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2025-11-12 Latest Published

Research on Orbital Angular Momentum of Low-Profile Ultra-Wideband Reflective Metasurface Download Full Article View Full Article

By Rongxian Bai Minquan Li Shuang Xiao Xin Qu Chen Li Guocui Zhu Yongkang Yuan Boyan Zhang Zhonghui Li

Progress In Electromagnetics Research Letters, Vol. 128, 26-34, 2025

doi:10.2528/PIERL25080603

Abstract

With the increasing demand for high-capacity communication systems, vortex beams endowed with orbital angular momentum (OAM) have emerged as a promising candidate for enhancing channel capacity of communication systems. Persistent limitations of conventional OAM generators, such as narrow bandwidth, single-mode constraints, and decreased purity in high-order OAM modes are addressed. In this work, by combining Pancharatnam-Berry (PB) phase theory and equivalent circuit, we design a metasurface unit with gradient phase compensation. The metasurface unit overcomes the bandwidth limits of the resonant structures, achieving 360˚ linear phase modulation over 8-20 GHz (85.7% relative bandwidth) and allowing vortex waves with multiple OAM modes and high order mode purity. Quantitative assessment of modal purity via OAM spectral decomposition demonstrates exceptional agreement between experimental measurements and full-wave simulations, thereby corroborating the theoretical framework and underscoring the methodology's potential for practical implementation.

2025-11-11

PIER Letters

Vol. 128, 18-25, 2025

doi:10.2528/PIERL25091106

download: 135

A New Method for Failure Diagnosis of Programmable Metasurfaces

Fang-Fang Wang, Wei Cheng, Yiqian Mao and Qing Huo Liu

In this paper, a new method is proposed for failure diagnosis of programmable metasurfaces, which jointly uses the single-point measurement strategy and Bernoulli-Gaussian (BG) prior. Specifically, leveraging the dynamic tuning property of programmable metasurfaces, the radiated fields is measured with a single fixed probe, therefore reducing the time and error of the measurement process. Moreover, the BG prior inherent in the programmable metasurface under test is exploited during the reconstruction process in order to perform the diagnosis with a small number of measurements without resorting to prior knowledge of the radiation pattern of the failure-free programmable metasurface. The accuracy, efficiency and robustness of the proposed method are verified through a set of representative numerical experiments, where the results are compared with those from existing diagnostic methods.

A New Method for Failure Diagnosis of Programmable Metasurfaces

2025-10-28

PIER Letters

Vol. 128, 10-17, 2025

doi:10.2528/PIERL25072303

download: 176

A Novel Compact Dual Open-Sleeve Multiband Antenna for Coal Mine Communication with Large Frequency Ratio

Bo Yin, Xiangdong Fu, Lilong Tan, Xiaolang Sheng and Peng Chen

In this paper, a novel compact dual open-sleeve multiband monopole omnidirectional antenna specifically designed for coal mine communication is proposed. Its core innovation lies in the structural optimization that enables multiband operation across a wide frequency range. To adapt to the confined mine tunnel environment, the antenna employs an ultra-small diameter design, which poses significant challenges for impedance matching below 1 GHz. Additionally, the substantial electrical size disparity between the sub-1 GHz and above-5 GHz bands further complicates multiband matching. The proposed open-sleeve monopole antenna consists of top and bottom dual open-sleeve structures along with resistive loads. Four length-adjustable thin copper columns replace the conventional sleeve, forming an open-sleeve structure. Through coordinated tuning of the two longest columns in the bottom open-sleeve structure together with the resistor loads, the antenna achieves favorable impedance matching in the low-frequency band (0.515-0.845 GHz). Furthermore, by adjusting the dimensions of the second-longest and shortest columns in the bottom open-sleeve, the antenna covers the 1.370-1.485 GHz and 4.660-6.000 GHz bands, respectively, while tuning the central monopole enables matching in the 2.210-2.525 GHz band. Ultimately, through independent adjustment of the four bottom column lengths and coordinated optimization of the resistor loads, the antenna effectively operates in four bands: 0.515-0.845 GHz, 1.370-1.485 GHz, 2.210-2.525 GHz, and 4.660-6.000 GHz, with the ratio between the lowest and highest operating frequencies reaching 10:1. Simultaneously, the top open-sleeve structure enhances the antenna's gain in the low-frequency band. Measured results show good agreement with simulation, demonstrating a gain of 1.21-4.59 dBi and radiation efficiency of 44%-77.7%. Moreover, the antenna exhibits omnidirectional radiation characteristics. This antenna shows potential for coal mine communication applications and also supports WLAN (2.4/5.2/5.8 GHz), WiMAX (2.3/5.8 GHz), and 5G NR (n5/n12/n28/n71/n79).

A Novel Compact Dual Open-sleeve Multiband Antenna for Coal Mine Communication with Large Frequency Ratio

2025-10-26

PIER Letters

Vol. 128, 1-9, 2025

doi:10.2528/PIERL25070303

download: 205

Improved Active-Disturbance Rejection Cascade Control of PMSM Based on New Fast Super-Twisting Non-Singular Terminal Sliding Mode Control Law

Junqin Liu, Zhentong Wang, Haicheng Zhong, Feng Deng, Kaihui Zhao and Xiangfei Li

To enhance the disturbance rejection capability and robust stability of PMSM under time-varying disturbances, an improved super-twisting higher-order sliding mode active disturbance rejection cascade control strategy is proposed. Firstly, a second-order mathematical model of the PMSM speed-current dual-loop system is established. Secondly, to address the oscillation issues caused by differentiation of the reference speed in conventional linear error feedback control, a composite sliding mode error feedback control law is designed by integrating the fast super-twisting (FST) algorithm and the fast non-singular terminal sliding mode control (FNFTSMC) method. The control law effectively suppresses system chattering and improves dynamic response. Meanwhile, an improved extended state observer (IESO) is constructed based on deviation control theory, which enhances real-time compensation of the cascade controller by optimizing convergence speed and disturbance estimation accuracy. Finally, hardware-in-the-loop (HIL) simulation results on an RT-LAB platform demonstrate that the proposed method outperforms traditional strategies in both dynamic performance and disturbance rejection, providing a viable solution for high-performance PMSM drive applications.