1,720,975 research outputs found
Design of a 24-GHz dual-polarized rectenna integrated on silicon
No full textThis paper presents the design of an integrated and differential rectenna on silicon, operating at 24 GHz. The antenna is dual-polarized and composed by four patches on a synthetized low effective permittivity dielectric. The substrate is a structure composed of three layers of high-resistivity silicon (εr = 11.9) where the central layer has an air cavity equal to the dimensions of the antennas. The feeding solution is performed by planar microstrip lines with inset feeds. A shunt configuration was chosen for the rectifiers with GaAs diodes. The silicon substrate assures the complete integration for on-chip systems and despite the lossy material chosen as substrate, each patch antenna presents 83% of radiation efficiency with a maximum gain of 4.82 dBi. The overall efficiency of the rectenna is 43% at a received power level of 14 dBm
Graphene-based Schottky diode integrated with a graphene bow-tie antenna for energy harvesting in the THz frequency band
No full text
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
27-GHz Silicon-Integrated Rectenna Based on Novel Multilayer Substrate
No full textThis paper presents the design, fabrication, and characterization of a multi-layer 27-GHz rectenna integrated entirely on silicon, aimed at achieving full CMOS compatibility for energy harvesting applications. The device is fabricated on a high-resistivity silicon (HRSi) substrate, which is selectively etched to create a low-permittivity region for the antenna while maintaining a high-permittivity full substrate for the rectifier circuit. The rectenna, operating in the millimeter-wave (mmWave) band, features a compact single-cell design with dimensions of 13 x 13 mm2 only, making it suitable for integrating IoT devices to support energy autonomy. The rectenna utilizes a GaAs diode rectifier and achieves a measured maximum RF-to-DC power conversion efficiency (PCE) of about 49% at an input power of 12 dBm. This work demonstrates the potential of HRSi-based, silicon-integrated rectennas for efficient energy harvesting in IoT applications. The proposed multilayer fabrication technology allows the realization of high-radiation-efficiency directive antennas and RF circuits directly onto the CMOS substrate, without increasing the overall size of the circuit and maintaining the structural integrity of the device
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
Graphene diodes for 5G energy harvesting: Design, simulations and experiments
No full textIn this paper, we propose a rectenna based on a graphene self-switching diode for Ka band applications in view of the upcoming 5G and internet-of-things telecommunication systems. A 4-element patch antenna array has been designed, simulated, and fabricated using a high-resistivity silicon/silicon dioxide/graphene multi-layer and tested on-wafer. By using analytical formulas to optimize the number of parallel channels for the diode, we have achieved highly improved DC current values (average value of ±2mA at ±3V). The diode has been integrated with the array in coplanar waveguide technology using a matching open stub, in order to maximize the array-to-diode power transfer. The rectenna has then been measured by using a 28GHz RF source: at 0V DC bias, a maximum DC voltage VDC of 2.4mV has been obtained, with a maximum DC current IDC of 1.2μA and a maximum DC power PDC of 2.9nW; when applying a small DC bias (1.2V), VDC reaches 71mV, IDC=35.5μA and PDC=2.5μW
Integration of Antenna Array and Self-Switching Graphene Diode for Detection at 28 GHz
Full text linkMicrowave Detection Using 2-Atom-Thick Heterojunction Diodes
No full textIn this paper, a two-dimensional material-based diode for microwave detection at 2.49 GHz with photo detector capabilities is presented. The diode consists of a molybdenum disulphide monolayer/graphene monolayer heterojunction transferred onto a silicon/silicon dioxide substrate, and patterned by means of nanolithography techniques to obtain a geometrical self-switching diode. The interaction between the two monolayers gives rise to a double-stage device, which behaves as a back-to-back diode in the [-3, +3] V range, and as a tunnel diode when exceeding +10 V. The heterojunction can be reproduced on large scale due to its CMOS compatibility; it does not need any particular doping process thanks to its geometrical nature and can be used efficiently as microwave detector up to 10 GHz, with the best performance around the ISM 2.45 GHz band. Last, a rigorous equivalent circuit model based on the Foster's method is provided, which relies on the measured scattering parameters at high frequencies. This way, the device can be exploited in circuit-based numerical tools for the desian of complex microwave front-ends
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
- …
