PIER M | PIER Journals

2026-11-06

PIER M

Vol. 141, 53-64, 2026

DOI:10.2528/PIERM26090901

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Lower Band-Edge Frequency Prediction for UWB Antennas via Knowledge-Based Artificial Neural Network

Zekun Zhang, Zihan Xu, Shuling Yin, Xia Cao and Bing Yang

To improve prediction accuracy for lower band-edge frequencies of ultra-wideband (UWB) printed monopole antennas, we propose a knowledge-based artificial neural network (KBANN) method. This approach uses antenna geometric parameters as inputs and introduces the lower band-edge frequency calculated from empirical formulas as prior knowledge into the neural network, integrating electromagnetic knowledge with machine learning. We construct a simulation dataset by performing electromagnetic simulations on antennas with various shapes and feed locations for model training and evaluation. Experimental comparisons show that the proposed knowledge-based artificial neural network achieves higher prediction accuracy and faster convergence than the empirical formula and data-driven models without prior knowledge, while maintaining lower prediction errors under limited-data conditions. Shapley additive explanation (SHAP) analysis further shows that prior knowledge contributes to the model predictions with the dominant antenna geometric parameters. The proposed method provides an efficient approach for lower band-edge frequency prediction of ultra-wideband antennas.

Lower Band-Edge Frequency Prediction for UWB Antennas via Knowledge-Based Artificial Neural Network

2026-11-05

PIER M

Vol. 141, 43-52, 2026

DOI:10.2528/PIERM26090803

download: 7

Study of Lightning-Induced Electromagnetic Interference on Sagging Conductors Above Rough Ground

Keyi Bai and Wei Tian

Lightning pulses are characterized by a wide coverage range, short duration, and high intensity. They can induce transient electromagnetic interference (EMI) on sagging high-voltage lines above the ground, posing a serious threat to the secure operation of power systems. In this paper, a random rough ground surface is simulated using the Monte Carlo method. The catenary function is employed to model the geometry of sagging high-voltage lines. The time-domain waveform of the lightning pulse is obtained based on the discharge current of a multi-component lightning cloud-to-ground stroke. The transient induced currents and power responses of three-phase transmission lines and connected loads under lightning excitation are numerically calculated. The effects of rough surfaces with different root-mean-square heights and tower heights configurations on electromagnetic interference characteristics are investigated. The broadband lightning interference characteristics are comprehensively obtained, providing a theoretical basis for the electromagnetic protection design of transmission lines above practical ground surfaces.

Study of Lightning-Induced Electromagnetic Interference on Sagging Conductors Above Rough Ground

2026-11-03

PIER M

Vol. 141, 34-42, 2026

DOI:10.2528/PIERM26091304

download: 12

NS-FDTD Modeling of Electromagnetic Wave Propagation in High-Loss Metallic Composites for Large-Scale Negative Medium Parameter Structures

Sikha Kolamkanny Simon, Nees Paul, Joe Kizhakooden, Bindu Cherala, Jolly Andrews, Vallikkavumkal Paily Joseph and Jovia Jose

The highly accurate and computationally advantageous nonstandard finite difference time domain (NS-FDTD) method is extensively used to study wave propagation through low-loss media. While applying this method in high-loss cases like metals, it is found that the algorithm fails to converge properly. In the present study, we address these convergence-related issues by analyzing the stability function for a fixed discretization of the computational domain. This novel approach to the NS-FDTD method is verified by exposing a metallic reflector slab to an incident sinusoidal electromagnetic wave, and the results are compared with those of the S-FDTD method. This approach provided a well-defined field distribution at a much lower discretization than that of the S-FDTD algorithm, giving a great advantage of much reduction in computational cost. Hence, this method finds application in simulating, accurately and precisely, composite high-loss media, including trending negative medium parameter structures like metamaterials.

NS-FDTD Modeling of Electromagnetic Wave Propagation in High-Loss Metallic Composites for Large-Scale Negative Medium Parameter Structures

2026-10-29

PIER M

Vol. 141, 17-33, 2026

DOI:10.2528/PIERM26082104

download: 10

Wireless Power and Data Transfer System for Cardiac Pacemakers Based on Dual-Strand Hybrid Magnetic Metamaterial Array

Weihua Chen, Pengyu Yan, Xiaoheng Yan, Bo Zuo and Feiyu Zhu

To address poor energy-transmission performance and weak anti-interference capability in wireless power and data transfer (WPDT) systems for implantable cardiac pacemakers, this study proposes an amplitude-shift-keying WPDT system for cardiac pacemakers based on a dual-strand hybrid magnetic metamaterial (DSH-MNG) array. First, we designed the DSH-MNG basic unit based on equivalent medium theory and the ohmic loss formula. We then analyze the influence of the metamaterial's structural parameters on the loss and optimize the number of turns and turn spacing of the basic unit to achieve optimal transmission efficiency. Next, an equivalent circuit model based on the DSH-MNG array system was derived. Finally, the improvement effect on the system's transmission performance is verified through simulation and experiments. The experimental results show that within a transmission distance of 20-40 mm, the system's transmission efficiency with the DSH-MNG array increased by 15.5% to 40.3%, and the modulation index has increased from 0.169-0.208 to 0.198-0.266. When the receiving coil is subjected to a horizontal offset of 5 mm to 15 mm and an angular offset of 15° to 45°, this system can still maintain a transmission efficiency of 24.8% to 66.3%, and the modulation index remains between 0.204 and 0.259.

Wireless Power and Data Transfer System for Cardiac Pacemakers Based on Dual-Strand Hybrid Magnetic Metamaterial Array

2926-10-28

PIER M

Vol. 141, 9-16, 2026

DOI:10.2528/PIERM26082204

download: 12

A Novel High-Sensitivity Photonic Crystal Sensor for Temperature Sensing

Fatima Zohra Siabah, Faiza Bounaas and Amel Labbani

This study proposes and numerically investigated a high-sensitivity two-dimensional photonic crystal temperature sensor using a hexagonal silicon lattice. The design features a resonant microcavity coupled with two quasi-linear waveguides to enhance light-matter interactions and optimise the thermo-optic response. Rigorous finite-difference time-domain (FDTD) simulations indicate that the sensor achieves a high thermal sensitivity of S_T = 105 pm/° C, accompanied by an excellent linear fitting coefficient. Furthermore, the optimised cavity demonstrates a high quality factor of Q =7739.5 and a narrow resonant linewidth, resulting in an ultra-low detection limit. With an ultra-compact footprint of 62.73 μm², the sensor is fully compatible with standard silicon-on-insulator (SOI) CMOS fabrication processes. These attributes render the proposed device a promising candidate for high-precision, dense thermal monitoring in integrated photonic circuits, lab-on-chip devices, and environmental sensing applications.

A Novel High-Sensitivity Photonic Crystal Sensor for Temperature Sensing

2026-10-28

PIER M

Vol. 141, 1-8, 2026

DOI:10.2528/PIERM25121804

download: 19

A Polarization Reconfigurable Dual-Band Dual-CP Shared Aperture Antenna Using RF MEMS Switch

Bhawna Kalra, Soumava Mukherjee, Ghanshyam Singh, Mahendra Mohan Sharma and Jaiverdhan

This paper presents a novel polarization reconfigurable, dual-band, dual-circularly polarized, shared-aperture antenna. The proposed antenna consists of multilayer configurations with two polarization states, i.e., left-hand circular polarization (LHCP) and right-hand circular polarization (RHCP) at L5 (1.164-1.88 GHz) and S (2.48-2.50 GHz) bands. A multisegmented ring is used as a radiator for the L5/S band and is excited electromagnetically through two coupling elements. These coupling elements are connected to a compact polarization reconfigurable hybrid power divider using two vias. This innovative reconfigurable circuit with a hybrid power divider performs circular polarization (LHCP/RHCP) reconfigurability operation using RF-MEMS switches, which improves the antenna's performance. Polarization states can be switched from LHCP to RHCP and vice versa using these RF MEMS switches. The proposed antenna provides a good agreement between simulated and measured results for both bands. Good impedance matching (return loss > 10 dB) and circular polarization (AR < 3) are obtained in the operating bands. The realized peak gain is of the order of 5.32 dBiC for LHCP and 5.66 dBiC for RHCP in the L5 band, and similarly it is 6.67 dBiC for LHCP and 6.99 dBiC for RHCP in the S band using a low-loss multilayer combination of substrate materials.