Bibliografie tematiche / Beam dividers

Letteratura scientifica selezionata sul tema "Beam dividers"

Autore: Grafiati

Pubblicato: 8 giugno 2024

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Articoli di riviste sul tema "Beam dividers":

Klein, Tobias, Peter Uhlig, Carsten Günner e Reinhard Kulke. "Substrate-integrated divider networks in LTCC with optimized tolerance / isolation properties for Ka-Band satellite systems". International Symposium on Microelectronics 2014, n. 1 (1 ottobre 2014): 000816–19. http://dx.doi.org/10.4071/isom-thp22.

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Low Temperature Cofired Ceramics (LTCC) technology is increasingly used for creating high-rel solutions, especially in class S products deployed in space. Current research, executed by the german and european space agencies, focuses inter alia on new, compact beam forming networks for Ka-band multiple feed per beam antennas. These networks consist of a high number of dividers and must provide a high isolation between neighbouring cells to ensure compliance with frequency plan regulations. While the LTCC process brings a number of advantages, its thick film printing process and the tolerances of available resistive paste systems introduce difficulties in implementing typical Wilkinson divider networks. This paper presents a novel concept to implement tolerance-optimized dividers, taking special focus on the properties of the LTCC process.

Li, Chong, Lai Bun Lok, Ata Khalid, Vasileios Papageorgiou, James Grant e David R. S. Cumming. "Millimeter-wave coplanar stripline power dividers". International Journal of Microwave and Wireless Technologies 5, n. 3 (1 maggio 2013): 205–12. http://dx.doi.org/10.1017/s1759078713000421.

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We present the design, fabrication, and measurement of a 2-way modified Wilkinson divider constructed in a coplanar geometry exhibiting ultra wideband isolation, transmission, and port matching in the millimeter-wave frequency range. The proposed divider replaces the lumped resistor in the conventional Wilkinson divider with two quarter-wave length transmission lines, a phase inverter, and two 2Z0 resistors. Except for the three ports that are coplanar waveguides (CPWs), the main body of the divider uses coplanar striplines (CPS). The phase inverter is realized using a simple airbridge-based crossover which is compatible with a modern monolithic microwave integrated circuit process. The divider has a ring-like configuration fabricated on a 620 µm thick semi-insulating GaAs wafer using electron beam lithography (EBL) technology. Three-dimensional (3D) full-wave electromagnetic simulations have been carried out to optimize the design and investigate the possible effect of fabrication tolerance on the performance of the crossover and the divider. Two dividers working at center frequencies of 25 and 80 GHz have been designed, fabricated, and tested. They all show consistent performance in terms of bandwidth, isolation, and port matching. Experimental and simulation results are in excellent agreement.

Boutayeb, Halim, Paul R. Watson, Weishan Lu e Tao Wu. "Beam Switching Dual Polarized Antenna Array With Reconfigurable Radial Waveguide Power Dividers". IEEE Transactions on Antennas and Propagation 65, n. 4 (aprile 2017): 1807–14. http://dx.doi.org/10.1109/tap.2016.2629469.

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Yip, G. L., e M. A. Sekerka-Bajbus. "Design of symmetric and asymmetric passive 3-branch power dividers by beam propagation method". Electronics Letters 24, n. 25 (1988): 1584. http://dx.doi.org/10.1049/el:19881080.

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Rudakov, Viacheslav, e Victor Sledkov. "Development of antenna arrays with a beam width 33 degrees at the level of half power". ITM Web of Conferences 30 (2019): 05030. http://dx.doi.org/10.1051/itmconf/20193005030.

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A new design of the antenna array for mobile base stations providing two orthogonal polarizations in 1.71-2.17GHz frequency band is proposed. The antenna array includes 16 radiators, 12 power dividers and two phase shifters disposed on a metal reflector having dimensions 320×1387 mm. The developed antenna array contains less radiators and power dividers than other known antennas of this kind therefore one is cheaper for production. The fabricated sample of the proposed antenna array has return loss is better than -18.5dB and isolation better than 33dB. Beam width in the horizontal plane is equal 36 ± 4 degrees and side lobes level doesn’t exceeding -20dB. The antenna array provides gain=20.5dBi.

Van Trinh, Thai, Son Trinh-Van, Kang-Yoon Lee, Youngoo Yang e Keum Cheol Hwang. "Design of a Low-Cost, Low-Sidelobe-Level, Differential-Fed SIW Slot Array Antenna with Zero Beam Squint". Applied Sciences 12, n. 21 (25 ottobre 2022): 10826. http://dx.doi.org/10.3390/app122110826.

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This paper presents a low-cost, low-sidelobe-level, differential-fed, substrate-integrated waveguide (SIW)-based slot array antenna with zero beam squint. The antenna consists of two identical six-way unequal power dividers (PDs) and a 6 × 16 slot array and is realized on a single-layer substrate. The six-way unequal PD provides tapered amplitude and in-phase excitation for six SIWs, and each of them has 16 radiating slots. The 1 × 16 linear slot array on each SIW is excited using a differential feed to avoid undesired beam squinting across its operating band. A two-way hybrid waveguide (WG)-to-SIW E-plane PD is developed to provide equal amplitude and out-of-phase excitation for two six-way unequal power dividers. Moreover, metallic decoupling walls are implemented between two adjacent linear slot arrays to reduce E-plane external mutual coupling. An antenna prototype is fabricated and experimentally verified. The fabricated antenna shows that the measured −10 dB reflection bandwidth is 7.15% (9.57–10.28 GHz), with the achieved gain ranging from 20.30 to 21.92 dBi. A stable boresight beam is observed over the entire operating band. Furthermore, at the designed frequency of 10 GHz, peak SLLs of −29.1 dB and −29.4 dB are achieved in the E- and H-plane, respectively.

Salem Hesari, Sara, e Jens Bornemann. "Antipodal Vivaldi Antenna Arrays Fed by Substrate Integrated Waveguide Right-Angled Power Dividers". Applied Sciences 8, n. 12 (14 dicembre 2018): 2625. http://dx.doi.org/10.3390/app8122625.

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This paper describes a novel feed system for compact antipodal Vivaldi antenna arrays on a single layer of substrate integrated waveguide (SIW) by using SIW H-plane right-angled power dividers. The proposed antenna systems are composed of a Vivaldi array and an H-plane right-angled corner power divider which includes an over-moded waveguide section. Based on the number of antennas in the Vivaldi array, mode converter sections at K-band and Ka-band frequencies are designed, fabricated, and measured when feeding Vivaldi antenna arrays with two, three, and four antennas. Right-angled SIW power dividers are employed to obtain controllable phase distribution over the output ports which consequently controls the beam shapes of the systems. The phase relationships in the output ports are varied to obtain different pattern directions for different applications. The two-way divider system with 180-degree phase difference and three-way divider system are fabricated and measured; simulation results are presented for other designs. The measured results are in good agreement with simulations which confirms the design approach. All systems achieve good performance and meet all design goals including a return loss better than 10 dB in the operating bandwidth, gain higher than 8 dB for all systems, and radiation and polarization efficiencies higher than 80% and 98%, respectively.

FIELDS, C. H., M. SOKOLICH, S. THOMAS, K. ELLIOT e J. JENSEN. "Progress toward 100 GHz Logic in InP HBT IC Technology". International Journal of High Speed Electronics and Systems 11, n. 01 (marzo 2001): 217–43. http://dx.doi.org/10.1142/s0129156401000836.

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Future wideband communications, mm-wave digital synthesis, and digital beam-steering will benefit from digital operation at clock frequencies between 50 and 100 GHz at reasonable power levels. HRL has developed InP-based HBT technology that is capable of supporting these needs. We have demonstrated InP HBTs with cutoff frequencies, ft, over 200 GHz and with f max over 300 GHz as well as fully static dividers operating at 72.8 GHz.

Arce, Armando, Enrique Stevens-Navarro, Ulises Pineda-Rico, Marco Cardenas-Juarez, Francisco R. Castillo-Soria e David H. Covarrubias. "Optimization of a Coherent Dual-Beam Array Feed Network for Aperiodic Concentric Ring Antennas". Applied Sciences 11, n. 3 (26 gennaio 2021): 1111. http://dx.doi.org/10.3390/app11031111.

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A dual-beam coherent feeding system design approach with a non-uniform layout on a concentric ring array is described and synthesized. In this case, the feeding system is based on a reconfigurable topology composed of a set of alternated power dividers and combiners, providing coherent in-phase outputs. Thus, in this paper, a two-beam architecture based on a coherent feeding system formed by a set of intercalated input signals feeding each circular ring in a non-uniform antenna array with multi-beam shaping and steering features is analyzed. The task of optimizing the aperiodic layout on the shared aperture based on the radii of the circular rings is realized by the differential evolution method. Numerical experiments grounded in antenna synthesis validate the capabilities and improved performance of the proposed dual-beam configuration with a non-uniform layout in contrast with its uniform counterpart, with enhanced performance on average by up to −6.1 dB for sidelobe level and 3.5 dB for directivity. Additionally, the results show a significantly less complex two-beam feeding network in contrast with the case of a typical electronically scanned array—in this proposal, each direction of maximum radiation is conformed and scanned with approximately half of the control inputs.

Yan, Lei, Wenbin Zou, Kaihong Zheng, Guangli Yang e Yong Luo. "A Dual-Polarized CTS Array Antenna with Four Reconfigurable Beams for mm-Wave Wind Profile Radar". Electronics 13, n. 1 (4 gennaio 2024): 238. http://dx.doi.org/10.3390/electronics13010238.

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The wind profiler radar (WPR) system requires a dual-polarized antenna with multiple low-sidelobe and high-gain beams to facilitate the detection of weak signals reflected by atmospheric turbulence. This paper proposes a dual-polarized continuous transverse stub (CTS) K-band antenna with four reconfigurable beams, which comprises a series-fed CTS array and four 1-to-14 power dividers as line source generators (LSGs) to generate a high-quality quasi-TEM wave. The CTS element incorporates a stepped transition radiation stub design and employs a short cutoff stub on the upper surface of the series-fed parallel plate waveguide (PPW) to achieve optimal impedance matching. The entire antenna is an all-metal structure with remarkably low loss, and low-cost standard fabrication processes are employed for the prototype, which achieves fast reconfigurable four-beam scanning to 15°, with a gain of 31.09 dBi and sidelobe levels below −17.6 dB. Measurement results in an anechoic chamber agree well with simulations, demonstrating the antenna’s ease of manufacture, stability, and suitability for wind profile radar applications.

Più fonti

Tesi sul tema "Beam dividers":

Alrifai, Rim. "Fonctions optiques robustes dans des structures de guides d'onde : liens avec des phénomènes quantiques". Electronic Thesis or Diss., Université de Lorraine, 2022. http://www.theses.fr/2022LORR0087.

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La propagation d'ondes dans des guides optiques couplés et la dynamique de transfert de population dans des systèmes quantiques discrets et couplés possèdent un formalisme commun via l'équation de Schrödinger. Une telle analogie permet un enrichissement mutuel de ces deux domaines. D'une part, des phénomènes complexes de physique quantique peuvent être démonter en optique, où les expériences sont généralement plus accessibles. D'autre part, les concepts de l'un des domaines peuvent être traduits dans l'autre pour concevoir, des dispositifs aux fonctionnalités étendues. Dans ce contexte, l'élément moteur de cette thèse est l'analogie entre les systèmes quantiques adiabatiques et robustes et des systèmes de guides d'onde analogues. En optique, la robustesse se traduit par une tolérance fortement accrue aux variations de longueur d'onde (achromaticité), de température ou aux perturbations et imperfections des guides. Les travaux précédents du laboratoire, portant sur ces analogies, ont traité de guides monomodes, et n'ont pas considéré les deux modes de polarisation orthogonale. Aussi, nous élargissons, ces travaux afin obtenir un séparateur de polarisation intégré, et un convertisseur de modes, tous deux large bande. Ils sont composés de trois guides couplés où les guides latéraux sont courbés selon une évolution adiabatique. Nous considérons enfin, un troisième système de guides, constants et droits, où une dissipation du guide central permet une répartition de puissance ultra-large bande. Les diviseurs de faisceaux polarisants intégrés jouent un rôle important dans de nombreux dispositifs photoniques intégrés nécessitant la manipulation de la polarisation lumineuse, avec un besoin d'être le plus large bande possible. Aussi, je propose dans cette thèse, une configuration à trois guides avec des indices de réfraction anisotropes qui s'inspire du phénomène quantique de STIRAP (STImulated Raman Adiabatic Passage). Cette étude montre qu'un rapport de 5 entre les contrastes d'indice des modes TM et TE est suffisant pour séparer efficacement les deux polarisations sur une plage d'environ 350 nm autour de la longueur d'onde centrale à 1,55 µm. La bande passante augmente avec le rapport d'anisotropie et la longueur d'onde centrale peut être ajustée en modifiant les paramètres. Par ailleurs, l'un des moyens envisagés pour augmenter la capacité des systèmes de télécommunications optiques repose sur le multiplexage spatial, où chaque canal est transmis sur un mode spatial différent d'une fibre multimode. Cette approche nécessite des (dé)multiplexeurs qui séparent ou en convertissent les modes. Là encore, un système adiabatique à trois guides d'onde peut être mis à profit pour concevoir une conversion entre un mode d'ordre supérieur et le mode fondamental (ou le contraire) sur une large gamme spectrale. Ce dispositif peut à nouveau être analogue au STIRAP, mais aussi au phénomène d'élimination adiabatique. Dans ce dernier cas, le guide d'onde central est fortement désaccordé avec les deux autres. Le troisième système étudié dans cette thèse ne repose pas sur des guides à évolution adiabatique, mais est analogue à un système quantique non hermitien, où le transfert de population s'effectue via un état intermédiaire dissipatif. Ici les trois guides sont parallèles et le guide central présente des pertes importantes. Cela conduit à une division de puissance ultra-large bande en contrepartie d'une perte globale de 50% (pour une diviseur puissance symétrique). L'absence d'évolution adiabatique permet des systèmes plus compacts, en particulier si le guide central est un guide plasmonique. Cette thèse démontre le fort potentiel des approches s'inspirant des phénomènes quantiques pour la photonique, où des fonctionnalités robustes, polyvalentes et larges bandes sont requises. De tels dispositifs peuvent être utilisés en photonique intégrée classique, ou avec comme perspective la manipulation de photons uniques en optique quantique
Wave propagation in coupled optical waveguides and population dynamics in quantum systems composed of coupled discrete levels share a common mathematical formalism related to the underlying Schrödinger equation. In the context of this thesis the key role is played by the relation between robust adiabatically evolving quantum systems and corresponding adiabatically evolving waveguide systems. In the optics case the robustness reflects in a strongly increased tolerance with respect to changes in wavelength (achromaticity), temperature, or unwanted variations in the waveguide parameters.Earlier works in our laboratory in the context of the above analogy were related to waveguides allowing propagation of the fundamental mode only and did not consider the possible propagation of both orthogonal polarization modes. In the present thesis we fill this gap by discussing ways for achieving broadband polarization separation as well as broadband mode conversions. The investigated systems are composed of three coupled waveguides with a spatial adiabatic evolution. In addition, we consider a third system where a dissipation in one of three waveguides allows to achieve ultra-broadband power splitting despite for the absence of any adiabatic evolution of the waveguide parameters.Integrated polarization beam splitters (PBS) play a significant role in many integrated photonic devices where the polarization state of light requires manipulation and important efforts are under way to make such a functionality as broadband as possible. Our proposal in this context involves a three-waveguides configuration with anisotropic refractive index either in the core or in the cladding and is inspired by the quantum STIRAP process (STImulated Raman Adiabatic Passage). Our analysis shows that an anisotropy ratio of 5 (ratio between the refractive index contrasts for the TM and TE waves) is sufficient for separating efficiently the two polarizations over a spectral range of ≈ 350 nm around the 1550 nm central wavelength. The bandwidth of such PBS increases by increasing the anisotropy factor and the central wavelength can be adjusted by modifying the waveguides.One of the ways presently envisaged for increasing the nearly saturated capacity of optical telecommunication systems relies on space division multiplexing, where signals are transmitted on different spatial modes of a multimode optical fiber. This kind of approach requires elements capable of demultiplexing the modes by separating and converting them. Our proof of concept in this context is based again on an adiabatic three-waveguide systems and permits conversion between a higher order mode and the fundamental mode (or vice-versa) over a wide spectral range. The underlying waveguide design is again analogous to the above quantum STIRAP process or in alternative to Adiabatic Elimination (AE) in which case the central waveguide is strongly detuned from the two others.As mentioned above, the third system studied in this thesis does not rely on adiabatically evolving waveguides but is related to the behavior of non-Hermitian quantum systems, specifically to quantum population transfer through a decaying intermediate state. Our approach is based on three parallel waveguides of which the central one is highly dissipating. It leads to ultra-broad band power division that has to be paid by a 50% overall loss if equal power is wished in the two output ports. Here the absence of the slow adiabatic variation allows for more compact systems, especially if the central waveguide is of the plasmonic type.The three systems that are discussed in this thesis show the great potential of quantum-inspired approaches for robust photonics, where tolerant, versatile and broadband functionalities are required. While devices of this kind may be used principally in classical integrated photonics, their use for single photon management in quantum optics is also an attractive perspective

Stetz, Jeffrey Brian. "Using noninvasive genetic sampling to assess and monitor grizzly bear population status in the in the northern continental divide ecosystem". [Missoula, Mont.] : The University of Montana, 2008. http://etd.lib.umt.edu/theses/available/etd-01142009-131434/unrestricted/JStetz_thesis_Final.pdf.

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Thesis (M.S.) --University of Montana, 2008.
Title from author supplied metadata. Description based on contents viewed on May 15, 2009. ETD number: etd-01142009-131434. Author supplied keywords: bear rubs ; grizzly bear ; mark-recapture ; noninvasive genetic sampling ; Northern Continental Divide Ecosystem ; Pradel model ; trend monitoring ; Ursus arctos. Includes bibliographical references.

Fee, Margery. "Articulating the Female Subject: The Example of Marian Engel's Bear". Atlantis: A Women's Studies Journal/Journal d'etudes sur la femme, 1988. http://hdl.handle.net/2429/11252.

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Lou, the heroine of Marian Engel's Bear, attempts to confront the difficulties she has with male domination in a relationship with a semi-tame bear, but fails to resolve them because both female subjectivity and the patriarchy are socially constructed.

Kojima, Seishiro. "Novel Beamforming and Antenna Techniques for Microwave Power Transmission in Radiating Near Field". Doctoral thesis, Kyoto University, 2021. http://hdl.handle.net/2433/263667.

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Kilic, Ozgehan. "Defected Ground Structure And Its Applications To Microwave Devices And Antenna Feed Networks". Master's thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/12612415/index.pdf.

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This thesis reports the analysis of the rectangular shaped defected ground structure (RS-DGS) and the application of the structure on some microwave devices. DGS is analyzed in terms of its superior properties, which enables the designers to easily realize many kind of microwave devices which are impossible to achieve with the standard applications. Within the scope of this thesis, the focus is on the rectangular shaped DGS and its characteristic properties. The basic slow wave and high impedance characteristics are utilized in the design of some microwave devices. The design is carried on at the two different frequency bands: X-band and Ka band, centering at 10 GHz and 35 GHz, respectively. Finally, using the high impedance property and the coupling between the defects, a wide band 1 : 4 beam forming network is designed and implemented at 10 GHz.

Suddason, Karina. "Exploring issues in empirical finance : international evidence on payout ratio, returns, earnings and dividends ; investigating duration dependence in bull and bear markets ; using survival analysis approach to model the duration of sovereign debt default". Thesis, University of Southampton, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.442776.

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Sharp, Michael G. "Ghost Water Exhibition". BYU ScholarsArchive, 2017. https://scholarsarchive.byu.edu/etd/6272.

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The Ghost Water exhibition of artworks by Michael Sharp was comprised of four main works titled: 30 x 60 Minute Grid Series, Suspension, History/Prehistory, and Lake Bonneville Remnants. The artwork was created as a reaction to the land that once held the prehistoric Lake Bonneville and to its current remnant Great Salt Lake. The work explores the dialogue between absence and presence.

Lee, Jungkyu. "Single-band and Dual-band Beam Switching Systems and Offset-fed Beam Scanning Reflectarray". Thesis, 2012. http://hdl.handle.net/1969.1/ETD-TAMU-2012-05-11012.

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The reflectarray has been considered as a suitable candidate to replace the conventional parabolic reflectors because of its high-gain, low profile, and beam reconfiguration capability. Beam scanning capability and multi-band operation of the microstrip reflectarray have been main research topics in the reflectarray design. Narrow bandwidth of the reflectarray is the main obstacle for the various uses of the reflectarray. The wideband antenna element with a large phase variation range and a linear phase response is one of the solutions to increase the narrow bandwidth of the reflectarray. A four beam scanning reflectarray has been developed. It is the offset-fed microstrip reflectarray that has been developed to emulate a cylindrical reflector. Unlike other microstrip reflectarrays which integrates phase tuning devices such as RF MEMS switches and another phase shifters to the reflectarray elements and control the reflected phase, the beam scanning capability of the reflectarray is implemented by a phased array feed antenna. This method can reduce the complexity of the design of the beam switching reflectarray. A simple method has been investigated to develop multi-band elements in this dissertation. In approach to increase the coverage of the operation bands, a six-band reflectarray has been developed with two layers. Each layer covers three frequency bands. A Butler matrix is one of the useful beamforming networks for a phased array antenna. A Double-Sided Parallel-Strip Line (DSPSL) is adapted for the feeding network of eight array elements. The DSPSL operate very well to feed the microstrip antenna array over the bandwidth to reduce the sidelobe level and a high gain. In another topic of a Butler matrix, a dual-band Butler matrix has been proposed for multi-band applications. A modified Butler matrix is used to reduce a size and a sidelobe level. The bandwidth of the microstrip antenna is inherently small. A broadband circularly polarized microstrip antenna with dual-offset feedlines is introduced in this dissertation. Aperture-coupled feed method is used to feed the stacked patch antennas and a slotcoupled directional coupler is used for the circularly polarized operation. The research presented in this dissertation suggests useful techniques for a beam scanning microstrip reflectarray, phased array antenna, and wideband antenna designs in the modern wireless communication systems.

Petropoulos, Ioannis, Konstantinos N. Voudouris, Raed A. Abd-Alhameed e Steven M. R. Jones. "Beam-forming module for backhaul link in a Relay-aided 4G network". 2015. http://hdl.handle.net/10454/7882.

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Yes
A novel beam-forming module based on Wilkinson power divider technology, including attenuators and phase shifter chips is designed, fabricated and evaluated to be incorporated in a Relay Station connecting it with the Base Station under a 4G network. The proposed module is a 1:8 port circuit, utilizing two substrates, providing approximately 700 MHz bandwidth over 3.5 GHz frequency band and less than −20 dB transmission line coupling. Moreover an external control unit that feeds the beam-forming module with code-words that define the proper amplitude/phase of the excitation currents is established and described. The presented module is connected to a planar array and tested for two beam-forming scenarios, providing satisfactory radiation patterns.

Jiang, Ming-Jyun, e 姜名駿. "A Study of Linear Retro-Beam Scanning Array System and On-Chip Dual-band Wilkinson Power Divider". Thesis, 2019. http://ndltd.ncl.edu.tw/handle/t4k8x9.

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碩士
國立臺灣科技大學
電機工程系
107
This thesis consists of two independent researches. In the first part, a linear retro-beam scanning system, capable of estimating the direction of arrival (DOA) and retransmitting the signal to a desired direction, is proposed and demonstrated. Studying the governing equations of the retrodirective array (RDA) reveals a possibility of steering the retransmitting signal from original direction (incident angle in the conventional RDA design) by introducing extra phase shifters between the receiving and transmitting paths. To do so, a simple DOA module is designed to trace out the incident angle while the required phase shift sourced by phase shifters will be automatically calculated by Arduino microcontroller as long as the desired retransmitting direction is pre-determined. To validate the design concept, the proposed system was constructed and test; the measured results illustrate that the proposed system can function as a relay unit to retransmit signals to an arbitrary direction with an acceptable scanning range from -30o to +30o. Secondly, a 28/60 GHz dual-band power divider aiming at mm-wave applications has been designed and validated on GaAs integrated passive device (IPD) process. The design concept is based on the unique response of the composite right/left handed transmission line (CRLH-TL) to control the second operating frequency of the Wilkinson power divider. Referring from the measured results, the proposed power divider not only shows the good in-band responses at both operating frequencies but also occupies a very compact footprint when compared to other studies in the open literature. It is believed to be the first on-chip dual-band power divider at mm-wave frequencies.

Libri sul tema "Beam dividers":

Knowles, Harvey C. The dividend investor: A safe, sure way to beat the market. Chicago: Probus Pub. Co., 1992.

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Knowles, Harvey C. The dividend investor: A safe and sure way to beat the market with high-yield dividend stocks. London: Irwin Professional Publishing, 1992.

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Barsky, Robert B. Bull and bear markets in the twentieth century. Cambridge, MA: National Bureau of Economic Research, 1989.

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Gardner, A. Dudley. Historic investigations of the Bear River Divide segment of the Oregon Trail. Rock Springs, Wyo: Archaeological Services, Western Wyoming College, 1987.

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Gardner, A. Dudley. Historic investigations of the Bear River Divide segment of the Oregon Trail. [Cheyenne, Wyo.?: Bureau of Land Management, Wyoming State Office], 1987.

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Gardner, A. Dudley. Historic investigations of the Bear River Divide segment of the Oregon Trail. [Cheyenne, Wyo.?: Bureau of Land Management, Wyoming State Office], 1987.

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Simon, Roger. Divided we stand: How Al Gore beat George Bush and lost the presidency. New York: Crown Publishers, 2001.

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United States. National Park Service, a cura di. Sleeping Bear Dunes National Lakeshore: Platte Plains hiking trail : 13 miles divided into shorter loops. 2^a ed. [Washington, D.C.?]: National Park Service, Dept. of the Interior, 1992.

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United States. National Park Service., a cura di. Sleeping Bear Dunes National Lakeshore: Platte Plains hiking trail : 15 miles divided into shorter loops. 3^a ed. [Washington, D.C.?: National Park Service, 1989.

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Emsbach, Michael, e Marcel Schippmann. Gestaltungsspielräume der Qualifizierung schwächer qualifizierter Bevölkerungssegmente beim Übergang von der Industriegesellschaft zur Informationsgesellschaft, untersucht am Beispiel grosser Hafenstädte der Welt. Aachen: Shaker, 2009.

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Capitoli di libri sul tema "Beam dividers":

Fuchs, Michael. "“I Can’t Believe This Is Happening!”: Bear Horror, the Species Divide, and the Canadian Fight for Survival in a Time of Climate Change". In Studies in Global Science Fiction, 257–73. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-15685-5_15.

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Sarid, Dror. "Heterodyne Detection System". In Scanning Force Microscopy, 91–100. Oxford University PressNew York, NY, 1994. http://dx.doi.org/10.1093/oso/9780195092042.003.0007.

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Abstract In a heterodyne detection system (Martin and Wickramasinghe 1987), shown schematically in Fig. 7.1, the first beam splitter divides into two components. One passes through an acousto-optic modulator that shifts the beam frequency by Om , and the other is reflected onto a mirror as a reference beam. The beam with the shifted frequency, serving as the signal beam, passes through a polarizing beam splitter, a quarter-wave plate, and finally, a microscope objective that focuses it onto the lever supporting the force-sensing tip. The lever reflects the beam back through the microscope objective and quarter-wave plate, which rotates the polarization on the two passes by 90°. The polarizing beam splitter then deflects the beam through an analyzer that adjusts the relative power of the beam incident on the photodetector. The reference beam is deflected by a second mirror, passes through the polarizing beam splitter and analyzer, and is incident on the same photodetector. The reference and signal beams interfere on the photodetector, which generates a current consisting of a spectrum of frequencies. The photocurrent is fed into a single side-band receiver driving a phase-sensitive detector that provides the signal used to display the force acting on the tip.

Houlahan, Micheál, e Philip Tacka. "Simple Meter". In Choral Sight Reading, 57—C7.P43. Oxford University PressNew York, 2023. http://dx.doi.org/10.1093/oso/9780197550533.003.0007.

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Abstract This unit adds to the student’s knowledge of rhythm. Initially, in rhythmic learning, students kept the beat, and then divided the beat into two sounds on the beat. Here they divide the beat into four even sounds. This is referred to as the second subdivision of the beat. Exercises and assessment forms are included.

Brooker, Geoffrey. "The Fabry–Perot". In Modern Classical Optics, 109–31. Oxford University PressOxford, 1992. http://dx.doi.org/10.1093/oso/9780198599647.003.0005.

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Abstract This chapter examines a particular case of multiple-beam interference: where light is bounced repeatedly between two highly reflecting mirrors. It is assumed that the reader has already encountered interference ‘by division of amplitude’ in its two-beam case, as happens when light is reflected from opposite faces of a slab or traces the two paths through a Michelson interferometer. It is further assumed that the following are familiar: The optical path difference is n 2d cos θ when a light beam divides at the surfaces (separation d) of a slab of refractive index n, and travels inside the slab at angle θ to the normal.

Whites, Leeann. "The Civil War as a Crisis in Gender". In Divided Houses, 3–21. Oxford University PressNew York, NY, 1992. http://dx.doi.org/10.1093/oso/9780195074079.003.0001.

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Abstract It was a cold winter’s day and greenish ice flows clogged the turbulent river. Across its vast expanse, Eliza could see the far shore of Ohio and freedom. Behind her, coming ever closer, she could hear the baying dogs of the slavetrader, Haley. What could she do? On the one side was slavery and the certain loss of her child to the slavetrader. On the other was an impassable river and probable death. Looking down at her small son, Eliza knew only that she could not bear to lose him. And with one desperate burst of courage, she jumped onto the nearest ice flow. Scrambling and leaping from one teetering piece of ice to another, she struggled across the mighty Ohio and gained the far shore of freedom for herself and her child.

"Reading Beat and Being Beat in Oslo – the Reception and Inspiration of Beat Culture in Post-war Norway". In Beat Literature in a Divided Europe, 253–72. Brill | Rodopi, 2018. http://dx.doi.org/10.1163/9789004364127_013.

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"Failure Analysis of Weldments". In Weld Integrity and Performance, 197–214. ASM International, 1997. http://dx.doi.org/10.31399/asm.tb.wip.t65930197.

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Abstract Weldment failures may be divided into two classes: those identified during inspection and mechanical testing and those discovered in service. Failures in service arise from fracture, wear, corrosion, or deformation. In this article, major attention is directed toward the analysis of service failures. The discussion covers various factors that may lead to the failure of arc welds, electroslag welds, electrogas welds, resistance welds, flash welds, upset butt welds, friction welds, electron beam welds, and laser beam welds.

"Introduction". In Beat Literature in a Divided Europe, 1–18. Brill | Rodopi, 2018. http://dx.doi.org/10.1163/9789004364127_002.

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"Literature in a State of Crisis – Beat Poetry, the Modernist Establishment and the Avant-Garde in Iceland". In Beat Literature in a Divided Europe, 19–42. Brill | Rodopi, 2018. http://dx.doi.org/10.1163/9789004364127_003.

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"In Kainuu as in Colorado – Receptions and Appropriations of Beat Literature in Finland in the 1960s". In Beat Literature in a Divided Europe, 43–62. Brill | Rodopi, 2018. http://dx.doi.org/10.1163/9789004364127_004.

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Atti di convegni sul tema "Beam dividers":

Shin, D., Robert Magnusson e M. G. Moharam. "Diffractive multiorder beam dividers". In OSA Annual Meeting. Washington, D.C.: Optica Publishing Group, 1989. http://dx.doi.org/10.1364/oam.1989.tuff5.

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Low spatial frequency gratings (i.e., Raman-Nath diffraction regime) exhibit multiple diffracted waves excited by a single incident plane wave. The energy distribution among the diffracted waves depends on the magnitude of the modulation and on the grating shape. For some applications, it is of interest to produce structures which support multiple diffracted waves with approximately equal intensities. Periodic arrays of dielectric cylinders were reported to have this property.1 In this paper, surface relief structures with conic (elliptic, hyperbolic, and parabolic) cross-sectional grating shapes are studied as an extension of this work. Better uniformity in the intensity distribution among the orders compared with dielectric cylinders is possible. In particular, a variable number of fairly evenintensity diffracted orders with reasonably sharp cutoff is found to be obtainable. Integral expressions, based on simple transmittance theory, are given for the complex amplitudes of the diffracted waves. These expressions are evaluated using an exact rigorous coupled wave theory2 and experiments. Potential applications include elements in multiple imaging, optical interconnection of networks and devices in integrated optics and communication systems, machine vision, as well as general beam division.

Knaak, K. M., K. Wendt e H. J. Kluge. "A Laser Operated Precision DC HV Voltmeter". In The European Conference on Lasers and Electro-Optics. Washington, D.C.: Optica Publishing Group, 1998. http://dx.doi.org/10.1364/cleo_europe.1998.cwc6.

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The precision of HV voltmeters based on voltage dividers is limited by the systematic errors induced by nonlinear currents and resistive drift. Therefore we take a different approach by accelerating ions with the potential to be measured. The resulting fast ion beam is collinearily superposed with a diode laser beam tuned to an optical resonance of the ions. Comparison to a cesium stabilized reference laser yields the absolute laser frequency to within a MHz. Now the accelerating voltage can be determined via the dopplershift of the optical resonance. Thus collinear laser spectroscopy [1] translates the voltage measurement to an absolute determination of an optical frequency.

Russell, P. St J., e T. A. Birks. "All-Fibre Frequency Shifters, Modulators and Switches". In The European Conference on Lasers and Electro-Optics. Washington, D.C.: Optica Publishing Group, 1998. http://dx.doi.org/10.1364/cleo_europe.1998.ctho1.

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Many all-fibre components already exist, such as multilayer mirrors (Bragg gratings), wavelength-sensitive beam splitters (tapered fibre couplers) and all-optical diode-laser-pumped lasers and amplifiers (by rare-earth doping of the core). Other desirable all-fibre components include electro-optic and acousto-optic modulators. These devices can be used as tunable filters, variable power dividers, frequency shifters and routing or packet switches They have a multitude of applications in telecommunications, sensing and lasers.

Albuquerque, T. C., T. L. V. N. Silva, A. J. R. Serres, R. C. S. Freire, J. Walheim, F. Podevin, F. Burdin, P. Ferrari e T. P. Vuong. "Implementation of beam-steering front-ends at 2.45 GHz using modified Wilkinson power dividers, reflexion type phase shifters and C-shape monopole antennas: First results". In 2015 SBMO/IEEE MTT-S International Microwave and Optoelectronics Conference (IMOC). IEEE, 2015. http://dx.doi.org/10.1109/imoc.2015.7369191.

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Yip, Gar Lam. "Modelling, Design Optimization and Fabrication of Guided-Wave Photonic Devices in Glass". In Gradient-Index Optical Imaging Systems. Washington, D.C.: Optica Publishing Group, 1994. http://dx.doi.org/10.1364/giois.1994.gtud1.

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Design optimization is very important to achieve high performance of integrated optical devices. For accurate designs, detailed information on the characteristics of slab and channel guides made in glass substrates must be known in relation to their fabrication conditions since these waveguides often form the basic units in more complicated waveguide structures used in devices. This paper will outline the characterization and modelling procedures of such waveguides, and present the methodology of design optimization of waveguide devices. In particular, the beam propagation method (BPM) combined with the effective index method (EIM) will be discussed. Illustrative examples will be given on power dividers, wavelength multi/demultiplexers and vertical directional couplers made by K+-ion exchange in glass. Comparisons between the measured performance figures of fabricated devices and design predictions will be presented.

Wang, Z. X., e W. B. Dou. "Uniform beam shaper and beam divider in millimeter wave band". In >2006 Joint 31st International Conference on Infrared Millimeter Waves and 14th International Conference on Teraherz Electronics. IEEE, 2006. http://dx.doi.org/10.1109/icimw.2006.368511.

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Hsu, Fu Kuo. "Laser-beam alignment stabilization by self-compensation". In OSA Annual Meeting. Washington, D.C.: Optica Publishing Group, 1990. http://dx.doi.org/10.1364/oam.1990.thrr3.

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Laser beams are usually unstable in terms of their pointing direction because of fluctuations of the resonant cavity. This angular fluctuation of laser beams can be somewhat reduced with a servomechanism.1,2 My approach uses an optical system capable of self-compensating the angular fluctuation of the laser. Because no servomechanism is required, the beam stabilizer reacts instantaneously. The stabilizer essentially uses the self-compensation principle. The input beam is first divided into two perpendicularly polarized beams, that then combine to form the output beam. Because the angular fluctuation of the input beam causes the two perpendicularly polarized component beams to deviate in exactly opposite directions, the angular error of the combined beam is automatically cancelled. This system works well for Gaussian beams, either cw or pulsed. The design and analysis of the proposed beam stabilizer are provided. Experimental demonstrations are also given.

Tamura, Shinji. "Theoretical Analysis of Natural Frequencies and Mode Shapes of Three-Dimensional Piping Systems". In ASME 2023 Pressure Vessels & Piping Conference. American Society of Mechanical Engineers, 2023. http://dx.doi.org/10.1115/pvp2023-106207.

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Abstract The vibration of piping system subjected to earthquake is a severe problem. However, the actual piping system is seems to be too complicated to analyze theoretically. Therefore, the finite element method is used to obtain the natural frequencies and mode shapes. For two-span beam, the theoretical method for the natural frequencies are written in the textbook of the vibrations of continuous systems. In this method, the beam is divided at the intermediate support, and the function for the displacement including unknown coefficients is assigned for each divided beam. The boundary conditions for the divided beams yield the characteristic equation for whole beam. In this paper, same approach is extended for the piping system with the elbows.

Capello, Edoardo, e Barbara Previtali. "Effect of Dual Beam on Reduction of Porosity in CO2 Laser Welding". In ASME 8th Biennial Conference on Engineering Systems Design and Analysis. ASMEDC, 2006. http://dx.doi.org/10.1115/esda2006-95388.

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In the recent past great study has been dedicated to porosity formation in laser welding. Using impressive apparatus for the experimentation Japanese authors have pointed out the main phenomenological causes of porosity produced by laser keyhole welding. Moreover, they have evidenced the effect of process parameters and bead configuration on porosity formation. Keyhole oscillation and consequently local vaporisation of the molten pool have been found to be present in all metals (stainless steel, carbon steel, aluminium and magnesium alloys) and in all process conditions (CO2 or Nd:YAG systems, continuous wave or pulsed lasers). Since keyhole porosity can not be totally avoided, the laser welding process should be accurately selected and process parameters designed in such a way as to minimise pore formation. The paper is aimed at studying the effect of laser configuration, single beam or dual beam, on the keyhole porosity. A dual beam system, allowing the laser beam to be divided in two beams, both of them working in keyhole mode, has been studied and compared to the traditional single beam welding process. In order to compare the two laser configurations, quantitative features of pores have to be individuated. Since the pores in the bead are supposed to have a negative effect on fatigue strength of the welded component, the main characteristics of investigated porosity were the porosity percentage and the pore diameter. The experimental results show that the dual beam configuration is effective in pore area reduction, if the related process parameters (inter-beam distance and feed rate) are accurately selected.

Xu, Huai Fang. "Real time optical 2-D array logic operation using two-wave mixing in photorefractive crystals". In OSA Annual Meeting. Washington, D.C.: Optica Publishing Group, 1989. http://dx.doi.org/10.1364/oam.1989.wl52.

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When coherent optical beams cross in a photorefractive crystal such as BaTiO3, SBN, there is an automatic 90° phase shift between beams A and B at the place of maximum refractive index of the photorefractive grating, because there is a 90° phase shift between the grating and the interference pattern of two beams A, B (A, B also indicate the amplitude of beams A, B). Because of the energy conservation law there is a 90° phase difference between A t and A d , Bt and B d (beams A and B will be divided into transmitted beam A t , B t and diffractive beam A d , B d , respectively).

Rapporti di organizzazioni sul tema "Beam dividers":

Salter e Weston. L51534 A Study of New Joining Processes for Pipelines. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), gennaio 1987. http://dx.doi.org/10.55274/r0010083.

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Over many decades it has been accepted that the most economical way to produce a pipeline is to join together the standard lengths of pipe as quickly as possible, using a highly mobile task force of welders and other technicians, leaving tie-ins, crossings, etc. to smaller specialist crews. The work pattern which evolved almost invariably involved several crews of welders strung out along the pipelines, progress being controlled by the rate at which the leading pair could complete the weld root. The spread from this first crew to final inspection could be a considerable distance, acceptable on land but not acceptable offshore (a rapidly increasing need which reached a peak in the 1970's). This operation, involving costly lay barges, demanded even higher throughput rates to be achieved from a more compact working spread. In common with most manufacturing technologies, there was an increasing dissatisfaction with a system which relied entirely on the skill of a limited number of highly paid men who had little incentive to change their working practices. Increasingly there came reports of the development of new approaches to joining line-pipe, ranging from the mechanization of arc welding to entirely different forms of joining, for example, electron beam welding or mechanical joining. The investment in some of these developments is reported to be several million dollars. The review of present pipelining practice shows that only a handful has been put to practical use, and in the western world, probably only one, an arc welding variant, has been used to produce more than a few hundred miles of pipeline. The information available on these developments is sparse and is scattered amongst a range of companies and research agencies. A literature review and research study to collect together as much of this information as is available, assemble it into a coherent and useable form and identify those developments which show the most promise to fulfill future needs. The main body of the report, which reviews development of the welding processes has been divided into three main joining categories, Fusion Welding, Forge Welding and Mechanical Interference Joining. Within each category each process is considered separately in terms of process principles, general applications, application to pipeline welding, equipment for pipe welding, consumables, process tolerance and skill requirements, weld quality and inspection, process economics, limitations and future developments. This study and comprehensive report compares the economics of the various alternatives. For each process an estimate has been made of the procedural and development costs involved as well as personnel needs and likely production rates.

APPLICATION OF HYDRAULIC SYNCHRONOUS LIFTING TECHNOLOGY IN THE CONSTRUCTION OF LONG-SPAN HYBRID STEEL STRUCTURES. The Hong Kong Institute of Steel Construction, agosto 2022. http://dx.doi.org/10.18057/icass2020.p.070.

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The aim of this study was to solve technical problems, such as uneven structures, multiple lifting points, high accuracy control requirements, and multi-disciplinary collaborative work, in the process of lifting and hoisting long-span hybrid steel structures based on the lifting work of a steel roof and steel beams of the Hunan Radio and Television studio F. First, after conducting research on the comparison and selection of the construction scheme, lifting process, quality control and other aspects, a floor assembly + hydraulic lifting + overhead supplementary bar construction plan was proposed. The large-section steel beam and truss hybrid structure system with different bottom chord elevations was divided into two units for synchronous lifting, with weights of 715 tons and 340 tons, lifting heights of 21.5 metres and 15 metres, and a maximum span of 50.4 metres , Second, the maximum vertical displacement, maximum stress ratio of the members, lifting reaction force frame and overall stability of the hybrid structure during the lifting process were analysed, and the results showed that they all met the requirements. Finally, the monitoring data of the field construction process were in good agreement with the numerical calculation results, further verifying the rationality and feasibility of hydraulic synchronous lifting technology, which can provide guidance and a reference for the construction of similar long-span hybrid steel structures.