PIER C | PIER Journals

2025-07-18

PIER C

Vol. 157, 239-246, 2025

download: 21

Compact Stepped-Impedance Low-Pass Filter Using Coplanar Open-Circuited Stubs

Yi-Ruo Chen, Kuan-Wei Chen and Chun-Long Wang

This paper proposes a compact stepped-impedance low-pass filter using coplanar open-circuited stubs. The coplanar open-circuited stubs, which are used to compensate for the capacitive effect of the stepped-impedance low-pass filter, are implemented underneath the stepped-impedance low-pass filter. Consequently, the size of the stepped-impedance low-pass filter can be significantly reduced from 11.1 mm × 23.4 mm to 5.6 mm × 9.4 mm without altering its performance, amounting to a reduction rate of 79.83%. In addition, The transmission coefficient is attenuated below -30 dB, which is less than -20 dB attenuation of the conventional stepped-impedance low-pass filter. To verify the simulation result, the conventional stepped-impedance low-pass filter and the compact stepped-impedance low-pass filter using coplanar open-circuited stubs are fabricated and measured where the measurement results agree well with the simulation ones.

2025-07-18

PIER C

Vol. 157, 227-237, 2025

doi:10.2528/PIERC24121301

download: 19

Integrated Adaptive Control of 2.45g Microwave Transceiver with Multi-Band Operation in Electrical Parameter Fluctuations Estimation

Ke Wang, Xiao Ning Li, Jing Peng, Chao Zou, Long Feng Tian and Zhuohao Li

Adaptive control techniques are crucial in optimizing the performance of 2.45 GHz microwave transceivers amidst varying electrical parameters. These transceivers, integral to modern wireless communication systems, often encounter fluctuations in operating conditions that can impact signal quality and reliability. Adaptive control mechanisms enable real-time adjustment of transceiver parameters, ensuring consistent and efficient operation across diverse environments. This study addresses the adaptive control of a 2.45 GHz microwave transceiver in the presence of electrical parameter fluctuations, complemented by a multi-band antenna design aimed at minimizing losses. Electrical parameter fluctuations in transceivers can significantly affect performance and reliability, particularly in dynamic environments. The proposed approach integrates adaptive control algorithms to dynamically adjust transceiver parameters in response to fluctuations, ensuring optimal operational conditions. The integrated approach for adaptive control of a 2.45 GHz microwave transceiver, coupled with a multi-band antenna system optimized to reduce total harmonic distortion (THD). The study addresses the challenges posed by electrical parameter fluctuations in transceiver performance by employing adaptive control algorithms that dynamically adjust operational parameters. The multi-band antenna design, optimized through advanced modeling techniques, achieves a THD reduction of up to 20% across different frequency bands. Experimental validation demonstrates significant improvements in signal purity and transmission efficiency, showcasing the efficacy of this integrated approach in enhancing the reliability and performance of microwave communication systems in dynamic environments.

Integrated Adaptive Control of 2.45G Microwave Transceiver with Multi-band Operation in Electrical Parameter Fluctuations Estimation

2025-07-18

PIER C

Vol. 157, 215-225, 2025

doi:10.2528/PIERC25050702

download: 17

Development of a Compact Planar Antenna with Multi-Resonant Geometry for Broadband CubeSat Applications

Swati Varun Yadav, Manish Varun Yadav and Dinesh Yadav

This article presents the design and analysis of a Compact Planar Antenna with Multi-Resonant Geometry for Broadband CubeSat Applications. The antenna features a dual-layer architecture comprising a front semi-circular radiator with strategically positioned circular and rectangular slots, and a complex ground plane etched with complementary geometries to enhance performance. The optimized geometry, with key dimensions such as an overall size of 15 mm × 15 mm × 1.5 mm, enables a wide impedance bandwidth ranging from 2.9 GHz to 11.6 GHz. The impedance bandwidth of the radiator is 120%, with an electrical size of 0.14λ × 0.14λ × 0.014λ. Confirmed through both simulation and measurement using a VNA in an anechoic chamber, the gain performance increases steadily with frequency, reaching a peak of 4.2 dBi at 9.2 GHz, while maintaining a stable gain above 3 dBi between 3.8 GHz and 10.1 GHz. Radiation efficiency peaks at 87% around 5.6 GHz and remains above 75% within the mid-band range (4-8 GHz), indicating highly effective power radiation and minimal losses. Surface current and 3D radiation pattern analysis show efficient and focused radiation behavior at 6 and 9 GHz, supporting its suitability for wideband radar and secure communication applications.

Development of a Compact Planar Antenna with Multi-resonant Geometry for Broadband CubeSat Applications

2025-07-17

PIER C

Vol. 157, 207-213, 2025

doi:10.2528/PIERC25052601

download: 26

Research on Random Phase Feeding Optimization and Sidelobe Suppression in Phased Arrays Based on Dynamic SFLA

Li Wang and Qiusheng Li

To address the challenge of balancing sidelobe suppression and computational efficiency in phased array random phase feeding optimization, this paper proposes a multi-objective collaborative optimization scheme based on the Dynamic Shuffled Frog Leaping Algorithm (DSFLA). By establishing a hardware-compatible binary encoding model for phase quantization errors and introducing sidelobe variance constraints, the method achieves joint optimization of peak sidelobe level (PSLL) and beam pattern flatness. Simulation results demonstrate: For 32-element Taylor-weighted arrays, optimized PSLL reaches -28.6 dB (8.8 dB improvement vs. initial) with sidelobe variance reduced from 3.5 dB² to 1.2 dB²; For Chebyshev-weighted arrays, PSLL achieves -31.2 dB. The algorithm maintains robust performance under practical imperfections including element spacing perturbations (0.02λ RMS error) where PSLL stabilizes at -27.3 dB (σ=0.9 dB), and phase quantization errors (5° RMS) yielding -27.9 dB PSLL. DSFLA significantly outperforms conventional methods - reducing convergence generations from 276 to 28 and computation time by 29.2% (85 s) versus ant colony optimization while demonstrating O(N^1.5) scalability to 128-element arrays (PSLL=-32.1 dB in 218 sec). Real-time operation is feasible with PSLL=-27 dB achievable in ≤40 ms, meeting 50 ms radar beam-switching deadlines. This approach provides a practical solution for real-time beam control in high-precision phased array radar systems.

Research on Random Phase Feeding Optimization and Sidelobe Suppression in Phased Arrays Based on Dynamic SFLA

2025-07-16

PIER C

Vol. 157, 201-206, 2025

doi:10.2528/PIERC25052401

download: 13

Miniaturized Broadband Dielectric Waveguide Resonator Bandpass Filter with Wide Stopband Using CPW Resonator

Chuanyun Wang, Hao Huang and Pin Wen

In this paper, a novel miniaturized broadband dielectric waveguide (DW) bandpass filter (BPF) with wide stopband response is proposed. The proposed BPF is composed of two square DW resonators operating in TM₁₀₁ mode. By etching a coplanar waveguide (CPW) resonator on a silver-plated metal surface in the middle of the two DW resonators, an additional resonant mode is introduced, thereby broadening the bandwidth of the filter while retaining the inherent advantages of the DW structure. Simultaneously, the CPW resonator creates a new coupling path that enables cross-coupling and introduces a controlled transmission zero (TZ). The position of the TZ can be adjusted to suppress the second harmonic of the filter, ensuring effective stopband performance. For verification, a DW BPF with center frequency of 5 GHz and a fractional bandwidth of 11.4% was designed, fabricated, and measured. The measured results are in excellent agreement with the simulated ones. Specifically, the upper stopband of the filter extends to twice of the center frequency (10 GHz), demonstrating the wide stopband characteristics of the filter.

Miniaturized Broadband Dielectric Waveguide Resonator Bandpass Filter with Wide Stopband Using CPW Resonator

2025-07-15

PIER C

Vol. 157, 193-199, 2025

doi:10.2528/PIERC25051003

download: 40

Crosstalk Cancellation Between Multiple Transmission Lines Based on the Inverse Matrix of Transfer Function Matrix

Yafei Wang, Xiaozhe Wang and Xuehua Li

Aiming at the crosstalk problem between multiple coupled transmission lines in high-speed interconnection, a crosstalk cancellation method based on the inverse matrix of the Coupled Transmission Lines-Transfer Function Matrix (CTL-TFM) is proposed. The method first constructs the transfer function matrix of multiple coupled microstrip lines, and then designs the corresponding circuit for the inverse matrix of the transfer function matrix at the output ports. This ensures that the transfer function matrix of the entire system is reduced to a unit matrix, effectively reducing the crosstalk between transmission lines. Simulation results show that the quality of the signal eye diagrams at the outputs of all three coupled microstrip lines is significantly improved after using this method, and the crosstalk amplitude and jitter are substantially reduced.

Crosstalk Cancellation between Multiple Transmission Lines Based on the Inverse Matrix of Transfer Function Matrix

2025-07-13

PIER C

Vol. 157, 183-192, 2025

doi:10.2528/PIERC25041706

download: 38

New Approach to Extract the Complex Relative Permittivity from Two Circular Coaxial Transmission Lines

Ghislain Fraidy Bouesse, Amour Elang Ghordanne Langa-Etotsou and Franck Moukanda Mbango

This paper investigates a new, simple, fast, and broadband procedure to extract the material intrinsic parameters through new mathematical modeling. It only uses the transmission coefficient of two identical lines. The method is based on the mathematical reformulation of the two transmission lines, taking into account the effects of discontinuities at the interface connecting the trapper and the connector, as well as the included S-parameters. These test cells have different lengths, so the sample under test (SUT) complex relative permittivity is determined after fixing the vacuum structure's electric length. At the same time, the mathematical formulation of the telecommunications equation, which links transmission and reflection coefficients, was used to determine the loss tangent parameter by combining the attenuation and phase coefficients. The correction of the electric length difference of the transmission coefficients resulting from the measurement of the vacuum-filled test cells is done using an affine function. The frequency is the variable parameter, and the slope (rate of variation) and the initial value (ordered at the origin) are computed according to the test cell used. On the one hand, the suggested principle has the advantage of extracting the relative permittivity of the sample under test beyond the limit set by the appearance of higher-order modes (propagated by considering the test fixture's transverse dimensions). On the other hand, the use of the reflection coefficient, although it improves the attenuation coefficient extraction, limits the characterization band of the loss tangent. A circular coaxial test fixture has been used in the 1-20 GHz frequency range to validate the proposed method with samples of various materials, including semolina, polenta, Q-Cell 5020 (ceramic powder), aquarium stone, distilled water, and phantom gel. The results are compared with those from the two transmission lines technique, as defined in its popular form.

New Approach to Extract the Complex Relative Permittivity from Two Circular Coaxial Transmission Lines

2025-07-11

PIER C

Vol. 157, 173-181, 2025

doi:10.2528/PIERC25042306

download: 46

The Plasma Nature of Lightning Channel by Correlating the EM Fields Generated by Lightning and Its Optical Spectrum

Chandima Gomes

The lightning channel is a rapidly evolving transient plasma that radiates intense electromagnetic (EM) fields and emits broadband optical radiation. This paper presents a theoretical and experimental investigation into the correlation between electromagnetic fields generated during lightning events and the corresponding optical spectra observed during various phases of the discharge. Using advanced EM field modelling and high-speed optical spectroscopy, we demonstrate that key plasma parameters such as temperature, electron density, and ionization state can be inferred from combined electromagnetic-optical datasets. This multidisciplinary analysis not only reveals the underlying physical characteristics of the lightning channel but also provides insights for future atmospheric diagnostics, lightning modelling, and protective technologies.

2025-07-11

PIER C

Vol. 157, 159-171, 2025

doi:10.2528/PIERC25053101

download: 41

A Compact Wideband MIMO Antenna Design for 5G

Tianchu Yang, Shanhua Yao and Xiaorong Qiu

In this paper, a novel multiple-input multiple-output (MIMO) antenna for 5G applications in n77, n78, n79 and 6 GHz bands is proposed. The antenna structure is compact, measuring 30×50×1.5 mm³. The antenna is composed of two microstrip antenna units, which are formed of two hexagonal rings with lotus and small human, with the floor partially removed. The antenna functions in a frequency range of 3.3 to 9 GHz. The flow of coupling currents is impeded, and the isolation of the antenna is improved by the use of stepped rectangular slots and the floor of the projecting T-shaped structure, resulting in the antenna having an isolation of less than -20 dB over the entire operating bandwidth. Furthermore, the envelope correlation coefficient (ECC) is less than 0.008, the diversity gain (DG) greater than 9.95, the total active reflectance coefficient (TARC) less than -30 dB, and the channel capacity loss (CCL) less than 0.32 bit/s/Hz. The simulations and measurements of the antenna demonstrate its reliability and stability, thus indicating its potential for significant applications in 5G wireless communications.

A Compact Wideband MIMO Antenna Design for 5G

2025-07-11

PIER C

Vol. 157, 147-158, 2025

doi:10.2528/PIERC25031003

download: 78

A Fabric-Based Double Rectangular Complementary Split Ring Resonator for Wideband Applications

Intan Shafinaz Abd. Razak, Zahriladha Zakaria, Ahmed Jamal Abdullah Al-Gburi, Maizatul Alice Meor Said, Ariffuddin Joret, Syah Alam and Merih Palandoken

This paper introduces a novel wideband antenna composed of fabric materials, suitable for wearable and flexible applications and a straightforward single-unit Metamaterial (MTM). The antenna design employs ShieldIT Super as the conductive fabric and Felt as the dielectric substrate, creating a lightweight and adaptable solution with dimensions of 58 mm × 34 mm × 2 mm. Operating over a frequency range of 1.88 to 6.88 GHz, the proposed antenna achieves a peak gain of 4.72 dBi and a radiation efficiency of 94%. The antenna has wide measured bandwidth from 1.2 to 3.5 GHz (97%) and 4.0 to 5.9 GHz (38%) with average measured gain of 3 dBi in the lower band and 4.6 dBi in the upper band. The MTM-inspired design features a double rectangular complementary split-ring resonator at the center of the radiating patch, which enhances bandwidth. The MTM structure exhibits epsilon-near-zero (ENZ) and Mu-negative (MNG) properties were proposed. This novel design illustrates significant advancements in wideband antenna performance and is suitable for fabric-based S band, C band, 5G, Wireless Body Area Network (WBAN), and microwave imaging applications.

A Fabric-based Double Rectangular Complementary Split Ring Resonator for Wideband Applications

2025-07-11

PIER C

Vol. 157, 139-146, 2025

doi:10.2528/PIERC25041504

download: 40

The Impact of the Late Stage of High-Altitude Nuclear Explosion Electromagnetic Pulse on 110 kV Transformer

Zhaomin Han, Jie-Qing Fan, Hanhan Hu and Rui Zhu

The late-phase electromagnetic pulse (E3) of high-altitude nuclear explosions induces DC bias currents in power transformers via geomagnetically induced currents (GICs), threatening grid stability. Existing studies lack consensus on failure thresholds under HEMP E3 conditions. This paper addresses this gap by developing a multiphysics model of an SSZ10-40000/110 transformer exposed to simulated HEMP E3 environments. Our results demonstrate that DC currents exceeding 16.5A cause tank wall displacement (100 μm limit) and noise levels (>90 dB), with insulation breakdown occurring at 19A DC. These thresholds provide critical benchmarks for transformer protection strategies.

The Impact of the Late Stage of High-altitude Nuclear Explosion Electromagnetic Pulse on 110 KV Transformer

2025-07-08

PIER C

Vol. 157, 129-138, 2025

doi:10.2528/PIERC25052103

download: 56

High-Isolation Ultra-Wideband MIMO Antenna Based on Sunflower-Shaped Radiating Patch and Defected Ground Structure

Qingqing Zhou, Zhonggen Wang, Wenyan Nie, Chenlu Li, Yiwei Tao and Wanying Ren

This paper presents a compact four-port ultra-wideband (UWB) multiple-input multiple-output (MIMO) antenna with exceptional isolation characteristics, specifically designed for high-frequency band communications. The antenna features a sunflower-shaped radiating patch and an irregularly stepped rectangular ground structure, which are optimized to achieve broadband impedance matching and low coupling. With dimensions of 1.26λ₀ × 1.26λ₀ × 0.025λ₀, the antenna operates across 5.4-20 GHz, covering C-band (4-8 GHz), X-band (8-12 GHz), and Ku-band (12-18 GHz), while supporting multi-band communication compatibility. Simulation and measurement results show a return loss (|S₁₁|) below -10 dB over the entire frequency range, with a fractional bandwidth of 109.5%. The inter-port isolation (S₁₂) exceeds -20 dB across the band and reaches -30 dB in the high-frequency range (10-20 GHz). The antenna exhibits a radiation efficiency exceeding 80%, a peak gain of 9.3 dBi, an envelope correlation coefficient (ECC) below 0.008, a total active reflection coefficient (TARC) below -30 dB, and a group delay less than 2.3 ns, thereby meeting the stringent requirements for MIMO systems. This design offers a high-performance solution for applications in 5G, satellite, and radar communications, which combines wide bandwidth, high isolation, and low coupling in a compact form factor. The 5.4-20 GHz antenna bandwidth supplements 5G/6G applications which caters to multi-scenarios of Wi-Fi and satellite communications and facilitates signal reception and preprocessing in LEO satellite systems.

High-isolation Ultra-wideband MIMO Antenna Based on Sunflower-shaped Radiating Patch and Defected Ground Structure

2025-07-07

PIER C

Vol. 157, 119-128, 2025

doi:10.2528/PIERC25043007

download: 49

Integrated High-Isolation Dual-Band Power Amplifier with Ring-Coupled Bandstop Filter

Jingchang Nan, Hai Jiang and Wenjin Liu

This paper addresses the challenge of inter-band interference suppression in Dual-Band Power Amplifier (DBPA) by proposing a high-isolation dual-band power amplifier design integrated with a Ring-Coupled Bandstop Filter (RCBSF). Through a ring-coupled structure of main transmission lines and coupled branches, combined with the collaborative tuning of λ/4 open stubs and coupling capacitor, the design achieves low-loss transmission in the dual-frequency passbands of 1.5 GHz and 2.1 GHz, forms a suppression band of ≥ 20 dB in the 1.6-2.0 GHz range, and realizes deep suppression of > 40 dB for second/third harmonics. The RCBSF is embedded into the output matching network of the power amplifier to form a dual-band power amplifier. Measured results show that the power-added efficiencies (PAEs) of the amplifier at 1.5 GHz and 2.1 GHz are 58% and 60%, respectively, with output powers of 38 dBm and 37 dBm, and gains of 15 dB and 14 dB, respectively. In non-target frequency bands, the PAE approaches 0%, and a suppression greater than 40 dB is achieved, verifying that the filter's high selectivity and compact layout enhance the performance of the dual-band power amplifier. This design achieves efficient power transmission and strong interference isolation, providing a cost-effective solution for multi-band communication systems.

Integrated High-isolation Dual-band Power Amplifier with Ring-coupled Bandstop Filter

2025-07-05

PIER C

Vol. 157, 109-117, 2025

doi:10.2528/PIERC25052004

download: 49

Broadband Circularly Polarized Implantable Antenna Loaded with Open Slots for Biomedical Applications

Leyuan Li, Guolong Wang, Ying Sun, Zhuopeng Wang and Lin Shao

This paper presents a broadband circularly polarized (CP) implantable antenna for biomedical applications operating in the 2.45 GHz Industrial, Scientific, and Medical (ISM) band. Its key innovation is an annular ground plane structure with a square open slot, which simultaneously broadens both impedance and axial ratio (AR) bandwidths. This achieves a wide effective bandwidth of 30.8% (2.17-2.96 GHz), demonstrating superior bandwidth compared to existing implantable CP antennas. The antenna employs an inverted S-shaped radiating patch, and by adjusting the position of the radiating branches, it can switch between left-hand circular polarization (LHCP) and right-hand circular polarization (RHCP). The simulated and measured results of the antenna show good agreement, and the SAR meets IEEE standards.

Broadband Circularly Polarized Implantable Antenna Loaded with Open Slots for Biomedical Applications

2025-07-03

PIER C

Vol. 157, 101-107, 2025

doi:10.2528/PIERC25042302

download: 50

Design and Performance Evaluation of a Single-Layer Planar UWB Antenna for Omnidirectional Coverage of 5G IoT Devices

Inaganti Rama Koteswara Rao, Ramavathu Sambasiva Nayak and Karumuri Rajasekhar

This paper presents the design and performance evaluation of a planar ultra-wideband (UWB) antenna employing an elliptical dipole structure, targeting comprehensive omnidirectional coverage within the 1-10 GHz frequency band for 5G Internet of Things (IoT) applications. The antenna, constructed on a cost-effective FR4 substrate, exhibits an impressive impedance bandwidth of 10:1 (S₁₁ ≤ -10 dB) and frequency-dependent gain ranging from 3 to 8 dBi. Its design features ensure minimal side lobe levels below -20 dB, contributing to enhanced signal integrity and reduced interference. Notably, the azimuthal plane radiation pattern maintains a remarkable 1 dB out-of-roundness, facilitating robust communication in diverse IoT environments. Extensive 3D radiation pattern measurements affirm the antenna's effectiveness in optimizing signal propagation and reliability across varying deployment scenarios. This study underscores the significance of the elliptical dipole configuration in advancing UWB technology, highlighting its potential for seamless integration into future 5G IoT networks.

Design and Performance Evaluation of a Single-layer Planar UWB Antenna for Omnidirectional Coverage of 5G IoT Devices

2025-07-01

PIER C

Vol. 157, 95-100, 2025

doi:10.2528/PIERC25042701

download: 64

Performance Analysis of Electrical Impedance and Acoustic Tomography for Early Breast Cancer Detection

Annapoorani Ganesan, Vani Rajamanickam and Vaishali Durgamahant

Breast cancer is considered one of the major cancers among women. Early identification of breast cancer is essential for improving treatment outcomes, necessitating the application of accurate, non-invasive imaging methods. This paper presents a comparative evaluation of Electrical Impedance Tomography (EIT) and Ultrasound Tomography (UST) for breast tumour diagnosis, employing a simulated multilayer breast model. The forward problem, which entails the determination of electrical conductivity and acoustic pressure distribution, was addressed through finite element analysis utilizing COMSOL Multiphysics software. The inverse problem of EIT was solved using Total Variation regularization with Primal-Dual Interior Point Method (TV-PDIPM) and that of ultrasound by employing attenuation-weighted bilinear interpolation to effectively resolve propagation losses through tissue layers, subsequently leading to segmentation. The images reconstructed and segmented from both modalities were subjected to quantitative evaluation employing metrics such as accuracy, Dice coefficient, sensitivity, specificity, and correlation coefficient (CC). The findings indicate that both approaches offers complimentary information regarding tumor, with each approach presenting distinct advantages based on tissue characteristics and image clarity.

Performance Analysis of Electrical Impedance and Acoustic Tomography for Early Breast Cancer Detection

2025-07-01

PIER C

Vol. 157, 85-93, 2025

doi:10.2528/PIERC25041704

download: 68

Research on Coherent Integration for Maneuvering Target Detection Based on KT-ITDCI

Aihua Li, Wei Liu, Yuhang Wang, Wenwen Xu, Jianyin Cao and Hao Wang

In order to enhance the detection capability of small targets, long-term coherent integration (LTCI) is commonly employed. The core idea of LTCI is to accumulate target energy over an extended observation period, thereby enhancing the signal-to-noise ratio (SNR) of the target signal. However, for maneuvering targets, defocusing may occur due to range migration (RM) and Doppler frequency migration (DFM). In this study, a novel method based on the keystone transform and improved 3-D coherent integration (KT-ITDCI) for maneuvering target detection is proposed. KT-ITDCI not only eliminates the RM induced by unambiguous velocity through KT, but also compensates for residual RM and DFM in the KT-processed echoes via ITDCI, ultimately achieving coherent integration. Simulation results show that, compared with the TDCI method, KT-ITDCI significantly reduces computational complexity while maintaining comparable noise resistance. Furthermore, the effectiveness of the proposed method is further validated through processing and analyzing real measured radar data.

Research on Coherent Integration for Maneuvering Target Detection Based on KT-ITDCI

2025-06-30

PIER C

Vol. 157, 75-83, 2025

doi:10.2528/PIERC25050202

download: 60

Low-Loss Microstrip Tri-Band Differential Bandpass Filters Using a Non-Edge-Coupled Structure

Chuan Shao, Yang Li, Liang Wang, Rong Cai and Kai Xu

In this paper, a novel differential tri-band bandpass filter with a low-loss characteristic and high selectivity is proposed. The low-loss feature is attributed to the non-coupled structure, which circumvents the additional radiation losses from coupling slots. Furthermore, the excellent isolation and significantly enhanced selectivity between passbands are achieved via the inherent transmission zeros among them. Three desirable differential operating passbands can be conveniently allocated by adjusting the impedance ratios of the tri-section stepped impedance resonators. Consequently, the proposed filter design demonstrates a straightforward and efficient design methodology. To validate the feasibility of this approach, a differential tri-band bandpass with passbands at 1.35 GHz, 4.5 GHz, and 7.6 GHz was constructed and experimentally verified. The measured minimum insertion losses were 0.15 dB, 0.5 dB, and 1.2 dB respectively, indicating high performance. Specifically, the roll-off rates of the lower and upper edges of the three passbands are as follows: for the first passband, 30 dB/GHz and 23 dB/GHz; for the second passband, 27 dB/GHz and 25 dB/GHz; and for the third passband, 24 dB/GHz and 29 dB/GHz. The achieved concordance between simulated and measured results confirms the practicality and viability of this design for advanced communication systems.

2025-06-29

PIER C

Vol. 157, 65-73, 2025

doi:10.2528/PIERC25012106

download: 129

Design and Integration of a Flexible RFID UHF Antenna with a 3D Printed Fluid Channel for Liquids Sensing Applications

Mohammed Ali Ennasar, Mohamed El Khamlichi, Youness Akazzim, Abdelmounaim Tachrifat, Mariem Aznabet, Otman El Mrabet and Mohsine Khalladi

This article presents an innovative UHF RFID tag sensor featuring a flexible ring resonator dipole integrated with a fluidic channel. Leveraging the unique characteristics of the resonator dipole, the sensor demonstrates high sensitivity in detecting the dielectric properties of various liquids. The RFID integration facilitates wireless communication and remote monitoring, enabling real-time, continuous measurement of sensor data. The sensor's flexible design allows for easy attachment on the PLA fluid channel, enhancing its practical utility. Experimental results show a strong correlation with reference measurements obtained using traditional laboratory methods using VNA. The sensor achieves effective impedance matching up to 1 GHz, even without the presence of a liquid in the channel. Moreover, confining liquids with high dielectric constants within the channel broadens the operational range across the UHF RFID band, spanning 865 MHz to 928 MHz, and the wireless RFID tag sensor is well suited for applications requiring real-time analysis and continuous monitoring. The proposed flexible ring resonator dipole UHF RFID tag sensor, coupled with fluidic channel-based tuning, offers significant potential for applications such as chemical analysis of liquids. Its unique blend of flexibility, wireless data communication, and accurate dielectric characterization opens new avenues for noninvasive and remote sensing in liquid-based system.

Design and Integration of a Flexible RFID UHF Antenna with a 3D Printed Fluid Channel for Liquids Sensing Applications

2025-06-29

PIER C

Vol. 157, 57-63, 2025

doi:10.2528/PIERC25051001

download: 54

High-Performance Compact Antenna for Sub-6 GHz 5G MIMO Applications

Rajendran Dhananjeyan, Mohit Pant, Kumarasamy Vishalatchi, Subramaniyan Janarthanan, Ponnusamy Sukumar, Dhanushkodi Siva Sundhara Raja and Dhandapani Rajeshkumar

This study presents a compact four-port antenna optimized for sub-6 GHz 5G MIMO systems. The design incorporates a crescent-shaped radiating element paired with a defected ground structure (DGS) to improve both bandwidth and port-to-port isolation. Operating within the 3.2-3.8 GHz frequency band, the antenna maintains a VSWR below 2. The orthogonal arrangement of the radiators effectively suppresses mutual coupling, ensuring that isolation levels exceed -15 dB. Simulated and measured results validate the design, demonstrating a maximum gain of 5 dBi and radiation efficiency reaching up to 80%. Key MIMO performance indicators - such as envelope correlation coefficient (ECC), total active reflection coefficient (TARC), channel capacity loss (CCL), and diversity gain (DG) - confirm the antenna's suitability for robust 5G communication.

High-performance Compact Antenna for Sub-6 GHz 5G MIMO Applications

2025-06-29

PIER C

Vol. 157, 49-56, 2025

doi:10.2528/PIERC25051103

download: 75

Analysis of a Novel Hybrid-Excitation External-Rotor Switched Reluctance Motor

Liyun Feng and Kaikai Diao

In this paper, a novel hybrid-excitation external-rotor switched reluctance motor is presented to solve the problem of low output torque of traditional switched reluctance motors (SRMs). The hybrid-excitation SRM, serving as an effective alternative to electric excitation SRMs, achieves comparable torque output with reduced excitation currents and lower power consumption within a certain range. First, the structural configuration and operational principles of the proposed SRM are presented and investigated. Then, key electromagnetic properties based on three-dimensional finite element analysis are analyzed in detail, such as the distribution of magnetic density, torque, and flux linkage. Furthermore, the validation is subsequently conducted through simulation data and performance comparisons with conventional outer-rotor 6/4 SRMs, conclusively confirming the theoretical framework's practical feasibility. Finally, the direct torque control with variable flux linkage based on the HESRM is executed, and the good control performance is verified under different conditions.

Analysis of a Novel Hybrid-excitation External-rotor Switched Reluctance Motor

2025-06-27

PIER C

Vol. 157, 37-47, 2025

doi:10.2528/PIERC25042305

download: 77

Study on Deployment Scheme of 5G Communication Devices in Complex Electromagnetic Environment of Substations

Hanhan Hu, Jie-Qing Fan, Rui Zhu and Zhaomin Han

Addressing the deployment challenges of 5G communication equipment in the complex electromagnetic environment of substations, this paper takes an actual substation as the research object. Through a combined approach of physical modeling and field measurement validation, it systematically investigates the deployment issues of 5G devices in substations. Firstly, a power frequency electromagnetic field model of the substation is established, and its reliability is verified by comparative analysis between simulation results and on-site measured data. Secondly, by establishing a radiation model of 5G communication equipment, the mutual interference between 5G devices and secondary equipment within the substation is investigated. Finally, leveraging the distribution characteristics of the power frequency electromagnetic field in the substation, a tailored deployment scheme for 5G communication equipment is proposed. This study provides both a theoretical foundation and technical support for the practical deployment of 5G in smart substations, thereby advancing the deep integration of power systems and communication systems.

Study on Deployment Scheme of 5G Communication Devices in Complex Electromagnetic Environment of Substations

2025-06-27

PIER C

Vol. 157, 27-36, 2025

doi:10.2528/PIERC25050704

download: 56

Modelling and Analysis of Magnetic Field Distribution Generated by a Magnetised Paraboloid

Van Tai Nguyen and Thi Phuoc Van Nguyen

Permanent magnets have a unique ability to generate a permanent magnetic field that has been found in various applications. In this study, to facilitate the design and optimization processes of magnetic devices, fast-computed expressions of the magnetic field created by a magnetised paraboloid are developed. It is demonstrated that the derived models are in good agreement with the conventional Finite Element Analysis (FEA). Moreover, these models are multiple magnitudes faster than the FEA in terms of computational time. Furthermore, analysing the magnetic field distribution generated by this magnet, it is shown that the field is concentrated around its revolute axis. In addition, the field is sharply concentrated and pointy, close to the apex of the paraboloid. The field expressions and their properties are expected to assist in the design and optimization processes of magnetic devices utilizing this magnet, such as in static magnetic field brain stimulation.

Modelling and Analysis of Magnetic Field Distribution Generated by a Magnetised Paraboloid

2025-06-25

PIER C

Vol. 157, 17-26, 2025

doi:10.2528/PIERC25032001

download: 110

Constant Voltage Output Control of WPT System Based on Two-Parameter Real-Time Identification

Zhongjiu Zheng, Qiangqiang Zhao, Hanxi Xu, Zhengyu Xue and Yanpeng Ma

Offsets in the coupling mechanism and load fluctuations usually lead to instability in the output voltage of wireless power transfer (WPT) systems. Therefore, accurate and rapid identification of the mutual inductance and load parameters of the system is crucial for achieving stable output control for communication-free WPT systems. In this paper, a method based on the joint real-time identification of both mutual inductance and load parameters is proposed. By measuring the primary inverter current and the current on the shunt compensation capacitor, two current equations about the mutual inductance and load resistance are constructed, in which only the RMS values of the above two currents need to be determined. The traditional equations are too slow to be solved, and the amount of computation is too large; therefore, this paper combines this method with particle swarm algorithm, which transforms the problem of the system parameter identification into a function optimization problem. Through this method, the identification results of mutual inductance and load resistance can be obtained in real time, and then the conduction angle of the inverter can be calculated quickly to realize the constant voltage output control. Finally, a wireless power transmission experimental platform is built, and in the experiment, the recognition accuracy of mutual inductance and load reaches more than 96.7% and 96.4%, respectively, which verifies the feasibility and practicality of the design.

Constant Voltage Output Control of WPT System Based on Two-parameter Real-time Identification

2025-06-25

PIER C

Vol. 157, 7-16, 2025

doi:10.2528/PIERC25041506

download: 53

Multi-Objective Optimization of Asymmetric Pole-Consequent Pole Permanent Magnet Motor

Jianwei Liang, Xinyu Zeng, Yuqian Zhao, Tian Song, Xiubin Zhu and Zhangsheng Liu

This paper addresses the problem of sizeable cogging torque and torque ripple of conventional consequent pole permanent magnet motor (CPPM) and proposes an asymmetric pole-consequent pole permanent magnet (AP-CPPM) motor as a solution. This paper proposes an asymmetric pole-consequent pole permanent magnet (AP-CPPM) motor. A combined strategy of response surface method and multi-objective genetic algorithm is adopted. Firstly, sensitivity analysis of design variables and stratification were carried out, and subsequently, the mathematical model between the design variables and the optimization objective is obtained by Response Surface Methodology (RSM). Then, the high-sensitivity parameters are optimized using a Multi-Objective Genetic Algorithm (MOGA) to get the optimal solution. Finally, the electromagnetic performances of the motor before and after optimization are compared using Finite Element Analysis (FEA) software. The results indicated that the optimized motor reduced the torque ripple by 39.9% and the peak-to-peak value of cogging torque by 62.41% with only a 3.1% reduction in the output torque, which ensured good output characteristics and verified the feasibility of the optimization scheme.

Multi-objective Optimization of Asymmetric Pole-consequent Pole Permanent Magnet Motor

2025-06-23

PIER C

Vol. 157, 1-6, 2025

doi:10.2528/PIERC25032102

download: 62

Ground Manipulation Techniques for Densified Small Cell Base Stations

Alyaa Syaza Azini and Tim W. C. Brown

Shorter frequency reuse distance in a densified small cell network for fifth generation (5G) could cause more substantial inter-cell interference. Rather than relying on down tilt, it is more necessary to design the azimuth patterns of the antennas to substantially reduce the gain at the sector edges which can reduce the line of sight radiation towards a sector positioned over a reuse distance. The antenna employs a modified ground plane, which utilizes both reflection and diffraction to reduce the gain at the sector edge, and is designed and prototyped from 3.5-4.2 GHz.