412 research outputs found
Dual-Band Gysel Filtering Power Divider with a Frequency Transform Resonator and Microstrip/Slotline Phase Inverter
No full textThis paper presents a novel dual-band Gysel filtering power divider (FPD) with an excellent isolation performance and a significantly wide isolation bandwidth. Although Gysel power dividers have been extensively studied in the field of radio frequency (RF), the integration of filtering functionality and the expansion of isolation bandwidth remain challenging. The proposed design addresses these challenges by incorporating frequency transform resonators (FTRs) and a microstrip/slotline (M/S) phase inverter into the classic Gysel topology. The FTR is directly connected to the output port to provide a dual-band response, enabling the Gysel FPD to operate without external coupling between the resonator and the port. The M/S phase inverter is a dual-layer 180° phase shifter, designed to replace the conventional 180° transmission lines loaded between the two isolation resistors of the Gysel FPD, achieving a wide isolation bandwidth. To validate the proposed design method, a dual-band Gysel FPD with center frequencies of 1.4 GHz and 1.7 GHz is designed, fabricated, and measured. The measured results show that the in-band return loss is greater than 20 dB, and the in-band insertion loss is about 0.6 dB, and the amplitude and phase imbalance characteristics are good. In addition, the 20 dB-isolation fractional bandwidth achieves 97% (0.78–2.25 GHz). The measured results show excellent agreement with the simulation results, validating the effectiveness of the proposed design methodology
Design of Gysel power combiners in E-plane rectangular waveguides
No full textThe design of 5-port power combiners using the Gysel-type architecture in full E-plane rectangular waveguide is presented. It exploits the high power handling capabilities of empty metallic waveguides and the achievable bandwidth of operation that Gysel combiners provide when compared to traditional combiners. The proposed new design takes into account the different requirements on the power handling capability of the terminating loads and their waveguide ports. This leads to having different port heights at the isolated ports, based on the need to handle certain power levels in the isolated ports in cases of phase and amplitude imbalance between inputs. The new realization is proposed in full E-plane rectangular waveguide topology for compactness, ease of fabrication, efficient full-wave analysis, and tailored power handling capabilities. A proof of concept Gysel combiner at X-band was designed, fabricated and tested, demonstrating excellent test results without any tuning: a combining loss of better than 0.5 dB over a 25% fractional bandwidth with a very compact volume of 1.2λ0 × 1.7λ0 × 1.9λ0
Compact ridge waveguide Gysel combiners for high power applications
No full text“© 2018 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works”This paper presents, to the authors´ knowledge, the first realizations of the Gysel-type power combiner/divider in ridge waveguide technology with two different configurations. Gysel combiners exhibit wider bandwidths than traditional combiners, while offering compact designs when implemented in ridge waveguide, compared with traditional waveguide combiners. In addition, Gysel combiners provide relaxed requirements on the power handling capability of the terminating loads in case of fault conditions, which may result from imbalance between the different inputs. The ridge waveguide designs offer better power handling capabilities, especially in comparison with planar designs. These advantages are shown with two different realizations, in top-bottom and side-by-side configurations, exhibiting very wide bandwidths while occupying very compact volumes. These two designs have been simulated, fabricated and tested. Excellent test results have been obtained confirming the validity of the concep
Investigation of the effective peak supersaturation for liquid-phase clouds at the high-alpine site Jungfraujoch, Switzerland (3580 m a.s.l.)
No full textAerosols influence the Earth's radiation budget directly through
absorption and scattering of solar radiation in the atmosphere but
also indirectly by modifying the properties of clouds. However,
climate models still suffer from large uncertainties as a result of
insufficient understanding of aerosol-cloud interactions. At the
high altitude research station Jungfraujoch (JFJ;
3580 m a.s.l., Switzerland) cloud condensation nuclei (CCN)
number concentrations at eight different supersaturations (SS) from
0.24% to 1.18% were measured using a CCN counter during
Summer 2011. Simultaneously, in-situ aerosol activation properties
of the prevailing ambient clouds were investigated by measuring the
total and interstitial (non-activated) dry particle number size
distributions behind two different inlet systems. Combining all
experimental data, a new method was developed to retrieve the
so-called effective peak supersaturation SSpeak,
as a measure of the SS at which ambient clouds are
formed. A 17-month CCN climatology was then used to retrieve the
SSpeak values also for four earlier summer
campaigns (2000, 2002, 2004 and 2010) where no direct CCN data were
available. The SSpeak values varied between
0.01% and 2.0% during all campaigns. An overall median
SSpeak of 0.35% and dry activation diameter
of 87 nm was observed. It was found that the difference in
topography between northwest and southeast plays an important role
for the effective peak supersaturation in clouds formed in the
vicinity of the JFJ, while differences in the number concentration
of potential CCN only play a minor role. Results show that air
masses coming from the southeast (with the slowly rising terrain of
the Aletsch Glacier) generally experience lower
SSpeak values than air masses coming from the
northwest (steep slope). The observed overall median values were
0.41% and 0.22% for northwest and southeast wind
conditions, respectively, corresponding to literature values for
cumulus clouds and shallow-layer clouds. These cloud types are
consistent with weather observations routinely performed at the JFJ
A novel compact six-pole filtering gysel combiner
No full textThis paper presents a novel two-way in-phase filtering Gysel splitter/combiner realized through a network of six-pole compact cross-coupled resonators. The network simultaneously realizes a filtering function and a two-way splitter/combiner function. Gysel combiners find application in high power amplifier designs. The five-port device uses a ring of six resonators arranged to realize, simultaneously, the combined filtering and coupling function. A rigorous coupling matrix describing the network is used to synthesize the integrated filtering and combining functions. This general network can be implemented in any of the available filter technologies. In this paper, compact combline coaxial resonators are employed and coupled using interconnected ridges to improve the bandwidth. The proposed design provides an integrated dual function module, reducing component counts and system complexity. A design was fabricated and tested demonstrating good resultsThis work was partially supported by the
Spanish Government under grant PID2020-116968RB-C32
(DEWICOM) and TED2021-130650B-C21 (ANT4CLIM)
funded by MCIN/AEI/ 10.13039/501100011033 (Agencia
Estatal de Investigacion) and by UE (European Union)
“NextGenerationEU”/PRT
Learning from Within: A Proposal for a New Approach to Education in Native Society
No full textTranslated by Jens Van Gysel. Originally published as: Kalisch, H. (2010). Escritura y oralidad Enlhet-Enenlhet: Sentido y significado de las publicaciones monolingües en la lengua autóctona (pp. 235-60), in J. M. Rodrigues (Ed.), Educación, lenguas y culturas en el Mercosur: Pluralidad cultural e inclusión social en Brasil y en Paraguay. Proceedings of the II Seminario Internacional de Educación Intercultural Bilingüe y Educación Indígena, Asunción, 22-23 July 2010 Asunción: CEADUC. The original translated title is “Enlhet-Enenlhet Writing and Orality: The Meaning and Significance of Monolingual Publications in Autochthonous Languages”.This article presents a new perspective on how to think about interculturality and education from the perspective of a native society in the Paraguayan Chaco. It highlights how formal schooling reaffirms the model of unidirectional relations advocated by national society. Within this model, indigenous peoples and persons are not allowed to participate in this national society on their own conceptual terms, and inclusion turns out to be mere shorthand for assimilation. This text, on the other hand, proposes modes of education and forms of relating that pay attention to the native dimension. These would contribute to the creation of spaces which indigenous societies as such can hold within national society and support indigenous people’s own processes of protagonism and initiative. In parallel, it proposes conceiving of education as from rather than for autochthonous societies; and conceiving of the learning process from the point of view of learning rather than from the point of view of education. This conceptual change, which includes a critique of the widespread concept of interculturality, entails that we must not design modes of education, but rather create preconditions for learning from within the native society, which also requires ways of relating from within. In this way, colonialist pressures in education can be overcome and new possibilities for native protagonism can be developed
The Ice Selective Inlet: a novel technique for exclusive extraction of pristine ice crystals in mixed-phase clouds
No full textClimate predictions are affected by high uncertainties partially due to an insufficient knowledge of aerosol-cloud interactions. One of the poorly understood processes is formation of mixed-phase clouds (MPCs) via heterogeneous ice nucleation. Field measurements of the atmospheric ice phase in MPCs are challenging due to the presence of supercooled liquid droplets. The Ice Selective Inlet (ISI), presented in this paper, is a novel inlet designed to selectively sample pristine ice crystals in mixed-phase clouds and extract the ice residual particles contained within the crystals for physical and chemical characterisation. Using a modular setup composed of a cyclone impactor, droplet evaporation unit and pumped counterflow virtual impactor (PCVI), the ISI segregates particles based on their inertia and phase, exclusively extracting small ice particles between 5 and 20 μm in diameter. The setup also includes optical particle spectrometers for analysis of the number size distribution and shape of the sampled hydrometeors. The novelty of the ISI is a droplet evaporation unit, which separates liquid droplets and ice crystals in the airborne state, thus avoiding physical impaction of the hydrometeors and limiting potential artifacts. The design and validation of the droplet evaporation unit is based on modelling studies of droplet evaporation rates and computational fluid dynamics simulations of gas and particle flows through the unit. Prior to deployment in the field, an inter-comparison of the WELAS optical particle size spectrometers and a characterisation of the transmission efficiency of the PCVI was conducted in the laboratory. The ISI was subsequently deployed during the Cloud and Aerosol Characterisation Experiment (CLACE) 2013 – an extensive international field campaign encompassing comprehensive measurements of cloud microphysics, as well as bulk aerosol, ice residual and ice nuclei properties. The campaign provided an important opportunity for a proof of concept of the inlet design. In this work we present the setup of the ISI, including the modelling and laboratory characterisation of its components, as well as a case study demonstrating the ISI performance in the field during CLACE 2013
1T memory cell based on PVDF-TrFE field effect transistor
No full textInterest in vinylidene fluoride (VDF) co-polymer with trifluorethylene (TrFE) P(VDF-TrFE) as ferroelectric material for memory application is driven by the prospect of having low cost and low operating voltage devices integrated on silicon and, at long term, migrate on flexible substrates. Some previous studies reported FET design using copolymers [1-8] but none of these structures were fully integrated on silicon wafers into a quasi-standard MOSFET fabrication process. We present for the first time the integration of a P(VDF-TrFE) (70%-30%) layer into a standard n-MOS transistor gate stack through a conventional semiconductor technology. This allows us to achieve a one-transistor (IT) Non Volatile Memory (NVM) cell. The operation voltage required for the 100nm organic ferroelectric thickness is less than 12V and a retention time ranging from few hours to few days is reported. © 2008 Materials Research Society
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