PIER C | PIER Journals

2025-06-23

PIER C

Vol. 156, 261-272, 2025

download: 7

Optimization of Optical Fiber Coupling Efficiency Based on Deep Reinforcement Learning and Adaptive Optics Technology

Fang Bai and Rongfu Qiao

Fibre optic coupling is a critical component in optical communication systems, which involves efficiently transmitting optical signals from a light source to an optical fibre and efficiently receiving optical signals from the optical fibre to an optical detector. This process requires minimizing the loss of optical signals during the coupling process to maintain the performance and stability of the communication system. The complex environmental conditions and dynamic changes in optical systems that traditional optimization methods face often make it difficult to handle effectively. Therefore, this study uses deep reinforcement learning and adaptive optics technology to optimize fibre coupling efficiency. The optical fibre transmission performance is analyzed and optimized. Because the 2.6 Gb/s optical transmission system is a highspeed optical communication system capable of transmitting 260 million bits of data per second on a single optical fibre, this study selected the 2.6 Gb/s optical transmission system for single fibre three-way optical components. The optimization results show that the thickness of the isolator has been reduced by 2.356 mm, and the coupling efficiency has reached 79.95%. The optimized coupling steps can effectively optimize the coupling process, and the optimized optical components have high coupling efficiency, yield, and integration. The analysis of multiple sets of experimental data showed that the proposed method could improve the fibre coupling efficiency by an average of 15% to 20% under different environmental conditions. These data also show that the new framework performs well in optical path optimization and demonstrates excellent stability and real-time response capabilities in complex environments.

Optimization of Optical Fiber Coupling Efficiency Based on Deep Reinforcement Learning and Adaptive Optics Technology

2025-06-22

PIER C

Vol. 156, 253-260, 2025

doi:10.2528/PIERC25031007

download: 12

Microwave Scattering from Sea Surfaces: CBFM Hybridized to Kirchhoff and Weak-Coupling Approximations and to Identical Block PBFs

Christophe Bourlier

In this paper, the characteristic basis function method (CBFM) is accelerated to calculate the monostatic and bistatic normalized radar cross sections from one-dimensional highly-conducting sea surfaces in the microwave bands (C and Ku). In the framework of the two-scale asymptotic model, the subsurface length of the block is judiciously derived to contain all the surface curvature components (small scale) and the associated PBFs, assumed to be identical for all blocks, are rapidly calculated from the Kirchhoff approximation. In addition, the reduced matrix calculation is accelerated by neglecting the interactions between far blocks and by introducing a roughness slight approximation (matrix-matrix products can be done from fast Fourier transforms), which also allows us to expedite the resolution of the linear system since the matrix is sparse. Numerical results show the efficiency of CBFM-KA.

Microwave Scattering from Sea Surfaces: CBFM Hybridized to Kirchhoff and Weak-coupling Approximations and to Identical Block PBFs

2025-06-22

PIER C

Vol. 156, 243-252, 2025

doi:10.2528/PIERC25030202

download: 26

A MIMO Antenna for 5G Wireless Applications, Designed with Hybrid Fractal Geometry and Incorporating CSRR Loading

Amandeep Kaur and Jagtar Singh Sivia

This paper demonstrates a Hybrid Fractal MIMO Antenna (HFMA) integrated with a Complementary Split Ring Resonator (CSRR) for fifth-generation wireless applications. Two radiating elements based on Meander and Minkowski Hybrid fractal geometry are included in the proposed design. The defected ground plane, along with CSRR, has been employed to enhance the isolation, bandwidth, gain, and other performance characteristics of the proposed HFMA. The proposed antenna was constructed using Rogers RT/duroid 5880 material. The designed model offers a maximum isolation of -55.86 dB and a wide bandwidth of 28.72 GHz, spanning the frequency range from 1.28 GHz to 30 GHz. All the diversity parameters of the designed antenna are found within operating limits. The proposed antenna is capable of covering multiple 5G spectrum bands, including LTE band 46 (5.15-5.925 GHz), 5G New Radio and 3.5 GHz frequency bands (3.3-5.0 GHz), the 26 GHz 5G spectrum, the European Union 5G spectrum (5.9-6.4 GHz), and is highly suitable for a range of other advanced applications, including Internet of Things (IoT), satellite communications, and vehicular networks in the frequency range of 1-30 GHz band.

A MIMO Antenna for 5G Wireless Applications, Designed with Hybrid Fractal Geometry and Incorporating CSRR Loading

2025-06-21

PIER C

Vol. 156, 233-241, 2025

doi:10.2528/PIERC25041710

download: 22

Hybrid Multi-Scale Simulation Workflow for Installation and Isolation of Flush-Mounted Antennas on Rockets

Akshaj Arora, Sahitya Singh, Irina Gordion and Shawn Carpenter

We present a full-physics simulation workflow for modelling the installation and isolation of flush-mounted antenna arrays on rockets, which employs a combination of finite array domain decomposition method (FADDM) and shooting and bouncing rays (SBR) solver. An advanced domain decomposition method is first demonstrated, incorporating `non-identical' unit cells to efficiently solve a 4×4 antenna array residing in a metal cavity and operating in the X-band at 8.5 GHz. The proposed workflow eliminates the need for any computer-aided design (CAD) modifications for constructing conformal geometries of antennas and recesses in the fuselage, enabling seamless flush mounting of the array into an accurate model of a SpaceX Dragon capsule. The SBR simulation in the workflow is enabled with essential methodologies such as automati current conformance, creeping-wave physics, physical theory of diffraction, uniform theory of diffraction and current source reduction technique to obtain a high-fidelity yet computationally economical solution that determines radiation characteristics of installed antenna array and isolation between two flush-mounted antenna arrays.

Hybrid Multi-scale Simulation Workflow for Installation and Isolation of Flush-mounted Antennas on Rockets

2025-06-21

PIER C

Vol. 156, 227-232, 2025

doi:10.2528/PIERC25041201

download: 12

Design and Analysis of a Half-Mode SSPP Transmission Line for Size Miniaturization

Wang Xu and Lin Li

By utilizing the symmetry of the field distribution of a coplanar waveguide (CPW) SSPP transmission line (TL), a half-mode SSPP (HMSSPP) transmission line (TL) is presented. Through electromagnetic simulations, it is demonstrated that the proposed HMSSPP TL has a lower asymptotic frequency than the CPW SSPP TL, while occupying only half of the size. Through equivalent circuit analysis, the miniaturization mechanism of the half-mode structure is revealed, and the method to further reduce the asymptotic frequency has been developed. The fabricated and measured HMSSPP TLs confirm the effectiveness and benefits of the half-mode transmission line, achieving significant size reduction and maintaining low insertion loss. Such compact transmission lines are particularly advantageous in space-constrained applications such as portable communication devices, radar systems, and compact RF modules for wireless sensing.

Design and Analysis of a Half-mode SSPP Transmission Line for Size Miniaturization

2025-06-17

PIER C

Vol. 156, 217-225, 2025

doi:10.2528/PIERC25022404

download: 60

A New Design of Tunable Dual Band-Notched UWB Flower-Shaped Antenna Verified by CMA

Azadeh Shahpari and Mohsen Shafeghati

In this paper, a tunable ultra-wideband antenna based on slot structures is presented and verified using Characteristic Mode Analysis. The antenna is backed with a partial ground plane and covers the 2.8-13.2 GHz frequency band. In this wide frequency range, satisfactory VSWR and gain are achieved. To avoid interference with wireless local area network WLAN (5.2 to 5.8 GHz) and X-Band satellite links (7.9 to 8.4 GHz), two notches are created using U-shaped and elliptical slots. An important feature of this paper is the use of varactor diode in the elliptical slot to achieve tunable frequencies for the second notched band. By applying different bias voltages, the center frequency of the second notched band is continuously tuned. The antenna performance is verified using modal parameters including modal significance and characteristic angle within the working region of the proposed antenna using the theory of characteristic modes analysis. This antenna is implemented on top of a cost-effective FR4 substrate with a 1 mm thickness. The proposed flower-shaped antenna is compact in size and provides ultra-wide bandwidth. The dimension of the optimized design is 25 × 35 × 1 mm³.

A New Design of Tunable Dual Band-notched UWB Flower-shaped Antenna Verified by CMA

2025-06-16

PIER C

Vol. 156, 207-216, 2025

doi:10.2528/PIERC25011403

download: 32

Compact Size of Multiband Planar Monopole Antenna for Portable Device Applications

Bharati B. Sayankar, Sarita B. Dhoble, Pravin Tajane, Kanchan D. Ganvir, Nitin K. Choudhari and Jyotsna S. Gawai

The proposed planar antenna features F and U shaped strips on the patch, along with U shaped slits on the ground plane, catering to WLAN/Bluetooth/WiMAX/HYPERLAN applications. Initially designed for a resonance frequency of 2.4GHz using standard formulae, the rectangular patch antenna boasts dimensions of 38.60 x 46.70 mm², totaling 1803 mm². However, employing the covering electrical length technique, the proposed antenna effectively reduces size for multiband applications. The lengths of the strips determine the resonance frequencies, while the U shaped slits facilitate adjustment of resonance frequencies as required. Following parametric optimization, the rectangular patch antenna becomes suitable for multiband operation, shrinking in size by up to 71.47% compared to its original form. The proposed antenna achieves resonance at 2.45 GHz, 3.55 GHz, and 5.37 GHz, effectively covering WLAN, Bluetooth, Zigbee, WiMAX, and HYPERLAN frequencies. Despite size reduction, the antenna maintains acceptable gain, ensuring its viability for multiband operations. The compact dimensions of the proposed planar antenna measure 39.5 x 13 mm², making it ideal for integration into small portable devices such as mobile handsets, laptop computers, and USB dongles. Following fabrication, various parameters of the antenna are measured using a Vector Network Analyzer (VNA), including reflection coefficient, Voltage Standing Wave Ratio (VSWR), and impedance.

Compact Size of Multiband Planar Monopole Antenna for Portable Device Applications

2025-06-16

PIER C

Vol. 156, 201-205, 2025

doi:10.2528/PIERC25041603

download: 42

Flat-Plate Dipole Antenna for Wi-Fi 8 and 6G Operation

Saou-Wen Su, Tung-Chan Yu and Ju-Cheng Huang

A planar, short-circuited dipole design, constructed from cutting a flat metallic plate, capable of operating in the 2.4/5/6 GHz Wi-Fi 8 bands and also the 6G upper mid-band in the 7125-8400 MHz range is presented. The antenna comprises two folded dipole arms, each of which has a cut-out portion, with one short-circuiting portion connecting them. The plate dipole can operate at its 0.5-, 1.5-, and 2.5-λ resonant modes with two higher-order resonances forming a very wide 10-dB impedance bandwidth of about 5.0-9.4 GHz, easily covering the 5150-8400 MHz band for the 5/6 GHz Wi-Fi bands and the 6G upper mid-band. The design is simple in structure, has a compact size of 10 mm × 30 mm (0.08-λ × 0.24-λ at 2.4 GHz), and also shows good radiation performance. The design concept is elucidated and discussed in this paper with the numerical and experimental results.

Flat-plate Dipole Antenna for Wi-Fi 8 and 6G Operation

2025-06-13

PIER C

Vol. 156, 195-200, 2025

doi:10.2528/PIERC25031004

download: 51

Hierarchical Matching Maximum Likelihood Estimation for Digital-Array Monopulse Tracking Radar

Haibo Wang, Wenhua Huang, Tao Ba, Yuchuan Zhang and Haichuan Zhang

Direction of arrival (DOA) estimation is an important issue for radar and communication applications. Monopulse is widely used to obtain the DOA result by the complex ratio from the sigma and delta beams of the antenna. In the case of digital array systems, various methods based on the covariance matrix of the received signal have been proposed to obtain the DOA result. However, it is impractical for tracking radar scenarios, as the covariance matrix is not easy to obtain. Nevertheless, there is merely one target echo in the vicinity of the range cell as forecasted. Thus, the Maximum Likelihood Estimation (MLE) is a relatively good estimator for tracking radar, which has high accuracy and robustness. However, MLE is often very computationally resource-intensive, as it needs to search the whole steering vector set. In this paper, in order to utilize MLE effectively, we propose an algorithm to quickly search the steering vector set by the binary tree hierarchical matching method, which can significantly reduce the computational cost. Furthermore, the computational complexity and accuracy performance have been studied from both theoretical analysis and simulation perspectives.

Hierarchical Matching Maximum Likelihood Estimation for Digital-array Monopulse Tracking Radar

2025-06-09

PIER C

Vol. 156, 175-182, 2025

doi:10.2528/PIERC25031006

download: 115

Innovative Optically Transparent Planar Antenna for WiMAX Communication Systems

Soukaina Sekkal, Moustapha El Bakkali, Jamal Abounasr, Zainab L'Gzouli, Naima Amar Touhami, Bousselham Samoudi, Adel Asselman and Othmane Bendaou

This paper presents a study of a novel optically transparent planar antenna operating at a resonant frequency of 8.5 GHz, specifically designed for WiMAX wireless communication systems. The antenna is fed by a 50 Ω microstrip line and exhibits a wide operational bandwidth. Measuring 30 × 30 mm² and achieving an optical transparency exceeding 70% of glass, the proposed antenna delivers outstanding performance while minimizing its visual impact. It is fabricated using an innovative rectangular meshed pure copper grid layer, deposited on a 0.7-mm-thick borosilicate flat glass substrate, optimizing both transparency and conductivity. Experimental evaluations of key performance parameters, including the reflection coefficient, radiation pattern, and gain, were conducted to assess the antenna's effectiveness at the target frequency of 8.5 GHz. The measured results confirm that the antenna exhibits excellent impedance matching at 8.5 GHz, achieving a peak realized gain of 5.2 dBi. These findings demonstrate the feasibility of transparent antennas that offer performance on par with non-transparent alternatives, while providing distinct aesthetic advantages. As a result, the proposed antenna presents a viable solution for applications requiring both functionality and visual integration, such as smart devices and architectural installations.

Innovative Optically Transparent Planar Antenna for WiMAX Communication Systems

2025-06-08

PIER C

Vol. 156, 169-174, 2025

doi:10.2528/PIERC25032503

download: 110

A Compact Hybrid Multi-Notched UWB BPF Using Defected Microstrip Structure (DMS) and Short-Circuited Stub

Raaed Thaaban Hammed and Hassan Saad Abdullah

In this letter, a compact passband filter with dual desirable attenuation narrow bands is developed for ultra wideband application. Indeed, a grounded stepped impedance resonator in defected microstrip structure (GSIR-DMS) is realized with a specified high pass cutoff frequency of (f GSIR ). Next, two cells of the designed GSIR-DMSs are cascaded to perform the proposed ultra wide passband filter. In addition, four λ_g/4 open-circuited stubs are inserted beside the GSIR-DMSs to create two transmission zeros and improve the filter rejection performance. In order to suppress interference with some expected network channels, two desirable λ_g/4 short-circuited microstrip stubs are implemented and coupled to the body of the UWB filter. Finally, the filter is constructed, simulated, and measured using a Rogers-ceramic RO4360 substrate with a permittivity of ε_r = 6.15 and a thickness of h = 1.016 mm. The filter responses from measurement and simulation are compared and discussed. The produced filter is very small covering circuit area of about (0.433λ_g × 0.244λ_g) excluding the feeding ports.

A Compact Hybrid Multi-notched UWB BPF Using Defected Microstrip Structure (DMS) and Short-circuited Stub

2025-06-07

PIER C

Vol. 156, 161-168, 2025

doi:10.2528/PIERC25040905

download: 124

Wideband Elliptical Patch Antenna Integrating a Circular Notch and Defected Ground Structure

Bharat D. Prajapati, Bhavesh Jaiswal and Pravin J. Dalvadi

A circular-slot embedded elliptical patch antenna with DGS ground is introduced for Wi-Fi, Bluetooth, Sub 6 GHz 5G, IRNSS, Wi-Max, and WLAN wireless network applications. The design consists of an elliptical radiating patch featuring a circular cutout positioned on the uppermost layer of the substrate, while the under layer incorporates a DGS structure with two symmetrical slots. The antenna is implemented on an FR4 substrate having a thickness of 1.6 mm and is excited using a microstrip line feed. The structural layout of the antenna corresponds to dimensions of 0.87λ × 0.81λ × 0.02λ. The developed antenna achieved a bandwidth of 86.74%, encompassing a BW extending from 1.73 to 4.38 GHz maintaining a reflection coefficient (S₁₁) lower than -10 dB, exhibiting 5.1 dB of peak gain. The radiation characteristics and surface current density distribution are examined at specific frequencies of 2.4 GHz, 2.78 GHz, 3.5 GHz, and 3.95 GHz. Additionally, the antenna's evolution and parameter effects were examined to better understand its performance characteristics.

Wideband Elliptical Patch Antenna Integrating a Circular Notch and Defected Ground Structure

2025-06-06

PIER C

Vol. 156, 147-159, 2025

doi:10.2528/PIERC25041302

download: 126

Simplified Duty Cycle Modulation Model Predictive Current Control of PMSM Without Cost Function

Dingdou Wen, Chaoyi Liu, Yanqin Zhang and Zhun Cheng

To reduce the prediction times and algorithm complexity of model predictive current control (MPCC) for permanent magnet synchronous motor (PMSM), a simplified duty cycle modulation model predictive current control without cost function (SDCM-MPCC) method is proposed. The proposed method uses two fixed voltage vectors to generate the three-phase duty cycles for any sector, which is directly applied to the inverter after correction, without using a cost function to traverse the combination and modulation of voltage vectors in different sectors with only 1 prediction. Deadbeat control on the d-q axis current is performed simultaneously to obtain the duty cycle for two fixed voltage vectors. The output voltage vectors can cover any amplitude and direction, effectively reducing current ripple and phase current harmonics. Simulations and experiments confirm the method's effectiveness and feasibility.

Simplified Duty Cycle Modulation Model Predictive Current Control of PMSM without Cost Function

2025-06-04

PIER C

Vol. 156, 141-146, 2025

doi:10.2528/PIERC25041602

download: 141

A Miniaturized Ultra-Wideband Ground Penetrating Radar Antenna Based on the Vivaldi Structure

Zhiyao Qin, Shunfeng Cao, Weiheng Li and Qiulin Huang

To meet the demands for a broader bandwidth, lower frequency, and enhanced gain, this article presents an innovative ultra-wideband miniaturized ground penetrating radar antenna based on traditional Vivaldi designs. The proposed antenna achieves an operational bandwidth spanning from 100 MHz to 2000 MHz (20:1 bandwidth ratio), with a peak gain reaching up to 9 dBi. Furthermore, it exhibits remarkable miniaturization. The antenna introduces novel dual-slotline configurations, side elliptical slots, metallic loading, and top-mounted lumped resistors, which collectively optimize its bandwidth and voltage standing wave ratio. These improvements make it particularly suitable for ground penetrating radar systems.

A Miniaturized Ultra-wideband Ground Penetrating Radar Antenna Based on the Vivaldi Structure

2025-06-03

PIER C

Vol. 156, 131-140, 2025

doi:10.2528/PIERC25012602

download: 134

A Fast Electromagnetic Coupling Model Analysis Method for Modular Multi-High Frequency Switching Circuits

Rui Zhang, Yanfeng Gao, Jixuan Wang and Han Meng

In this paper, a fast electromagnetic coupling model analysis method is proposed to solve the challenging problems such as complex switching state, difficult electromagnetic modeling and long parameter optimization process of multi-switch modular circuits with wide application prospects. In this method, a multi-loop circuit connected by multiple series-parallel high-speed switching devices is used as the research object, and each single loop can be regarded as a modular switching circuit for spatial electromagnetic coupling analysis. Considering the six complex states of the switching device, the speed and time change law dI/dt of the multi-loop electromagnetic coupling and the multi-switch switching state are simulated by using the circuit current change rate, and the circuit voltage fluctuation value dV is simplified to calculate the fast electromagnetic coupling model of the modular high-frequency switching circuit. By comparing with the electromagnetic coupling relationship calculated by the traditional Maxwell equations, the validity and rapidity of the fast electromagnetic coupling model are verified for the spatial electromagnetic field calculation of multi-switch modular circuit topology. By using the model analysis method, the optimal switching path with minimum power loss and maximum output efficiency can be predicted.

A Fast Electromagnetic Coupling Model Analysis Method for Modular Multi-high Frequency Switching Circuits

2025-06-03

PIER C

Vol. 156, 121-130, 2025

doi:10.2528/PIERC25040201

download: 141

Bernoulli Filter for Low-Grazing Angle Track-Before-Detect with Monopulse Radar

Fei Cai

Target tracking in a low-grazing angle scenario is a challenging problem in radar because of the multipath phenomenon. When the signal-to-noise ratio (SNR) is low, this problem becomes more difficult. This paper applies a Bernoulli filter for low-grazing angle track-before-detect with monopulse radar. A measurement model is established using the Swerling II radar target model. The filter is implemented approximately as a particle filter. Simulation results show that the proposed filter is effective at detection and tracking in a multipath scenario and under low SNR.

Bernoulli Filter for Low-grazing Angle Track-before-detect with Monopulse Radar

2025-06-02

PIER C

Vol. 156, 113-120, 2025

doi:10.2528/PIERC25041608

download: 164

Subwavelength Resonator for the Design of a Waveguide-Fed Metasurface Antenna

Ivan Eduardo Diaz Pardo, Carlos Arturo Suarez Fajardo, Juan Domingo Baena Doello and Hector Guarnizo

Antennas are one of the most important elements in modern communication systems. Recently, significant progress has been made in developing metasurface antennas as an alternative for beam steering, commonly used in radar and communication applications. Metasurface antennas consist of an array of metamaterial elements, uniformly distributed and with subwavelength dimensions, which can be excited by a progressive wave. This work focuses on the application of the Incremental Difference Method for estimating the magnetic polarizability of metamaterial arrays embedded in a waveguide-fed linear configuration. The method is validated through full-wave simulations and further assessed using a weighting function introduced in prior studies. The design is demonstrated using a WR340 waveguide-based metasurface antenna model.

Subwavelength Resonator for the Design of a Waveguide-fed Metasurface Antenna

2025-05-31

PIER C

Vol. 156, 101-112, 2025

doi:10.2528/PIERC25031005

download: 158

A Novel Coaxial Magnetic Gearbox with a Single Input Shaft and Dual Identical Output Shafts

Ali Hosseini-Fard, Seyed Hamid Shahalami and Esmaeil Fallah Choolabi

This paper presents an innovative magnetic gearbox with a three-rotor coaxial structure capable of providing a single input and dual identical outputs. The low-speed rotor magnets of this gear are flux-focusing, while the high-speed rotors magnets are surface-mounted. The performance of this gear was analyzed using finite element analysis. Initially, the gear with initial dimensions was modeled and simulated in ANSYS/Maxwell software, and the results of static and time-dependent analyses were examined. Subsequently, a parametric study of the gear was conducted to investigate the impact of geometric dimension variations on rotor torques and volumetric torque density. The optimal dimensions for achieving the highest volumetric torque density were then selected. The gear was then simulated with the final dimensions, demonstrating that this multi-rotor design is capable of achieving high torque densities (291.61 Nm/L in this gear). Following this, the proposed magnetic gear was compared with another gear of similar dimensions but with three flux-focusing rotors. Additionally, the slicing method was employed for the high-speed rotors magnets to reduce cogging torque, and it was shown that this method successfully reduces the cogging torque of the gear's rotors.

A Novel Coaxial Magnetic Gearbox with a Single Input Shaft and Dual Identical Output Shafts

2025-05-31

PIER C

Vol. 156, 93-100, 2025

doi:10.2528/PIERC25021901

download: 192

Analysis of Absorbed Power Density and Power Loss Density in Human Skin Model from 5G mmWave Exposure

Ibrahim Tahir, Aduwati Sali, Sangin Qahtan Wali, Alyani Ismail, Darko Suka and Muhammad Zamir Mohyedin

This study investigates the Absorbed Power Density (APD) and Power Loss Density (PLD) of 5G downlink signals in Frequency Range 2 (FR2), in particular at millimetre-wave (mmWave) frequencies, in an outdoor scenario in Malaysia. The electric field (E-field) was measured, and the data were collected from a base station (BS) located in Cyberjaya, Malaysia, operating at 29.5 GHz, as documented in the previous work of authors. The APD and PLD were simulated using Computer Simulation Technology (CST) software. The radiation source was modelled using a patch antenna, while a four-layer human skin model represented the sample. This work simulated three different types of applications: voice calls, video calls, and video streaming. It was found that the maximum APD is 0.0364 W/m² for voice calls, 0.0498 W/m² for video calls, and 0.0584 W/m² for video streaming. All the investigated applications produced APD within the safe limit of 20 W/m² set by the International Commission on Non-Ionizing Radiation Protection (ICNIRP). PLD was analysed to investigate the depth of radiation penetration into the skin. The results show that the PLD decreased from 18.1 W/m³ to 3.1 W/m³, 24.8 W/m³ to 4.1 W/m³, and 29.1 W/m³ to 4.8 W/m³ from the skin surface to the skin at 1 mm depth for voice call, video call and video streaming, respectively. It shows a significant drop in PLD due to the short wavelength of the mmWave frequencies.

Analysis of Absorbed Power Density and Power Loss Density in Human Skin Model from 5G mmWave Exposure

2025-05-27

PIER C

Vol. 156, 79-91, 2025

doi:10.2528/PIERC25031703

download: 184

Sensorless Control Strategy for PMSM Based on Model Reference Adaptive Control Combined with Fast Super-Twisting Algorithm

Feng Yu, Xiping Liu, Zhangqi Liu, Qiang Ge and Yuxin Liu

To address the issues of large speed fluctuations and slow current convergence in traditional model reference adaptive system (MRAS) algorithms, this paper proposes an improved model reference adaptive algorithm based on the fast super-twisting algorithm (FASTA). First, a feedforward compensation term is introduced into the traditional MRAS framework. Additionally, an adaptive feedback gain coefficient is designed, which can be dynamically adjusted in real-time to track speed variations and adapt to different external operating conditions, thereby effectively reducing speed fluctuation amplitude. Furthermore, a fast super-twisting algorithm with a dynamic adjustment exponential gain term is designed and integrated with the model reference adaptive system, replacing the traditional PI controller used in MRAS, significantly improving convergence speed of the system. Finally, experimental results verify the effectiveness and feasibility of the proposed strategy.

Sensorless Control Strategy for PMSM Based on Model Reference Adaptive Control Combined with Fast Super-twisting Algorithm

2025-05-26

PIER C

Vol. 156, 67-77, 2025

doi:10.2528/PIERC25031301

download: 177

Half-Mode Substrate Integrated Waveguide Cavity Slot Antenna with Half-Octagonal Ring Slot at S-Band Frequency

Andri Setyawan, Dian Widi Astuti, Mudrik Alaydrus, Yuyu Wahyu and Norbahiah Misran

This paper presents a design of a half-mode substrate integrated waveguide (HMSIW) antenna for S-band frequencies using half-octagonal ring slots to achieve significant bandwidth enhancement. The proposed structure integrates a half-octagonal ring slot within the HMSIW cavity to enhance impedance bandwidth by exciting dual resonant modes - TE₁₀₁ and TE₁₀₂. The antenna achieves a measured fractional bandwidth (FBW) of 5.6%, corresponding to an operational range of 3.15 to 3.33 GHz, and a simulated FBW of 5.2% from 3.17 to 3.40 GHz. Compared to conventional cavity-backed SIW antennas, this configuration offers a 50% size reduction while maintaining stable gain between 3.1 dBi and 5.6 dBi and exhibiting a directional linear radiation pattern in the horizontal plane. The integration of dual-resonance excitation within a single compact HMSIW cavity represents a significant advancement in bandwidth enhancement for planar antennas. This design offers a feasible and efficient solution for modern wireless applications requiring miniaturized and compact size in S-band frequencies.

Half-mode Substrate Integrated Waveguide Cavity Slot Antenna with Half-octagonal Ring Slot at S-band Frequency

2025-05-26

PIER C

Vol. 156, 59-65, 2025

doi:10.2528/PIERC25040702

download: 203

A Defect Scanning Sensor Based on a Reconfigurable Spiral-Shaped DGS

Zhi Chen

Microwave non-destructive testing (NDT), with its high sensitivity and non-contact advantages, is widely applied in the defect detection of non-metallic composite materials. However, conventional microwave NDT requires frequent mechanical repositioning to modify the detection area, significantly reducing the detection efficiency. To address this limitation,this paper proposes a reconfigurable spiral defect-ground structure (DGS)-based defect scanning sensor. The sensor incorporates multiple spiral DGS units and connects them in parallel with PIN diodes. By electronically switching the state of the diodes, the location of the electric field concentration is altered, thereby controlling the sensitive detection area without mechanical movement. Compared to the existing complementary split-ring resonator (CSRR) sensors, which have a unit detection area of 3 mm × 3 mm, the proposed sensor achieves an enhanced unit detection area of 15.5 mm × 11 mm. Additionally, relying on the unique structural characteristics of the spiral shape, the field distribution is more uniform, effectively reducing blind spots in detection. Experimental results demonstrate that the proposed reconfigurable spiral DGS-based defect scanning sensor can effectively detect defects in non-metallic composite materials.

A Defect Scanning Sensor Based on a Reconfigurable Spiral-shaped DGS

2025-05-25

PIER C

Vol. 156, 49-57, 2025

doi:10.2528/PIERC25030802

download: 161

Numerical Analysis of Electric Field Distribution in Segmented Lightning Diverter Strip

Rudra Narayan Barik and Hrishikesh Sonalikar

This paper investigates the distribution of the electric field around a circular segmented diverter strip designed for lightning protection. This is accomplished by performing parametric analysis on various geometry parameters of the circular-shaped segmented lightning diverter strip and numerically calculating the electric field and crossover voltage using full-wave simulation. The results demonstrate that as the spacing between the segments decreases, there is a significant increase in electric field strength, reaching a maximum value of 438.22 MV m^-1, while the crossover voltage decreases from 2990.59 V to 744.35 V. An increase in the diameter of the segments is associated with a stronger electric field, with the maximum field strength reaching 300.36 MV m^-1, while in this case, the crossover voltage decreases from 1493.36 V to 1462.36 V. In contrast, the electric field increases as the segment height decreases, with no significant change in the crossover voltage. The study also analyzes the impact of curvature and different substrate materials on the electric field distribution and crossover voltage. Additionally, simulation results on the electric field distribution and capacitance calculations for various segments of the diverter are utilized to predict the probable location of the lightning attachment.

Numerical Analysis of Electric Field Distribution in Segmented Lightning Diverter Strip

2025-05-24

PIER C

Vol. 156, 39-47, 2025

doi:10.2528/PIERC25030203

download: 210

A Compact 4 × 4 UWB MIMO Antenna with 5G and WLAN Band Rejected Operation

Lei He, Youming Miao and Gui Liu

An ultra-compact four-port ultra-wideband (UWB) antenna with dual notches, which can reject the 5G (3.3-4.2 GHz, 4.8-5 GHz) and the WLAN (5.15-5.825 GHz), is designed. Four orthogonal antenna elements and some defected ground planes constitute the proposed antenna. A double T-shaped filter structure is employed on the radiation unit, which can generate a notch frequency band of 3.3-4.2 GHz. The complementary split resonant ring (CSRR) structure is created on the ground plane. It is intended to suppress the frequency band from 4.8 GHz to 6 GHz by adjusting the size and position of the slots. Finally, the measured -10 dB impedance bands are 4.2-4.8 GHz and 6.0-11.0 GHz. The isolation performance exceeds 17 dB across the operational bandwidth. Additionally, the ECC remains consistently below 0.06 (and below 0.01 within the 4.2-4.8 GHz and 6.0-11.0 GHz range). Furthermore, within the operational band, the efficiency exceeds 85%. The proposed antenna is applicable in civil communication, military, and medical fields.

A Compact 4 × 4 UWB MIMO Antenna with 5G and WLAN Band Rejected Operation

2025-05-24

PIER C

Vol. 156, 31-38, 2025

doi:10.2528/PIERC25040404

download: 190

Distributed Uplink Power Control in User-Centric Cell-Free Massive MIMO with Grey Wolf Optimization

Nguyen Van Cuong, Bo Quoc Bao, Hoang Manh Kha and Tong Van Luyen

User-centric cell-free massive multiple-input multiple-output (UC-CFmMIMO) networks require efficient uplink power control to ensure both fairness and spectral efficiency (SE). However, existing schemes such as fractional power control (FPC) struggle to balance minimum SE and total SE, especially in large-scale deployments. To address this, we propose a grey wolf optimization (GWO)-based power control scheme, optimizing power allocation to maximize minimum SE while also improving total SE. Simulation results in a 1 km × 1 km UC-CFmMIMO network with 50 access points (APs) and 10 user equipments (UEs) show that our method outperforms FPC and fixed-point algorithm in both fairness and SE. Specifically, it achieves a minimum SE of 1.37 bit/s/Hz (vs. FPC: 0.13 bit/s/Hz) and a total SE of 39.17 bit/s/Hz at 100 APs (vs. FPC: 36.77 bit/s/Hz). The proposed approach scales effectively with AP and UE densities, making it a practical solution for future UC-CFmMIMO deployments.

Distributed Uplink Power Control in User-centric Cell-free Massive MIMO with Grey Wolf Optimization

2025-05-23

PIER C

Vol. 156, 23-29, 2025

doi:10.2528/PIERC25031902

download: 182

Optimization of MIMO Radar Sparse Array Based on Improved Adaptive Genetic Algorithm

Shun He, Junting Wang and Zhiwei Yang

In order to solve the problem of transceiver array optimization for multiple input multiple output (MIMO) radar under the conditions of fixed number of array elements and aperture length, an improved adaptive genetic algorithm is proposed in this paper. The algorithm takes the joint transceiver beam of MIMO radar as the optimization target, and optimizes the positions of the array elements of the transmitting and receiving arrays by introducing new crossover and mutation operators and elite protection strategie, which effectively reduces the number of array elements, while maintaining the main flap gain and reducing the side flap level. The effectiveness and superior optimization performance of the proposed algorithm is verified through experiments, which has certain theoretical reference significance in MIMO radar design.

Optimization of MIMO Radar Sparse Array Based on Improved Adaptive Genetic Algorithm

2025-05-22

PIER C

Vol. 156, 13-22, 2025

doi:10.2528/PIERC25041001

download: 197

High-Gain Dual-Band Metasurface MIMO Antenna for Enhanced 5G and Satellite Applications

Hanbo Feng, Zhonggen Wang, Wenyan Nie and Ming Yang

In this paper, a novel single-layer dual-band metasurface MIMO antenna suitable for high-density 5G base stations, satellite terminals and IoT devices is proposed. The antenna utilizes Characteristic Mode Analysis (CMA) to optimize the patch dimensions, achieving independent design for the low and high-frequency bands. It also suppresses surface waves through a ground triple-slot structure. Additionally, the antenna abandons the traditional coplanar waveguide (CPW) and innovatively adopts an H-shaped slot feeding structure. This groundbreaking design successfully eliminates the need for complex matching networks and multi-layer stacking structures. Simulation and measurement results show that the MIMO antenna achieves an isolation below -22 dB and envelope correlation coefficient (ECC) less than 0.0025 in two operating frequency bands (4.13-5.94 GHz with a relative bandwidth of 36%; 7.6-8.4 GHz with a relative bandwidth of 10%), with a peak gain of 10.75 dB. Additionally, the antenna exhibits a diversity gain (DG) greater than 9.9 dB, with aperture efficiencies of 72% (low-frequency) and 36.8% (high-frequency). Compared with existing designs, the MIMO antenna proposed in this paper shows significant improvements in isolation, bandwidth flexibility, and structural simplicity.

High-gain Dual-band Metasurface MIMO Antenna for Enhanced 5G and Satellite Applications

2025-05-20

PIER C

Vol. 156, 1-12, 2025

doi:10.2528/PIERC25031903

download: 155

Leveraging Time-Domain Signals for Multi-Tag Classification in Chipless RFID Systems Using Classifier Chains

Athul Thomas, Midhun Muraleedharan Sylaja and James Kurian

Chipless Radio Frequency Identification (CRFID) systems have emerged as a cost-effective and scalable solution for various identification and tracking applications. However, multi-tag classification remains a significant challenge due to overlapping signal characteristics and the absence of on-chip processing, which hinders accurate tag differentiation, increases interference, reduces classification accuracy, and necessitates advanced signal processing techniques for reliable identification. This study presents a novel machine learning-based approach utilizing a Classifier Chain-AdaBoost (CC-AdaBoost) model to improve multi-tag classification accuracy. Unlike conventional methods that rely on calibration or background subtraction, the proposed approach directly processes raw time-domain signals, enabling efficient and accurate classification of multiple tags simultaneously. The model is evaluated on simulated CRFID data, achieving an overall accuracy of 85%. Performance metrics such as accuracy, Hamming loss, Jaccard score, and F1-score are analysed to assess both overall classification performance and label-wise evaluation. Results indicate that CC-AdaBoost effectively differentiates tag classes, particularly excelling in high-confidence classifications while maintaining a balance between precision and recall. This study demonstrates the feasibility of CC-AdaBoost for real-world CRFID applications and suggests potential improvements for optimizing multi-tag recognition in complex environments.