in indoor localization accuracy. Still there are many limitations to overcome in performing and achieving good accuracy in indoor localization. The interest in estimating the location of something inside a building with good accuracy is very strong. In this thesis we first propose an indoor localization technique relative to Wi-Fi access points along with a novel heuristic search based algorithm, named MuSLoc. Through simulation and comparative studies, we have shown that MuSLoc outperforms other indoor localization models without the help of fingerprinting or crowdsourcing about the environment. MuSLoc provides almost the same accuracy in LOS (Line of Sight) and NLOS (Non-Line of Sight) environments with regular infrastructure that has recently been provided by smart phones. This model doesn't require any additional hardware support in order to perform well.
Further, we propose another indoor localization based Wi-Fi device tracker model, named MSTracker, which is able to track both moving and non-moving devices inside a building. This model is also free from specialized infrastructure and can perform well without any training data information. Through real time simulation and analysis we have shown that it performs more accurately than other available models.
Through extensive simulations in a real time environment and analysis of performance comparatives with other available models, we have shown that both MuSLoc and MSTracker perform more accurately with COTS than any other method of indoor localization and tracking of objects inside a building. The complete package of MuSLoc and MSTracker can perform perfectly with recently available Wi-Fi modules and smartphones.
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Vlasits, Tamas. "Modelling and application of a cross-aperture coupled single feed circularly polarised patch antenna". Thesis, Northumbria University, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.245262.
Testo completo
43
Vinci, Joseph J. "Sparse Aperture Measurement in a Non-Ideal Semi-Anechoic Chamber". University of Dayton / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1557426154482334.
Testo completo
44
Křivák, Jiří. "Analysis of feeding techniques of a patch antenna array for 5G NR". Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2021. http://www.nusl.cz/ntk/nusl-449165.
Testo completoAbstract (sommario):
Tato diplomová práce se zabývá analízou různých napájecích struktur pro 2x2 flíčkové antenní pole. Evaluace probíhá na střední frekvenci 25.5GHz, která spadá do pásma přiřazeného páté generaci mobilních komunikačního standardu. Zvolené napájecí struktury byly napájení blízkým polem, napájení aperturou a napájení mikropáskem.
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Pelham, Timothy George. "Analysis of conformal antenna array design using beamforming methods and on-platform aperture modelling". Thesis, University of Bristol, 2018. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.738323.
Testo completo
46
Bílek, Ondřej. "Flíčkový reflektor s elektronickým řízením směrové charakteristiky". Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2017. http://www.nusl.cz/ntk/nusl-316447.
Testo completoAbstract (sommario):
The diploma thesis is aimed to design, optimize, produce and subsequently measure the properties of the reflector with the electronic steering direction for the frequency of the 24,125 GHz band ISM. The problem chosen is solved by a group of voltage-controlled varicaps. The reflector consists of a matrix of two rows, each containing 3 cells. The reflector was designed by full-wave software CST Microwave Studio 2015.
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Pulipati, Sravan Kumar. "Electronically-Scanned Wideband Digital Aperture Antenna Arrays using Multi-Dimensional Space-Time Circuit-Network Resonance". University of Akron / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=akron1499440141479455.
Testo completo
48
Henrion, Stéphane. "Traitements SAR (Synthetic Aperture Radar) spatial très haute résolution". Toulouse, INPT, 2001. http://www.theses.fr/2001INPT050H.
Testo completoAbstract (sommario):
Le Radar à Synthèse d'Ouverture (RSO) est un instrument embarqué, utilisé en télédétection pour obtenir des images tout temps, toute heure de la surface terrestre. Les utilisations actuelles de ces images requièrent des résolutions métriques à sub-métriques. Alors que la résolution en site (transversale au déplacement du radar) est essentiellement limitée par la technologie (principe de compression d'impulsion), la réelle difficulté algorithmique de l'imagerie RSO tient dans l'obtention de la résolution azimutale, parallèle au déplacement du support, qui exploite les contributions successives des cibles élémentaires dans les échos reçus. Le recensement et la formalisation analytique unifiée des traitements Haute Résolution proposés dans la littérature permet dans un premier temps de mettre en évidence les spécificités du traitement de Synthèse d'Ouverture, qui doit s'accommoder de la dispersion temporelle, donc spatiale, des échos d'une même cible au cours de la prise de vue. Ensuite, la prise en compte d'une configuration spatiale Très Haute Résolution (THR), qui nécessite notamment l'utilisation de modes opératoires évolués (spotlight pur ou glissant), nous conduit à proposer des traitements qui répondent efficacement à la modélisation plus complète des signaux obtenus dans ce contexte. Ces solutions proposent un "principe d'extension" applicable aux traitements recensés et qui permet de s'accommoder de la non stationnarité du traitement sur la profondeur fauchée. Le repliement des données brutes acquises dans les modes opératoires abordés est traité par une étape de "mise en forme". La validation de ces solutions est enfin effectuée par un ensemble de simulations numériques.
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Liu, Lei. "Investigation of aperture coupled microstrip antenna to obtain a high efficient active integrated antenna by using Class F and Inverse Class F power amplifiers". Thesis, Northumbria University, 2013. http://nrl.northumbria.ac.uk/21425/.
Testo completoAbstract (sommario):
In wireless communications and radar systems, there are requirements for high efficiency, small size, low cost, and wide bandwidth of transmitter front –end usage for commercial and also military applications. Active integrated antenna (AIA) could satisfy almost all the requirements. The overall objective of the proposed research is to model, optimise, and design a compact and high efficient AIA using an aperture coupled microstrip antenna (ACMA) by integrating with a power amplifier (PA). Research on ACMA has been focused on the transmissions line (TL) model (TLM) and full wave electromagnetic (EM) model analysis. The full wave investigation is rigorous and elegant but because the dimension of the physical model and the value of the circuit elements are interdependent, the design of the antenna is still difficult. TLM analysis has lower accuracy but easier to analysis and optimise than full wave EM model analysis. To increase the accuracy, the challenge is the coupling ratios between feed/slot, and slot/patch where no unique solution at the moment exists. In this thesis, a novel and simplified method has been produced to investigate these ratios using Scattering (S) parameters. A dual frequency ACMA has been designed to verify these results. Research on the class F and inverse class F PAs is carried out by a novel and simplified load/pull method. A new design method of harmonic load matching network has been presented using lump elements and TLs. Both linear and nonlinear modelling has been investigated. High power added efficiency (PAE) and high gain which are up to 60% and 12dB have been obtained. Finally AIAs have been produced based on previous investigation on class F, inverse class F PAs and a broadband circular polarized ACMA design with 350 MHz bandwidth and 8.5 dB gain at 2 GHz.
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Ashok, Amit. "Implementation and analysis of a bayesian approach to topographic reconstruction with multiple antenna synthetic aperture radar interferometry". Master's thesis, University of Cape Town, 2001. http://hdl.handle.net/11427/5237.
Testo completoAbstract (sommario):
Bibliography: leaves 81-84.Multiple-antenna synthetic aperture radar (SAR) interferometry is a single-pass interferometry technique for topographic mapping. A Bayesian model-base approach to topographic recontruction with multiple-antenna SAR interferomety, proposed by Dr. A. J. Wilkinson, is implemented and analysed in this dissertation.