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This communication investigates a simple and efficient approach for evaluating the effective permittivity of triply periodic minimal surface (TPMS) structures. In the proposed approach, each unit cell of the TPMS is first uniformly divided into many thin layers along the parallel and vertical directions of the incident electric field, forming the parallel and the series two models. Each layer can be homogenized as a diagonal anisotropic medium using the Bruggeman (BM) effective medium theory. Then the transversal and the longitudinal entries of the effective permittivity tensors for a unit cell are obtained using the parallel and the series equivalent formula, respectively. Finally, the calculated permittivity tensor entries are averaged to further equivalent the TPMS structure as a uniform isotropic medium. Numerical examples are presented to study and validate the effectiveness of the proposed approach.

This study advances the discontinuous Galerkin (DG) integral equation methodology for the analysis of antennas incorporating dielectric slabs and radomes, addressing the increasing spatial-scale contrast challenges in antenna systems due to advanced manufacturing and integration techniques. By integrating the combined field integral equation for dielectric surfaces with the electric field integral equation for metallic structures, we establish a DG discretization framework for surface integral equations for antenna analysis. A novel aspect of our approach is the straightforward definition of basis functions and unknowns at multiple material junctions, which circumvents the complications encountered in traditional conformal mesh-based integral equation methods. Demonstrated through examples, including a multiport patch antenna array encapsulated by a large dielectric radome, our method significantly enhances the flexibility of S-parameter and radiation pattern analysis for the realistic, multiscale antenna with radome configurations.

In this letter, we introduce a backpropagation (BP) neural network-based inversion method for deriving the equivalent electromagnetic parameters of cellular microwave absorbing honeycomb structures. The conventional honeycomb structure is first homogenized into homogenous layers using the Hashin–Shtrikman (H–S) variational theory. Then, the sample honeycombs are generated by sampling the H–S unknown variables using prior knowledge of the physical and geometric characteristics of the honeycomb, and the training dataset are generated by computing the scattered field using the finite element-boundary integral-multilevel fast multipole algorithm. A BP neural network is trained using the scattered field from the sample honeycomb structures as the input, while the output is the undetermined variables for describing the equivalent electromagnetic parameters of the layered homogenous sample honeycomb using H–S theory. Numerical examples are presented to demonstrate the accuracy and effectiveness of the proposed BP neural network for predicting equivalent electromagnetic parameter of microwave absorbing honeycomb structures.

The surface-wire integral equation method is an efficient and well-established approach in microwave engineering, as it simplifies mesh generation and improves efficiency without sacrificing accuracy. However, it faces significant challenges when applied to multiscale structures with densely distributed wire-surface junctions, such as vias or interconnections. This difficulty arises because junction points must align with surface mesh vertices, imposing additional constraints on mesh generation. To address this limitation and enhance the flexibility of mesh generation for complex structures, in this work, we extend the discontinuous Galerkin integral equation (DGIE) method to surface-wire structures, so that the mesh for wire and surface can be discretized independently. The nonoverlapping subdomain partitioning scheme and the simple basis function definitions for surface-wire junctions are provided. Similar to the surface DGIE method, the numerical discretization procedure is derived to guarantee the current continuity and zero charge accumulation on the DG contour lines, to ensure the correctness of electromagnetic analysis. Different numerical examples are provided to demonstrate the correctness, accuracy, and flexibility of the proposed method, and to exhibit its superior performance over conventional methods in challenging multiscale problems.

We present a multiregion surface integral equation (MR-SIE) solution for the analysis of electromagnetic (EM) scattering from an aircraft with plasma sheath. The MR-SIE offers advantages over volume-meshed methods in terms of lower dimensionality of unknowns but requires homogeneity within each region. A flexible piecewise homogeneous modeling method based on K-means clustering is proposed, which accurately and efficiently maps the inhomogeneous plasma sheath into a multiregion model. Compared with the conventional K-means clustering method, a distance formula designed for plasma EM parameters was investigated for the partition of plasma sheath. To further prompt the convenience and efficiency of the MR-SIE solver, the discontinuous Galerkin (DG) method is used to discretize the electric and magnetic current combined field integral equations (JMCFIE) of the multiregion model. Numerical experiments demonstrate that the MR-SIE solution with the flexible piecewise homogeneous modeling exhibits accuracy and efficiency, showing good potential for fast analyzing the EM scattering characteristics of hypersonic vehicles.

The coaxial cable is widely employed in radio frequency (RF) engineering as a crucial component for feeding or connecting structures that transmit RF signals or energy. Given its significant impact on the performance of connected devices, a high-definition mesh for coaxial-fed structures is often essential. Typically, the mesh for the inner conductor needs to be extremely fine, which can make simulations using the method of moments (MoM) quite cumbersome. To address this challenge, this communication explores the efficient simulation of coaxial-fed structures using the discontinuous Galerkin integral equation (DGIE) method. This approach allows for the independent meshing of inner conductors and other surfaces. Furthermore, by assuming that the diameter of the inner conductor is electrically small, we adopt a wire model to reduce the number of unknowns in the MoM simulation. Extensive numerical examples are carried out to validate the correctness, accuracy, and robustness of the proposed DGIE scheme, where two adjacent subdomains are discretized using different kinds of basis functions.

In this communication, we introduce a semi-analytical shooting and bouncing ray (SBR) modified by ray refinement technology to address the complex multiple scattering components in composite scenes. Compared to the traditional SBR method, the proposed method reduces the ray number and tracing times while maintaining accuracy, thereby significantly enhancing computational efficiency. Furthermore, we refine the computation of the reflection coefficient based on the bistatic scattering coefficient. This refinement makes the model suitable for simulating coupling scattering between targets with rough surfaces. We apply the proposed method to calculate the radar cross section (RCS) of both a cube-sea surface model and a freighter-sea surface model. The results obtained are then compared with those of the parallel multilevel fast multipole algorithm (PMLFMA). Additionally, the calculation efficiency of the proposed method is compared with that of the traditional SBR. The validation results demonstrate that our method achieves accuracy comparable to PMLFMA and improves efficiency by tens of times when compared with the traditional SBR.

Surface discontinuities (SDs), such as cylindrical protrusions or dents, are commonly found on artificial aircraft or vehicle surfaces. Despite being electrically small in size, their sheer quantity can significantly affect the scattering characteristics of the target. Due to the large contrast between the surface discontinuity and surrounding geometry, the efficient scattering analysis of these targets is technically challenging in both mesh generation and numerical simulation. In this communication, two novel basis functions are presented based on the discontinuous Galerkin integral equation (DGIE) framework. Using the so-called extended half-Rao–Wilton–Glisson (RWG) and modified top junction basis functions, the cylindrical SDs with different or variable height–radius ratios can be efficiently discretized without requiring mesh conformality. Extensive numerical simulations of SDs on a low-radar cross section (RCS) testbed are performed to verify the accuracy, flexibility, and robustness of the proposed method.