Electronics

Research

Jump to: Review

14 pages, 2122 KB

Open AccessArticle

An Ultra-Wide-Angle Mechanically Steered Reflectarray Antenna (RA) Based on Non-Specular Reflection

by Jae-Min Jeong, Tae-Uk Jung and Jae-Gon Lee

Electronics 2026, 15(15), 3434; https://doi.org/10.3390/electronics15153434 - 3 Aug 2026

Viewed by 256

Abstract

This paper presents a non-specular reflection-based mechanically steered reflectarray antenna (RA) that achieves ultra-wide beam steering up to 80° while preserving mainlobe integrity. Conventional mechanically steered RAs are fundamentally constrained by specular reflection, where the reflection angle follows the incident angle symmetrically. Consequently, [...] Read more.

This paper presents a non-specular reflection-based mechanically steered reflectarray antenna (RA) that achieves ultra-wide beam steering up to 80° while preserving mainlobe integrity. Conventional mechanically steered RAs are fundamentally constrained by specular reflection, where the reflection angle follows the incident angle symmetrically. Consequently, large scan angles inherently require extreme incident angles, which exacerbate aperture projection loss, element angular instability, and beam distortion. To overcome this limitation, an asymmetric reflection phase distribution is engineered to decouple the reflection angle from the incident angle, thereby relaxing the incident angle requirement for wide-angle beam steering. By mitigating extreme angular excitation of the unit cells, the proposed approach enhances angular stability and improves beam robustness at large scan angles. Full-wave simulation and measurement demonstrate stable radiation patterns without mainlobe splitting up to a scan angle of 80°. Although a gain reduction of approximately 6 dB is observed at the maximum steering angle due to intrinsic aperture projection effects, the mainlobe characteristics remain well preserved. The proposed approach provides a physically grounded and practical pathway toward ultra-wide-angle beam steering in mechanically steered RAs. Full article

(This article belongs to the Special Issue New Challenges in Beyond 5G/6G Network Wireless Technologies)

► Show Figures

Figure 1

10 pages, 3101 KB

Open AccessArticle

A Frequency-Reconfigurable Dual-Band Variable-Gain Phase Shifter for 5G mm-Wave Beamforming

by Jaehun Lee, Eun-Taek Sung, Dong-Ho Lee, Gwanghyeon Jeong and Songcheol Hong

Electronics 2026, 15(15), 3300; https://doi.org/10.3390/electronics15153300 - 27 Jul 2026

Viewed by 376

Abstract

This paper presents a frequency-reconfigurable dual-band phase shifter operating in the n257 (26.5–29.5 GHz) and n260 (37–40 GHz) bands for fifth-generation (5G) communication. The proposed phase shifter is based on an active vector-summing architecture and provides simultaneous gain and phase control for beamforming [...] Read more.

This paper presents a frequency-reconfigurable dual-band phase shifter operating in the n257 (26.5–29.5 GHz) and n260 (37–40 GHz) bands for fifth-generation (5G) communication. The proposed phase shifter is based on an active vector-summing architecture and provides simultaneous gain and phase control for beamforming applications. To support dual-band operation with a large frequency separation, a reconfigurable RC–RL polyphase filter (PPF) is employed for in-phase/quadrature (I/Q) signal generation. The proposed PPF reconfigures its inductance and capacitance according to the operating band, reducing insertion loss and minimizing I/Q phase error in both frequency bands. Gain and phase are controlled by digital-to-analog converter (DAC)-assisted vector summation with 4-bit gain and 6-bit phase control resolution, while a reconfigurable output matching network provides optimized impedance matching in each operating mode. The phase shifter is implemented in a 28 nm fully depleted silicon-on-insulator (FDSOI) process with a core area of 0.26 mm². The measured RMS phase errors are <1.18° and <1.5°, and the RMS gain errors are <0.26 dB and <0.35 dB in the n257 and n260 bands, respectively. The measured DC power consumption is 11 mW and 15.4 mW in the n257 and n260 bands, respectively. Full article

(This article belongs to the Special Issue New Challenges in Beyond 5G/6G Network Wireless Technologies)

► Show Figures

Figure 1

11 pages, 3336 KB

Open AccessArticle

Mechanically Reconfigurable Dielectric Transmitarray for Dual-Beam Communications

by Francesco Alessio Dicandia and Simone Genovesi

Electronics 2026, 15(14), 3144; https://doi.org/10.3390/electronics15143144 - 16 Jul 2026

Viewed by 342

Abstract

A mechanically reconfigurable transmitarray (TA) to support point-to-multipoint (PtM) communications via simultaneous dual-beam radiation is presented. The architecture employs two independently rotating flat dielectric TAs whose transmitting element permittivity values are rigorously synthesized to transform the feeder spherical wavefront into concurrent multiple beams, [...] Read more.

A mechanically reconfigurable transmitarray (TA) to support point-to-multipoint (PtM) communications via simultaneous dual-beam radiation is presented. The architecture employs two independently rotating flat dielectric TAs whose transmitting element permittivity values are rigorously synthesized to transform the feeder spherical wavefront into concurrent multiple beams, thereby enabling simultaneous dual-beam scanning in both elevation and azimuth. The numerical analysis and full-wave simulations demonstrate that the proposed design strategy can achieve a maximum dual-beam elevation scan of 55° with a 3 dB dual-beam gain bandwidth larger than 18%. A prototype comprising two flat dielectric TAs operating at 35 GHz and producing a mechanically scanned dual-beam has been manufactured using an additive manufacturing process. The measurements are in good agreement with the expected outcomes and confirm the effectiveness of the proposed synthesis strategy. Full article

(This article belongs to the Special Issue New Challenges in Beyond 5G/6G Network Wireless Technologies)

► Show Figures

Figure 1

21 pages, 6363 KB

Open AccessArticle

Design and Implementation of a 28-GHz Four-Phase Beam-Steering Antenna Based on a Butler Matrix Network

by Ming-An Chung, Chia-Wei Lin and Bing-Ruei Chuang

Electronics 2026, 15(12), 2505; https://doi.org/10.3390/electronics15122505 - 6 Jun 2026

Viewed by 483

Abstract

This paper presents a four-phase beam-steering antenna for 28 GHz wireless communication, targeting the demand for high-efficiency and low-complexity beam-steering solutions in millimeter-wave systems. The proposed design employs a Butler matrix network to achieve multi-directional beam switching while reducing implementation complexity. The antenna [...] Read more.

This paper presents a four-phase beam-steering antenna for 28 GHz wireless communication, targeting the demand for high-efficiency and low-complexity beam-steering solutions in millimeter-wave systems. The proposed design employs a Butler matrix network to achieve multi-directional beam switching while reducing implementation complexity. The antenna is realized using microstrip technology on a printed circuit board (PCB), and the overall architecture consists of a 1 × 4 microstrip antenna array and a 4 × 4 Butler matrix network. Each component is carefully designed and analyzed to ensure optimized performance and proper system balance. The proposed antenna exhibits excellent performance in terms of bandwidth and compact size, while also providing advantages that include low cost, ease of fabrication, and structural simplicity. The beam-steering capability is experimentally verified through far-field measurements. The measurement results indicate that the four beam directions are −38°, −13°, +19°, and +41°, with corresponding gains of 8.79, 9.66, 10.8, and 9.21 dBi, respectively. In addition, a good agreement between the measurement and simulation results is observed, which validates the effectiveness and feasibility of the proposed design. Full article

(This article belongs to the Special Issue New Challenges in Beyond 5G/6G Network Wireless Technologies)

► Show Figures

Figure 1

21 pages, 5710 KB

Open AccessArticle

Impact of Antenna Radiation Pattern Modeling on 5G NR mmWave Ray-Tracing Accuracy at 27 GHz: Insights from an Urban Walk-Test Campaign

by Pierpaolo Salvo, Francesca Lodato, Alessio Carmenini, Andrea Petroni, Marcello Folli, Riccardo Suman, Massimo Perobelli and Antonio Iodice

Electronics 2026, 15(9), 1967; https://doi.org/10.3390/electronics15091967 - 6 May 2026

Viewed by 660

Abstract

Deterministic Ray Tracing (RT) is widely used for coverage prediction and network planning in 5G New Radio systems. Jointly with reliable environmental reconstruction, RT accuracy depends strongly on antenna radiation pattern modeling, especially at millimeter-wave (mmWave) frequencies. This paper compares three antenna modeling [...] Read more.

Deterministic Ray Tracing (RT) is widely used for coverage prediction and network planning in 5G New Radio systems. Jointly with reliable environmental reconstruction, RT accuracy depends strongly on antenna radiation pattern modeling, especially at millimeter-wave (mmWave) frequencies. This paper compares three antenna modeling strategies implemented in the Matlab 5G Toolbox and validates their predictions against an extensive 27 GHz urban walk-test dataset. The assessment combines point-wise error metrics, empirical cumulative distribution functions, and spatial correlation analysis. Results highlight the absence of an optimal antenna model; rather, the provided accuracy is context-specific. The beam-based model achieves the best agreement in guided propagation conditions, whereas the envelope and isotropic models yield more robust macroscopic coverage estimates in heavily obstructed areas affected by incomplete environmental representation and unmodeled clutter. Full article

(This article belongs to the Special Issue New Challenges in Beyond 5G/6G Network Wireless Technologies)

► Show Figures

Figure 1

12 pages, 3132 KB

Open AccessArticle

A Compact On-Chip Ka-Band Bandpass Filter Using Folded Crossed Interdigital Coupling Structure

by Ming-An Chung, Chia-Wei Lin and Bing-Ruei Chuang

Electronics 2026, 15(7), 1455; https://doi.org/10.3390/electronics15071455 - 31 Mar 2026

Viewed by 714

Abstract

This paper proposes a millimeter-wave miniature on-chip bandpass filter (BPF) implemented using a 0.18 μm CMOS process. To address the issues of insufficient coupling capability, limited control of transmission zeros, and excessive chip area in traditional on-chip filters, a folded cross-interdigital coupling structure [...] Read more.

This paper proposes a millimeter-wave miniature on-chip bandpass filter (BPF) implemented using a 0.18 μm CMOS process. To address the issues of insufficient coupling capability, limited control of transmission zeros, and excessive chip area in traditional on-chip filters, a folded cross-interdigital coupling structure is proposed to enhance coupling efficiency and reduce size. The design incorporates metal–insulator–metal (MIM) capacitors to increase the coupling capacitance between resonators without increasing the area, and utilizes a defected ground structure (DGS) to modify the current distribution at the ground plane, generating additional transmission zeros to improve selectivity. An LC equivalent circuit model was established and verified through full-wave electromagnetic simulation, and the design was validated through chip fabrication and on-wafer measurements. The measurement results show an insertion loss of 3.36 dB and a fractional bandwidth of 49.1% at 32 GHz, with two transmission zeros. The core dimensions are 0.25 mm × 0.18 mm. This design achieves a good balance between miniaturization, selectivity, and insertion loss, making it suitable for millimeter-wave SoC applications. Full article

(This article belongs to the Special Issue New Challenges in Beyond 5G/6G Network Wireless Technologies)

► Show Figures

Figure 1

Review

Jump to: Research

33 pages, 5267 KB

Open AccessReview

Photonic THz Wireless Communications: Beyond Faster and Farther Link Demonstrations

by Bo Li, Ming Che, Shenghong Ye, Hussein Ssali and Kazutoshi Kato

Electronics 2026, 15(15), 3338; https://doi.org/10.3390/electronics15153338 - 28 Jul 2026

Viewed by 767

Abstract

Photonic THz wireless communications have developed primarily through point-to-point demonstrations aimed at achieving higher data rates and longer transmission distances. In this development, uni-traveling-carrier photodiodes (UTC-PDs) have played a central role by enabling optical heterodyne generation of widely tunable and modulation-transparent THz carriers. [...] Read more.

Photonic THz wireless communications have developed primarily through point-to-point demonstrations aimed at achieving higher data rates and longer transmission distances. In this development, uni-traveling-carrier photodiodes (UTC-PDs) have played a central role by enabling optical heterodyne generation of widely tunable and modulation-transparent THz carriers. This review revisits the progress of UTC-PD-enabled photonic THz wireless links from a faster-and-farther perspective. Specifically, we first examine how representative demonstrations have pushed the performance frontier and then identify the technical factors underlying this progress, with emphasis on low-noise optical source engineering, multiplexing, and equalization-based reception. We further discuss how the same capacity-driven trend has begun to reshape the field beyond fixed point-to-point links, giving rise to laser-enabled functional expansion and array-based beam manipulation. In this context, photonic THz transmitters are increasingly viewed not only as sources of spectrally pure carriers but also as platforms for arbitrary waveform generation and spatial beam control. Taken together, recent progress in photonic THz wireless communications is less a sequence of record updates than a shift from record-oriented links toward function-oriented transmitter architectures. Full article

(This article belongs to the Special Issue New Challenges in Beyond 5G/6G Network Wireless Technologies)

► Show Figures

Figure 1

20 pages, 8476 KB

Open AccessReview

Optoelectronic Terahertz Sources for Next-Generation Communication Systems: Technologies, Challenges, and Future Directions

by Hussein Ssali, Bo Li, Ming Che and Kazutoshi Kato

Electronics 2026, 15(11), 2477; https://doi.org/10.3390/electronics15112477 - 4 Jun 2026

Viewed by 608

Abstract

The terahertz (THz) frequency band has emerged as a promising frontier for next-generation wireless communication systems targeting ultra-high data rates, ultra-low latency, and spectrum expansion beyond conventional millimeter-wave regimes. Realizing practical THz communication links, however, critically depends on stable, tunable, and integrable signal [...] Read more.

The terahertz (THz) frequency band has emerged as a promising frontier for next-generation wireless communication systems targeting ultra-high data rates, ultra-low latency, and spectrum expansion beyond conventional millimeter-wave regimes. Realizing practical THz communication links, however, critically depends on stable, tunable, and integrable signal sources capable of delivering sufficient output power while maintaining spectral purity and energy efficiency. Among the various THz generation approaches, optoelectronic techniques offer unique advantages, including large bandwidth, wide frequency tunability and compatibility with fiber-optic infrastructures. This review provides a technology-focused assessment of key optoelectronic THz source technologies, namely photoconductive antennas, quantum cascade lasers, and unitraveling carrier photodiode (UTC-PD)-based photomixers, with particular emphasis on UTC-PD photomixers due to their strong suitability for continuous-wave THz generation and fiber-compatible architectures. The implications of optoelectronic THz sources for system-level architectures, including THz-over-fiber links, coherent detection schemes, and phased-array integration, are further examined. Finally, critical challenges and emerging research directions toward monolithic photonic–terahertz integration and deployable high-capacity wireless front-ends are discussed. This review aims to provide a structured perspective on the state of optoelectronic THz source technologies and their role in enabling practical next-generation communication systems. Full article

(This article belongs to the Special Issue New Challenges in Beyond 5G/6G Network Wireless Technologies)

► Show Figures

Figure 1

Journal Menu

Journal Browser

New Challenges in Beyond 5G/6G Network Wireless Technologies

Share This Special Issue

Editors

Special Issue Information

Keywords

Benefits of Publishing in a Special Issue

Published Papers (8 papers)

Research

Review

Further Information

Guidelines

MDPI Initiatives

Follow MDPI