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Tadolini, Cesare (author)The analysis of integrated front ends operated in the high-frequency regimes is addressed in this work. The analysis of these problems has been a critical bottleneck for decades due to the difficulties arising in adopting full-wave techniques. Assuming, as typical at lower frequencies, that the structures are planar leads to the inaccurate...master thesis 2024
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Zhang, H. (author)In recent decades, dielectric lens antennas have been more and more adopted and developed for sensing and imaging applications at sub-millimeter (sub-mm) wavelengths because they can achieve high gain while keeping their physical size and weight acceptable at these wavelengths. More recently, as low-loss and low-cost lens materials have become...doctoral thesis 2024
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Coco Martin, C.M. (author), Hu, Weiya (author), Cavallo, D. (author)This work aims to provide guidelines on the design of wideband flat lenses based on artificial dielectric layers (ADLs). Planar lenses based on metasurfaces are typically narrowband, due to the phase wrapping over the period of 2\pi that is strongly frequency-dependent. On the contrary, true-time-delay (TTD) planar lenses, which do not resort...journal article 2024
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Hu, Weiya (author), Coco Martin, C.M. (author), Cavallo, D. (author)A semi-analytical method is presented for the design of gradient index (GRIN) flat lenses. Closed-form expressions are derived to define the refractive index distribution of the lens, for several cases: collimating lenses with on-axis feed, collimating lenses with off-axis feed, lenses converting spherical wavefronts with different...journal article 2024
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Dabironezare, Shahab Oddin (author), Nair, A. (author), Neto, A. (author), Llombart, Nuria (author)The use of lens arrays in (sub)-millimeter sensing and communication applications will enable the development of integrated antenna front-ends with multiple independent beams as well as dynamic scanning capabilities. In applications such as MIMO communications, interferometric arrays, and Tx/Rx duplexing capabilities, a key parameter is the...journal article 2024
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Aslan, Y. (author), Roederer, A.G. (author)This paper in the roadmap presents the research trends on antenna systems for Satellite Communication terminals. To address the challenges posed by this application in terms of wide fractional bandwidth and large field-of-view, several antenna concepts and architectures are being investigated, which can be grouped in three main technology areas:...conference paper 2024
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Tan, Junyao (author)This master thesis explores the capacity of MIMO arrays for communication in the radiative near field through antenna design. This research applies an in-house MATLAB model based on free space Green’s function to calculate the channel matrix, revealing the potential increase of capacity through the use of incoherent arrays with directive...master thesis 2023
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Zhang, Muhan (author)Recently, there has been an increasing demand for security in public places. As a result, non-destructive and fast millimetre-wave and submillimetre-wave imaging systems have gained more and more attention.<br/>This project is based on Concealed Objects Stand-off Real-Time Imaging for Security (CONSORTIS), which is a European next-generation...master thesis 2023
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Hu, Weiya (author)Flat lens antennas are convenient solutions to realize highly directive antennas for millimeter wave and terahertz frequencies. Unlike the traditional three-dimensional bulky lens antennas, flat lenses are compact, low profile, and planar structures that can be manufactured with standard multi-layer technology, e.g. printed circuit board (PCB)...master thesis 2023
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Griffith, Kiana (author)This thesis analyzes and describes a wearable pressure sensor to detect intraocular pressure and guide clinician diagnosis of glaucoma. Although glaucoma has many<br/>symptoms and risk factors, high intraocular pressure is the most predominant. A method to continuously and accurately record intraocular pressure measurements and fluctuations in a...master thesis 2023
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Bechrakis Triantafyllos, Alexandros (author)In the framework of this MSc thesis the analysis of core-shell leaky-wave lens antennas is presented, based on a combination of asymptotic and Physical Optics techniques. This study aims to develop an analysis approach which can be subsequently used for the optimization of the Fly’s Eye antenna concept, through enabling the investigation of...master thesis 2023
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Mavropoulou, Alexandra (author)In the framework of this MSc thesis, the analysis and design guidelines for part of the quasi-optical system of a proposed astronomical instrument, called TIFUUN, are presented. The TIFUUN instrument is an imaging spectrometer, planned to be placed in the ASTE telescope to perform ground-based astronomical observations in the mm-submm wavelength...master thesis 2023
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Davidov, Lyuben (author)There is a growing demand for precision and high-quality optical objectives and lenses due to their numerous advantages and uses. The market for high precision objective lenses has tremendous potential for development and is a sector that is expanding quickly. <br/><br/>Measuring the aberrations of optical systems is an essential step in the...master thesis 2023
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Mekkes, Erik (author)Large Language Models of code have seen significant jumps in performance recently. However, these jumps tend to accompany a notable and perhaps concerning increase in scale and costs. We contribute an evaluation of prediction performance with respect to model size by assessing the layer-wise progression for language and user-defined elements in...bachelor thesis 2023
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Zhang, Yizhuo (author)The urban spaces that arise as a result of urban shrinkage and decay are loosely defined (Franck & Stevens, 2007). The ambiguity of these spaces provides a potential outlet for accidental or spontaneous encounters, informal activities and alternatives to our increasingly commodified, controlled and privatised 'open' urban spaces. Many...master thesis 2023
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Hou, Z. (author)In this thesis, we explore how lens design and optimization techniques can adapt to the design (optimization) space in order to increase the lens design efficiency. We extensively discuss the Saddle Point Construction (SPC), a method that can systematically search for new solutions, as well as replace high-dimensional searches with a discrete...doctoral thesis 2023
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Savundranayagam, Reka (author)In vitro neuromodulation studies play a crucial role in understanding the underlying interaction mechanisms between cells and ultrasound, which is important in the development of new therapies for various neurological disorders. Acoustic focusing, the ability to focus ultrasound at a specific focal length with high spatial resolution, provides a...master thesis 2023
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Bosma, S. (author)Millimeter- and submillimeter wave applications, such as point-to-point wireless communications in beyond-5G scenarios, long-range automotive radars and astronomy and astrophysics science cases from space require antennas with high-gain beams that are steerable. At lower (microwave) frequencies, fully sampled phased arrays with thousands of...doctoral thesis 2023
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Herzog, Alexander (author), Benkner, Simon (author), Zandi, Babak (author), Buffolo, Matteo (author), van Driel, W.D. (author), Meneghini, Matteo (author), Khanh, Tran Quoc (author)We report on the degradation mechanisms and dynamics of silicone encapsulated ultraviolet A (UV-A) high-power light-emitting diodes (LEDs), with a peak wavelength of 365nm. The stress tests were carried out for a period of 8665 hours with forward currents between 350mA and 700mA and junction temperatures up to 132°C. Depending on stress...journal article 2023
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Hesam Mahmoudi Nezhad, N. (author), Ghaffarian Niasar, M. (author), Hagen, C.W. (author), Kruit, P. (author)The design of electrostatic electron lenses involves the choice of many geometrical parameters for the lens electrodes as well as the choice of voltages applied to the electrodes. The purpose of the design is to focus the electrons at a specific point and to minimize the aberrations of the lens. In a previous study, genetic algorithm...conference paper 2023