294 research outputs found

    Beam scanning by liquid-crystal biasing in a modified SIW structure

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    A fixed-frequency beam-scanning 1D antenna based on Liquid Crystals (LCs) is designed for application in 2D scanning with lateral alignment. The 2D array environment imposes full decoupling of adjacent 1D antennas, which often conflicts with the LC requirement of DC biasing: the proposed design accommodates both. The LC medium is placed inside a Substrate Integrated Waveguide (SIW) modified to work as a Groove Gap Waveguide, with radiating slots etched on the upper broad wall, that radiates as a Leaky-Wave Antenna (LWA). This allows effective application of the DC bias voltage needed for tuning the LCs. At the same time, the RF field remains laterally confined, enabling the possibility to lay several antennas in parallel and achieve 2D beam scanning. The design is validated by simulation employing the actual properties of a commercial LC medium

    1-D broadside-radiating leaky-wave antenna based on a numerically synthesized impedance surface

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    A newly-developed deterministic numerical technique for the automated design of metasurface antennas is applied here for the first time to the design of a 1-D printed Leaky-Wave Antenna (LWA) for broadside radiation. The surface impedance synthesis process does not require any a priori knowledge on the impedance pattern, and starts from a mask constraint on the desired far-field and practical bounds on the unit cell impedance values. The designed reactance surface for broadside radiation exhibits a non conventional patterning; this highlights the merit of using an automated design process for a design well known to be challenging for analytical methods. The antenna is physically implemented with an array of metal strips with varying gap widths and simulation results show very good agreement with the predicted performance

    Feebly Interacting Particles: FIPs 2022 workshop report

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    Particle physics today faces the challenge of explaining the mystery of dark matter, the origin of matter over anti-matter in the Universe, the origin of the neutrino masses, the apparent fine-tuning of the electro-weak scale, and many other aspects of fundamental physics. Perhaps the most striking frontier to emerge in the search for answers involves new physics at mass scales comparable to familiar matter, below the GeV-scale, or even radically below, down to sub-eV scales, and with very feeble interaction strength. New theoretical ideas to address dark matter and other fundamental questions predict such feebly interacting particles (FIPs) at these scales, and indeed, existing data provide numerous hints for such possibility. A vibrant experimental program to discover such physics is under way, guided by a systematic theoretical approach firmly grounded on the underlying principles of the Standard Model. This document represents the report of the FIPs 2022 workshop, held at CERN between the 17 and 21 October 2022 and aims to give an overview of these efforts, their motivations, and the decadal goals that animate the community involved in the search for FIPs

    ATHENA Research Book, Volume 2

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    ATHENA European University is an association of nine higher education institutions with the mission of promoting excellence in research and innovation by enabling international cooperation. The acronym ATHENA stands for Association of Advanced Technologies in Higher Education. Partner institutions are from France, Germany, Greece, Italy, Lithuania, Portugal and Slovenia: University of Orléans, University of Siegen, Hellenic Mediterranean University, Niccolò Cusano University, Vilnius Gediminas Technical University, Polytechnic Institute of Porto and University of Maribor. In 2022, two institutions joined the alliance: the Maria Curie-Skłodowska University from Poland and the University of Vigo from Spain. Also in 2022, an institution from Austria joined the alliance as an associate member: Carinthia University of Applied Sciences. This research book presents a selection of the research activities of ATHENA University's partners. It contains an overview of the research activities of individual members, a selection of the most important bibliographic works of members, peer-reviewed student theses, a descriptive list of ATHENA lectures and reports from individual working sections of the ATHENA project. The ATHENA Research Book provides a platform that encourages collaborative and interdisciplinary research projects by advanced and early career researchers

    The development of a heterodyne receiver at 10.7 THz for the observation of molecular hydrogen

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    The focus of this thesis is the development of a superconducting hot electron bolometer(HEB) mixer intended for the operation as a heterodyne receiver for the observation of the electric quadrupole transition of molecular hydrogen in space at 10.7 THz. The developed detector is based on a quasi-optical receiver concept using a lens to couple the RF-signal to an antenna. The mixing element is a phonon-cooled niobium nitride microbridge that is integrated in the center of the antenna. The detector consists of a copper tellurium detector block containing the IF-board and IF-connector and the HEB-device glued to the flat backside of the silicon lens. The HEB-device is a circular RF-chip based on a 9 μm thick silicon carrier membrane with the RF-circuit structures and integrated HEB-element on its upper side. For the development of the RF-circuits the dielectric properties of the carrier substrate that consists of high resistivity float zone silicon (HRFZ Si) have been determined since the data available is insufficient for this high frequency range at cryogenic temperatures. The dielectric properties were investigated by means of transmission measurements of different plane parallel silicon samples with two Fourier Transform Spectrometers (FTS) within a frequency range from 4 THz to 18 THz for temperatures between 5 K to 300 K. The measured refractive index increases less than 0.002 with frequency within a frequency interval of 12 THz. From 300 K to 5 K it is reduced by 0.83 % in average. The absorption coefficient of HRFZ Si roughly decreases by 35 % from 300 K to 5 K. The determined permittivity of the carrier substrate at cryogenic operating temperatures of the receiver is 11.4(±0.1). In total 20 different designs of RF-circuits have been developed and fabricated on one wafer by E-beam and UV-lithography technology in the in-house microfabrication facility. The RF-circuits are based on three different broadband antennas and variations of a narrow-band antenna. One narrow-band and one broadband RF-circuit address an operating frequency around 4.7 THz instead of 10.7 THz to enable a comparison with the UpGreat receiver which has been developed in our research group. The broadband antennas are a self-complementary logarithmic, a logarithmic and an Archimedean spiral antenna. The narrow-band antenna is a double-slot antenna of a full effective wavelength in length that is attached to an RF-filter. To investigate the influence of the lens on the antenna beam of the 10.7 THz double-slot antennas a software has been developed and evaluated that is based on a spectral ray tracing technique because the available commercial CST software is not suitable for that task within the present resources and time constraints. According to numerical calculations the double-slot antenna out of the investigated antennas reaches the highest overall coupling efficiency. The predicted Gaussian coupling efficiency without considering losses within the gold layers is 49 % for the designed 4.7 THz double-slot antenna when being mounted at the backside of the silicon lens without an anti-reflection coating. From all broadband antennas the Archimedean spiral antenna that typically is used for distinct lower frequencies below 1 THz, is predicted to obtain the highest overall power coupling to a Gaussian beam of about 39.4 %. Applying an anti-reflection layer on the lens these Gaussian coupling efficiencies are expected to increase to about 64% and 57% for the double-slot antenna and for the Archimedean spiral antenna,respectively. In total five different RF-circuits have successfully been assembled in the detector block and used as an external power detector of an FTS to determine their spectral response within an interval from 3 THz to 12 THz. They are based on three narrow-band designs for 10.7 THz, one narrow-band design for 4.7 THz and a broadband circuit based on the Archimedean spiral antenna. The detectors with the double-slot antennas exhibit a distinct polarization-dependent sensitivity that is maximal at the dedicated polarization direction of the DS-antenna and vanishes for the polarization direction perpendicular to it. All assembled 10.7 THz narrow-band detectors show a response peak slightly below the intended operating frequency with deviations of the center frequencies less than 4 % to 8 %. The measured curves of the RF-response around the operating frequency agree well with the predicted curves of the coupling efficiency between the HEB-element and the antenna. The detector with the Archimedean spiral antenna shows a significant direct response over the entire frequency range from 3 THz to 12 THz. To our knowledge the Archimedean spiral antenna as well as the double-slot antenna till now so far are the only antennas designed for 10.7 THz that have been realized and verified as direct HEB power detectors. The measurement results confirm that these HEB-devices are suitable candidates for future heterodyne measurements. The local oscillator (LO) source that is needed to operate the detectors in heterodyne mode is a Quantum Cascade Laser developed by the Quantum Optoelectronics Group of the IQE, ETH Zurich, and has not yet been completed at the end of this work

    Feebly-interacting particles: FIPs 2022 Workshop Report

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    Particle physics today faces the challenge of explaining the mystery of dark matter, the origin of matter over anti-matter in the Universe, the origin of the neutrino masses, the apparent fine-tuning of the electro-weak scale, and many other aspects of fundamental physics. Perhaps the most striking frontier to emerge in the search for answers involves new physics at mass scales comparable to familiar matter, below the GeV-scale, or even radically below, down to sub-eV scales, and with very feeble interaction strength. New theoretical ideas to address dark matter and other fundamental questions predict such feebly interacting particles (FIPs) at these scales, and indeed, existing data provide numerous hints for such possibility. A vibrant experimental program to discover such physics is under way, guided by a systematic theoretical approach firmly grounded on the underlying principles of the Standard Model. This document represents the report of the FIPs 2022 workshop, held at CERN between the 17 and 21 October 2022 and aims to give an overview of these efforts, their motivations, and the decadal goals that animate the community involved in the search for FIPs

    Feebly-interacting particles: FIPs 2022 workshop report

    Get PDF
    Particle physics today faces the challenge of explaining the mystery of dark matter, the origin of matter over anti-matter in the Universe, the origin of the neutrino masses, the apparent fine-tuning of the electro-weak scale, and many other aspects of fundamental physics. Perhaps the most striking frontier to emerge in the search for answers involves new physics at mass scales comparable to familiar matter, below the GeV-scale, or even radically below, down to sub-eV scales, and with very feeble interaction strength. New theoretical ideas to address dark matter and other fundamental questions predict such feebly interacting particles (FIPs) at these scales, and indeed, existing data provide numerous hints for such possibility. A vibrant experimental program to discover such physics is under way, guided by a systematic theoretical approach firmly grounded on the underlying principles of the Standard Model. This document represents the report of the FIPs 2022 workshop, held at CERN between the 17 and 21 October 2022 and aims to give an overview of these efforts, their motivations, and the decadal goals that animate the community involved in the search for FIPs
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