1,720,970 research outputs found
A novel shape of bowtie antenna arranged in a linear array for energy harvesting in MID-IR band
No full textIn this paper, a novel shape of bowtie antenna arranged in a linear array for energy harvesting (EH) in MID-IR band is proposed. In detail, the analysis, design, optimization, and simulation of an arrow bowtie obtained by modifying the geometry of a bowtie antenna operating at 28.3 THz is proposed. Specifically, the single element of both shapes arranged in a linear array 1 x 2 are designed and simulated by CST Studio suite 2022 using gold as antenna electrode material with a fixed gap distance g = 3 nm, moreover both shape of antennas are printed on a chromium-silicon-gold three-layer stack-up. The Drude model describes the gold's behavior at 28.3 THz. A comparative study of the performance of both geometries is carried out. The proposed arrow bowtie array exhibits better performance in terms of adaptive and radiative diagrams compared to a bowtie antenna array with a gain of 2.783 dBi a directivity of 6.719 dBi and a compact size
A mid-IR plasmonic graphene nanorectenna-based energy harvester to power IoT sensors
No full textEnergy harvesting (EH) sensors operating up to tens GHz are commercially available nowadays, whereas only a few EH sensors operate over the THz range. To
compensate for this lack, we present a rectenna resonant at 10 μm wavelength (28.3 THz) composed of a graphene arrow-bowtie nanoantenna integrated with a metalinsulator-metal (MIM) diode with the aim to power supply a hypothetic IoT wireless sensor. The characteristics of the MIM diode have been analyzed and discussed. The antenna is designed using 3D CST 2021. The performance of the designed nanoantenna placed on two-layer substrate SiO2 and Si respectively have been investigated in terms of graphene sheets and chemical potential (μcp). Finally, the whole system constituted by an NxM (24153846x805128205) nanorectenna array of approximately 78 cm2 integrated with relative MIMs, lowpass filter and a DC-DC converter indicates an output
voltage value of 3.3 V and an output current of 10 mA. The results obtained for whole system indicate an encouraging solution to powering IoT wireless sensors
Progress in THz Rectifier Technology: Research and Perspectives
Get PDFSchottky diode (SD) has seen great improvements in the past few decades and, for many THz applications, it is the most useful device. However, the use and recycling of forms of energy such as solar energy and the infrared thermal radiation that the Earth continuously emits represent one of the most relevant and critical issues for this diode, which is unable to rectify signals above 5 THz. The goal is to develop highly efficient diodes capable of converting radiation from IR spectra to visible ones in direct current (DC). A set of performance criteria is investigated to select some of the most prominent materials required for developing innovative types of electrodes, but also a wide variety of insulator layers is required for the rectification process, which can affect the performance of the device. The current rectifying devices are here reviewed according to the defined performance criteria. The main aim of this review is to provide a wide overview of recent research progress, specific issues, performance, and future directions in THz rectifier technology based on quantum mechanical tunneling and asymmetric structure
Broadband TE10 to TE20 mode transformer for X band
No full textThis paper deals with a broadband TE10 to TE20 mode transformer in a WR90 rectangular waveguide with more than 35 dB suppression of the fundamental mode and only 0.4 dB of maximum transformation loss. Two fin lines are employed with appropriate configuration in order to obtain a broadband mode transformation. The proposed mode converter can be suitably employed in Spatial Power Combining amplifier to increase the number of parallel combined devices
New Six-Way Waveguide to Microstrip Transition applied in X Band Spatial Power Combiner
No full textA Spatial Power Combiner is proposed using an innovative waveguide to microstrip transition capable to divide the electric field in six equal parts per card. This device can combine 12 MMIC Solid State Power Amplifiers in the whole X Band with 13 dB of return loss and only 2.2 dB losses in a small size, high power and high efficiency system
Replacing noble metals with alternative metals in MID-IR frequency: A theoretical approach
No full textAn ideal plasmonic material should respect different parameters as tunable plasma frequency, low energy loss, high chemical, mechanical and thermal stability, low cost and high integrability with existing technology. Obviously, not all these properties in a single material are reachable; this will depend on the specific application. Noble metals (especially Au and Ag) are considered the plasmonic materials per excellence, and are largely used for several applications as realizing micro-antennas for energy harvesting. However, the imaginary part of the permittivity and high-energy losses at THz frequency prevent their use imposing to find alternative materials. The permittivity response plays an important role in the design process and efficiency of a micro-antenna. In this paper the permittivity response of some metals such as Gold (Au), Silver (Ag), Copper (Cu) and Aluminum (Al) are investigated at MID-IR frequencies. Comparison among simulated dispersion curves allows us to investigate the origin of the dissipative behavior of the materials, which are an unavoidable prerequisite for any realistic application. Relationships among several parameters are under investigation. Moreover. the performance of each material is evaluated relying on quality factors Q or figure of merit (FOM) defined for each metal. Finally, the suitability and limitation of each one of these plasmonic materials will be discussed, starting with the more traditional noble metals to end up with alternative plasmonic metals at IR wavelengths
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe 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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