PIER C | PIER Journals

2026-03-26

PIER C

Vol. 167, 254-264, 2026

doi:10.2528/PIERC26012303

download: 24

An Anti-Interrupted Sampling Repeater Jamming Method Based on SSFA-MCPC Waveform Design Combined with Segmented Mismatched Filtering

Ji Li, Hai Liu and Wei Wang

Interrupted Sampling Repeater Jamming (ISRJ) is a typical intra-pulse coherent deceptive interference that poses a serious threat to radar target detection and tracking performance. This paper proposes an anti-jamming method that integrates a dual-modulated SSFA-MCPC waveform with a segmented mismatched filtering scheme. Based on the multi-carrier phase-coded (MCPC) signal, we apply random sub-pulse frequency agility and chaotic time-domain phase coding to design the SSFA-MCPC waveform. This design enhances the distinction between the radar signal and interference and improves the mutual masking among sub-pulses. To counter ISRJ, a segmented mismatched filtering algorithm is proposed. Specifically, a bank of sub-pulse matched filters is constructed to perform segmented pulse compression on the received echoes, and the Otsu algorithm is employed to adaptively identify jammed sub-pulses. Finally, a reconstructed mismatched filter is applied to suppress interference. Simulation results demonstrate that the proposed method does not rely on prior knowledge of the jamming parameters and can effectively suppress ISRJ under three different forwarding modes. Compared with existing methods, the proposed approach has lower computational complexity and shows strong potential for practical engineering applications.

An Anti-Interrupted Sampling Repeater Jamming Method Based on SSFA-MCPC Waveform Design Combined with Segmented Mismatched Filtering

2026-03-26

PIER C

Vol. 167, 246-253, 2026

doi:10.2528/PIERC26011502

download: 33

Multi-Band Double-Sided Printed Dipole Antenna for Sub-6 GHz Bands of 5G Network

Tarit Sarkar, Rajendra Prosad Ghosh and Radha Raman Pal

The Fifth-Generation (5G) radio network consists of two spectrums: one millimeter-wave band (24-40 GHz) and the other below 6 GHz, which is also popularised as sub-6 GHz band. The spectrum of a sub-6 GHz radio network may be divided into three bands, i.e., low-band (below 1 GHz), mid-band (1-2.6 GHz), and upper mid-band (3.5-6 GHz). The low-band provides a good network coverage, and the mid-band offers a balance between coverage and capacity, whereas the high-band provides the super data capacity and speed. The service providers use combinations of different bands from these three segments of sub-6 GHz spectrum to deliver smooth 5G services. In this work, a novel design of a multiband Double Sided Printed Dipole Antenna (DSPDA) system is proposed that operates at least at one band in each segment of the sub-6 GHz spectrum. The design consists of two DSPDAs, a symmetric one and an asymmetric one, fed in series by a common line in a tree-like structure. The multiple bands are obtained by having fundamental resonant frequencies and their harmonics. All bands are predictable by the design equations. It also provides the flexibility of choosing any band of operation. The antenna is experimentally verified.

Multi-band Double-sided Printed Dipole Antenna for Sub-6 GHz Bands of 5G Network

2026-03-25

PIER C

Vol. 167, 242-243, 2026

doi:10.2528/PIERC26020202

download: 30

Comment on “Transfer Matrix Method for General Bianisotropic Layers”: Correction of Explicit Formulations

Joosun Yun

This comment addresses errors in the explicit expressions of the Ω matrix presented by Blankenship et al. (2025) [1]. We show that sign inconsistencies in the original formulation can lead to non-physical results, including the violation of energy conservation in passive lossless environments. We provide corrected formulas for the affected matrix entries and numerically verify that the corrected formulation restores physical consistency, with the total energy conserved to the displayed precision in the lossless benchmark.

2026-03-24

PIER C

Vol. 167, 230-241, 2026

doi:10.2528/PIERC25110402

download: 38

Complex Vector Control Based Three-Level Inverter with Centre-Tap Inductor Without Direct Current

Yao He, Xiangyi Sun, Xinxin Zheng, Xintian Liu, Yanan Zhou and Lin He

A direct-through three-level inverter topology based on center-tap inductance and its complex vector control strategy are proposed. This topology structurally avoids the direct short-circuit problem of the DC side capacitor, eliminates the need to set a dead zone in the drive signal, and eliminates the low-order harmonics introduced by the dead zone. For this direct-through inverter, the corresponding complex vector control strategy is studied. By establishing a full-frequency domain model of the system, the fundamental cause of the coupling of DQ-axis currents in the synchronous rotating coordinate system was analyzed. To address the issue of poor dynamic response caused by coupling, a complex coefficient controller was designed. By introducing imaginary parts into the controller parameters, the additional poles introduced by coordinate transformation were offset, achieving decoupling control of active and reactive currents.Simulation and experimental results show that, compared with the traditional real-coefficient PI controller, the proposed complex vector control strategy can effectively reduce the coupling degree of DQ-axis current, improve the dynamic performance of the system, and verify the correctness and effectiveness of the proposed topology and control method. This inverter topology features both high reliability and excellent output performance without increasing the number of power switch devices.

Complex Vector Control Based Three-Level Inverter with Centre-Tap Inductor without Direct Current

2026-03-24

PIER C

Vol. 167, 223-229, 2026

doi:10.2528/PIERC26012009

download: 32

Design of Dual-Band Class-F-1 Power Amplifier Based on the Integration of Harmonic Control and Fundamental Matching

Wen Huang, Junhao Zhao, Jiang Liu and Honggang Hao

This paper proposes a dual-band class-F^-1 high-efficiency power amplifier with an integrated structure for harmonic suppression and fundamental matching. The fundamental matching network employed a dual-frequency coupler with open branches. This structure is partially reused for third-harmonic control by leveraging two open branches and two branch lines. By adjusting the characteristic impedance of the quarter-wavelength transmission line, the third-harmonic impedance is adjusted to a short circuit at both fundamental frequencies at the drain of the power amplifier. The second-harmonic control network consists of a quarter-wavelength open stub and a drain bias line loaded with a double spiral defected ground structure (DGS), which controls the second-harmonic impedance to an open circuit state at the drain, satisfying the class F^-1 harmonic conditions. A dual-band high-efficiency class F^-1 power amplifier operating at 2.6 GHz/3.4 GHz is designed and fabricated. The measured results show drain efficiencies of 73.5% and 74.3% at 2.6 GHz/3.4 GHz, with output power exceeding 40 dBm and gain above 10 dB.

Design of Dual-Band Class-F<sup>-1</sup> Power Amplifier Based on the Integration of Harmonic Control and Fundamental Matching

2026-03-23

PIER C

Vol. 167, 218-222, 2026

doi:10.2528/PIERC26012002

download: 49

Descriptor-Based Screening of Nanocatalysts for CO2 Conversion: A Computational Data-Driven Study

Osama Aziz and Muhibur Rahman

CO₂ conversion is a central strategy for closing the carbon cycle and enabling sustain- able energy and chemical production through catalytic pathways. In this work, a descriptor-based, data-driven computational framework is employed to screen nanocatalysts for CO₂ conversion using density functional theory data reported in the literature. Key adsorption and electronic descriptors, including CO₂∗ and CO∗ binding energies, are analyzed to establish structure-activity relationships governing catalytic performance. Correlation and volcano-type analyses reveal that moderate adsorption strengths are essential for balancing CO₂ activation and product desorption, while excessively strong binding leads to surface poisoning and reduced activity. The results demonstrate that descriptor-guided screening can effectively rank catalyst candidates and provide rational design rules, without relying on new computationally intensive simulations. This framework offers a computationally efficient pathway for accelerating nanocatalyst discovery for CO₂ conversion.

Descriptor-Based Screening of Nanocatalysts for CO2 Conversion: A Computational Data-Driven Study

2026-03-22

PIER C

Vol. 167, 205-217, 2026

doi:10.2528/PIERC25110201

download: 43

Complex Vector-Based PI Parameter Optimization for PMSM Systems with LCL Filter

Xintian Liu, Yunyue Sun, Xinxin Zheng, Yao He, Yanan Zhou and Lin He

To address the challenge of achieving both steady-state accuracy and fast dynamic response in permanent magnet synchronous motor (PMSM) systems equipped with LCL filters, this paper proposes a complex vector PI controller optimization method. The proposed approach extends the conventional real-axis PI control to the complex domain, enabling unified modeling of current decoupling and harmonic suppression. Based on this formulation, the response surface methodology (RSM) is employed to optimize the controller parameters. A quadratic response model is established through design of experiments (DOE), with steady-state error, dynamic overshoot, and harmonic suppression indices defined as optimization objectives to obtain the optimal parameter set. The core contribution of this work is the integration of a frequency-domain complex-vector model with a systematic multi-objective optimization framework using Response Surface Methodology (RSM) and Generalized Reduced Gradient (GRG) algorithms. This approach addresses the inherent coupling and resonance issues in LCL-filtered PMSM systems. Quantitative experimental results demonstrate that, compared with conventional tuning methods, the proposed strategy reduces the current settling time by 47.6% and suppresses torque overshoot by 92.8%, thereby achieving a superior balance between fast transient response and steady-state accuracy.

Complex Vector-Based PI Parameter Optimization for PMSM Systems with LCL Filter

2026-03-21

PIER C

Vol. 167, 196-204, 2026

doi:10.2528/PIERC26012803

download: 59

Compact Tri-Band Semi-Elliptical Monopole Antenna with Improved Filtering Characteristics for 5G, V2X, WLAN, and Wi-Fi 6E Applications

Sheetal Mete, Jagadish Jadhav, Brijesh Iyer, Anjali Rochkari and Sanjay Laxmikant Nalbalwar

In this paper, an elliptical monopole antenna is modified and loaded with stubs and slots to improve filtering characteristics over tri-band operation. As the surface current is concentrated at the periphery of the monopole and decreases away from the feed, therefore, a slotted elliptical monopole is designed and sliced from the top. A rectangular strip is added at the top and center to create two symmetrical loops. A slot in each loop at a different position causes the antenna to operate over dual/tri-bands. A rectangular stub is added in the feed-line to improve the band-stop/filtering characteristics. The parameters of the structure are optimized to obtain S₁₁ ≤ -10 dB over 3.22-3.64 GHz, 5.53-6.03 GHz and 6.71-7.14 GHz for 5G, V2X, WLAN and Wi-Fi 6E applications. The three bands can be tuned independently. The compact 0.171λ₀ × 0.184λ₀ antenna, fabricated on 1.6 mm FR4 substrate (λ₀ is the free-space wavelength at 3.22 GHz), offers maximum S₁₁ of -0.9 dB and -4.9 dB, respectively, between the lower and middle bands and middle and upper bands. Minimum S₁₁ of -55 dB, -25 dB and -27 dB are obtained over the lower, middle, and upper bands respectively. The measured results validate the simulation ones.

Compact Tri-Band Semi-Elliptical Monopole Antenna with Improved Filtering Characteristics for 5G, V2X, WLAN, and Wi-Fi 6E Applications

2026-03-21

PIER C

Vol. 167, 186-195, 2026

doi:10.2528/PIERC26011303

download: 49

Ultra-Miniaturized Meander Line Implantable Antenna for Leadless Pacemaker System at 1.4 GHz WMTS Band

Archana Mohan and Niraj Kumar

This paper presents the ultraminiaturized implantable antenna based on a meander-line structure, specifically tailored for leadless pacemaker applications operating within the Wireless Medical Telemetry Services (WMTS) band of 1395-1400 MHz. The projected antenna has an ultraminiaturized volume of 3.25 mm³, surface area of 5 mm × 5 mm, and thickness of 0.13 mm. The substrate and superstrate were made of Rogers RO 3010 (ε_r = 10.2, tan⁡δ = 0.0035). Using a meandered line as the radiating element and including a shorting pin helps achieve impedance matching, reduces the overall antenna size, and improves the bandwidth performance. The proposed implantable antenna is validated using both homogeneous and heterogeneous heart phantoms. Experimental measurements were performed by embedding the antenna in minced pork tissue.; achieving a peak gain of -21.3 dBi and an impedance bandwidth of 360 MHz. Additionally, to ensure patient safety, Specific Absorption Rate (SAR) assessments were performed and the values are 202.52 W/kg (1-g) and 43.4 W/kg (10-g). With a 10 dB margin at 1.4 GHz, the results show that the antenna can successfully enable wireless communication at distances greater than 10 m.

Ultra-Miniaturized Meander Line Implantable Antenna for Leadless Pacemaker System at 1.4 GHz WMTS Band

2026-03-19

PIER C

Vol. 167, 175-185, 2026

doi:10.2528/PIERC26011201

download: 62

Slot-Loading-Enabled Compact UWB Planar Antenna with Circuit-Backed Modeling and Design for Defense Communication

Sonal Dubal, Hetal Pathak and Vikas Gupta

This paper proposes a slot-loading-enabled compact ultra-wideband (UWB) planar antenna supported by circuit-backed modelling that targets defense communication systems. The antenna was realized on a compact footprint of 10 × 12 × 1.5 mm³, corresponding to an electrical size of approximately 0.29λ × 0.35λ × 0.043λ at the center frequency. Through the combined use of a modified circular radiator, strategically introduced slots, a stepped feed network, and a defected ground plane, the antenna achieves a continuous impedance bandwidth from 2.4 to 15 GHz. This corresponds to an absolute bandwidth of 12.6 GHz, a fractional bandwidth of nearly 145%, and a center frequency of 8.7 GHz, confirming the UWB operation. The antenna attains a maximum gain of 6.37 dB with a radiation efficiency reaching 89%. Stable radiation characteristics were observed, with dominant co-polarized fields and well-suppressed cross-polarization in both the principal planes. An electrical equivalent circuit provides physical insight into the multi-resonant behavior and enables efficient circuit-level validation. The measured results were in close agreement with the simulations, demonstrating the suitability of the antenna for compact UWB defense communication applications.

Slot-Loading-Enabled Compact UWB Planar Antenna with Circuit-Backed Modeling and Design for Defense Communication

2026-03-19

PIER C

Vol. 167, 165-174, 2026

doi:10.2528/PIERC25112501

download: 84

Double Slabs of Magnetic Meta-Material for Improving the Efficiency of Wireless Power Transfer Systems

Noor Fadhel Habib, Mohammad Sajjad Bayati and Nasr Alkhafaji

This paper focuses on enhancing the efficiency of wireless power transfer (WPT) using metamaterials (MTMs) only in the transmitter section, without modifying the receiver section. Power transfer efficiency (PTE) is the ratio of the actual power to the load resistance R_load that is transmitted to the load to the maximum available power at the source, V_s. Enhancing the PTE of a WPT system is essential, given the wide range of WPT applications. Magnetic MTMs can significantly increase the PTE. This research proposes a structure for the transmitter coil (Tx) and the receiver coil (Rx), incorporating the MTM slab, in a WPT system to enhance efficiency. The MTM was fabricated on a thin FR-4 substrate and positioned in front of and behind the Tx coil. Full-wave simulations show a clear improvement in coupling after adding the MTM plate. The transmission coefficient S₂₁ is increased by 0.4 when the MTM is placed in front of the Tx coil. When the two plates of the MTM were inserted, the S₂₁ improved by 0.2 compared to a single slab due to dielectric losses. In all cases, the magnetic field became more distributed and focused on the receiver side after the addition of the MTMs. The power transfer efficiency reaches 53.3% with double-layer MTMs at 12 MHz and a distance of 35 mm. Finally, the results of the measurements and simulations showed acceptable agreement, indicating that the proposed method is effective in overcoming reduced efficiency issues. The proposed design is suitable for various electronic applications, such as multiple-device charging pads.

Double Slabs of Magnetic Meta-material for Improving the Efficiency of Wireless Power Transfer Systems

2026-03-18

PIER C

Vol. 167, 155-164, 2026

doi:10.2528/PIERC25122408

download: 56

A High-Sensitivity Microwave Patch Sensor for Olive Oil Adulteration Detection

Cheng Chen and Shen-Yun Wang

In this paper, a high-sensitive microwave patch sensor for detecting adulteration in olive oil is proposed. First, a broadband electromagnetic property of olive oil adulterated with corn oil is characterized by using a Cole-Cole function. Next, a microwave patch sensor is designed with a circular patch integrated with a meandered slot and a complementary split ring resonator (CSRR) in the ground plane. A prototype of the microwave patch sensor is fabricated to detect the adulterant in olive oil. Results indicate that the proposed microwave patch sensor can detect adulteration ratio of corn oil in the parent olive oil ranging from 0 to 100%. The sensitivity, resonance frequency shift, and quality factors are 6.16%, 41 MHz, and 173, respectively. The proposed microwave patch sensor maintains a simple structure and electrically small size (ka = 0.83), high sensitivity, low cost, and ability to fast detect adulterant for olive oil.

A High-Sensitivity Microwave Patch Sensor for Olive Oil Adulteration Detection

2026-03-18

PIER C

Vol. 167, 149-154, 2026

doi:10.2528/PIERC25120501

download: 76

Millimeter Wave Wideband Patch Antenna with DGS Slots and Truncated Corners for 5G Applications

Ruchika Singh and Mukesh Arora

This paper presents the design, simulation, fabrication and experimental validation of a compact millimeter-wave microstrip patch antenna intended for fifth-generation (5G) wireless applications. The proposed antenna employs a coplanar waveguide (CPW) feed, a defected ground structure (DGS), and truncated patch corners to enhance impedance bandwidth and radiation characteristics while maintaining a compact footprint. The antenna is designed on a Rogers RT/Duroid 5880 substrate (ε_r = 2.2, tanδ = 0.0009, thickness = 0.502 mm) and operates in the Ka-band with a center frequency of 30 GHz. Measured results demonstrate an impedance bandwidth from 29 to 34 GHz and a peak realized gain of 7 dBi, showing good agreement with simulated predictions. These results indicate that the proposed antenna is a suitable candidate for compact 5G millimeter-wave communication systems.

Millimeter Wave Wideband Patch Antenna with DGS Slots and Truncated Corners for 5G Applications

2026-03-17

PIER C

Vol. 167, 141-148, 2026

doi:10.2528/PIERC26010101

download: 57

A New Hybrid Approach Based on ANN and z-Transformation for RIS Unit Cells Characterization

Marwah Abdulrazzaq Naser, Jit Singh Mandeep, Taha Ahmed Elwi and Mohammad Tariqul Islam

Integrating Reconfigurable Intelligent Surfaces (RIS) with wideband systems, such as millimeter-wave (mm-wave) and terahertz (THz) systems, has shown great potential for improving communication system performance. However, accurate circuit-level modeling for RIS unit cell remains to date a significant challenge. This is because the unit cell in wideband systems faces a strongly coupled electromagnetic behavior that cannot be accurately captured using conventional circuit models. To address this challenge, this study introduces a novel hybrid modeling framework that combines Artificial Neural Networks (ANN) with discrete transfer functions H(z) for accurately modeling the unit cell in wideband systems. Specifically, the proposed framework allows a direct prediction of the H(z) coefficients from the S₁₂ data obtained from a full-wave Computer Simulation Technology (CST) simulation. The proposed framework aims to bridge the electromagnetic theory and circuit theory, which are considered to be complex, by representing the unit cell behavior using computationally efficient H(z) modeling. The results show that the proposed framework can accurately capture the sharp resonant characteristics of the RIS unit cell. The proposed hybrid framework achieves a performance improvement of 6 dB in Root Mean Square Error (RMSE) in comparison with the basic fitting model over all the Ka-band frequencies (30-40 GHz).

A New Hybrid Approach Based on ANN and z-transformation for RIS Unit Cells Characterization

2026-03-17

PIER C

Vol. 167, 129-140, 2026

doi:10.2528/PIERC25122004

download: 159

Reconfigurable Metamaterial-Loaded Vivaldi Antennas for Biomedical Microwave Imaging: A Review

Ajeet Kumar, Nand Kishore and Ashok Kumar Shankhwar

Vivaldi antennas loaded with metamaterials are currently being utilized in the form of reconfigurable metamaterial-loaded Vivaldi antennas, representing a promising class of antennas in advanced biomedical imaging and sensing applications. The design is an enhancement of the naturally ultra-wideband and high-directivity Vivaldi structure with the miniaturization and field enhancement properties of metamaterial inclusions. Frequency, polarization, and radiation pattern are some of the key features of biomedical diagnostics that can be dynamically reconfigured using tuneable elements like P-I-N diode, varactors, and graphene-based switches. This paper will give a summary of recent findings related to the design, analysis, and uses of reconfigurable metamaterial-loaded Vivaldi antennas in the field of biomedical imaging, especially in the determination of tumours and tissue characterization in non-invasive systems. The discussion notes the development of metamaterial integration methods, reconfigurable mechanisms, choice of substrate materials and their influence on the measure of antenna performance like gain, bandwidth and Specific Absorption rate (SAR). Moreover, fabrication strategies, experimental validation of the use of tissue phantoms, and performance comparison with the traditional antennas are tackled. The future research outlooks have been given at the end of the paper, highlighting compact and low-SAR and optically-controlled antenna architectures of the next-generation biomedical imaging systems.

Reconfigurable Metamaterial-Loaded Vivaldi Antennas for Biomedical Microwave Imaging: A Review

2026-03-17

PIER C

Vol. 167, 117-128, 2026

doi:10.2528/PIERC25110308

download: 84

Wearable UWB Antenna on Jeans Substrate for High-Speed 5G and IoT Devices

Amalraj Taksala Devapriya and Savarimuthu Robinson

A flexible ultra-wideband antenna is presented using a denim (jeans) textile substrate for wearable 5G and Internet of Things (IoT) applications. The antenna employs a coplanar waveguide (CPW) feed with a rectangular defected ground structure (DGS) etched in the ground plane to improve impedance matching. Bandwidth enhancement is achieved by introducing a nested U-slot in the radiating patch. The proposed design operates over the 1.28-6 GHz frequency range, providing an impedance bandwidth of approximately 4.72 GHz. The measured realized gain varies from 2.1 to 5.3 dBi, while the simulated radiation efficiency remains above 80% across most of the operating band. Good agreement between simulated and measured results confirms stable radiation characteristics, demonstrating the suitability of the antenna for wearable ultra-wideband and sub-6 GHz communication systems.

Wearable UWB Antenna on Jeans Substrate for High-Speed 5G and IoT Devices

2026-03-16

PIER C

Vol. 167, 104-116, 2026

doi:10.2528/PIERC26011603

download: 80

Multiband Characteristic of a Microwave Triangular Patch Antenna with Harmonic Suppression Capability

Ammar Daniel Abd Azis, Shipun Anuar Hamzah, Khairun Nidzam Ramli, Bilal A. Khawaja, Saeed Alzahrani, Mohd Noh Dalimin and Muhammad Sani Yahya

In this paper, a multiband patch antenna with harmonic suppression capability is developed for LoRa and GPS applications. The antenna configuration consists of a triangular patch as the primary radiator and a microstrip feed line as the excitation source. A parasitic element and a U-shaped slot are incorporated to generate the second and third resonance bands, while two stubs suppress the unwanted harmonics and improve impedance matching. The antenna is implemented on an FR-4 substrate (ε_r = 4.4), consisting of a main radiator measuring 84.5 mm × 92.45 mm, a parasitic element of 56 mm × 6.2 mm, a U-slot of 35 mm × 1.8 mm, and two stubs measuring 7 mm × 3 mm and 15 mm × 3 mm, respectively. The dimension of the antenna width and length are both 140 mm with a 50-Ω feed line of width 3 mm and length 19.5 mm. The bottom of the antenna contains a full ground plane. An extensive parametric study is conducted to optimize the antenna. The simulation and measurement results confirm that the antenna meets the -10 dB return-loss criterion throughout its operating frequencies with a bandwidth of 19 MHz (426-445 MHz) for the 433-MHz band, 13 MHz (916-929 MHz) for the 923-MHz band, and 19 MHz (1.559-1.578 GHz) for the 1.57-GHz band. The unwanted harmonics at 1.68 GHz, 2.00 GHz, and 2.67 GHz are successfully attenuated. The simulated current distributions, radiation patterns, and gain values for each band validate the antenna's multiband operation and harmonic-suppression capability.

Multiband Characteristic of a Microwave Triangular Patch Antenna with Harmonic Suppression Capability

2026-03-15

PIER C

Vol. 167, 92-103, 2026

doi:10.2528/PIERC25122005

download: 75

12-Port SRR Loaded Flower-Shaped UWB MIMO Antenna System for 5G Smartphones

Diksha Thakur and Naveen Jaglan

This article presents a 12-element multiple-input multiple-output (MIMO) antenna system for fifth-generation mobile phones. To improve isolation, split-ring resonators are positioned adjacent to the radiating elements in the proposed design, which features a flower-shaped antenna radiator etched along the side frames of the device. The antenna system provides an isolation of over 15 dB between the elements with a wide operational band of 3.0-7.5 GHz. Simulations and experiments demonstrate that sublime presentations have an overall efficiency of 58%-78% across the operational band and an ECC of less than 0.05. Additionally, the impact of user's hand grip, plastic frame, and battery integration is analyzed. The robustness of the proposed design was confirmed by the alignment between the simulated and measured results.

12-Port SRR Loaded Flower-Shaped UWB MIMO Antenna System for 5G Smartphones

2026-03-14

PIER C

Vol. 167, 83-91, 2026

doi:10.2528/PIERC25111305

download: 71

Large-Scale Grounding System Modeling and Characteristics Analysis in Urban Underground Utility Tunnels

Shangmao Hu, Yasong Cao and Wen Cao

The coupling of extensive metallic components within utility tunnels significantly complicates the earth-entry and dispersion pathways of cable short-circuit fault currents.This study focuses on a conventional three-compartment utility tunnel to guarantee steady and dependable operation of transmission lines. An integrated grounding system model with a concrete shell, vertical grounding electrodes, and grounding busbar bonding was constructed under various soil-resistivity conditions. The effects of bonding distance, vertical grounding electrode arrangement, and resistivity of the concrete shell on the grounding resistance, ground potential rise, touch voltage, and step voltage were methodically investigated by parametric simulations using CDEGS software. The findings indicate that an appropriate grounding grid spacing can significantly improve the electrical properties of the grounding system, whereas excessive density diminishes these advantages owing to the reciprocal coupling. The incorporation and deepening of the vertical grounding electrodes significantly diminished the ground resistance and ground potential rise. As the resistivity of the concrete shell increased, both the equivalent electrical parameters and surface potential gradient increased markedly. Research has shown that the interaction between the grounding network in utility tunnels and the adjacent soil influences fault-current dispersion pathways. This study provides a reference for optimizing the design of grounding systems for utility tunnels.

Large-Scale Grounding System Modeling and Characteristics Analysis in Urban Underground Utility Tunnels

2026-03-13

PIER C

Vol. 167, 76-82, 2026

doi:10.2528/PIERC26020406

download: 82

Multi-Step Predictive Control of Permanent Magnet Synchronous Motor Based on Fuzzy PSO Full Parameter Identification

Dazuo Zhou and Xin Wang

A multi-step deadbeat predictive control method for permanent magnet synchronous motors based on fuzzy adaptive particle swarm optimization (PSO) parameter identification is proposed to address the problem of performance degradation under parameter mismatch conditions. First, this method dynamically adjusts the learning factors of the PSO algorithm through fuzzy control, improving the convergence speed and stability of parameter identification. Secondly, this method can accurately identify key parameters such as stator resistance, inductance, and permanent magnet flux without the need for additional injection of excitation signals injections, effectively solving the problem of the under rank model under rank in traditional identification methods. The experimental results demonstrate that this method significantly improves the dynamic response speed and steady-state control accuracy of the system under parameter mismatch conditions, effectively suppresses speed fluctuations and current surges, improves current ripple characteristics, and provides a high-performance solution for high-precision driving scenarios such as CNC machine tools.

Multi-Step Predictive Control of Permanent Magnet Synchronous Motor Based on Fuzzy PSO Full Parameter Identification

2026-03-13

PIER C

Vol. 167, 69-75, 2026

doi:10.2528/PIERC26010703

download: 48

Intelligent Harmonic Current Suppression Algorithm for Permanent Magnet Synchronous Motors in Industrial Servo Systems

Xing Zhang, Lin Wang, Lihui Guo, Guanghui Zhu, Shibo Jin and Yanyan Ye

A dual adaptive neural network-based harmonic compensation algorithm is proposed to improve the low-speed machining accuracy of permanent magnet synchronous motor (PMSM) drives. First, the mechanism of harmonic current generation and its influence on torque ripple and speed fluctuation in PMSMs is analyzed. Second, the structure of the dual adaptive neural network is designed: the first network is used to extract harmonic current components in real time, and the second network dynamically generates corresponding harmonic voltage compensation signals to suppress current distortion, with the advantages of fast dynamic response and high compensation accuracy. Finally, the proposed method is verified on an experimental platform. The experimental results show that the 6th harmonic amplitude is suppressed from 0.094 to 0.016, and the 12th harmonic amplitude is reduced from 0.025 to 0.004, which is significantly better than the traditional compensation method. The proposed algorithm effectively reduces torque ripple and speed fluctuations, thereby improving the control accuracy and machining performance of the PMSM drive system.

Intelligent Harmonic Current Suppression Algorithm for Permanent Magnet Synchronous Motors in Industrial Servo Systems

2026-03-13

PIER C

Vol. 167, 61-68, 2026

doi:10.2528/PIERC26012306

download: 75

Design of an Ultra-Wideband LDMOS Power Amplifier Based on a Two-Stage Harmonic Suppression Network

Tianyi Li, Jingchang Nan, Jiawei Wang and Jesur Turxun

This study proposes an improved output matching design technique based on a two-stage harmonic suppression network, with the core innovation being a hybrid matching mode combining microstrip lines and lumped-parameter components in the output matching. In the first-stage harmonic suppression network, a third-order Butterworth filter serves as the prototype. Utilizing the Richards transformation and Kuroda rule, it is converted into a cross-shaped microstrip line, achieving high-frequency matching while suppressing second-harmonic components. The second-stage harmonic suppression network employs two series-connected LC resonant circuits to suppress third- and fifth-harmonics, respectively. To broaden bandwidth and enhance circuit stability, an improved negative feedback structure based on a second-order Butterworth low-pass filter prototype is introduced. Practical circuit testing within the 0.4-1.2 GHz operating bandwidth demonstrated output power ranging from 40.1 to 41.3 dBm and drain efficiency exceeding 51.63%, robustly validating the effectiveness of this approach.

Design of an Ultra-Wideband LDMOS Power Amplifier Based on a Two-Stage Harmonic Suppression Network

2026-03-12

PIER C

Vol. 167, 50-60, 2026

doi:10.2528/PIERC25121301

download: 155

Enhanced Gain Ultra-Wideband Antenna with Different Notch Response

Mohammed Fadhel Hasan, Hussein Al-Jeshami, Hussam Al-Saedi, Hussain A. Hammas, Muhannad Y. Muhsin and Jawad K. Ali

This article presents an enhanced-gain ultra-wideband (UWB) antenna with multiple notch responses to suppress the effects of coexisting wireless systems. The proposed antenna is developed in two stages. In the first stage, a reduced-ground U-shaped monopole with parasitic patches was designed to obtain a wide bandwidth between 3.02 and 10.76 GHz while maintaining a peak realized gain higher than 7 dB. In the second stage, selective frequency-rejection capabilities are tuned using split-ring structures (SRSs) for dual and higher-order notch responses. Two configurations are studied: dual-set SRS, which gives rise to low and high region notches centered at 5.73 GHz and 8.31 GHz, respectively, and higher-order SRS notch configuration providing a broad notch about 6.78 GHz with a 5.45% fractional rejection bandwidth. Parametric analysis indicated that the notch depth, notch bandwidth, and center frequency were independent and could be controlled via geometric tuning. The simulated results, supported by measurements from Keysight's PNA-X, corroborate the reflection coefficient, gain behavior, and notch performance; any deviations are attributed to variations experienced during the fabrication. The proposed approach achieves a UWB, increased gain, and flexible interference suppression, qualifying it for modern UWB communication systems that require a compact design.

Enhanced Gain Ultra-Wideband Antenna with Different Notch Response

2026-03-11

PIER C

Vol. 167, 39-49, 2026

doi:10.2528/PIERC26011705

download: 86

Mode Analysis for Prediction of Heating Patterns in Microwave Cavities Powered by Magnetron

Freda Carvalho, Ashwini Kotrashetti and Kaustubh Bhattacharyya

Microwave heating, widely employed in the food industry, offers significant advantages due to its volumetric heating capabilities. However, its efficiency is often hindered by non-uniform heating patterns. This study aims to analyse heating patterns in a rectangular, single-fed domestic microwave oven, leveraging cost-effective methodologies. Theoretical analyses, electromagnetic simulations, and experimental measurements were conducted to characterise the resonant modes within an empty cavity and with a load. The mathematical computation of multiple mode superposition within the cavity was performed for two domestic microwave ovens. Mathematical and experimental analyses demonstrate a close agreement in results. The findings reveal that mode distribution, influenced by cavity dimensions, load properties, load placement, and magnetron characteristics, significantly impacts heating patterns. This study helps us understand that in spite of the dynamic nature of magnetron, it is important to superimpose multiple resonant modes prevalent within the cavity to understand influences on microwave heating pattern of any food materials.

Mode Analysis for Prediction of Heating Patterns in Microwave Cavities Powered by Magnetron

2026-03-08

PIER C

Vol. 167, 32-38, 2026

doi:10.2528/PIERC25122306

download: 120

Design of a π-Type Broadband Flat Negative Group Delay Circuit

Aixia Yuan, Zhiyang Feng, Junzheng Liu, Yuwei Meng, Niannan Chang and Hongjun Zhang

This study proposes a novel π-type circuit topology designed to achieve broadband and flat negative group delay (NGD) characteristics. Featuring a simple structure composed entirely of passive lumped elements, the proposed design offers significant advantages in terms of ease of fabrication, low cost, and seamless integration into larger microwave systems. First, a comprehensive theoretical analysis was conducted to establish the operational principles and derive the design equations. We then systematically investigated the sensitivity of the circuit's performance to variations in individual component values, which provides crucial guidelines for practical implementation. To validate our theoretical findings, a physical prototype with compact dimensions of 32 mm × 35 mm was designed and fabricated. Experimental results demonstrate that at the center frequency of 107.5 MHz, the circuit achieves an NGD of -2.27 ns with an insertion loss of 19.5 dB. Notably, the circuit maintains a wide flat NGD bandwidth of 151 MHz, exhibiting a group delay fluctuation of merely 4.1% across the band. These results confirm the effectiveness and robustness of the proposed circuit for broadband microwave applications.

Design of a π-type Broadband Flat Negative Group Delay Circuit

2026-03-06

PIER C

Vol. 167, 21-31, 2026

doi:10.2528/PIERC25120702

download: 152

Optimized Hierarchical Nested Array for Enhanced Uniform Degrees of Freedom in Sparse Array DOA Estimation

Guibao Wang, Keyi Yu, Xianghui Wang and Shuzhen Wang

Sparse arrays have been extensively investigated for their capability to enhance degrees of freedom (DOFs). However, conventional nested array configuration is susceptible to strong mutual coupling (MC), while its achievable uniform DOFs (uDOFs) remains limited. To address these challenges, this paper proposes two optimized hierarchical nested arrays, designated as OHNA-I and OHNA-II. OHNA-I reconstructs the spatial arrangement of subarrays through a hierarchical shifting operation, effectively extending the continuous segment of the difference co-array (DCA). Building on this, OHNA-II further optimizes the subarray geometry via sensor displacement, achieving a better balance between uDOF enhancement and MC suppression, thereby maintaining higher uDOFs while reducing inter-sensor coupling interference. Numerical simulation results demonstrate that, under the same number of physical sensors, the proposed structures - particularly OHNA-II - achieve a greater number of uDOFs than existing classical sparse arrays. Furthermore, in scenarios with strong MC, the proposed structure exhibits superior robustness and lower root mean square error (RMSE) in DOA estimation.

Optimized Hierarchical Nested Array for Enhanced Uniform Degrees of Freedom in Sparse Array DOA Estimation

2026-03-06

PIER C

Vol. 167, 15-20, 2026

doi:10.2528/PIERC25123001

download: 127

Ac Losses Modeling in ReBCO Superconducting Coils Using the Volume Integral Method

Sara Fawaz and Hocine Menana

This paper presents a fast and efficient modeling approach based on the volume integral method for the characterization of AC losses in high-temperature superconducting coils made of second-generation Rare-earth Barium Copper Oxide (ReBCO) tapes. Three modeling strategies are investigated and compared, considering the detailed multilayer tape configuration, the homogenized tape configuration, and the simplified single-layer superconducting tape representation. These approaches aim to evaluate the impact of geometrical and electromagnetic simplifications on the accuracy of the results while significantly reducing computational time. In particular, the homogenization of the electromagnetic properties of the tape is explored to accelerate simulations without compromising the accuracy of key physical quantities such as AC losses and current density distribution. The modeling results are compared to measurements.

AC Losses Modeling in ReBCO Superconducting Coils Using the Volume Integral Method

2026-03-04

PIER C

Vol. 167, 4-14, 2026

doi:10.2528/PIERC26011606

download: 226

High Gain Circularly Polarized Dual-Band Antenna Array Using Hybrid Couplers

Qurratul Ayn, Yuvaraj Sivasubramanian and Kiran Kumar Gurrala

This work presents a dual-band circularly polarized antenna array in which adjacent elements are excited with quadrature phase progression using a cascaded hybrid-coupler feeding network comprising one rat-race coupler and two branch-line couplers. Double-T monopole elements enable dual-band operation, achieving impedance bandwidths of 300 MHz (2.4-2.7 GHz) and 975 MHz (5.025-6 GHz) with corresponding axial-ratio bandwidths of 110 MHz and 525 MHz. The array provides peak gains of 9.19 dB and 9.49 dB with simulated radiation efficiencies of 90% and 87% in the respective bands. The array yields peak realized gains of 9.19 dBic and 9.49 dBic with simulated total efficiencies of 90% and 87% in the corresponding bands. Unlike sequential rotation or multilayer CP arrays, the proposed single-layer planar hybrid-coupler network ensures frequency-stable dual band circular polarization. An analytical formulation of the array factor and axial ratio sensitivity is provided to clarify the CP synthesis mechanism and its suitability for compact vehicular platforms.

High Gain Circularly Polarized Dual-band Antenna Array Using Hybrid Couplers

2026-03-04

PIER C

Vol. 167, 1-3, 2026

doi:10.2528/PIERC25101605

download: 103

Phase Noise Experimental Characterization of CRLH Distributed Oscillators

Walter Ciccognani, Antonio Serino, Giancarlo Bartolucci, Lucio Scucchia and Stefan Simion

The phase noise levels of the output signals provided by two CRLH (Composite Right-/Left-Handed) distributed oscillator configurations are measured and compared. The first CRLH oscillator configuration provides two output signals, drain-line and gate-line output signals, available at the ends of the drain-line and gate-line that are not used for connecting the oscillator feedback. The second CRLH oscillator configuration is obtained by adding a Wilkinson power combiner to the first configuration that sums the drain-line and gate-line output signals for a single-output signal, a combined output signal. The experimental results show that the best performance in terms of output power and spectral purity can be obtained for the single-output CRLH oscillator.