PIER B | PIER Journals

2026-01-03

PIER B

Vol. 116, 107-124, 2026

doi:10.2528/PIERB25081601

download: 79

Design and Implementation of Metamaterial Inspired Reconfigurable Multiband Antenna for 5G/Sub 6 GHz NR and Wireless Applications

Hareetaa Mallani, Archana Agrawal and Ritesh Kumar Saraswat

In this article, the authors propose the design and implementation of a frequency reconfigurable metamaterial-inspired octagon-shaped antenna for multiple wireless standards. The multiband functionality is achieved by incorporating a slotted self-similar octagonal radiating part with two SRR cells. The antenna design incorporates PIN diode switching elements on the slotted radiating patch, along with metamaterial-based SRR cell loading and a modified trapezoid-shaped partial ground plane, enabling its use across multiple wireless standards. The proposed design is resonating across five microwave frequency bands, including S-band WiMAX (3.5 GHz - IEEE 802.16e), 5G NR bands (n48: 3.55-3.70 GHz, n46: 5.15-5.925 GHz, n47: 5.855-5.925 GHz, n77: 3.3-4.2 GHz, n78: 3.3-3.8 GHz, n79: 4.4-5.0 GHz), C-band WLAN (5.0/5.8 GHz - IEEE 802.11a/ac), X-band (satellite communication, radar, terrestrial broadband, space communication), lower Ku-band for radar communication (13.43-14.55 GHz), upper Ku-band for molecular rotational spectroscopy (17.25-18.32 GHz), and lower K-band for astronomical observation services (18.81-19.96 GHz). The multiband antenna is then fabricated and tested, with measured and simulated results for return loss, gain, radiation efficiency, E-plane, and Hplane showing good agreement. The antenna's penta-band operation, compact size, stable radiation characteristics, and good impedance across the entire resonating band make it well-suited for various wireless applications.

Design and Implementation of Metamaterial Inspired Reconfigurable Multiband Antenna for 5G/Sub 6 GHz NR and Wireless Applications

2026-01-01

PIER B

Vol. 116, 94-106, 2026

doi:10.2528/PIERB25101302

download: 85

Microstrip Array Antenna Design for a 24 GHz Radar-Based Vital Signs Monitoring System

Murtini Murtini, Nurhayati Nurhayati, Usman Rizqi Iman, Fitri Yuli Zulkifli, Dewiani Dewiani and Lilik Anifah

Non-contact vital signs monitoring using radar technology has become increasingly important in modern healthcare, as it enables continuous physiological measurement without direct skin contact, minimizing patient discomfort and the risk of infection. To address these needs, this study presents the design and analysis of a 24 GHz microstrip array antenna developed for a radar-based vital signs monitoring system. Array configurations consisting of one to five circular patch elements were analyzed to optimize reflection coefficient, gain, and radiation characteristics, aiming to achieve high sensitivity, compactness, and safety for biomedical radar applications. Simulation results indicate that the four-element array achieves optimal performance, with a reflection coefficient of -39.27 dB, gain of 5.29 dBi, and bandwidth of 1.35 GHz at 24 GHz. To evaluate electromagnetic safety, Specific Absorption Rate (SAR) analysis using a three-layer human tissue model (skin, fat, and muscle) yielded values of 0.637 W/kg (1 g) and 0.205 W/kg (10 g) at a 50 mm separation distance, both within ICNIRP and FCC limits. Furthermore, bending simulations with curvature radii of 5 mm, 15 mm, and 50 mm confirmed stable impedance matching and minimal frequency variation, demonstrating strong mechanical flexibility. Overall, the proposed antenna exhibits high gain, reliable performance, and safety compliance, making it suitable for integration into portable radar-based medical devices for continuous and contactless monitoring of heart rate and respiration.

Microstrip Array Antenna Design for a 24 GHz Radar-Based Vital Signs Monitoring System

2025-12-22

PIER B

Vol. 116, 81-93, 2026

doi:10.2528/PIERB25092602

download: 315

Research on RIS-Assisted Millimeter Wave Beam Tracking Algorithms for Vehicular Communications

Chenwei Feng, Zhenzhen Lin, Yawei Sun, Yu Sun, Yangbin Huang and Yinhua Wu

In this paper, for millimeter wave (mmWave) vehicle-to-infrastructure communication, a reconfigurable intelligent surface (RIS) is introduced for assisted beam tracking in order to overcome the problem that the line-of-sight (LOS) transmission characteristics of mmWave are highly susceptible to communication disconnection caused by large vehicles or obstacles in a highly mobile scenario like Internet of Vehicles (IoV). In this paper, we study the case of switching to the RIS-assisted virtual-line-of-sight (VLOS) path for temporary beam tracking when the direct connection LOS path is disconnected. The cascading channel model for the VLOS path used for tracking after the introduction of RIS is investigated. Combining the new state model of position and velocity, a three-dimensional beam tracking model of the VLOS path is derived based on the extended Kalman filter algorithm. The beam tracking process is designed, and the beam tracking performance is analyzed for different cases under this scheme. Simulation results show that the scheme in this paper has lower tracking error than the scheme of the conventional state model, and the introduction of RIS can overcome the problem that mmWave IoV communication is vulnerable to occlusion.

Research on RIS-Assisted Millimeter Wave Beam Tracking Algorithms for Vehicular Communications

2025-12-14

PIER B

Vol. 116, 65-80, 2026

doi:10.2528/PIERB25080106

download: 99

Rainfall DSD Modelling Using Supervised Learning Techniques for Rain Attenuation Prediction in South Africa

Tsietsi Condry Ramatladi and Akintunde Ayodeji Alonge

Reliable modelling of rainfall-induced attenuation is crucial for designing and operating high-frequency communication systems, particularly those operating above 10 GHz, in regions with severe rainfall conditions such as subtropical climates. This study offers a comparison of supervised machine learning (ML) models - k-nearest neighbours (KNN), decision trees (DT), and random forests (RF) - against traditional statistical methods such as the lognormal and gamma distributions for estimating raindrop size distribution (DSD) and specific attenuation. Rainfall measurements taken between 2018 and 2019 were obtained from 1-minute disdrometer at the measurement location in Durban, South Africa (29.8651°S, 30.9734°E). The investigated models were then tested across four different rainfall regimes processed from the dataset: drizzle, widespread rain, shower, and thunderstorm. An adaptive tuning method for selecting the best k-value in KNN was introduced to enhance prediction accuracy across various rainfall intensities. Model performances are evaluated using error metrics of root mean square error (RMSE), mean absolute error (MAE), and the coefficient of determination (R²). The results show that KNN outperforms RF and DT, providing the highest accuracy and lowest prediction errors across all rainfall regimes. The confidence interval (CI) analysis confirms that KNN delivers more precise and stable estimates, while RF and DT exhibit greater variability and uncertainty in performance. Additionally, specific attenuation estimations from these ML models are compared at different rain rates with the ITU-R P.838-8 estimations for frequencies up to 100 GHz. These findings highlight the superiority of data-driven model, particularly the adaptive KNN, in capturing complex rainfall microstructures and improving attenuation predictions. This has direct implications for planning and deploying rain-resilient wireless networks in variable climatic regions.

Rainfall DSD Modelling Using Supervised Learning Techniques for Rain Attenuation Prediction in South Africa

2025-10-31

PIER B

Vol. 116, 48-64, 2026

doi:10.2528/PIERB25072304

download: 172

Research on Multi-Vehicle Beam Tracking Algorithm Based on Aerial Reconfigurable Intelligent Surface Assistance

Chenwei Feng, Zhenzhen Lin, Yawei Sun, Yangbin Huang and Yinhua Wu

With the growth of demand for high-rate and high-quality wireless communication services, Unmanned Aerial Vehicle (UAV) communication technology has received a lot of attention. By deploying Reconfigurable Intelligent Surface (RIS) on the UAV, more users can be reached while effectively expanding the signal coverage. The rotational nature of the UAV also provides new degrees of freedom in the design of RIS-assisted millimeter-wave Multiple Input Multiple Output (MIMO) systems. In this paper, using the advantages of UAV and RIS technologies, Aerial Reconfigurable Intelligent Surface (ARIS) is introduced to assist the communication, and the millimeter-wave Vehicle to Infrastructure (V2I) communication scenario based on the ARIS-assisted multi-vehicle beam tracking problem. First, Zero Forcing (ZF) beamforming is employed at the base station to eliminate inter-vehicle interference. On this basis, the vehicle-side beam combining matrix, the RIS-side reflection beamforming matrix, along with the rotation angle of the ARIS, are jointly designed to maximize the number of vehicles and data rates, thereby providing high-quality communication for beam tracking studies. Secondly, an ARIS-assisted multi-vehicle beam tracking model is derived in a MIMO-based 3D communication scenario. Finally, an Extended Kalman Filter (EKF) algorithm based on the angular deviation correction mechanism is proposed to realize the beam tracking of multiple vehicles. Simulation results show that the proposed EKF algorithm can effectively reduce the beam tracking error in multi-vehicle communication scenarios with robust beam tracking capability under the joint design based on beam merging matrix, beamforming matrix and ARIS rotation angle.

Research on Multi-vehicle Beam Tracking Algorithm Based on Aerial Reconfigurable Intelligent Surface Assistance

2025-10-30

PIER B

Vol. 116, 33-47, 2026

doi:10.2528/PIERB25082704

download: 252

Comprehensive Phase Shifter Review: State of the Art and Future Trends

Sana Gharsalli, Radhoine Aloui, Sofien Mhatli, Alonso Corona-Chavez, Zabdiel Brito-Brito, Satyendra Kumar Mishra and Ignacio Llamas-Garro

RF signals are widely used in various applications, including radar systems, wireless communication systems, and telecommunications. Phase shifters allow tuning of the signal's phase, using digital and analog designs. This adjustment is essential for antenna beam steering and shaping, signal cancellation, and frequency synthesis in antenna arrays. Phase control is essential to improve the performance of wireless communication and radar systems by enhancing signal reception and transmission. This study examines different types of phase shifters, including a comparative analysis of different phase shifter topologies and technologies, highlighting advantages and limitations according to applications. In addition, this review includes a specific study on liquid metal phase shifters. Finally, the article outlines future research directions for liquid metal phase shifters: It is emphasized that there is a constant need for innovative design strategies to keep pace with the evolving wireless communications and radar fields. Therefore, this article can be a reference for the next milestones in RF phase shifter research.

Comprehensive Phase Shifter Review: State of the Art and Future Trends

2025-10-17

PIER B

Vol. 116, 19-32, 2026

doi:10.2528/PIERB25071805

download: 172

Model of a Planar Cherenkov-Type Antenna for Microwave Applications

Vadym Pazynin, Kostyantyn Sirenko and Wilhelm Keusgen

In this paper, a radiator employing the Cherenkov mechanism for electromagnetic energy transfer from an optically less dense medium into a more dense one is developed and studied using a two-dimensional numerical model. The radiator’s principal components are a dielectric prism and an open dielectric waveguide, where the phase velocity of eigenwaves exceeds that within the prism. For two linear field polarizations in the 24 GHz to 64 GHz range, this radiator exhibits high efficiency (over 93%) and radiation patterns with main lobes that closely coincide in both direction and width. The direction of radiation demonstrates strong agreement with predictions from the Cherenkov wave theory and shows weak dependence on frequency. These characteristics make the developed antenna suitable for directional emission and reception of electromagnetic pulses of various polarizations with spectral bandwidths of up to one octave or more. It is demonstrated that the radiation patterns of such antennas can be electrically controlled by altering the permittivity of the dielectric waveguide using an external control signal. The proposed antenna design avoids expensive fabrication processes and can be scaled to sub-millimeter wave ranges without significant modifications.

Model of a Planar Cherenkov-type Antenna for Microwave Applications

2025-10-14

PIER B

Vol. 116, 1-18, 2026

doi:10.2528/PIERB25072205

download: 159

Reconfigurable Designs of U-Slot Cut Microstrip Antennas for Dual Band Circularly Polarized Response

Amit A. Deshmukh and Venkata A. P. Chavali

Resonant slot cut microstrip antenna is a single patch solution to achieve circularly polarized response, but it does not offer tunability in the center frequency of axial ratio bandwidth. This paper presents reconfigurable designs of shorting post loaded U-slot cut circular and equilateral triangular microstrip antennas that offer tunable circularly polarized response. Shorting posts positions alter the excitation of resonant modes on the U-slot cut patch that achieves tuning in the circularly polarized frequency. On substrate thickness of ~0.05λ_cAR, using the circular patch, tuning in the center frequency of axial ratio bandwidth by 253 MHz (28.26%) is obtained, whereas equilateral triangular patch design offers 319 MHz (32.68%) of frequency tuning. In both the designs, broadside radiation pattern with a peak gain of larger than 7 dBic is obtained across the axial ratio bandwidth. Design methodology is proposed that yields a similar configuration as per specific wireless application. With the obtained frequency tuning in axial ratio bandwidth, redesigned variations of the proposed configurations can cater to pairs of GPS L-band applications.