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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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van Schelven, R.M. (author), Syed, Waqas (author), Carluccio, G. (author), Doris, Kostas (author), de Graauw, Anton (author), Neto, A. (author), Cavallo, D. (author)In this work, we investigate antenna architectures to implement dual-mode operation in phased array designs. Planar slot antenna elements are used in array configuration, in combination with artificial dielectrics layers (ADLs) located in the close proximity of the array, to achieve pattern shaping. The artificial dielectric superstrate...journal article 2023
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Patel, Kartik (author), Myers, N.J. (author), Heath, Robert W. (author)Millimeter wave (mmWave) technology can achieve high-speed communication due to the large available spectrum. Furthermore, the use of directional beams in mmWave system provides a natural defense against physical layer security attacks. In practice, however, the beams are imperfect due to mmWave hardware limitations such as the low-resolution...journal article 2023
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Van de Kreeke, N. (author), Aslan, Y. (author), Onat, N.B. (author), Yarovoy, Alexander (author)The effects of multipath on the statistical cell-edge user service quality is for the first time investigated for mm-wave multi-user communication systems. The focus is given on setting the user spacing constraints and the transmit array topology via thinning, which can be used to enhance wireless security or decrease analog/digital complexity....conference paper 2023
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Çelik, F.T. (author), Aslan, Y. (author)In this study, the thermal management problem of the modern communication systems with small array sizes is addressed. A novel dual-functional active antenna design strategy is introduced for adjustable frequency of operation and cooling extension at millimeter-wave bands. The concept is based on placing different types of heatsinks on the same...conference paper 2023
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Kumaran, A.K. (author), Pashaeifar, M. (author), Nemati, Hossein Mashad (author), de Vreede, L.C.N. (author), Alavi, S.M. (author)This paper presents a 40nm CMOS mm-wave 3-way Doherty power amplifier (PA) suitable for 5G mm-wave transmitters. It features a bandwidth-enhanced technique using a compact single-supply balun-first 3-way Doherty combiner. The realized front-end with a core area of 0.77 mm2delivers a peak power/gain of more than 20 dBm/16 dB and a drain...conference paper 2023
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Assabumrungrat, Rawin (author), Kumchaiseemak, N. (author), Wang, J. (author), Wang, D. (author), Punpeng, Phoom (author), Fioranelli, F. (author), Wilaiprasitporn, Theerawit (author)We present a deep learning-based approach called DipSAR for reconstructing millimeter-wave synthetic aperture radar (SAR) images from sparse samples. The primary challenge lies in the requirement of a large training dataset for deep learning schemes. To overcome this issue, we employ the deep image prior (DIP) technique, which eliminates the...conference paper 2023
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Mortazavi, S.M. (author), Shen, Y. (author), Mul, D.P.N. (author), de Vreede, L.C.N. (author), Spirito, M. (author), Babaie, M. (author)This article presents an efficient digital polar transmitter (DPTX) at mm-wave frequencies that exploit a novel N -way series Doherty combiner (SDC) to enhance its drain and system efficiency at deep power back-off (PBO). The proposed N -way SDC is scalable and can be implemented elegantly using N transformers and N-1 shunt capacitors. As a...journal article 2022
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Huijten, Esmee (author), Roelvink, Yannick (author), Brackenhoff, Stefanie A. (author), Zaalberg, S.L. (author), Doing, Anne Kee (author), Baselmans, J.J.A. (author), Karatsu, K. (author), Pascual Laguna, A. (author), van Hoven, M.B. (author), Endo, A. (author)The next technological breakthrough in millimeter–submillimeter astronomy is three-dimensional imaging spectrometry with wide instantaneous spectral bandwidths and wide fields of view. The total optimization of the focal-plane instrument, the telescope, the observing strategy, and the signal-processing software must enable efficient removal...journal article 2022
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Endo, A. (author), Pascual Laguna, Alejandro (author), Hähnle, S.A. (author), Karatsu, K. (author), Thoen, David (author), Murugesan, Vignesh (author), Baselmans, J.J.A. (author)Superconducting resonators and transmission lines are fundamental building blocks of integrated circuits for millimeter-submillimeter astronomy. Accurate simulation of radiation loss from the circuit is crucial for the design of these circuits because radiation loss increases with frequency, and can thereby deteriorate the system performance....journal article 2022
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Zhang, L. (author), Shen, Y. (author), de Vreede, L.C.N. (author), Babaie, M. (author)This letter presents a millimeter-wave (mm-wave) vector-modulated phase shifter (VMPS) for phased-array applications. To improve the phase-shift accuracy without drastically increasing design complexity, the proposed VMPS structure employs variable-gain amplifiers (VGAs) that offer 2× better resolution at their low-gain...journal article 2022
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Bosma, S. (author), van Rooijen, N. (author), Alonso Del Pino, M. (author), Llombart, Nuria (author)We present a resonant leaky-wave lens antenna, fed by a circular waveguide with annular corrugations in the ground plane. The proposed leaky-wave feed reduces the impact of the spurious TM0 leaky-wave mode in all planes over a wide bandwidth while reducing assembly complexity compared to previous methods. The proposed leaky-wave antenna has...journal article 2022
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Bosma, S. (author), van Rooijen, N. (author), Alonso Del Pino, M. (author), Spirito, M. (author), Llombart, Nuria (author)We report on the first demonstration of dynamic beam steering using a scanning lens phased array. A scanning lens phased array relies on a combination of mechanical and electrical phase shifting to dynamically steer a high-gain beam beyond the grating-lobe free region using a sparse array. These two concepts have been demonstrated separately in...journal article 2022
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Zhang, Youming (author), Wei, Zhennan (author), Tang, Xusheng (author), Zhang, L. (author), Huang, Fengyi (author)This letter presents a convenient approach based on the two-port kQ-product theory to analyze the influence of interwinding capacitive coupling on the efficiency of the transformer. It is demonstrated that a transformer with proper size can benefit from the interwinding capacitive coupling to maximize its efficiency at a desired frequency....journal article 2022
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Rezapoor, Pouyan (author), Tamminen, Aleksi (author), Tamminen, Aleksi (author), Ala-Laurinaho, Juha (author), Llombart, Nuria (author), Rodilla, Helena (author), Stake, Jan (author), Taylor, Zachary D. (author)The optical behavior of a terahertz imaging system employing a train of four identical off-axis parabolic mirrors with oblique incidence angle illumination is investigated in this work. The aperture filling and aberrations of a single off-axis parabolic mirror when illuminated by a Gaussian terahertz beam at its focus point is measured and...conference paper 2022
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Pashaeifar, M. (author), de Vreede, L.C.N. (author), Alavi, S.M. (author)This letter presents a novel load-modulation-based 3rd-order intermodulation distortion (IMD3) cancellation technique for class-B CMOS power amplifiers (PAs). In a class-B PA, the IMD3 generated by the 3rd-order transconductance ( $g_{m3}$ ) and the gain compression have opposite signs, and thus, they can cancel each other at specific bias...journal article 2022
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Kumari, Preeti (author), Myers, N.J. (author), Heath, Robert W. (author)Millimeter-wave (mmWave) joint communication-radar (JCR) will enable high data rate communication and high-resolution radar sensing for applications such as autonomous driving. Prior JCR systems that are based on the mmWave communications hardware, however, suffer from a limited angular field-of-view and low estimation accuracy for radars due...journal article 2021
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Zhang, H. (author), Bosma, S. (author), Neto, A. (author), Llombart, Nuria (author)A dual-polarized 4 x 4 scanning phased array antenna with leaky-wave enhanced lenses operating at 28 GHz is presented. Such an antenna can be used for point-to-point fifth-generation (5G) communications that require high gain, wide bandwidth (BW), and limited steering ranges. The proposed array has a periodicity of two wavelengths, and the...journal article 2021
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Pallotta, Luca (author), Cauli, Michela (author), Clemente, Carmine (author), Fioranelli, F. (author), Giunta, Gaetano (author), Farina, Alfonso (author)In this paper a method capable of automatically classify radar signals of human hand-gestures exploiting the micro-Doppler signature is designed. In particular, the methodology focuses on the extraction of the Chebyshev moments from the cadence velocity diagram (CVD) of each recorded signal. The algorithm benefits from interesting properties of...conference paper 2021
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Hersyandika, Rizqi (author), Wang, Q. (author), Pollin, Sofie (author)We exploit a dense cell-free mmWave network where User Equipments (UEs) are served by multiple highly directional beams provided by multiple Base Stations (BSs) simultaneously. Such multi-beam scenarios can either offer high spectral efficiency when different information is transmitted through each beam or a diversity gain when each beam...conference paper 2021