scholarly journals Design of Symmetrical Beam Triple-Aperture Waveguide Antenna for Primary Feed of Reflector

2016 ◽  
Vol 2016 ◽  
pp. 1-14 ◽  
Author(s):  
Kanawat Nuangwongsa ◽  
Chuwong Phongcharoenpanich

This research presents a triple-aperture waveguide antenna as the primary feed of parabolic reflectors. The proposed antenna is able to rectify the asymmetry and also achieve a symmetrical unidirectional beam through the application of two parasitic coupling apertures. The design of the antenna is that of a rectangular waveguide (radiating aperture) vertically jointed to the two coupling apertures of the same measurement widthwise (i.e., one stacked on top and the other underneath) to achieve the symmetrical beam. The rectangular waveguide is 97.60 mm and 46.80 mm in width (a) and height (b), respectively, to propagate the WLAN frequency band of 2.412–2.484 GHz. Simulations were carried out to determine the optimal antenna parameters and an antenna prototype was subsequently fabricated and tested. The simulated beamwidths in theE- andH-planes at-3 dB were equally 67° (i.e., 67° for both theE- andH-planes) and at-10 dB also equally 137°, while the measured results at-3 dB were equally 65° and at-10 dB equally 135°. The simulation and measured results are thus in good agreement. The simulated and measured antenna gains are, respectively, 8.25 dBi and 9.17 dBi. The findings validate the applicability of the antenna as the prime feed for rotationally symmetric parabolic reflectors.

2020 ◽  
Vol 10 (14) ◽  
pp. 4979
Author(s):  
José M. Pérez-Escudero ◽  
Alicia E. Torres-García ◽  
Ramón Gonzalo ◽  
Iñigo Ederra

In this paper two different simple to design and easy to manufacturing transitions from a microstrip to rectangular waveguide based on ridge and groove gap waveguides are studied. The first one is based on a combination of a groove and ridge gap waveguide. In this case, the microstrip substrate occupies the whole bottom metallic housing block, namely, the transition and the gap between the bed of nails and the lid; therefore, it does not require any substrate shaping. Nevertheless, the transition needs to replace groove waveguide by ridge gap waveguide sections to avoid higher-order mode excitation. In the second approach, based on only a groove gap waveguide, the substrate is shaped to be only in the microstrip section, that is, outside the bed of nails area. This leads to a simplification of the design procedure. Prototypes of both transitions have been characterized, showing good agreement with the simulations taking into account the manufacturing tolerances. Performance comparable to the state-of-the-art in this frequency band has been achieved.


Author(s):  
Arno J. Bleeker ◽  
Mark H.F. Overwijk ◽  
Max T. Otten

With the improvement of the optical properties of the modern TEM objective lenses the point resolution is pushed beyond 0.2 nm. The objective lens of the CM300 UltraTwin combines a Cs of 0. 65 mm with a Cc of 1.4 mm. At 300 kV this results in a point resolution of 0.17 nm. Together with a high-brightness field-emission gun with an energy spread of 0.8 eV the information limit is pushed down to 0.1 nm. The rotationally symmetric part of the phase contrast transfer function (pctf), whose first zero at Scherzer focus determines the point resolution, is mainly determined by the Cs and defocus. Apart from the rotationally symmetric part there is also the non-rotationally symmetric part of the pctf. Here the main contributors are not only two-fold astigmatism and beam tilt but also three-fold astigmatism. The two-fold astigmatism together with the beam tilt can be corrected in a straight-forward way using the coma-free alignment and the objective stigmator. However, this only works well when the coefficient of three-fold astigmatism is negligible compared to the other aberration coefficients. Unfortunately this is not generally the case with the modern high-resolution objective lenses. Measurements done at a CM300 SuperTwin FEG showed a three fold-astigmatism of 1100 nm which is consistent with measurements done by others. A three-fold astigmatism of 1000 nm already sinificantly influences the image at a spatial frequency corresponding to 0.2 nm which is even above the point resolution of the objective lens. In principle it is possible to correct for the three-fold astigmatism a posteriori when through-focus series are taken or when off-axis holography is employed. This is, however not possible for single images. The only possibility is then to correct for the three-fold astigmatism in the microscope by the addition of a hexapole corrector near the objective lens.


2005 ◽  
Vol 48 (1-2) ◽  
pp. 7-19
Author(s):  
Miroslava Andjelkovic

This paper deals with a criticism of Ryle's claim that the so called Intellectualist legend leads to an infinite regress. Critics have attempted to show that Ryle's argument cannot even get off the ground since its two basic premises cannot be true at the same time. In the paper I argue that this objection is based on a misinterpretation of Ryle's argumentation, which is complex and consists of two arguments, not of a single one as it is claimed. One of Ryle's argument attacks the thesis that an intelligent act is an indirect result of propositional knowledge, while the other, which I call the Asymmetry argument, claims that not every manifestation of knowledge that is accompanied with the manifestation of knowing how. In the paper I argue that both Ryle's arguments are valid and resistant to recent critique so it can be said that Ryle's distinction between knowledge that and knowing how is still an important distinction within contemporary epistemology.


Sensors ◽  
2021 ◽  
Vol 21 (2) ◽  
pp. 499
Author(s):  
Caroline Bonazza ◽  
Jiao Zhu ◽  
Roger Hasler ◽  
Rosa Mastrogiacomo ◽  
Paolo Pelosi ◽  
...  

An electronic biosensor for odors was assembled by immobilizing the silk moth Bombyx mori pheromone binding protein (BmorPBP1) on a reduced graphene oxide surface of a field-effect transistor. At physiological pH, the sensor detects the B. mori pheromones, bombykol and bombykal, with good affinity and specificity. Among the other odorants tested, only eugenol elicited a strong signal, while terpenoids and other odorants (linalool, geraniol, isoamyl acetate, and 2-isobutyl-3-methoxypyrazine) produced only very weak responses. Parallel binding assays were performed with the same protein and the same ligands, using the common fluorescence approach adopted for similar proteins. The results are in good agreement with the sensor’s responses: bombykol and bombykal, together with eugenol, proved to be strong ligands, while the other compounds showed only poor affinity. When tested at pH 4, the protein failed to bind bombykol both in solution and when immobilized on the sensor. This result further indicates that the BmorPBP1 retains its full activity when immobilized on a surface, including the conformational change observed in acidic conditions. The good agreement between fluorescence assays and sensor responses suggests that ligand-binding assays in solution can be used to screen mutants of a binding protein when selecting the best form to be immobilized on a biosensor.


2003 ◽  
Vol 96 (1) ◽  
pp. 33-42 ◽  
Author(s):  
Keiko Nakamoto

Camac and Glucksberg reported there was no priming effect between constituent terms of a metaphor and argued that there was no prior similarity or association between the constituents. However, their study had several limitations. An important one was that they neglected the asymmetry of metaphor constituent terms. The purpose of this study is to replicate their experiment under the condition in which one of the constituents preceded the other. The experiment was conducted with Japanese participants using Japanese metaphoric sentences as stimuli. The results showed that the decision was facilitated if the vehicle served as prime and the topic served as target. In contrast, if the topic preceded the vehicle, no priming effect was found. These results are discussed in terms of the class inclusion model proposed earlier by Glucksberg and Keysar.


2004 ◽  
Vol 18 (09) ◽  
pp. 1351-1368
Author(s):  
ANDREI DOLOCAN ◽  
VOICU OCTAVIAN DOLOCAN ◽  
VOICU DOLOCAN

Using a new Hamiltonian of interaction we have calculated the cohesive energy in three-dimensional structures. We have found the news dependences of this energy on the distance between the atoms. The obtained results are in a good agreement with experimental data in ionic, covalent and noble gases crystals. The coupling constant γ between the interacting field and the atoms is somewhat smaller than unity in ionic crystals and is some larger than unity in covalent and noble gases crystals. The formulae found by us are general and may be applied, also, to the other types of interactions, for example, gravitational interactions.


Perception ◽  
1996 ◽  
Vol 25 (12) ◽  
pp. 1419-1436 ◽  
Author(s):  
Paul Locher ◽  
Sharon Gray ◽  
Calvin Nodine

Two experiments were performed to examine how the subjective balance of a painting is created by its structural features and to determine if balance influences the way people look at paintings. Stimuli consisted of sixteen reproductions of twentieth-century paintings varying in artistic style and a reconstructed less-balanced version of each. Participants in experiment 1 determined the location of the balance center of each composition, assigned ‘weights’ to the pictorial features which contributed to the location of the balance center, and rated the picture for balance. It was found that design and museum professionals and individuals untrained in the visual arts were in good agreement as to the structural framework underlying the balance organization of a painting. For all participants, disruption of the balanced organizations of the original compositions led to reliable shifts in the location of the perceived balance centers of the originals compared with their less-balanced perturbations. Additionally, it was observed that particular features as such were not the origin of the balance phenomenon; rather, judgments concerning the balance structure and its center were dependent on the global integration of information across a wide area of the display field, but especially from its central region. Last, the subtle changes in balance structure between versions resulted in lower ratings of balance being assigned to the less-balanced perturbations by the design professionals only; the other two participant groups evaluated overall balance of the versions as comparable. In experiment 2, eye movements of a different group of untrained individuals were recorded as they performed similar tasks on the art stimuli. It was found that disruption of the balance structure of the original representational but not abstract compositions resulted in different regions of the original and perturbed versions being visually explored. Findings of both experiments are related to theoretical notions of balance.


2020 ◽  
Vol 73 (1) ◽  
pp. 113-158
Author(s):  
Timur Maisak

AbstractThis paper gives an account of participial clauses in Agul (Lezgic, Nakh-Daghestanian), based on a sample of 858 headed noun-modifying clauses taken from two text corpora, one spoken and one written. Noun-modifying clauses in Agul do not show syntactic restrictions on what can be relativized, and hence they instantiate the type known as GNMCCs, or general noun-modifying clause constructions. As the text counts show, intransitive verbs are more frequent than transitives and experiencer verbs in participial clauses, and among intransitive verbs, locative statives with the roots ‘be’ and ‘stay, remain’ account for half of all the uses. The asymmetry between the different relativization targets is also significant. Among the core arguments, the intransitive subject (S) is the most frequent target, patient (P) occupies second place, and agent (A) is comparatively rare. The preference of S and, in general, of S and P over A also holds true for most other Nakh-Daghestanian languages for which comparable counts are available. At the same time, Agul stands apart from the other languages by its high ratio of non-core relativization which accounts for 42% of all participial clauses. Addressee, arguments and adjuncts encoded with a locative case, as well as more general place and time relativizations show especially high frequency, outnumbering such arguments as experiencers, recipients, and predicative and adnominal possessors. Possible reasons for the high ratio of non-argument relativization are discussed in the paper.


Author(s):  
Azar Maalouf ◽  
Ronan Gingat ◽  
Vincent Laur

This study examines K-band rectangular waveguide terminations with three-dimensional (3D)-printed loads, and proposes an Asymmetrical Tapered Wedge topology. This geometry shows a good tradeoff between microwave performance and 3D-printing issues (printing directions and support material requirements), thus improving noticeably the reproducibility of the devices. The effect of the density of the 3D-printed load on the reflection parameter of the termination was investigated. Even for a low density, reflection level remained below −27.5 dB between 18 and 26.5 GHz. Reproducibility was demonstrated by the characterization of six loads that were 3D printed under the same conditions. Measurements demonstrate that a maximum reflection parameter level of −33.5 dB can be ensured over the whole frequency band without any post-machining of the 3D-printed devices.


Virittäjä ◽  
2017 ◽  
Vol 121 (2) ◽  
Author(s):  
Krista Ojutkangas

Tutkimuksen tavoitteena on selvittää, millaisissa konstruktioissa suomen seuralaisuutta ilmaisevat mukana ja mukaan esiintyvät. Seuralaisuussuhteelle on tyypillistä, että suhteen osallistujat tai vähintään kiintopiste ovat ihmisiä ja että osallistujien välillä on symmetriaero: seuralainen (engl. companion) osallistuu tilanteeseen epäsuorasti, seurattavan (engl. accompanee) välityksellä. Suomen grammeille ominaiseen tapaan mukana- ja mukaan-sanoja käytetään syntaktisesti monenlaisissa asemissa siten, että kiintopisteen (seurattavan) ilmaisun tyyppi vaihtelee. Tutkimuksessa selvitetäänkin, mikä on kiintopisteen ilmaisutavan rooli siinä, miten seuralaisuussuhteen osallistujien välinen epäsymmetria hahmottuu. Tutkimuksen syntaktisessa luokittelussa pidetään lähtökohtana postpositiokonstruktiota, jossa osallistujien välisen symmetriaeron voi katsoa perustuvan kiintopisteen viitepisteroolin kautta grammin semantiikkaan (tyyppi lapio oli kaivajan mukana). Symmetriaero sen sijaan voimistuu, kun kiintopiste edustuu omistusliitteen välityksellä subjektina (tyyppi hän otti lapion mukaansa) tai kun se ilmaistaan teemapaikalla paikallissijaisena adverbiaalina (tyyppi hänellä oli lapio mukana[an]). Symmetriaero sen sijaan heikkenee, jos (toissijainen) kiintopiste ilmaistaan adverbiaalina muualla kuin teemapaikalla (tyyppi hän oli mukana kaivamassa), ja vetäytyy taustatiedoksi, kun kiintopistettä ei ilmaista lainkaan (tyyppi hän on mukana). Tutkimus perustuu aineistoon, jossa ovat edustettuina 1800-luvun kirjakieli, Lauseopin arkiston murrehaastattelut ja nykykirjakieli. Aineisto osoittaa, että mukana- ja mukaan-grammeilla ilmaistuissa seuralaisuussuhteissa on tapahtunut muutos: 1800-luvun kirjakielen ja pääosin 1960-luvulla tallennetun murreaineiston esiintymissä yleisin kiintopiste on ihminen, kun taas nykykirjakielen aineistossa kiintopisteeksi hahmottuu tyypillisimmin toiminta. Kiintopisteen semanttinen tyyppi ja sen kielellinen ilmaisukeino ovat suorassa suhteessa toisiinsa. Ihmiskiintopiste ilmaistaan yleisimmin subjektin kanssa samaviitteisellä omistusliitteellä tai teemapaikkaisella paikallissijaisella elementillä ja toimintakiintopiste puolestaan ei-teemapaikkaisella paikallissijaisella elementillä. Eri ilmaisukeinot jakautuvat eri verbien ympärille rakentuvien konstruktioiden kesken. Tutkimuksen perusteella voi todeta, että esiintymäkonstruktiolla on merkittävä rooli siinä, millaista seuralaisuutta mukana- tai mukaan-grammilla kuvataan.   Finnish mukana and mukaan ‘with, along’ as comitative markers: Grammatical roles of expressions of the landmarks, constructions, and asymmetry between the participants of the accompaniment relation The topic of this article is the syntax of Finnish comitative markers mukana and mukaan ’with, along’. Comitative markers express accompaniment relations, which are typically conceived as being asymmetrical: the accompanee (landmark) is the pre-dominant participant, while the companion (trajector) is involved in the situation only via the accompanee (see Stolz et al. 2006: 26–27). However, markers such as mukana and mukaan are used in several syntactic constructions where the grammatical roles of expressions of the accompanees/landmarks vary. The main research question of the article is, how does the grammatical role of expression of the accompanee/landmark affect the asymmetry between the participants of the accompaniment relation. Five syntactic construction types were analysed from a corpus data. On the basis of this study, it is shown that syntactic variation has an effect on the conceived asymmetry between the accompanee and the companion, and that syntax makes an important contribution to the semantics of comitative constructions. In strongly asymmetric accompaniment relations, a human accompanee is expressed by a possessive suffix affixed to the comitative marker, or by a clause-initial adverbial. On the other hand, the question of asymmetry contracts to the background when the accompanee is expressed by a non-clause-initial adverbial and when the accompanee is implicit, without any overt marking. The research is based on a corpus data comprising 19th-century written Finnish, dialect interviews, and modern written Finnish. The data shows that accompaniment relations expressed by mukana and mukaan have changed: in the 19th-century and dialect data, the majority of the landmarks are humans, but in the modern data activities dominate as (secondary) landmarks.  


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