PIER | PIER Journals

2025-04-03

PIER

Vol. 183, 21-32, 2025

download: 219

Design of Absorption-Scattering Integrated Multi-Layer Metasurfaces for Large-Angle Anomalous Reflection

Jie Zhang, Wangchang Li, Yue Kang, Ting Zou, Xiao Han, Yao Ying, Jing Yu, Jingwu Zheng, Liang Qiao, Juan Li, Faxiang Qin and Shenglei Che

This paper presents a novel absorption-scattering integrated multi-layer metasurface (ASIMMS) designed to effectively control the propagation and absorption of electromagnetic waves. Special attention is paid to the efficient suppression of abnormal reflection and parasitic reflection under oblique incidence conditions. The research achieved high efficient beam coupling in the desired direction by precise impedance modulation and excitation of an appropriate set of evanescent wave patterns. The high conductivity of multi-walled carbon nanotube films (MWCNTFs) is used to enhance the localization of electromagnetic field inside the metasurface, thereby improving the absorption efficiency. The experimental results show that the designed ASIMMS achieves 86.8% electromagnetic wave absorption, 11.1% expected directional reflection efficiency, and 97.9% absorption-scattering efficiency at the operating frequency of 10 GHz under 15° oblique incidence. This method proficiently controls both direction and magnitude of scattering while effectively utilizing any diffraction order, paving the way for innovative applications in beam manipulation, stealth technology, and electromagnetic shielding.

Design of Absorption-scattering Integrated Multi-layer Metasurfaces for Large-angle Anomalous Reflection

2025-03-26

PIER

Vol. 183, 9-20, 2025

doi:10.2528/PIER24120904

download: 258

Efficient Design of a Novel Multibeam Antenna Using Scalar Metasurfaces

Mounia Djoudi, Mohamed Lamine Tounsi, Julien Sarrazin and Massimiliano Casaletti

This paper presents a simple and innovative approach to the design of multibeam scalar metasurface antennas. The proposed method, based on the equivalent currents on the antenna aperture, allows beams to be radiated in arbitrary directions with the desired polarization. Unlike other solutions available in the literature, this approach uses scalar metasurfaces, which are much simpler to implement than tensor ones, and also do not require optimizations through ad hoc developed numerical analysis tools. Analytical design equations based on the physics are introduced, and a block diagram for the designs of such antennas is presented. Two antenna designs are presented, and the corresponding numerical results demonstrate the flexibility of the presented method. A prototype of a two-beam antenna with orthogonal circular polarizations, operating at 20 GHz, was fabricated and measured. These results confirm the effectiveness of scalar metasurfaces in creating multibeam patterns, paving the way for various applications in advanced communication systems.

Efficient Design of a Novel Multibeam Antenna Using Scalar Metasurfaces

2025-03-18

PIER

Vol. 183, 1-8, 2025

doi:10.2528/PIER24121803

download: 181

All-Dielectric Cylindrical Metasurfaces for Enhanced Directional Scattering

Rasmus E. Jacobsen and Samel Arslanagic

We present a detailed analytical and numerical study of cylindrical metasurfaces for enhanced scattering applications. Analytical expressions are derived for the surface impedances of single and double metasurface configurations, respectively, which are required to maximize scattering in the forward direction. A surface impedance model is developed for 1-D arrays of dielectric cylinders that is subsequently used to realize and implement numerically the required surface impedances. Our analytical and full-wave numerical results reveal that cylindrical all-dielectric metasurfaces may exhibit superior forward scattering and balanced higher-order mode excitation in comparison to traditional solid dielectric resonators. Two examples, both with silicon dielectric cylinder, have been chosen to showcase our results, and they were found to exhibit extraordinary directional scattering properties with the respective forward scattering efficiencies being 9 and 19 times that of a single mode resonator. The choice of silicon for the cylinder dielectrics highlights the potential of the proposed configuration in optical communications, although the presented theory applies across the other parts of the electromagnetic spectrum.

All-dielectric Cylindrical Metasurfaces for Enhanced Directional Scattering

2025-05-06

PIER

Vol. 183, 45-57, 2025

doi:10.2528/PIER25012103

download: 53

Acceleration of Solving Volume Integral Equations through a Physics Driven Neural Network and Its Applications to Random Media Scattering

Jiayi Du, Yuanhao Cao, Chunzeng Luo, Gaoang Wang and Shurun Tan

In this paper, a novel framework is proposed which combines physical scattering models with artificial neural networks (ANN) to solve electromagnetic scattering problems of random media through a volume integral equation formulation. The framework is applied to a snow scattering problem where snow is represented by a bicontinuous random medium. A neural network is constructed linking the random media structure to the induced dipole moments on the media. The volume integral equation (VIE) serves as a natural physical constraint on the network input-out relations and is used to guide the training of the network. A discrete dipole approximation (DDA) strategy is adopted to convert the VIE into matrix equations which also defines the loss function of the surrogate neural network. For addressing deterministic scattering problems, this represents a viable alternative to traditional iterative algorithms, providing comparable accuracy at the expense of reduced efficiency. In solving statistical scattering problems, neural networks with physics-informed loss function achieve accuracy comparable to that of data-driven models while significantly reducing the dependency on extensive precomputed training datasets. The physics-based loss function also allows the network to self-diagnose the prediction accuracy in real operations. This work demonstrates a novel strategy to effectively merge physical equations with artificial neural networks, and the idea can be inspiring to many relevant fields, especially when randomness effects are exhibited through a complicated nonlinear system.

Acceleration of Solving Volume Integral Equations through a Physics Driven Neural Network and Its Applications to Random Media Scattering

2025-05-03

PIER

Vol. 183, 33-44, 2025

doi:10.2528/PIER25021402

download: 88

Finite Element Boundary Integral Approach for Inhomogeneous-Background Magnetic Resonance Electrical Properties Tomography

Yuyue Zhang, Hariharan Mohanabala Krishnan, Tiantian Yin and Xudong Chen

This paper introduces a novel finite element boundary integral approach for magnetic resonance electrical properties tomography (MR-EPT) with an inhomogeneous background which improves imaging quality by utilizing inhomogeneous background inversion and allows for a flexible selection of areas for fine reconstruction, thereby saving resources and quickly obtaining the most important information. In the proposed approach, a fictitious inhomogeneous background is initialized, followed by a preliminary reconstruction conducted across the entire field of view (FOV) through a few iterations. This fictitious inhomogeneous background aims to enhance the quality of reconstruction, surpassing that achieved through inversion in a homogeneous background. The proposed method is significantly suitable to the prevailing refinement mechanism, where the refinement area identified from the preliminary reconstruction image is embedded in an inhomogeneous background. This method combines the advantages of the computational efficiency of local methods and the noise robustness of global methods. Numerical examples have validated that the inversion with a fictitious inhomogeneous background yields a superior reconstruction quality. The subsequent narrowing of the inversion area results in a more focused inversion process, significantly reducing reconstruction time.