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Electronics
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Advanced Wireless Technologies for Next-G Networks: Antennas, Circuits, and Systems
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Advanced Wireless Technologies for Next-G Networks: Antennas, Circuits, and Systems

A special issue of Electronics (ISSN 2079-9292). This special issue belongs to the section "Microwave and Wireless Communications".

Deadline for manuscript submissions: 15 June 2025 | Viewed by 21552

Special Issue Editors

Dr. Ya Fei Wu

E-Mail Website
Guest Editor
School of Electronic Science and Engineering, University of Electronic Science and Technology of China, Chengdu 611731, China
Interests: antennas; RF microsystems
Dr. Ji-Wei Lian

E-Mail Website
Guest Editor
School of Microelectronics, Nanjing University of Science and Technology, Nanjing 210094, China
Interests: millimeter-wave antenna; metasurface antenna; feeding network
Dr. Yujie Zhang

E-Mail Website
Guest Editor
Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117576, Singapore
Interests: antenna design on the Internet-of-Things applications; reconfigurable intelligent antenna and surface; MIMO systems; millimeter wave; RF energy harvesting; wireless power transmission and 6G
Dr. Zijian Shao

E-Mail Website
Guest Editor
Department of Electrical and Computer Engineering, Princeton University, Princeton, NJ 08540, USA
Interests: antennas; integrated electronics; RFICs

Special Issue Information

Dear Colleagues,

With continuously evolving wireless communication technologies and the imminent arrival of Next-G networks, innovative solutions to antennas, circuits, and systems are needed. This Special Issue of Electronics seeks to amalgamate state-of-the-art research and developments in the field of advanced wireless technologies, thereby facilitating the imminent generation of wireless communication systems. The compendium aspires to not only showcase the vanguard of current technological advancements, but also to instigate discourse on the potential future directions, ensuring a comprehensive understanding and readiness for the challenges and opportunities presented by Next-G networks.

This Special Issue aims to provide a platform for researchers, engineers, and academics to share their latest findings and insights into antennas, circuits, and systems designed for Next-G  networks. The topics of interest include, but are not limited to:

  • Advanced antenna design and optimization for 5G and beyond.
  • Millimeter-wave and terahertz antennas for high-speed data transmission.
  • Novel circuit designs for efficient and high-performance wireless communication.
  • The integration of RF and microwave circuits with advanced signal processing techniques.
  • MIMO and beamforming technologies for enhanced network capacity.
  • Energy-efficient wireless systems and power management.
  • Antenna and circuit solutions for emerging applications such as IoT, smart cities, and autonomous vehicles.
  • Security and privacy considerations in Next-G network technologies.

Dr. Ya Fei Wu
Dr. Ji-Wei Lian
Dr. Yujie Zhang
Dr. Zijian Shao
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Electronics is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2400 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • antenna design and optimization
  • millimeter-wave and terahertz antennas
  • circuit designs
  • integration of RF system
  • MIMO and beamforming technologies
  • wireless systems
  • next-G network technologies

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Further information on MDPI's Special Issue policies can be found here.

Published Papers (15 papers)

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Research

18 pages, 3238 KiB  
Article
Multilayer Printed Circuit Board Design Based on Copper Paste Sintering Technology for Satellite Communication Receiving Phased Array
by Sicheng Sun, Yijiu Zhao, Sitao Mei, Naixin Zhou and Yongling Ban
Electronics 2025, 14(2), 322; https://doi.org/10.3390/electronics14020322 - 15 Jan 2025
Viewed by 602
Abstract
A 2048-element dual-polarized receive (RX) phased array for Ku-band (10.7–12.7 GHz) satellite communication (SATCOM) is presented in this paper. The design of the multilayer printed circuit board (PCB) it uses adopts a novel copper paste sintering interconnection technology that allows for [...] Read more.
A 2048-element dual-polarized receive (RX) phased array for Ku-band (10.7–12.7 GHz) satellite communication (SATCOM) is presented in this paper. The design of the multilayer printed circuit board (PCB) it uses adopts a novel copper paste sintering interconnection technology that allows for more flexibility in the design of vias and can reduce the PCB’s lamination number. This technology is more suitable for manufacturing multilayer and complex PCBs than traditional processes. The array is designed to consist of sixteen 8 × 16 element subarrays, each based on the silicon RX beamformer and multilayer PCB. Dual-polarized antenna elements are arranged in a regular rectangle with a spacing of 0.5 for a wavelength of 12.7 GHz, thus achieving a scanning range of ±70° in all planes. By adjusting the amplitude and phase of two line polarizations with cross-polarization levels better than −25 dB at boresight, the array can generate linear or circular polarization. Moreover, the antenna gain-to-noise temperature is above 12 dB/K (Tant = 20 K) at boresight. The aperture of the 2048-element RX phased array is 768 × 450 mm. With its low profile, the array is appropriate for usage in Ku-band SATCOM terminals. Full article
(This article belongs to the Special Issue Advanced Wireless Technologies for Next-G Networks: Antennas, Circuits, and Systems)
►▼ Show Figures

Figure 1

Figure 1
<p>Typical quasi-coaxial interconnect structures to be modeled with analytical equation-based methodologies. (<b>a</b>) Top view. (<b>b</b>) Side view.</p> Full article ">Figure 2
<p>Equivalent <math display="inline"><semantics> <mi>π</mi> </semantics></math>-type circuit model of the quasi-coaxial with lumped parameters.</p> Full article ">Figure 3
<p>Quasi-coaxial structure with a copper stub in the PCB. (<b>a</b>) PCB stackup. (<b>b</b>) Equivalent <math display="inline"><semantics> <mi>π</mi> </semantics></math> type circuit model.</p> Full article ">Figure 4
<p>LC circuits for impedance matching between the stripline and signal via. (<b>a</b>) Impedance matching structure. (<b>b</b>) Equivalent <math display="inline"><semantics> <mi>π</mi> </semantics></math> type circuit model.</p> Full article ">Figure 5
<p>Common cases of interconnection using copper paste sintering technology.</p> Full article ">Figure 6
<p>2048-element RX phased array for <math display="inline"><semantics> <mrow> <mi>K</mi> <mi>u</mi> </mrow> </semantics></math>-band SATCOM with 16 subarrays.</p> Full article ">Figure 7
<p>Detailed architecture of the subarray.</p> Full article ">Figure 8
<p>2 × 2 antenna cell based on 8-channel RX beamformer chip.</p> Full article ">Figure 9
<p>Multilayer PCB stackup of the subarray. Units: mm.</p> Full article ">Figure 10
<p>Structure of the proposed dual–polarized antenna element. Units: mm.</p> Full article ">Figure 11
<p>Simulated return losses of the antenna from the chip ports for the V– and H–polarization. (<b>a</b>) Azimuth plane. (<b>b</b>) Elevation plane.</p> Full article ">Figure 12
<p>Simulated co– and cross–polarization level of the antenna for the V– and H–polarization. (<b>a</b>) Azimuth plane. (<b>b</b>) Elevation plane.</p> Full article ">Figure 12 Cont.
<p>Simulated co– and cross–polarization level of the antenna for the V– and H–polarization. (<b>a</b>) Azimuth plane. (<b>b</b>) Elevation plane.</p> Full article ">Figure 13
<p>Equivalent RX chain of the 2048-element array.</p> Full article ">Figure 14
<p>(<b>a</b>) Top view showing the antenna elements on a subarray. (<b>b</b>) Back view showing surface-mounted chips on a subarray. (<b>c</b>) Photograph of the fabricated RX phased array. (<b>d</b>) Experimental setup for measurement in an anechoic chamber.</p> Full article ">Figure 15
<p>Residual errors after calibration of the array (<b>a</b>) Amplitude. (<b>b</b>) Phase. (Different colors represent different subarrays).</p> Full article ">Figure 16
<p>Measured scanning patterns at 11.7 GHz for the V− and H− polarizations. (<b>a</b>) Azimuth plane. (<b>b</b>) Elevation plane.</p> Full article ">Figure 17
<p>Measured axial ratio (AR) values of the array over (<b>a</b>) different frequencies at boresight, and (<b>b</b>) different scanning angles at 11.7 GHz.</p> Full article ">Figure 18
<p>Measured G/T values of the array over (<b>a</b>) different frequencies at boresight, and (<b>b</b>) different scanning angles at 11.7 GHz.</p> Full article ">
8 pages, 1529 KiB  
Article
Double Resonance of Electromagnetically Induced Transparency of Rydberg Atom in Counter-Propagating Configuration
by Chao Li, Guo Ma, Mingwei Lei and Meng Shi
Electronics 2024, 13(22), 4391; https://doi.org/10.3390/electronics13224391 - 8 Nov 2024
Viewed by 636
Abstract
The double resonance phenomenon of EIT is studied through the ladder three-level Rydberg system. A probe laser with the wavelength λp=852.35 nm is used to coupling the ground state 6S1/2 to the middle state 6P3/2, and a [...] Read more.
The double resonance phenomenon of EIT is studied through the ladder three-level Rydberg system. A probe laser with the wavelength λp=852.35 nm is used to coupling the ground state 6S1/2 to the middle state 6P3/2, and a coupling laser with the wavelength λc=509.08 nm is implemented to couple the state 6P3/2 to the Rydberg state 62D5/2. A special optical scheme is designed, in which the co-propagating and counter-propagating configurations are both used. As a result, the double resonance of electromagnetically induced transparency (EIT) with the Rydberg atom is observed. By comparing the distance between the double peaks, it is found that the double resonance phenomenon comes from the Doppler effect, and the distance between the two resonance peaks in the absorption spectrum is related to the detuning of the resonant lasers. Full article
(This article belongs to the Special Issue Advanced Wireless Technologies for Next-G Networks: Antennas, Circuits, and Systems)
►▼ Show Figures

Figure 1

Figure 1
<p>The ladder type of EIT for the two lasers. The red arrow and the green arrow indicate the probe laser (<math display="inline"><semantics> <mrow> <msub> <mrow> <mi>λ</mi> </mrow> <mrow> <mi>p</mi> </mrow> </msub> </mrow> </semantics></math> = 852 nm) and coupling laser (<math display="inline"><semantics> <mrow> <msub> <mrow> <mi>λ</mi> </mrow> <mrow> <mi>c</mi> </mrow> </msub> </mrow> </semantics></math> = 510 nm), respectively.</p> Full article ">Figure 2
<p>An optical schematic of the experimental setup. ISO: isolator, <sup>1/2</sup> P: half-wave plate, PBS: polarization beam splitter, NPBS: non-polarization beam splitter, B1, B2, B3: block 1, 2, 3, M1: reflecting mirror for probe laser, M2: reflecting mirror for coupling laser, M3: reflecting mirror for both probe laser and coupling laser, PD: the detector.</p> Full article ">Figure 3
<p>The laser path in cell 1. The “In peak” represents the incident laser, and the “Re peak” represents the exit laser.</p> Full article ">Figure 4
<p>The spectrums of scanning the coupling laser frequency. (<b>Left</b>) <math display="inline"><semantics> <mrow> <msub> <mrow> <mi mathvariant="sans-serif">Δ</mi> </mrow> <mrow> <mi>p</mi> </mrow> </msub> <mo>&gt;</mo> <mn>0</mn> </mrow> </semantics></math>, (<b>middle</b>) <math display="inline"><semantics> <mrow> <msub> <mrow> <mi mathvariant="sans-serif">Δ</mi> </mrow> <mrow> <mi>p</mi> </mrow> </msub> <mo>=</mo> <mn>0</mn> </mrow> </semantics></math>, and (<b>right</b>) <math display="inline"><semantics> <mrow> <msub> <mrow> <mi mathvariant="sans-serif">Δ</mi> </mrow> <mrow> <mi>p</mi> </mrow> </msub> <mo>&lt;</mo> <mn>0</mn> </mrow> </semantics></math>. There is no Doppler background. For PD1, the small peak comes from the reflection mirror.</p> Full article ">Figure 5
<p>The spectrums when scanning the probe laser. (<b>Left</b>) <math display="inline"><semantics> <mrow> <msub> <mrow> <mi mathvariant="sans-serif">Δ</mi> </mrow> <mrow> <mi>c</mi> </mrow> </msub> <mo>&gt;</mo> <mn>0</mn> </mrow> </semantics></math>, (<b>middle</b>) <math display="inline"><semantics> <mrow> <msub> <mrow> <mi mathvariant="sans-serif">Δ</mi> </mrow> <mrow> <mi>c</mi> </mrow> </msub> <mo>=</mo> <mn>0</mn> </mrow> </semantics></math>, and (<b>right</b>) <math display="inline"><semantics> <mrow> <msub> <mrow> <mi mathvariant="sans-serif">Δ</mi> </mrow> <mrow> <mi>c</mi> </mrow> </msub> <mo>&lt;</mo> <mn>0</mn> </mrow> </semantics></math>. For PD1, the large peak in the middle comes from saturation absorption, and the EIT signals are the small peaks on the left and right sides under the Doppler background.</p> Full article ">
15 pages, 20922 KiB  
Article
A Versatile Shared-Aperture Antenna for Vehicle Communications
by Mingtang Li, Yihong Su, Wenxin Zhang and Xianqi Lin
Electronics 2024, 13(20), 4009; https://doi.org/10.3390/electronics13204009 - 12 Oct 2024
Cited by 1 | Viewed by 945
Abstract
This communication introduces a versatile, multi-service, shared-aperture antenna system for multiple vehicle applications. The design comprises three antenna elements: a rotatable microstrip antenna for global positioning system (GPS) communication, a cross-dipole circularly polarized antenna for satellite communication in the S-band, and a pattern [...] Read more.
This communication introduces a versatile, multi-service, shared-aperture antenna system for multiple vehicle applications. The design comprises three antenna elements: a rotatable microstrip antenna for global positioning system (GPS) communication, a cross-dipole circularly polarized antenna for satellite communication in the S-band, and a pattern reconfigurable antenna for V2V (vehicle-to-vehicle) communication. These antennas collectively support GPS, satellite communication (Satcom), and V2V communication in a single, shared-aperture design. This shared-aperture antenna system offers cost savings and occupies less space compared to using separate antennas for each service. The microstrip antenna covers the 1575 MHz frequency band used for GPS communication. The cross-dipole circularly polarized antenna provides continuous wideband coverage for S-band satellite communication. The pattern reconfigurable antenna, tailored for the specific application scenario, covers the 5.9 GHz V2V working frequency band (5.855–5.925 GHz). Practical testing and simulation results confirm the effectiveness of this antenna system for the intended applications. In summary, the microstrip antenna has a bandwidth of 1.565–1.578 GHz and a realized gain of 7 dBi with radiation efficiency of 81%, the cross-dipole antenna has a bandwidth of 2.2–3.8 GHz (53.3%) and a realized gain of 8.3 dBi with radiation efficiency of 90%, and the pattern reconfigurable antenna has a 5.8–6 GHz bandwidth and a realized gain of 3.7 dBi with radiation efficiency of 85%, and the isolation between antennas with different frequencies is 25 dB, 20 dB, and 30 dB in three frequency bands. Full article
(This article belongs to the Special Issue Advanced Wireless Technologies for Next-G Networks: Antennas, Circuits, and Systems)
►▼ Show Figures

Figure 1

Figure 1
<p>Vehicular communication network diagram.</p> Full article ">Figure 2
<p>Configuration of tri-band shared-aperture antenna. (<b>a</b>) Perspective view; (<b>b</b>) top view; (<b>c</b>) bottom view.</p> Full article ">Figure 3
<p>Comparison of the distribution and array spacing of two shared-aperture arrays.</p> Full article ">Figure 4
<p>Geometry of proposed microstrip antenna.</p> Full article ">Figure 5
<p>Reflection coefficient and realized gain of microstrip antenna.</p> Full article ">Figure 6
<p>Geometry of proposed cross dipole antenna. (<b>a</b>) Top view; (<b>b</b>) side view.</p> Full article ">Figure 7
<p>Wide beam principle of proposed cross dipole.</p> Full article ">Figure 8
<p>Current distribution of antenna at 3 GHz.</p> Full article ">Figure 9
<p>Geometry of proposed pattern reconfigurable antenna. (<b>a</b>) Top view; (<b>b</b>) bottom view.</p> Full article ">Figure 10
<p>Equivalent circuit of BAP70-03. (<b>a</b>) PIN on; (<b>b</b>) PIN off.</p> Full article ">Figure 11
<p>The S11 and realized gain results of proposed pattern reconfigurable antenna.</p> Full article ">Figure 12
<p>The prototype, the test environment, and the port definition.</p> Full article ">Figure 13
<p>The antenna test architecture.</p> Full article ">Figure 14
<p>Simulated and measured reflection coefficient of (<b>a</b>) microstrip antenna; (<b>b</b>) cross-dipole antenna; (<b>c</b>) pattern reconfigurable antenna.</p> Full article ">Figure 15
<p>Simulated and measured iso-frequency port isolation at (<b>a</b>) GPS L1 band; (<b>b</b>) S band; (<b>c</b>) V2V band.</p> Full article ">Figure 16
<p>Radiation performance of microstrip antenna. (<b>a</b>) Radiation pattern; (<b>b</b>) axial ratio.</p> Full article ">Figure 17
<p>Radiation pattern of cross dipoles at (<b>a</b>) 2 GHz, (<b>b</b>) 3 GHz, and (<b>c</b>) 4 GHz.</p> Full article ">Figure 18
<p>Simulated and measured radiation pattern of pattern reconfigurable antenna. (<b>a</b>) state 1. (<b>b</b>) state 2. (<b>c</b>) state 3. (<b>d</b>) state 4.</p> Full article ">Figure 19
<p>Comparison of the distribution and array spacing of two shared-aperture arrays.</p> Full article ">Figure 20
<p>(<b>a</b>) The schematic diagram of antenna installation on a car. (<b>b</b>) Horizontal radiation pattern of pattern reconfigurable antenna. (<b>c</b>) Vertical radiation pattern of pattern reconfigurable antenna.</p> Full article ">
12 pages, 2566 KiB  
Article
A Wideband Polarization-Reconfigurable Antenna Based on Fusion of TM10 and Transformed-TM20 Mode
by Xianjing Yuan, Siyuan Zheng, Binyun Yan and Weixing Sheng
Electronics 2024, 13(18), 3760; https://doi.org/10.3390/electronics13183760 - 22 Sep 2024
Viewed by 890
Abstract
A wideband polarization-reconfigurable microstrip antenna based on a mode-fusion mechanism is proposed. This simple antenna structure consists of a rectangular radiation patch and a ground, both with crossed slots. The slots crossing the ground are connected by eight PIN diodes and four capacitors [...] Read more.
A wideband polarization-reconfigurable microstrip antenna based on a mode-fusion mechanism is proposed. This simple antenna structure consists of a rectangular radiation patch and a ground, both with crossed slots. The slots crossing the ground are connected by eight PIN diodes and four capacitors such that two orthogonal linear-polarization radiation modes can be realized. The radiation patch is slotted such that a transformed TM20 mode is excited, realizing broadside radiation that the traditional TM20 mode is unable to. With fusion of the fundamental TM10 mode and the transformed-TM20 (T-TM20) mode, a wide bandwidth of 30.1% is achieved in two reconfigurable polarizations. The measured results agree well with the simulation results. The total efficiency of the proposed antenna is more than 80.0% over the bandwidth. Full article
(This article belongs to the Special Issue Advanced Wireless Technologies for Next-G Networks: Antennas, Circuits, and Systems)
►▼ Show Figures

Figure 1

Figure 1
<p>Geometrical configuration of the proposed antenna: (<b>a</b>) 3D view, (<b>b</b>) Sub1 view, and (<b>c</b>) Sub2 view.</p> Full article ">Figure 2
<p>The equivalent magnetic currents (black dashed lines with arrow) and <span class="html-italic">E</span>-plane electric field distributions (red lines) of (<b>a</b>) the traditional <math display="inline"><semantics> <msub> <mi>TM</mi> <mn>10</mn> </msub> </semantics></math> mode and (<b>b</b>) <math display="inline"><semantics> <msub> <mi>TM</mi> <mn>20</mn> </msub> </semantics></math> mode with the typical radiation patterns.</p> Full article ">Figure 3
<p>The equivalent magnetic currents (black dashed lines with arrow) and <span class="html-italic">E</span>-plane electric field distributions (red lines) of (<b>a</b>) TM10 mode and (<b>b</b>) T-TM20 mode with the improved radiation patterns.</p> Full article ">Figure 4
<p>Current distribution of the antenna: (<b>a</b>) state1 and (<b>b</b>) state2. Top view of the current distribution on the antenna patch in (<b>c</b>) state1 and (<b>d</b>) state2. PIN diodes on/off on antenna ground in (<b>e</b>) state1 and (<b>f</b>) state2.</p> Full article ">Figure 5
<p>Vector electric field distributions of the substrate around the radiation patch: (<b>a</b>) 2.4 GHz and (<b>c</b>) 2.8 GHz in state1; (<b>b</b>) 2.4 GHz and (<b>d</b>) 2.8 GHz in state2.</p> Full article ">Figure 5 Cont.
<p>Vector electric field distributions of the substrate around the radiation patch: (<b>a</b>) 2.4 GHz and (<b>c</b>) 2.8 GHz in state1; (<b>b</b>) 2.4 GHz and (<b>d</b>) 2.8 GHz in state2.</p> Full article ">Figure 6
<p>Parametric analysis: (<b>a</b>) frequency response of |S11| as a function of the side length of the metal cavity and (<b>b</b>) frequency response of the antenna’s cross-polarization gain with dPIN at 2.4 GHz.</p> Full article ">Figure 7
<p>Equivalent circuit models for MADP-000907-14020: (<b>a</b>) ON-state and (<b>b</b>) OFF-state.</p> Full article ">Figure 8
<p>Prototype of proposed polarization-reconfigurable antenna: (<b>a</b>) top view of Sub1, (<b>b</b>) top view of Sub2, (<b>c</b>) bottom view of sub2, and (<b>d</b>) setup for measuring radiation.</p> Full article ">Figure 9
<p>(<b>a</b>) Simulated and measured input reflection coefficients and (<b>b</b>) gain and co-gain frequency response curves for states 1 and 2.</p> Full article ">Figure 10
<p>Radiation patterns of: (<b>a</b>) state 1 and (<b>b</b>) state 2 at 2.4 GHz; (<b>c</b>) state 1 and (<b>d</b>) state 2 at 2.8 GHz.</p> Full article ">Figure 11
<p>Efficiency frequency response curve.</p> Full article ">
24 pages, 7011 KiB  
Article
A Comprehensive Review of Traditional and Deep-Learning-Based Defogging Algorithms
by Minxian Shen, Tianyi Lv, Yi Liu, Jialiang Zhang and Mingye Ju
Electronics 2024, 13(17), 3392; https://doi.org/10.3390/electronics13173392 - 26 Aug 2024
Cited by 1 | Viewed by 2282
Abstract
Images captured under adverse weather conditions often suffer from blurred textures and muted colors, which can impair the extraction of reliable information. Image defogging has emerged as a critical solution in computer vision to enhance the visual quality of such foggy images. However, [...] Read more.
Images captured under adverse weather conditions often suffer from blurred textures and muted colors, which can impair the extraction of reliable information. Image defogging has emerged as a critical solution in computer vision to enhance the visual quality of such foggy images. However, there remains a lack of comprehensive studies that consolidate both traditional algorithm-based and deep learning-based defogging techniques. This paper presents a comprehensive survey of the currently proposed defogging techniques. Specifically, we first provide a fundamental classification of defogging methods: traditional techniques (including image enhancement approaches and physical-model-based defogging) and deep learning algorithms (such as network-based models and training strategy-based models). We then delve into a detailed discussion of each classification, introducing several representative image fog removal methods. Finally, we summarize their underlying principles, advantages, disadvantages, and give the prospects for future development. Full article
(This article belongs to the Special Issue Advanced Wireless Technologies for Next-G Networks: Antennas, Circuits, and Systems)
►▼ Show Figures

Figure 1

Figure 1
<p>Schematic diagram for physical-model-based defogging approaches.</p> Full article ">Figure 2
<p>The network architecture diagram of deep learning defogging algorithms.</p> Full article ">Figure 3
<p>A visualization to illustrate ResNet.</p> Full article ">Figure 4
<p>Example description of how different training modes are embedded in the network.</p> Full article ">Figure 5
<p>Comparison figure of image enhancement-based traditional defog algorithms on synthetic images.</p> Full article ">Figure 6
<p>Comparison figure of physical-model-based traditional defog algorithm on synthetic images.</p> Full article ">Figure 7
<p>Comparison figure of different deep learning models on synthetic images.</p> Full article ">Figure 8
<p>Comparison figure of supervised, unsupervised and semi-supervised methods on synthetic images.</p> Full article ">
15 pages, 394 KiB  
Article
User Scheduling and Path Planning for Reconfigurable Intelligent Surface Assisted MISO UAV Communication
by Yang Gu, Zhiyu Huang, Yuan Gao and Yong Fang
Electronics 2024, 13(14), 2797; https://doi.org/10.3390/electronics13142797 - 16 Jul 2024
Viewed by 885
Abstract
The high mobility of unmanned aerial vehicles (UAVs) enables them to improve system throughput by establishing line-of-sight (LoS) links. Nevertheless, in urban environments, these LoS links can be disrupted by complex urban structures, leading to potential interference issues. Reconfigurable intelligent surfaces (RIS) provide [...] Read more.
The high mobility of unmanned aerial vehicles (UAVs) enables them to improve system throughput by establishing line-of-sight (LoS) links. Nevertheless, in urban environments, these LoS links can be disrupted by complex urban structures, leading to potential interference issues. Reconfigurable intelligent surfaces (RIS) provide an innovative approach to enhance communication performance by intelligently reflecting incident signals. Recent studies suggest that utilizing multi-antenna transmission can increase system efficiency, while single-antenna transmission may be more prone to interference. To address these challenges, this article introduces a RIS-assisted multiple-input single-output (MISO) UAV communication system. Our objective is to optimize the minimum user rate, thereby guaranteeing equitable communication for all users. Nevertheless, the non-convexity inherent in this optimization problem complicates the pursuit of a direct solution. Hence, we decompose the problem into four subproblems: user scheduling optimization, RIS phase-shift optimization, UAV trajectory optimization, and UAV transmit beamforming optimization. To obtain suboptimal solutions, we have developed an alternating iterative optimization algorithm for addressing the four subproblems. Numerical results demonstrate that our algorithm effectively boosts the minimum user rate of the entire system. Full article
(This article belongs to the Special Issue Advanced Wireless Technologies for Next-G Networks: Antennas, Circuits, and Systems)
►▼ Show Figures

Figure 1

Figure 1
<p>RIS-assisted MISO UAV communication system.</p> Full article ">Figure 2
<p>Max-min user rate versus the iteration number.</p> Full article ">Figure 3
<p>UAV trajectory with three ground users.</p> Full article ">Figure 4
<p>UAV trajectory with five ground users.</p> Full article ">Figure 5
<p>The service time provided for each user.</p> Full article ">Figure 6
<p>Max-min user rate versus time.</p> Full article ">Figure 7
<p>Max-min user rate versus UAV velocity.</p> Full article ">Figure 8
<p>Max-min user rate versus power.</p> Full article ">
14 pages, 7922 KiB  
Article
An Ultra-Thin Multi-Band Logo Antenna for Internet of Vehicles Applications
by Jun Li, Junjie Huang, Hongli He and Yanjie Wang
Electronics 2024, 13(14), 2792; https://doi.org/10.3390/electronics13142792 - 16 Jul 2024
Cited by 1 | Viewed by 1379
Abstract
In this paper, an ultra-thin logo antenna (LGA) operating in multiple frequency bands for Internet of Vehicles (IoVs) applications was proposed. The designed antenna can cover five frequency bands, 0.86–1.01 GHz (16.0%) for LoRa communication, 1.3–1.36 GHz (4.6%) for GPS, 2.32–2.71 GHz (16.3%) [...] Read more.
In this paper, an ultra-thin logo antenna (LGA) operating in multiple frequency bands for Internet of Vehicles (IoVs) applications was proposed. The designed antenna can cover five frequency bands, 0.86–1.01 GHz (16.0%) for LoRa communication, 1.3–1.36 GHz (4.6%) for GPS, 2.32–2.71 GHz (16.3%) for Bluetooth communication, 3.63–3.89 GHz (6.9%) for 5G communication, and 5.27–5.66 GHz (7.1%) for WLAN, as the simulation indicated. The initial antenna started with a modified coplanar waveguide (CPW)-fed circular disk monopole radiator. To create extra current paths and further excite other modes, the disk was hollowed out into the shape of the car logo of the Chinese smart EV brand XPENG composing four rhombic parasitic patches. Next, four triangular parasitic patches were inserted to improve the impedance matching of the band at 5.6 GHz. Finally, four metallic vias were loaded for adjusting resonant points and the return loss reduction. Designed on a flexible substrate, the antenna can easily bend to a certain degree in complex vehicular communication for IoV. The measured results under horizontal and vertical bending showed the LGA can operate in a bending state while maintaining good performance. The proposed LGA addresses the issue of applying one single multi-band antenna to allow vehicles to communicate over several channels, which relieves the need for a sophisticated antenna network. Full article
(This article belongs to the Special Issue Advanced Wireless Technologies for Next-G Networks: Antennas, Circuits, and Systems)
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<p>(<b>a</b>) Geometry of the proposed antenna; (<b>b</b>) logo of the Chinese Smart EV brand XPENG; (<b>c</b>) evolution process of the proposed LGA; (<b>d</b>) simulated return losses of ANT I, II, III, and IV.</p> Full article ">Figure 2
<p>Configuration of (<b>a</b>) ANT Ref., (<b>b</b>) ANT I, and (<b>c</b>) return losses of both antennas.</p> Full article ">Figure 3
<p>(<b>a</b>) Simulated return losses and surface current distributions of (<b>b</b>) ANT I and (<b>c</b>) ANT II at 3.8 GHz.</p> Full article ">Figure 4
<p>(<b>a</b>) Simulated return losses of ANT II, III, and surface current distributions of (<b>b</b>) ANT II and (<b>c</b>) ANT III at 5.6 GHz.</p> Full article ">Figure 5
<p>Simulated return losses of the proposed LGA (<b>a</b>) with varied number of vias, and (<b>b</b>) radius. (<b>c</b>) Comparison of ANT III and IV.</p> Full article ">Figure 6
<p>Parameter analysis of the proposed LGA. (<b>a</b>) <span class="html-italic">L</span><sub>3</sub> = 5.5 mm with varied <span class="html-italic">W</span><sub>3</sub>; (<b>b</b>) <span class="html-italic">W</span><sub>3</sub> = 7.5 mm with varied <span class="html-italic">L</span><sub>3</sub>; (<b>c</b>) <span class="html-italic">W</span><sub>3</sub> = 0.75 mm, <span class="html-italic">L</span><sub>3</sub> = 5.5 mm with varied <span class="html-italic">D</span><sub>2</sub>.</p> Full article ">Figure 7
<p>Simulated radiation pattern on XOY and XOZ plane at each resonant frequency.</p> Full article ">Figure 8
<p>Simulated surface current distribution on surface at five resonant frequencies.</p> Full article ">Figure 9
<p>Photograph of the fabricated flexible antenna and under bending around a bottle.</p> Full article ">Figure 10
<p>(<b>a</b>) A blueprint of the proposed antenna installed on a car in vehicular communication; (<b>b</b>) measured environment of the antenna.</p> Full article ">Figure 11
<p>Measured and simulated (<b>a</b>) return losses; (<b>b</b>) realized gain of the proposed antenna.</p> Full article ">Figure 12
<p>Simulated and measured normalized radiation pattern at 0.92, 1.32, 2.4, 3.75, and 5.46 GHz.</p> Full article ">Figure 13
<p>Measured environment of the antenna under (<b>a</b>) horizontal and (<b>b</b>) vertical bending.</p> Full article ">Figure 14
<p>Measurement of the |S<sub>11</sub>| under horizontal and vertical bending.</p> Full article ">
12 pages, 12837 KiB  
Article
Improved Convolutional Neural Network for Wideband Space-Time Beamforming
by Ming Guo, Zixuan Shen, Yuee Zhou and Shenghui Li
Electronics 2024, 13(13), 2492; https://doi.org/10.3390/electronics13132492 - 26 Jun 2024
Viewed by 1593
Abstract
Wideband beamforming technology is an effective solution in millimeter-wave (mmWave) massive multiple-input multiple-output (MIMO) systems to compensate for severe path loss through beamforming gain. However, traditional adaptive wideband digital beamforming (AWDBF) algorithms suffer from serious performance degradation when there are insufficient signal snapshots, [...] Read more.
Wideband beamforming technology is an effective solution in millimeter-wave (mmWave) massive multiple-input multiple-output (MIMO) systems to compensate for severe path loss through beamforming gain. However, traditional adaptive wideband digital beamforming (AWDBF) algorithms suffer from serious performance degradation when there are insufficient signal snapshots, and the training process of the existing neural network-based wideband beamforming network is slow and unstable. To address the above issues, an AWDBF method based on the convolutional neural network (CNN) structure, the improved wideband beamforming prediction network (IWBPNet), is proposed. The proposed method increases the network’s feature extraction capability for array signals through deep convolutional layers, thus alleviating the problem of insufficient network feature extraction capabilities. In addition, the pooling layers are introduced into the IWBPNet to solve the problem that the fully connected layer of the existing neural network-based wideband beamforming algorithm is too large, resulting in slow network training, and the pooling operation increases the generalization ability of the network. Furthermore, the IWBPNet has good wideband beamforming performance with low signal snapshots, including beam pattern performance and output signal-to-interference-plus-noise ratio (SINR) performance. The simulation results show that the proposed algorithm has superior performance compared with the traditional wideband beamformer with low signal snapshots. Compared with the wideband beamforming algorithm based on the neural network, the training time of IWBPNet is only 10.6% of the original neural network-based wideband beamformer, while the beamforming performance is slightly improved. Simulations and numerical analyses demonstrate the effectiveness and superiority of the proposed wideband beamformer. Full article
(This article belongs to the Special Issue Advanced Wireless Technologies for Next-G Networks: Antennas, Circuits, and Systems)
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<p>The wideband FB with pre-steering delays.</p> Full article ">Figure 2
<p>The structure diagram of improved wideband beamforming prediction network.</p> Full article ">Figure 3
<p>A simple schematic diagram of the convolutional process.</p> Full article ">Figure 4
<p>Schematic diagram of max pooling.</p> Full article ">Figure 5
<p>Beam patterns of traditional FCFB with 4000 snapshots and 400 snapshots for interferences from <math display="inline"><semantics> <mrow> <mi>θ</mi> <msub> <mi>j</mi> <mn>1</mn> </msub> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <mi>θ</mi> <msub> <mi>j</mi> <mn>2</mn> </msub> </mrow> </semantics></math> and <math display="inline"><semantics> <mrow> <mi>θ</mi> <msub> <mi>j</mi> <mn>3</mn> </msub> </mrow> </semantics></math>. (<b>a</b>) FCFB-SS <math display="inline"><semantics> <mrow> <mo>(</mo> <msub> <mi>θ</mi> <mn>0</mn> </msub> <mo>,</mo> <mrow> <mi>θ</mi> <msub> <mi>j</mi> <mn>1</mn> </msub> </mrow> <mo>)</mo> </mrow> </semantics></math>. (<b>b</b>) FCFB-SS <math display="inline"><semantics> <mrow> <mo>(</mo> <msub> <mi>θ</mi> <mn>0</mn> </msub> <mo>,</mo> <mrow> <mi>θ</mi> <msub> <mi>j</mi> <mn>2</mn> </msub> </mrow> <mo>)</mo> </mrow> </semantics></math>. (<b>c</b>) FCFB-SS <math display="inline"><semantics> <mrow> <mo>(</mo> <msub> <mi>θ</mi> <mn>0</mn> </msub> <mo>,</mo> <mrow> <mi>θ</mi> <msub> <mi>j</mi> <mn>3</mn> </msub> </mrow> <mo>)</mo> </mrow> </semantics></math>. (<b>d</b>) FCFB-IS <math display="inline"><semantics> <mrow> <mo>(</mo> <msub> <mi>θ</mi> <mn>0</mn> </msub> <mo>,</mo> <mrow> <mi>θ</mi> <msub> <mi>j</mi> <mn>1</mn> </msub> </mrow> <mo>)</mo> </mrow> </semantics></math>. (<b>e</b>) FCFB-IS <math display="inline"><semantics> <mrow> <mo>(</mo> <msub> <mi>θ</mi> <mn>0</mn> </msub> <mo>,</mo> <mrow> <mi>θ</mi> <msub> <mi>j</mi> <mn>2</mn> </msub> </mrow> <mo>)</mo> </mrow> </semantics></math>. (<b>f</b>) FCFB-IS <math display="inline"><semantics> <mrow> <mo>(</mo> <msub> <mi>θ</mi> <mn>0</mn> </msub> <mo>,</mo> <mrow> <mi>θ</mi> <msub> <mi>j</mi> <mn>3</mn> </msub> </mrow> <mo>)</mo> </mrow> </semantics></math>.</p> Full article ">Figure 6
<p>Beam patterns of WBPNet, BWGN and IWBPNet with 400 snapshots for interferences from <math display="inline"><semantics> <mrow> <mi>θ</mi> <msub> <mi>j</mi> <mn>1</mn> </msub> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <mi>θ</mi> <msub> <mi>j</mi> <mn>2</mn> </msub> </mrow> </semantics></math> and <math display="inline"><semantics> <mrow> <mi>θ</mi> <msub> <mi>j</mi> <mn>3</mn> </msub> </mrow> </semantics></math>. (<b>a</b>) WBPNet-IS <math display="inline"><semantics> <mrow> <mo>(</mo> <msub> <mi>θ</mi> <mn>0</mn> </msub> <mo>,</mo> <mrow> <mi>θ</mi> <msub> <mi>j</mi> <mn>1</mn> </msub> </mrow> <mo>)</mo> </mrow> </semantics></math>. (<b>b</b>) WBPNet-IS <math display="inline"><semantics> <mrow> <mo>(</mo> <msub> <mi>θ</mi> <mn>0</mn> </msub> <mo>,</mo> <mrow> <mi>θ</mi> <msub> <mi>j</mi> <mn>2</mn> </msub> </mrow> <mo>)</mo> </mrow> </semantics></math>. (<b>c</b>) WBPNet-IS <math display="inline"><semantics> <mrow> <mo>(</mo> <msub> <mi>θ</mi> <mn>0</mn> </msub> <mo>,</mo> <mrow> <mi>θ</mi> <msub> <mi>j</mi> <mn>3</mn> </msub> </mrow> <mo>)</mo> </mrow> </semantics></math>. (<b>d</b>) BWGN-IS <math display="inline"><semantics> <mrow> <mo>(</mo> <msub> <mi>θ</mi> <mn>0</mn> </msub> <mo>,</mo> <mrow> <mi>θ</mi> <msub> <mi>j</mi> <mn>1</mn> </msub> </mrow> <mo>)</mo> </mrow> </semantics></math>. (<b>e</b>) BWGN-IS <math display="inline"><semantics> <mrow> <mo>(</mo> <msub> <mi>θ</mi> <mn>0</mn> </msub> <mo>,</mo> <mrow> <mi>θ</mi> <msub> <mi>j</mi> <mn>2</mn> </msub> </mrow> <mo>)</mo> </mrow> </semantics></math>. (<b>f</b>) BWGN-IS <math display="inline"><semantics> <mrow> <mo>(</mo> <msub> <mi>θ</mi> <mn>0</mn> </msub> <mo>,</mo> <mrow> <mi>θ</mi> <msub> <mi>j</mi> <mn>3</mn> </msub> </mrow> <mo>)</mo> </mrow> </semantics></math>. (<b>g</b>) IWBPNet-IS <math display="inline"><semantics> <mrow> <mo>(</mo> <msub> <mi>θ</mi> <mn>0</mn> </msub> <mo>,</mo> <mrow> <mi>θ</mi> <msub> <mi>j</mi> <mn>1</mn> </msub> </mrow> <mo>)</mo> </mrow> </semantics></math>. (<b>h</b>) IWBPNet-IS <math display="inline"><semantics> <mrow> <mo>(</mo> <msub> <mi>θ</mi> <mn>0</mn> </msub> <mo>,</mo> <mrow> <mi>θ</mi> <msub> <mi>j</mi> <mn>2</mn> </msub> </mrow> <mo>)</mo> </mrow> </semantics></math>. (<b>i</b>) IWBPNet-IS <math display="inline"><semantics> <mrow> <mo>(</mo> <msub> <mi>θ</mi> <mn>0</mn> </msub> <mo>,</mo> <mrow> <mi>θ</mi> <msub> <mi>j</mi> <mn>3</mn> </msub> </mrow> <mo>)</mo> </mrow> </semantics></math>.</p> Full article ">
13 pages, 7796 KiB  
Article
Transformer-Based User Charging Duration Prediction Using Privacy Protection and Data Aggregation
by Fei Zeng, Yi Pan, Xiaodong Yuan, Mingshen Wang and Yajuan Guo
Electronics 2024, 13(11), 2022; https://doi.org/10.3390/electronics13112022 - 22 May 2024
Cited by 2 | Viewed by 1016
Abstract
The current uneven deployment of charging stations for electric vehicles (EVs) requires a reliable prediction solution for smart grids. Existing traffic prediction assumes that users’ charging durations are constant in a given period and may not be realistic. In fact, the actual charging [...] Read more.
The current uneven deployment of charging stations for electric vehicles (EVs) requires a reliable prediction solution for smart grids. Existing traffic prediction assumes that users’ charging durations are constant in a given period and may not be realistic. In fact, the actual charging duration is affected by various factors including battery status, user behavior, and environment factors, leading to significant differences in charging duration among different charging stations. Ignoring these facts would severely affect the prediction accuracy. In this paper, a Transformer-based prediction of user charging durations is proposed. Moreover, a data aggregation scheme with privacy protection is designed. Specifically, the Transformer charging duration prediction dynamically selects active and reliable temporal nodes through a truncated attention mechanism. This effectively eliminates abnormal fluctuations in prediction accuracy. The proposed data aggregation scheme employs a federated learning framework, which centrally trains the Transformer without any prior knowledge and achieves reliable data aggregation through a dynamic data flow convergence mechanism. Furthermore, by leveraging the statistical characteristics of model parameters, an effective model parameter updating method is investigated to reduce the communication bandwidth requirements of federated learning. Experimental results show that the proposed algorithm can achieve the novel prediction accuracy of charging durations as well as protect user data privacy. Full article
(This article belongs to the Special Issue Advanced Wireless Technologies for Next-G Networks: Antennas, Circuits, and Systems)
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<p>The structure of the charging duration prediction.</p> Full article ">Figure 2
<p>Training loss vs. number of communications, under different numbers of training charging stations.</p> Full article ">Figure 3
<p>Training loss vs. number of communications, under different batch sizes.</p> Full article ">Figure 4
<p>Training loss vs. number of communications, under different numbers of local epoch.</p> Full article ">Figure 5
<p>Success rate vs. different percentage of number of charging piles, under sign-flipping attack.</p> Full article ">Figure 6
<p>The success rate of the algorithm in detecting attacks on charging pile data at different proportions.</p> Full article ">
8 pages, 3108 KiB  
Communication
A High-Gain Metallic-via-Loaded Antipodal Vivaldi Antenna for Millimeter-Wave Application
by Jun Li, Junjie Huang, Hongli He and Yanjie Wang
Electronics 2024, 13(10), 1898; https://doi.org/10.3390/electronics13101898 - 12 May 2024
Cited by 6 | Viewed by 1760
Abstract
This paper presents a miniaturized-structure high-gain antipodal Vivaldi antenna (AVA) operating in the millimeter-wave (mm-wave) band. A gradient-length microstrip-patch-based director is utilized on the flares of the AVA to enhance gain. Additionally, an array of metallic vias is incorporated along the lateral and [...] Read more.
This paper presents a miniaturized-structure high-gain antipodal Vivaldi antenna (AVA) operating in the millimeter-wave (mm-wave) band. A gradient-length microstrip-patch-based director is utilized on the flares of the AVA to enhance gain. Additionally, an array of metallic vias is incorporated along the lateral and horizontal edges of the antenna for further gain enhancement and bandwidth extension. Based on the proposed structure, the AVA can achieve a peak gain of 11.9 dBi over a relative bandwidth of 71.24% within 16.5–36.6 GHz as measured, while the electrical dimension is only 1.54 × 2.69 × 0.07 λc3. The measured results show good agreement with the simulated ones. Owning the characteristics of being high-gain and ultra-wideband, and having a compact size, the proposed AVA can be a competitive candidate for future millimeter-wave communication. Full article
(This article belongs to the Special Issue Advanced Wireless Technologies for Next-G Networks: Antennas, Circuits, and Systems)
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<p>Configuration of the AVAs: (<b>a</b>) Ant I, (<b>b</b>) Ant II, and (<b>c</b>) Ant III.</p> Full article ">Figure 2
<p>Simulated (<b>a</b>) reflection coefficients and (<b>b</b>) gains of Ant I, II, and III.</p> Full article ">Figure 3
<p>Simulated E-field distribution on surface with (<b>b</b>,<b>d</b>,<b>f</b>) and without (<b>a</b>,<b>c</b>,<b>e</b>) director at 22 GHz, 26 GHz, and 30 GHz, respectively.</p> Full article ">Figure 4
<p>Surface current distribution at 26 GHz: (<b>a</b>) Ant II and (<b>b</b>) Ant III.</p> Full article ">Figure 5
<p>Photograph of the fabricated antenna: (<b>a</b>) front view and (<b>b</b>) back view.</p> Full article ">Figure 6
<p>Measured and simulated results of (<b>a</b>) reflection coefficients, and (<b>b</b>) gain and radiation pattern on (<b>c</b>) E-plane and (<b>d</b>) H-plane at 26 GHz.</p> Full article ">
18 pages, 31412 KiB  
Article
Design of a 3-Bit Circularly Polarized Reconfigurable Reflectarray
by Zhe Chen, Chenlu Huang, Xinmi Yang, Xiaoming Yan, Xianqi Lin and Yedi Zhou
Electronics 2024, 13(10), 1886; https://doi.org/10.3390/electronics13101886 - 11 May 2024
Viewed by 1230
Abstract
In this paper, a 3-bit circularly polarized reconfigurable reflectarray is proposed. The array consists of 64 units in an 8 × 8 configuration, with each unit containing a circular metal patch loaded with phase-delay lines and eight PIN diodes. To independently control each [...] Read more.
In this paper, a 3-bit circularly polarized reconfigurable reflectarray is proposed. The array consists of 64 units in an 8 × 8 configuration, with each unit containing a circular metal patch loaded with phase-delay lines and eight PIN diodes. To independently control each unit, a corresponding DC control circuit was designed and tested with the array. In the bandwidth of 3.43–3.71 GHz, the circularly polarized reconfigurable reflectarray achieved a gain of 16 dB, an aperture efficiency of 27%, an axial ratio of ≤3 dB, an operating bandwidth of 8%, and a beam scanning range of ±60°. The circularly polarized reconfigurable reflectarray can also achieve a good dual-beam radiation performance after testing. The 3-bit circularly polarized reconfigurable reflectarray proposed in this paper offers several advantages, including low loss, high aperture efficiency, a wide beam scanning range, and excellent stability in wide-angle oblique incidence. It has potential applications in low-cost phased array, satellite communications, and deep space exploration. Full article
(This article belongs to the Special Issue Advanced Wireless Technologies for Next-G Networks: Antennas, Circuits, and Systems)
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<p>Photograph of the TRL calibration parts.</p> Full article ">Figure 2
<p>The equivalent circuit models of PIN diode (1–6 GHz): (<b>a</b>) on-state and (<b>b</b>) off-state.</p> Full article ">Figure 3
<p>The circularly polarized reflecting unit. (<b>a</b>) Simulation results of S parameters. (<b>b</b>) Reflection characteristics of circular polarization.</p> Full article ">Figure 4
<p>Model of the 3-bit circularly polarized reconfigurable reflecting unit: (<b>a</b>) overall structure and (<b>b</b>) lateral structure.</p> Full article ">Figure 5
<p>The operating characteristics of 3-bit circular polarization reconfigurable reflecting unit. Right-hand circular polarization: (<b>a</b>) reflection amplitude and (<b>b</b>) reflection phase. Left-hand circular polarization: (<b>c</b>) reflection amplitude and (<b>d</b>) reflection phase.</p> Full article ">Figure 6
<p>Influence of the oblique incidence angle on the operating characteristics of the unit: xoz plane (<b>a</b>) reflection amplitude and (<b>b</b>) reflection phase; yoz plane (<b>c</b>) reflection amplitude and (<b>d</b>) reflection phase.</p> Full article ">Figure 6 Cont.
<p>Influence of the oblique incidence angle on the operating characteristics of the unit: xoz plane (<b>a</b>) reflection amplitude and (<b>b</b>) reflection phase; yoz plane (<b>c</b>) reflection amplitude and (<b>d</b>) reflection phase.</p> Full article ">Figure 7
<p>The efficiency of a reflectarray antenna varies with the position of the feed: (<b>a</b>) height and (<b>b</b>) offset feed angle.</p> Full article ">Figure 8
<p>Structure of the 3-bit circularly polarized reconfigurable reflectarray: (<b>a</b>) model and (<b>b</b>) the distribution diagram of units.</p> Full article ">Figure 9
<p>DC control circuit diagram of PIN diode.</p> Full article ">Figure 10
<p>Right-handed circularly polarized spiral antenna: (<b>a</b>) sample, (<b>b</b>) test scene, (<b>c</b>) reflection coefficient and axial ratio, and (<b>d</b>) radiation pattern.</p> Full article ">Figure 11
<p>Sample of the 3-bit circularly polarized reconfigurable reflectarray: (<b>a</b>) sample and (<b>b</b>) test scene.</p> Full article ">Figure 12
<p>Diagram of antenna operating characteristics at 0° beam pointing. Radiation pattern: (<b>a</b>) xoz plane and (<b>b</b>) yoz plane. (<b>c</b>) Gain and axial ratio. (<b>d</b>) Gain of the feed antenna.</p> Full article ">Figure 13
<p>Measurement results of antenna beam scanning at different frequencies (xoz plane): (<b>a</b>) 3.45 GHz, (<b>b</b>) 3.5 GHz, (<b>c</b>) 3.6 GHz, and (<b>d</b>) 3.7 GHz.</p> Full article ">Figure 14
<p>Measurement results of antenna beam scanning at different frequencies (yoz plane): (<b>a</b>) 3.45 GHz, (<b>b</b>) 3.5 GHz, (<b>c</b>) 3.6 GHz, and (<b>d</b>) 3.7 GHz.</p> Full article ">Figure 15
<p>Comparison of simulation results and measurement results of gain and axial ratio at different scanning angles: (<b>a</b>) xoz plane and (<b>b</b>) yoz plane.</p> Full article ">Figure 16
<p>Radiation pattern of double beam: (<b>a</b>) xoz plane and (<b>b</b>) yoz plane.</p> Full article ">
16 pages, 3903 KiB  
Article
A Broadband Three-Way Series Doherty Power Amplifier with Deep Power Back-Off Efficiency Enhancement for 5G Application
by Xianfeng Que, Jun Li and Yanjie Wang
Electronics 2024, 13(10), 1882; https://doi.org/10.3390/electronics13101882 - 11 May 2024
Cited by 1 | Viewed by 1589
Abstract
This article presents a new broadband three-way series Doherty power amplifier (DPA) topology, which enables a broadband output power back-off (OBO) efficiency enhancement of up to 10 dB or higher. The proposed DPA topology achieves Doherty load modulation and three-way power combining through [...] Read more.
This article presents a new broadband three-way series Doherty power amplifier (DPA) topology, which enables a broadband output power back-off (OBO) efficiency enhancement of up to 10 dB or higher. The proposed DPA topology achieves Doherty load modulation and three-way power combining through a transformer, which requires only a low coupling factor, thus facilitating its implementation in double-sided PCBs or monolithic microwave integrated circuit (MMIC) processes. The design equations for the proposed DPA topology are proposed and analyzed in detail. A proof-of-concept PA at the 2.1–2.8 GHz band using commercial GaN transistors was designed and fabricated to validate the proposed concept. Within the operating frequency band, it achieves a saturated output power (Psat) of 44.5–46.5 dBm with a peak drain efficiency (DE) of 60–72%, and 43–52% DE at 10 dB OBO. Moreover, under a 20 MHz long-term evolution (LTE)-modulated signal, the PA demonstrates a 36.8–37.5 dBm average output power (Pavg) and 47–53% average drain efficiency (DEavg). Notably, the adjacent channel leakage ratio (ACLR) is as low as −35–−28.2 dBc without any digital predistortion (DPD). Full article
(This article belongs to the Special Issue Advanced Wireless Technologies for Next-G Networks: Antennas, Circuits, and Systems)
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<p>(<b>a</b>) Parallel Doherty topology. (<b>b</b>) Series Doherty topology.</p> Full article ">Figure 2
<p>(<b>a</b>) Proposed three-way Doherty topology. (<b>b</b>) Realization of the transformer using coupled inductors. (<b>c</b>) Shortening of the <math display="inline"><semantics> <mrow> <mi>λ</mi> <mo>/</mo> <mn>4</mn> </mrow> </semantics></math> TL. (<b>d</b>) Integrating <math display="inline"><semantics> <msub> <mo>C</mo> <mn>02</mn> </msub> </semantics></math> with <math display="inline"><semantics> <msub> <mo>C</mo> <mi>p</mi> </msub> </semantics></math>.</p> Full article ">Figure 3
<p>Normalized impedance (<math display="inline"><semantics> <mrow> <msub> <mi>R</mi> <mi>L</mi> </msub> <mo>/</mo> <msub> <mi>Z</mi> <mrow> <mn>3</mn> <mo>,</mo> <mi>s</mi> <mi>a</mi> <mi>t</mi> </mrow> </msub> </mrow> </semantics></math>) and OBO range under various <math display="inline"><semantics> <mi>α</mi> </semantics></math> values.</p> Full article ">Figure 4
<p>Efficiency versus OBO under various <math display="inline"><semantics> <mi>α</mi> </semantics></math> values.</p> Full article ">Figure 5
<p>Load modulations of the Main PA and Auxiliary PAs under <math display="inline"><semantics> <mrow> <mi>α</mi> <mo>=</mo> <mn>1</mn> </mrow> </semantics></math>.</p> Full article ">Figure 6
<p>Optimal load impedance with maximum output power obtained from load-pull simulation.</p> Full article ">Figure 7
<p>(<b>a</b>) Layout of the output network. (<b>b</b>) EM simulation and other parameters of the output network.</p> Full article ">Figure 8
<p>(<b>a</b>) Practical coupled coils model containing parasitic capacitors <math display="inline"><semantics> <msub> <mi>C</mi> <mi>m</mi> </msub> </semantics></math>, <math display="inline"><semantics> <msub> <mi>C</mi> <mrow> <mi>g</mi> <mi>p</mi> </mrow> </msub> </semantics></math>, and <math display="inline"><semantics> <msub> <mi>C</mi> <mrow> <mi>g</mi> <mi>s</mi> </mrow> </msub> </semantics></math>. (<b>b</b>) Values of the parasitic capacitors and resonant inductors in the proposed output network.</p> Full article ">Figure 9
<p>(<b>a</b>) Load impedances of the Auxiliary PAs at saturation. (<b>b</b>) Load impedances of the Main PA at saturation and 9.5 dB OBO.</p> Full article ">Figure 10
<p>Schematic of the designed DPA. Transmission line width and length (W/L) are given in millimeters.</p> Full article ">Figure 11
<p>Simulated drain efficiency and gain versus output power within the frequency range of 2.1–2.8 GHz.</p> Full article ">Figure 12
<p>Simulated load impedance at the drain of the Main PA and output currents of the Main, Aux.1, and Aux.2 PAs versus output power at 2.5 GHz.</p> Full article ">Figure 13
<p>(<b>a</b>) Photograph of the fabricated PA. (<b>b</b>) Measurement setup.</p> Full article ">Figure 14
<p>Measured and simulated S-parameters of the proposed PA.</p> Full article ">Figure 15
<p>Measured drain efficiency and gain versus output power within the frequency range of 2.1–2.8 GHz.</p> Full article ">Figure 16
<p>Measured PAE versus output power within the frequency range of 2.1–2.8 GHz.</p> Full article ">Figure 17
<p>Measured CW results of the proposed PA.</p> Full article ">Figure 18
<p>Output spectra of 20 MHz LTE signal with 8.5 dB PAPR at (<b>a</b>) 2.4 GHz and (<b>b</b>) 2.7 GHz without DPD.</p> Full article ">Figure 19
<p>Measured modulation results of the proposed PA.</p> Full article ">
20 pages, 1057 KiB  
Article
Low-Resolution Optimization for an Unmanned Aerial Vehicle Communication Network under a Passive Reconfigurable Intelligent Surface and Active Reconfigurable Intelligent Surface
by Qiangqiang Yang, Yufeng Chen, Zhiyu Huang, Hongwen Yu and Yong Fang
Electronics 2024, 13(10), 1826; https://doi.org/10.3390/electronics13101826 - 8 May 2024
Viewed by 953
Abstract
This paper investigates the optimization of an unmanned aerial vehicle (UAV) network serving multiple downlink users equipped with single antennas. The network is enhanced by the deployment of either a passive reconfigurable intelligent surface (RIS) or an active RIS. The objective is to [...] Read more.
This paper investigates the optimization of an unmanned aerial vehicle (UAV) network serving multiple downlink users equipped with single antennas. The network is enhanced by the deployment of either a passive reconfigurable intelligent surface (RIS) or an active RIS. The objective is to jointly design the UAV’s trajectory and the low-bit, quantized, RIS-programmable coefficients to maximize the minimum user rate in a multi-user scenario. To address this optimization challenge, an alternating optimization framework is employed, leveraging the successive convex approximation (SCA) method. Specifically, for the UAV trajectory design, the original non-convex optimization problem is reformulated into an equivalent convex problem through the introduction of slack variables and appropriate approximations. On the other hand, for the RIS-programmable coefficient design, an efficient algorithm is developed using a penalty-based approximation approach. To solve the problems with the proposed optimization, high-performance optimization tools such as CVX are utilized, despite their associated high time complexity. To mitigate this complexity, a low-complexity algorithm is specifically tailored for the optimization of passive RIS-programmable reflecting elements. This algorithm relies solely on closed-form expressions to generate improved feasible points, thereby reducing the computational burden while maintaining reasonable performance. Extensive simulations are created to validate the performance of the proposed algorithms. The results demonstrate that the active RIS-based approach outperforms the passive RIS-based approach. Additionally, for the passive RIS-based algorithms, the low-complexity variant achieves a reduced time complexity with a moderate loss in performance. Full article
(This article belongs to the Special Issue Advanced Wireless Technologies for Next-G Networks: Antennas, Circuits, and Systems)
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<p>RIS-assisted multi-user communication network.</p> Full article ">Figure 2
<p>The convergence of the proposed algorithms.</p> Full article ">Figure 3
<p>Achieved min-rate versus transmit power, <math display="inline"><semantics> <msub> <mi>P</mi> <mrow> <mi>o</mi> <mi>u</mi> <mi>t</mi> </mrow> </msub> </semantics></math>.</p> Full article ">Figure 4
<p>Achieved min-rate versus the number of RIS elements <math display="inline"><semantics> <mrow> <msub> <mi>M</mi> <mi>x</mi> </msub> <mo>,</mo> <msub> <mi>M</mi> <mi>z</mi> </msub> </mrow> </semantics></math>.</p> Full article ">Figure 5
<p>Achieved min-rate versus the flight time <span class="html-italic">T</span>.</p> Full article ">Figure 6
<p>Optimized UAV trajectory of different algorithms.</p> Full article ">Figure 7
<p>Achieved min-rate versus the reflection coefficient resolution <span class="html-italic">b</span>.</p> Full article ">
15 pages, 4907 KiB  
Article
Design of UWB Electrically Small Antenna Based on Distributed Passive Network Loading
by Zhe Chen, Xianqi Lin, Yuchen Luan, Xinjie Hao, Xiaoming Yan and Guo Liu
Electronics 2024, 13(5), 914; https://doi.org/10.3390/electronics13050914 - 28 Feb 2024
Cited by 1 | Viewed by 1748
Abstract
In this paper, an ultra-wideband electrically small antenna based on distributed passive network loading is proposed. Based on the Vivaldi antenna theory, magnetic dipole antenna theory, and distributed loading theory, the electrically small antenna achieves the purpose of being wideband using a three-dimensional [...] Read more.
In this paper, an ultra-wideband electrically small antenna based on distributed passive network loading is proposed. Based on the Vivaldi antenna theory, magnetic dipole antenna theory, and distributed loading theory, the electrically small antenna achieves the purpose of being wideband using a three-dimensional design of a planar Vivaldi antenna structure under limited space constraints. At the same time, the magnetic dipole antenna is introduced to effectively expand the low-frequency bandwidth of the electrically small antenna without increasing the aperture size. Finally, through the distributed passive network loading, the wideband-conjugated matching of the electrically small antenna is achieved without increasing the size of the electrically small antenna. The −6 dB bandwidth of the electrically small antenna is 0.2 GHz–3 GHz, and the overall size is 0.06 λ0 × 0.05 λ0 × 0.12 λ0, where λ0 is the wavelength of the lowest frequency of the antenna. One sample of the proposed UWB electrically small antenna is fabricated and tested. Good agreement between simulation results and measurement results are obtained. The design method of UWB electrically small antenna proposed in this paper can be applied to the base station antenna, low-frequency detection, microwave sensing, and microwave measurement. Full article
(This article belongs to the Special Issue Advanced Wireless Technologies for Next-G Networks: Antennas, Circuits, and Systems)
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<p>The structural model of the three-dimensional Vivaldi antenna.</p> Full article ">Figure 2
<p>The S-parameter simulation result of the three-dimensional Vivaldi antenna.</p> Full article ">Figure 3
<p>The longitudinal electric field distributions of the three-dimensional Vivaldi antenna.</p> Full article ">Figure 4
<p>The structural model of the improved three-dimensional Vivaldi antenna.</p> Full article ">Figure 5
<p>The S-parameter simulation results of the improved three-dimensional Vivaldi antenna.</p> Full article ">Figure 6
<p>The longitudinal electric field distributions of the improved three-dimensional Vivaldi antenna.</p> Full article ">Figure 7
<p>The design schematic diagram of electrically small Vivaldi antenna based on distributed passive network loading.</p> Full article ">Figure 8
<p>The structural model of the electrically small Vivaldi antenna based on distributed passive network loading.</p> Full article ">Figure 9
<p>The S-parameter simulation results of the electrically small Vivaldi antenna based on distributed passive network loading.</p> Full article ">Figure 10
<p>The radiation pattern simulation results of the proposed electrically small Vivaldi antenna based on distributed passive network loading.</p> Full article ">Figure 10 Cont.
<p>The radiation pattern simulation results of the proposed electrically small Vivaldi antenna based on distributed passive network loading.</p> Full article ">Figure 11
<p>The photograph of the proposed ultra-wideband electrically small antenna and the test scheme.</p> Full article ">Figure 12
<p>The S-parameter measurement results of the proposed electrically small Vivaldi antenna based on distributed passive network loading.</p> Full article ">Figure 13
<p>The radiation pattern measurement results of the proposed electrically small Vivaldi antenna based on distributed passive network loading.</p> Full article ">Figure 13 Cont.
<p>The radiation pattern measurement results of the proposed electrically small Vivaldi antenna based on distributed passive network loading.</p> Full article ">
12 pages, 4621 KiB  
Article
Ultrathin Antenna-in-Package Based on TMV-Embedded FOWLP for 5G mm-Wave Applications
by Yuhang Yin, Chenhui Xia, Shuli Liu, Zhimo Zhang, Chen Chen, Gang Wang, Chenqian Wang and Yafei Wu
Electronics 2024, 13(5), 839; https://doi.org/10.3390/electronics13050839 - 22 Feb 2024
Cited by 2 | Viewed by 1981
Abstract
In this paper, a novel through mold via (TMV)-embedded fan-out wafer-level package (FOWLP) technology was demonstrated to manufacture the well-designed Antenna in Package (AiP) with ultrathin thickness (0.04 λ0). Double-sided redistribution layers (RDLs) were employed to build the patch antenna, while [...] Read more.
In this paper, a novel through mold via (TMV)-embedded fan-out wafer-level package (FOWLP) technology was demonstrated to manufacture the well-designed Antenna in Package (AiP) with ultrathin thickness (0.04 λ0). Double-sided redistribution layers (RDLs) were employed to build the patch antenna, while a TMV interposer was used to connect the front and back RDLs. By optimizing the AiP’s parameters, the patch antenna can achieve a wide impedance bandwidth of 17.8% from 24.2 to 28.5 GHz, which can cover the 5G frequency bands. Compared with previous works, the proposed AiP has significant benefits in terms of its ultralow profile, easy processing, and high gain. Hence, the TMV-embedded FOWLP should be a promising technology for fifth generation (5G) millimeter wave (mm-Wave) applications. Full article
(This article belongs to the Special Issue Advanced Wireless Technologies for Next-G Networks: Antennas, Circuits, and Systems)
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<p>Illustration of a TMV-embedded FOWLP.</p> Full article ">Figure 2
<p>Process flow of the TMV-embedded FOWLP technology.</p> Full article ">Figure 3
<p>Optical images of (<b>a</b>) TMV interposer embedded in reconstituted wafer, (<b>b</b>) the front side RDL, (<b>c</b>) reconfigured wafer back side after thinning, and (<b>d</b>) cross-section SEM image of the package.</p> Full article ">Figure 4
<p>Topology of the coplanar waveguide (CPW) structure. The black is substrate and the yellow is metal.</p> Full article ">Figure 5
<p>(<b>a</b>) Stack-up, (<b>b</b>) 3D, and (<b>c</b>) top views of the patch antenna.</p> Full article ">Figure 6
<p>Simulated |S11|of the patch antenna with and without the symmetrical parasitic patch.</p> Full article ">Figure 7
<p>Variation trend of |S11|s in relation to (<b>a</b>) TMV height and (<b>b</b>) TMV size.</p> Full article ">Figure 8
<p>Variation trend of |S11| in relation to different (<b>a</b>) <span class="html-italic">a</span> and (<b>b</b>)<span class="html-italic">c</span> values.</p> Full article ">Figure 9
<p>Optical micrographs of the proposed patch antenna.</p> Full article ">Figure 10
<p>Simulated and measured (<b>a</b>) S11 and (<b>b</b>) gain of the proposed miniaturized patch antenna element.</p> Full article ">Figure 11
<p>Simulated and measured far-field radiation patterns for proposed patch antenna: (<b>a</b>) 24 GHz E-plane, (<b>b</b>) 26 GHz E-plane, (<b>c</b>) 28 GHz E-plane, (<b>d</b>) 24 GHz H-plane, (<b>e</b>) 26 GHz H-plane, and (<b>f</b>) 28 GHz H-plane.</p> Full article ">
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