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14 pages, 20644 KiB

Open AccessArticle

A High-Gain Circularly Polarized Magnetoelectric Dipole Antenna Array for Millimeter-Wave Applications

by Jun Xiao, Jing Wu, Zihang Ye, Tongyu Ding, Chongzhi Han and Qiubo Ye

Sensors 2025, 25(10), 3046; https://doi.org/10.3390/s25103046 - 12 May 2025

Viewed by 457

A high-gain circularly polarized (CP) magnetoelectric dipole (ME-dipole) radiating element is demonstrated at a millimeter-wave (MMW) 5G band of 37–43.5 GHz. Each ME-dipole radiating element, consisting of two pairs of ring-shaped and L-shaped metal posts is excited by a cross-shaped substrate-integrated waveguide (SIW) [...] Read more.

A high-gain circularly polarized (CP) magnetoelectric dipole (ME-dipole) radiating element is demonstrated at a millimeter-wave (MMW) 5G band of 37–43.5 GHz. Each ME-dipole radiating element, consisting of two pairs of ring-shaped and L-shaped metal posts is excited by a cross-shaped substrate-integrated waveguide (SIW) coupling slot to achieve CP radiation. Through the use of all-metal radiating structures with a height of 3.4 mm, high-gain and high-efficiency radiation performances are achieved. For proof of concept, a 4 × 4 antenna array with a SIW feeding network is designed, fabricated, and measured. The measured impedance bandwidth of the proposed 4 × 4 CP antenna array is 19.2% from 33.9 to 41.1 GHz for |S11| ≤ −10 dB. The measured 3 db AR bandwidth is 10.3% from 37 to 41 GHz. The measured peak gain is 20.3 dBic at 41 GHz. The measured and simulated results are in good agreement. Full article

(This article belongs to the Special Issue Design and Measurement of Millimeter-Wave Antennas)

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12 pages, 6812 KiB

Open AccessArticle

Design of a Dual-Band Filter Based on the Band Gap Waveguide

by Shaohang Li, Yuan Yao, Xiaohe Cheng and Junsheng Yu

Electronics 2024, 13(20), 3982; https://doi.org/10.3390/electronics13203982 - 10 Oct 2024

Cited by 4 | Viewed by 1152

Abstract

In this paper, the design of a dual-band filter based on the band gap waveguide (BGW) is presented. In the low-frequency band, the TE₂₀₁ mode rectangular waveguide cavity resonator was used to design the bandpass filter, which significantly reduces the impact of [...] Read more.

In this paper, the design of a dual-band filter based on the band gap waveguide (BGW) is presented. In the low-frequency band, the TE₂₀₁ mode rectangular waveguide cavity resonator was used to design the bandpass filter, which significantly reduces the impact of the high-frequency transmission line (TL). In the high-frequency band, a TE₁₀₁ mode cavity resonator based on the gap waveguide (GW) structure was used to design the high-frequency band filter. A lower insertion loss can be achieved with the use of all-metal structure. A dual-band filter prototype was fabricated to verify its performance. According to the measurement results, the insertion loss is less than 1.3 dB and the return loss is better than 14 dB in the frequency range of 5.92–6.06 GHz; and the insertion loss is less than 1.77 dB and the return loss is better than 15 dB in the frequency range of 80.6–86.2 GHz. The frequency ratio is as large as 13.9, and because the high-frequency band filter is embedded in the cavity resonator of the low-frequency band filter, it saves space to a certain extent and realizes the integrated design of the dual-band filter, which is of great significance for the improvement of the performance of the dual-band communication system in higher-frequency bands. Full article

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14 pages, 7057 KiB

Open AccessArticle

Vibration Fatigue Analysis of Two Different Variants of Oil Suction Pipes

by Marko Zadravec, Srečko Glodež, Christian Buzzi, Peter Brunnhofer, Martin Leitner and Janez Kramberger

Materials 2024, 17(5), 1057; https://doi.org/10.3390/ma17051057 - 25 Feb 2024

Cited by 1 | Viewed by 1275

Abstract

In order to reduce the overall mass of the product, an improved variant of the engine oil suction pipe in hybrid design is developed and analysed as part of this paper. The vibration fatigue analysis of a simple all-metal suction pipe and the [...] Read more.

In order to reduce the overall mass of the product, an improved variant of the engine oil suction pipe in hybrid design is developed and analysed as part of this paper. The vibration fatigue analysis of a simple all-metal suction pipe and the new hybrid suction pipe variant is derived using computer FEA simulations and vibration measurements on the shaker. The hybrid design of the technical components makes it possible to combine different types of materials in order to achieve the best possible properties and behaviours for the components under the influence of external loads. In our case, we combine a suction pipe made of S235JR mild steel with a 3D-printed polyamide intake funnel featuring a grid designed to prevent particles from entering the engine’s lubrication circuit. This design reduces the mass and shifts the centre of gravity closer to the attachment point of the pipe, as well as to the engine crankcase, which has a positive effect on the values of natural frequencies and vibration amplitudes. The main objective of such a hybrid suction pipe is precisely to reduce vibrations, and thus extend the service life of the components. Full article

(This article belongs to the Section Metals and Alloys)

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15 pages, 9951 KiB

Open AccessArticle

A Dual-Polarized CTS Array Antenna with Four Reconfigurable Beams for mm-Wave Wind Profile Radar

by Lei Yan, Wenbin Zou, Kaihong Zheng, Guangli Yang and Yong Luo

Electronics 2024, 13(1), 238; https://doi.org/10.3390/electronics13010238 - 4 Jan 2024

Cited by 3 | Viewed by 2343

Abstract

The wind profiler radar (WPR) system requires a dual-polarized antenna with multiple low-sidelobe and high-gain beams to facilitate the detection of weak signals reflected by atmospheric turbulence. This paper proposes a dual-polarized continuous transverse stub (CTS) K-band antenna with four reconfigurable beams, which [...] Read more.

The wind profiler radar (WPR) system requires a dual-polarized antenna with multiple low-sidelobe and high-gain beams to facilitate the detection of weak signals reflected by atmospheric turbulence. This paper proposes a dual-polarized continuous transverse stub (CTS) K-band antenna with four reconfigurable beams, which comprises a series-fed CTS array and four 1-to-14 power dividers as line source generators (LSGs) to generate a high-quality quasi-TEM wave. The CTS element incorporates a stepped transition radiation stub design and employs a short cutoff stub on the upper surface of the series-fed parallel plate waveguide (PPW) to achieve optimal impedance matching. The entire antenna is an all-metal structure with remarkably low loss, and low-cost standard fabrication processes are employed for the prototype, which achieves fast reconfigurable four-beam scanning to 15°, with a gain of 31.09 dBi and sidelobe levels below −17.6 dB. Measurement results in an anechoic chamber agree well with simulations, demonstrating the antenna’s ease of manufacture, stability, and suitability for wind profile radar applications. Full article

(This article belongs to the Special Issue Feature Papers in Microwave and Wireless Communications Section)

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13 pages, 4465 KiB

Open AccessArticle

All-Metal Coding Metasurfaces for Broadband Terahertz RCS Reduction and Infrared Invisibility

by Ming Zhang, Najiao Zhang, Peng Dong, Lin Yang, Baozhu Wang, Ruihong Wu and Weimin Hou

Photonics 2023, 10(9), 962; https://doi.org/10.3390/photonics10090962 - 23 Aug 2023

Cited by 9 | Viewed by 2129

Abstract

With the rapid advancement of modern technology and radar detection systems, electromagnetic (EM) stealth technology has become increasingly significant, particularly in aircraft stealth and military radar applications. In this work, an all-metal metasurface is designed for broadband terahertz radar cross-section (RCS) reduction and [...] Read more.

With the rapid advancement of modern technology and radar detection systems, electromagnetic (EM) stealth technology has become increasingly significant, particularly in aircraft stealth and military radar applications. In this work, an all-metal metasurface is designed for broadband terahertz radar cross-section (RCS) reduction and infrared invisibility. The all-metal metasurface possesses extremely low infrared emissivity and high polarization conversion in the terahertz band. Through the joint simulation of MATLAB and CST, a genetic algorithm is used to optimize the random phase distribution of 2, 3, and 4-bit metasurfaces, so that the reflected wave is scattered to achieve broadband terahertz RCS reduction. Simulation results show that the metasurface can simultaneously achieve broadband terahertz RCS reduction in 3–5 THz and infrared invisibility in 24–38 THz (8–12.5 μm). The RCS reduction of the coding metasurface is greater than 10 dB compared to the metal plate, and the maximum RCS reduction of the 4-bit metasurface can reach 21.1 dB. Compared to the traditional design method, the proposed method can reduce time consumption and find the optimal result to achieve high performance. We believe the proposed method can provide significant guidance for surface coating in camouflage applications and opens up new possibilities for improving the information capacity of coding metasurfaces. Full article

(This article belongs to the Special Issue Multifunctional Metasurfaces: Design Strategies and Applications)

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17 pages, 6715 KiB

Open AccessArticle

Additive Manufacturing of Co₃Fe Nano-Probes for Magnetic Force Microscopy

by Robert Winkler, Michele Brugger-Hatzl, Lukas Matthias Seewald, David Kuhness, Sven Barth, Thomas Mairhofer, Gerald Kothleitner and Harald Plank

Nanomaterials 2023, 13(7), 1217; https://doi.org/10.3390/nano13071217 - 29 Mar 2023

Cited by 12 | Viewed by 3320

Abstract

Magnetic force microscopy (MFM) is a powerful extension of atomic force microscopy (AFM), which mostly uses nano-probes with functional coatings for studying magnetic surface features. Although well established, additional layers inherently increase apex radii, which reduce lateral resolution and also contain the risk [...] Read more.

Magnetic force microscopy (MFM) is a powerful extension of atomic force microscopy (AFM), which mostly uses nano-probes with functional coatings for studying magnetic surface features. Although well established, additional layers inherently increase apex radii, which reduce lateral resolution and also contain the risk of delamination, rendering such nano-probes doubtful or even useless. To overcome these limitations, we now introduce the additive direct-write fabrication of magnetic nano-cones via focused electron beam-induced deposition (FEBID) using an HCo₃Fe(CO)₁₂ precursor. The study first identifies a proper 3D design, confines the most relevant process parameters by means of primary electron energy and beam currents, and evaluates post-growth procedures as well. That way, highly crystalline nano-tips with minimal surface contamination and apex radii in the sub-15 nm regime are fabricated and benchmarked against commercial products. The results not only reveal a very high performance during MFM operation but in particular demonstrate virtually loss-free behavior after almost 8 h of continuous operation, thanks to the all-metal character. Even after more than 12 months of storage in ambient conditions, no performance loss is observed, which underlines the high overall performance of the here-introduced FEBID-based Co₃Fe MFM nano-probes. Full article

(This article belongs to the Special Issue Preparation and Application of Nanowires: 2nd Edition)

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19 pages, 5643 KiB

Open AccessEditor’s ChoiceArticle

3D Nanoprinting of All-Metal Nanoprobes for Electric AFM Modes

by Lukas Matthias Seewald, Jürgen Sattelkow, Michele Brugger-Hatzl, Gerald Kothleitner, Hajo Frerichs, Christian Schwalb, Stefan Hummel and Harald Plank

Nanomaterials 2022, 12(24), 4477; https://doi.org/10.3390/nano12244477 - 17 Dec 2022

Cited by 8 | Viewed by 2874

Abstract

3D nanoprinting via focused electron beam induced deposition (FEBID) is applied for fabrication of all-metal nanoprobes for atomic force microscopy (AFM)-based electrical operation modes. The 3D tip concept is based on a hollow-cone (HC) design, with all-metal material properties and apex radii in [...] Read more.

3D nanoprinting via focused electron beam induced deposition (FEBID) is applied for fabrication of all-metal nanoprobes for atomic force microscopy (AFM)-based electrical operation modes. The 3D tip concept is based on a hollow-cone (HC) design, with all-metal material properties and apex radii in the sub-10 nm regime to allow for high-resolution imaging during morphological imaging, conductive AFM (CAFM) and electrostatic force microscopy (EFM). The study starts with design aspects to motivate the proposed HC architecture, followed by detailed fabrication characterization to identify and optimize FEBID process parameters. To arrive at desired material properties, e-beam assisted purification in low-pressure water atmospheres was applied at room temperature, which enabled the removal of carbon impurities from as-deposited structures. The microstructure of final HCs was analyzed via scanning transmission electron microscopy—high-angle annular dark field (STEM-HAADF), whereas electrical and mechanical properties were investigated in situ using micromanipulators. Finally, AFM/EFM/CAFM measurements were performed in comparison to non-functional, high-resolution tips and commercially available electric probes. In essence, we demonstrate that the proposed all-metal HCs provide the resolution capabilities of the former, with the electric conductivity of the latter onboard, combining both assets in one design. Full article

(This article belongs to the Special Issue Nanomaterials Fabricated by Electron-Beam-Induced Deposition and Related Processes)

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20 pages, 2230 KiB

Open AccessArticle

Electromagnetic Metasurfaces: Insight into Evolution, Design and Applications

by Khushboo Singh, Foez Ahmed and Karu Esselle

Crystals 2022, 12(12), 1769; https://doi.org/10.3390/cryst12121769 - 6 Dec 2022

Cited by 12 | Viewed by 6333

Abstract

Metasurfaces have emerged as game-changing technology ranging from microwaves to optics. This article provides a roadmap to the evolution of electromagnetic metasurfaces with a focus on their synthesis techniques, materials used for their design and their recent and futuristic applications. A broad classification [...] Read more.

Metasurfaces have emerged as game-changing technology ranging from microwaves to optics. This article provides a roadmap to the evolution of electromagnetic metasurfaces with a focus on their synthesis techniques, materials used for their design and their recent and futuristic applications. A broad classification is provided, and the design principle is elaborated. The efficient and economical use of available computational resources is imperative to work with state-of-the-art metasurface systems. Hence, optimization becomes an integral part of metasurface design. Several optimization methodologies reported to date have been discussed. An extensive study on the current research database gathered a comprehensive understanding of meta-atom topologies and the preferred fabrication technologies. The study concludes with a critical analysis and highlights existing and future research challenges to be addressed. Full article

(This article belongs to the Special Issue Active Hybrid Soft Metamaterials)

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11 pages, 4166 KiB

Open AccessArticle

Methodology for Improving Scanning Performance Loading an Array Element with a 3D All-Metal WAIM

by Diego Bermúdez-Martín, Raphaël Gillard, Carlos Molero, Hervé Legay and María García-Vigueras

Electronics 2022, 11(18), 2848; https://doi.org/10.3390/electronics11182848 - 9 Sep 2022

Cited by 6 | Viewed by 2361

Abstract

All-metal 3D printing technologies are allowing the conception of new structures for different applications. This publication explores the potential of employing for the first time an all-metal 3D unit-cell topology to perform wide-angle impedance matching layers. A new equivalent circuit is derived for [...] Read more.

All-metal 3D printing technologies are allowing the conception of new structures for different applications. This publication explores the potential of employing for the first time an all-metal 3D unit-cell topology to perform wide-angle impedance matching layers. A new equivalent circuit is derived for the oblique incidence, providing a good estimation of the cell response for the scanning range (

θ = [0 °, 55 °]

) in the main scanning planes for a linearly polarized radiated field. This analytical model is later used to develop a wide-angle impedance matching design methodology for a generic antenna. This methodology is tested in practice to match a phased array made of metallic horns at 18 GHz. An improvement of 5 dB is obtained in the simulations for angles

θ > 35 °

for the H-plane. Full article

(This article belongs to the Special Issue Metastructures and Antennas with Enhanced Properties for Modern Microwave and Millimeter-Wave Applications)

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14 pages, 4811 KiB

Open AccessArticle

Effect of the Microsand Fraction on the Ballistic Resistance of UHP-SFRC

by Přemysl Kheml, Kristýna Carrera and Pavel Horák

Materials 2022, 15(17), 5916; https://doi.org/10.3390/ma15175916 - 26 Aug 2022

Viewed by 1312

Abstract

This work investigates the effect of various sand fractions on the ballistic resistance of ultra-high-performance steel-fibre-reinforced concrete (UHP-SFRC) samples. We specifically investigated replacing expensive and generally inaccessible microsands with commonly available sands. The tests and the measured values show that replacing part of [...] Read more.

This work investigates the effect of various sand fractions on the ballistic resistance of ultra-high-performance steel-fibre-reinforced concrete (UHP-SFRC) samples. We specifically investigated replacing expensive and generally inaccessible microsands with commonly available sands. The tests and the measured values show that replacing part of the microsand with the more commonly and economically acceptable 0/2 mm aggregate fraction minimises the resulting mechanical properties and ballistic resistance. The most common type of ammunition was used to test all sample bodies, which is a 7.62 × 39 mm calibre with an all-metal jacket and a mild steel core. The damage’s extent and mode were determined using a 3D scanner operating on photogrammetry. Full article

(This article belongs to the Section Construction and Building Materials)

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18 pages, 5661 KiB

Open AccessArticle

Experimental and Numerical Research on a Pipe Element Passing through Bulkhead with Symmetrical Elastic Installation

by Yiwan Wu, Yu Tang, Zhiqiang Qin, Xiaochao Chen and Hongbai Bai

Symmetry 2022, 14(3), 453; https://doi.org/10.3390/sym14030453 - 24 Feb 2022

Cited by 85 | Viewed by 2196

Abstract

To reduce the transmission of vibration energy from the ship’s pipeline to the bulkhead, a novel all-metal pipe element passing through the bulkhead with symmetrical elastic installation was proposed in this paper. A metal bellow, a multi-layer thin-walled symmetrical structure, was used as [...] Read more.

To reduce the transmission of vibration energy from the ship’s pipeline to the bulkhead, a novel all-metal pipe element passing through the bulkhead with symmetrical elastic installation was proposed in this paper. A metal bellow, a multi-layer thin-walled symmetrical structure, was used as an elastic element and entangled metallic wire materials (EMWM) were used as a damping element. The insertion loss was adopted to evaluate the vibration damping performance. The results show that compared with the pipe element passing through the bulkhead with rigid installation, the vibration damping performance of the pipe element passing through bulkhead with symmetrical elastic installation can significantly isolate the vibration transition, and the maximum average insertion loss in each direction can reach 25.4 dB. A thermal-vibration joint test system of the pipe element passing through the bulkhead was built. A series of comparison experiments were carried out to investigate the influence of temperature, symmetrical measure points, and exciting directions on the vibration response transmitted to the bulkhead. Therefore, the vibration damping performance was verified. Full article

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15 pages, 4857 KiB

Open AccessArticle

Design of a Planar Array of Low Profile Horns at 28 GHz

by Jou-Yi Wang, Malcolm Ng Mou Kehn and Eva Rajo-Iglesias

Sensors 2020, 20(23), 6989; https://doi.org/10.3390/s20236989 - 7 Dec 2020

Cited by 1 | Viewed by 3313

Abstract

A planar array of low profile horns fed by a transverse slotted waveguide array in the low millimeter-wave regime (28 GHz) is presented. The array of transverse slots cannot be directly used as antenna as it has grating lobes due to the fact [...] Read more.

A planar array of low profile horns fed by a transverse slotted waveguide array in the low millimeter-wave regime (28 GHz) is presented. The array of transverse slots cannot be directly used as antenna as it has grating lobes due to the fact that slot elements must be spaced a guided wavelength. However, these slots can be transformed into low profile horns that with their radiation patterns attenuate the grating lobes. To this aim, low profile horns with less than 0.6

λ_{0}

height were designed. The horns include a couple of chips that contribute to further reduce the grating lobes especially in the H-plane. The good performance of the designed array was demonstrated by both simulations and experiments performed on a manufactured prototype. A 5 × 5 array was designed that has a measured realized gain of 26.6 dBi with a bandwidth below 2%, still useful for some applications such as some radar systems. The total electrical size of the array is 6.63

λ_{0}

× 6.63

λ_{0}

. The radiation efficiency is very high and the aperture efficiency is above 80%. This all-metal solution is advantageous for millimeter-wave applications where losses sustained by dielectric materials become severe and it can be easily scaled to higher frequencies. Full article

(This article belongs to the Section Physical Sensors)

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9 pages, 664 KiB

Open AccessArticle

Experimental Evaluation of Three Designs of Electrodynamic Flexural Transducers

by Tobias J. R. Eriksson, Michael Laws, Lei Kang, Yichao Fan, Sivaram N. Ramadas and Steve Dixon

Sensors 2016, 16(9), 1363; https://doi.org/10.3390/s16091363 - 25 Aug 2016

Cited by 9 | Viewed by 5624

Abstract

Three designs for electrodynamic flexural transducers (EDFT) for air-coupled ultrasonics are presented and compared. An all-metal housing was used for robustness, which makes the designs more suitable for industrial applications. The housing is designed such that there is a thin metal plate at [...] Read more.

Three designs for electrodynamic flexural transducers (EDFT) for air-coupled ultrasonics are presented and compared. An all-metal housing was used for robustness, which makes the designs more suitable for industrial applications. The housing is designed such that there is a thin metal plate at the front, with a fundamental flexural vibration mode at ∼50 kHz. By using a flexural resonance mode, good coupling to the load medium was achieved without the use of matching layers. The front radiating plate is actuated electrodynamically by a spiral coil inside the transducer, which produces an induced magnetic field when an AC current is applied to it. The transducers operate without the use of piezoelectric materials, which can simplify manufacturing and prolong the lifetime of the transducers, as well as open up possibilities for high-temperature applications. The results show that different designs perform best for the generation and reception of ultrasound. All three designs produced large acoustic pressure outputs, with a recorded sound pressure level (SPL) above 120 dB at a 40 cm distance from the highest output transducer. The sensitivity of the transducers was low, however, with single shot signal-to-noise ratio

(SNR) ≃ 15

dB in transmit–receive mode, with transmitter and receiver 40 cm apart. Full article

(This article belongs to the Special Issue Ultrasonic Sensors)

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