1,720,966 research outputs found
Ultra-compact pseudoelliptic waveguide filters using TM dual-mode dielectric resonators
No full textThis paper presents a solution for ultra-compact pseudoelliptic dual-mode filters using high permittivity dielectric resonators. The basic idea consists of using a pair of degenerate resonant TM modes within a cavity loaded with a very high-permittivity puck. Nonresonating modes, instead, are exploited so as to produce a direct coupling between the input and the output of the dielectric-loaded cavity. In this way, a single cavity can provide two transmission poles and zeros, thus leading to N-pole and N-zero filters. The proposed configuration yields very compact and geometrically simple structures with resonator unloaded Q around 3000 at C-band. The geometrical dimensions of a 4-pole and 4-zero waveguide filter for C-band applications are 32×32×20 mm3 (using εr=34). Its FBW is 2.4% and the in-band IL is 0.3 dB by HFSS® simulations. The first prototype of the 4th order filter is going to be fabricated
Miniaturized Dual-Band Waveguide Filter Using TM Dielectric-Loaded Dual-Mode Cavities
No full textIn this letter a class of very compact dual-band band-pass filters based on TM dual-mode cavities loaded with high permittivity dielectric is presented. Filters consist of cascaded doublets resulting in in-line structures with a high degree of design modularity where each doublet is designed separately. Each doublet provides two poles and two transmission zeros resulting in a filter with an equal number of poles and zeros. Zeros can be placed in both the lower and upper stop-bands as well as between the two pass-bands to increase their insulation. The feasibility of the proposed approach is demonstrated through the design and manufacturing of a 6th order dual-band filter with central frequencies at 4.25 and 4.55 GHz having six transmission zeros
p-i-n-Diode-Based Four-Channel Switched Filter Bank With Low-Power TTL-Compatible Driver
No full textThe design of a four-channel switched filter bank in the S- and C-band using p-i-n-diode switches is described. Narrowband filters (3.2%-3.5%) are designed on suspended substrate stripline. The biasing circuit allows the switches to be driven with transistor-transistor-logic-compatible voltages and minimum biasing current. The average insertion loss measured is 3.6 dB corresponding to a Q-factor of 580. Spurious responses were suppressed from dc to roughly 19 GHz
Ka-band surface-mountable pseudo-elliptic filter in multilayer micromachined technology for on-board communication systems
No full textThis paper presents the design, manufacturing and testing of a new type of compact and low loss Ka-band filter in multilayer micromachined technology. It consists of a 4th order pseudo-elliptic filter realized by stacking six silicon layers for a reduced footprint. The filter is based on λ/2 TEM Si membrane resonators placed inside shielding cavities and short-circuited at both anchored ends. With respect to conventional cavities based on TE101 resonant mode, the footprint of the proposed resonators is reduced by more than 50% at the expenses of a reduced Q factor degradation (<;20%). The measurements of the 4th order filter at Ka-band show insertion loss better than 3dB and Q factor above 500 in Ka-band. The filter robustness to manufacturing and the assembly tolerances has been verified on eight samples, showing good reproducibility of the filter response. Environmental tests are on-going to demonstrate the space compatibility of the filter
Ultra-compact filters using TM dual-mode dielectric-loaded cavities with asymmetric transmission zeros
No full textThis paper presents ultra-compact dual-mode dielectric-loaded waveguide bandpass filters with Nth-order pseudoelliptic filtering function and asymmetric positioning of N transmission zeros. A waveguide cavity is loaded with a very high-permittivity rod (εr>30). Two degenerate resonant TM modes are employed along with nonresonating modes. In contrast to previous works, that are limited to structures with a symmetric response, in the proposed solution both modes are directly coupled to the input and output interconnections. Nonresonating modes are exploited to produce a direct source-load coupling. In this way, a single cavity generates two transmission poles and two transmission zeros located either below or above the two poles, thus realising a basic building block for N-pole and N-zero filters with asymmetric response. The dimensions of a 3% FBW 4th-order filter with 4 zeros at 4.35 GHz are 40×40×12 mm3 (using εr=34). A preliminary prototype has been fabricated and measured showing an unloaded Q of 1750 and good agreement with HFSS® simulations
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Design and manufacturing of X-Band tunable microcavity resonator in MEMS technology
Full text linkThis paper presents the design modeling and
hardwire prototypes fabrication of a X-band tunable cavity
resonator based on MEMS technology. Brass metallic
cavities with inner post have been thermo-compressive
bonded on a silicon substrates having 4 MEMS varactors
based on toggle mechanism. The tunable resonator was
simulated in ANSYS® HFSS full wave environment,
resulting in a continuous tuning range of 22% with an
unloaded quality factor (Q) in the range of 80-180 and a
very small volume of 3.2x3.2x1.4 mm3. Preliminary
experimental results are presented. The measurements on
hardwired prototypes result in a maximum unloaded
quality factor (Q) of 80 and tuning range of 14%, centered
at the frequency of about 9GHz. The main responsible of the
lower measured quality factor, respect to the simulated one,
was found to be the additional losses in the silicon substrate
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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