Propagation of Millimeter Waves in Composite Materials

Meier, Dominik; Zech, Christian; Baumann, Benjamin; Gashi, Bersant; Schlechtweg, M.; Kuhn, Jutta; Rösch, Markus; Reindl, Leonhard M.

doi:10.1109/tap.2019.2955213

Cited by 9 publications

(6 citation statements)

References 47 publications

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“…With regard to the inspection of materials and objects, FMCW techniques at the interface between the microwave and THz frequency regimes have established themselves by now [377][378][379][380], and the measurement systems continue to be improved [381][382][383][384][385].…”

Section: Thz Mcw Imagingmentioning

confidence: 99%

Roadmap of Terahertz Imaging 2021

Valušis

Lisauskas

Yuan

et al. 2021

Sensors

193

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In this roadmap article, we have focused on the most recent advances in terahertz (THz) imaging with particular attention paid to the optimization and miniaturization of the THz imaging systems. Such systems entail enhanced functionality, reduced power consumption, and increased convenience, thus being geared toward the implementation of THz imaging systems in real operational conditions. The article will touch upon the advanced solid-state-based THz imaging systems, including room temperature THz sensors and arrays, as well as their on-chip integration with diffractive THz optical components. We will cover the current-state of compact room temperature THz emission sources, both optolectronic and electrically driven; particular emphasis is attributed to the beam-forming role in THz imaging, THz holography and spatial filtering, THz nano-imaging, and computational imaging. A number of advanced THz techniques, such as light-field THz imaging, homodyne spectroscopy, and phase sensitive spectrometry, THz modulated continuous wave imaging, room temperature THz frequency combs, and passive THz imaging, as well as the use of artificial intelligence in THz data processing and optics development, will be reviewed. This roadmap presents a structured snapshot of current advances in THz imaging as of 2021 and provides an opinion on contemporary scientific and technological challenges in this field, as well as extrapolations of possible further evolution in THz imaging.

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Section: Thz Mcw Imagingmentioning

confidence: 99%

Roadmap of Terahertz Imaging 2021

Valušis

Lisauskas

Yuan

et al. 2021

Sensors

193

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“…Dependent on which portion of the stack is considered, the height h varies between 4.98 and 51.4 μm. Equations ( 9) and (10), are dependent on the shape of the metastructure unit cell, thus the effective capacitance C G -originating from the capacitive coupling of adjacent structures-and effective inductance L G -originating from the surface currents on the straight portions of the repeating unit cell. The following equations represent slight alterations to what can be found in [43] for expressing L G and C G of these heavily altered Jerusalem-star-like structures:…”

Section: A Metastructuresmentioning

confidence: 99%

Broadband 400 GHz On-Chip Antenna With a Metastructured Ground Plane and Dielectric Resonator

Gashi

Meier

John³

et al. 2022

IEEE Trans. Antennas Propagat.

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The analysis, modeling, design, simulation, and experimental evaluation of a 400 GHz on-chip antenna is presented, with a novel combination of metastructures, a microstrip patch, a quartz-based dielectric resonator, and a diamond-based antireflex layer-all integrated on a 35 nm InGaAs metamorphic high-electron-mobility transistor (mHEMT) technology. The said combination represents a first-time implementation for all submillimeter-wave-capable semiconductor technologies. Circumventing a substrate-thickness limitation of 4.98 µm, a state-of-the-art broadband, efficient, and to-the-broadside radiating on-chip antenna solution is realized. It achieves a measured impedance bandwidth of 100 GHz, 25.6%, spanning from 340 to 440 GHz. A consistent pattern bandwidth of 75 GHz is recorded, with an efficiency of 50%-66% and a directivity of up to 10.4 dBi-or 27 dBi, with the utilization of a polypropylene-based dielectric lens. The theoretical analysis of the proposed on-chip antenna is presented, and two modeling approaches are shown and compared. Between the analytical and the 3-D electromagnetic (EM) model, the latter is chosen as it offers greater precision in defining the metastructure unit cell and enables the inclusion of the remaining components of the proposed antenna setup. The measured reflection coefficient and far-field patterns are compared to simulations via the utilized model, and a strong agreement is observed. These far-field patterns are acquired with the on-chip antenna inserted within a broadband 400 GHz transmitter submillimeter-wave monolithic integrated circuit, processed on the 35 nm mHEMT technology.

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“…In a typical composite material, the reflected mmW signal is a combination of multilayer reflections from the individual fiber layers, excited radiating coupled modes, and reflections from any dielectric interface boundary-which could be the sample's top-surface, backside, or a deviation in the component's layout [9]. Based on this information, the detection of inhomogeneities in the material's internal structure, like fiber perturbations or variations in the relative fiber-to-resin volume ratio in GFRP, becomes possible.…”

Section: Millimeter-wave Tomographic Imagingmentioning

confidence: 99%

Millimeter-Wave Radar Sensor for Automated Tomographic Imaging of Composite Materials in a Manufacturing Environment

et al. 2021

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To unlock the full potential of composite materials, reliable measurement methods during and after their manufacturing are required. Established measuring methods are commonly based on ultrasound or thermographic imaging techniques and offer only a limited usability. A promising alternative to the aforementioned methods are millimeterwave-based systems. It has already been demonstrated that such systems can provide a tomographic representation of composite materials, enabling the detection, localization, and classification of critical defects within the component. The tomographic millimeter-wave imaging system presented here is operating in the W band and is packaged for the operation in a manufacturing environment. For this purpose, it is enclosed by a dustproof housing and can be mounted on an industrial robot, which enables the development of an automated measurement procedure during and after the manufacturing process of composite materials. The direct integration of the measurement system into the manufacturing process allows for early-stage fault detection and classification, which is essential for the production of high-quality, high-performance, and highly reliable composite materials.Index Terms-Microwave/millimeter wave sensors, composite materials, millimeter-wave (mmW) radar, nondestructive testing, radar imaging, robot programming.

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Propagation of Millimeter Waves in Composite Materials

Cited by 9 publications

References 47 publications

Roadmap of Terahertz Imaging 2021

Roadmap of Terahertz Imaging 2021

Broadband 400 GHz On-Chip Antenna With a Metastructured Ground Plane and Dielectric Resonator

Millimeter-Wave Radar Sensor for Automated Tomographic Imaging of Composite Materials in a Manufacturing Environment

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