Metallic nanoparticles (NPs) support localized surface plasmon resonances (LSPRs), which enable to concentrate sunlight at the active layer of solar cells. However, full-wave modeling of the plasmonic solar cells faces great challenges in terms of huge computational workload and bad matrix condition. It is tremendously difficult to accurately and efficiently simulate near-field multiple scattering effects from plasmonic NPs embedded into solar cells. In this work, a preconditioned volume integral equation (VIE) is proposed to model plasmonic organic solar cells (OSCs). The diagonal block preconditioner is applied to different material domains of the device structure. As a result, better convergence and higher computing efficiency are achieved. Moreover, the calculation is further accelerated by two-dimensional periodic Green’s functions. Using the proposed method, the dependences of optical absorption on the wavelengths and incident angles are investigated. Angular responses of the plasmonic OSCs show the super-Lambertian absorption on the plasmon resonance but near-Lambertian absorption off the plasmon resonance. The volumetric method of moments and explored physical understanding are of great help to investigate the optical responses of OSCs.

The low-frequency fast multipole algorithm (LFFMA) based on the approximate diagonalization of Green’s function for the electric field integral equation (EFIE) is proposed for open and complex structures with high accuracy. Moreover, the multiresolution preconditioner is employed to the mixed potential form of EFIE with RWG basis functions for stability. Herein, a triangle-grouping scheme is adopted for the scalar potential so that the accuracy of the LFFMA can be guaranteed. Furthermore, the computational resources can be reduced largely since part of the radiation pattern of vector potential can share one of the scalar potentials by taking advantage of some mathematical deductions.

An efficient equivalence principle algorithm with spherical equivalent source is proposed to analyze the electromagnetic scattering from a metal-dielectric composite and randomly distributed bodies of revolution (BoRs) cluster, which is called SEPA-CBoR for short. Due to the rotationally symmetrical property, the electromagnetic currents on the BoRs and the equivalence spheres are all expanded by the basis functions of BoR. In this way, whether the self-action or the inter-action are both calculated by using the method of moment for BoR (BoR-MoM). With the repeatability fully used, the self-action for the BoRs with the same size just needs to be calculated once. Moreover, the inter-action can also be got once when the size and relative displacement vector of their corresponding ESs are same. Since these self/inter-action matrices are constructed in mutually orthogonal Fourier modals, the entire problem is eventually solved by a couple of small matrix equations independently. As a result, the SEPA-CBoR method can greatly save the memory requirement and solution time. Several numerical examples are presented to demonstrate the accuracy and efficiency for the composite BoRs cluster problems. Especially, it is helpful to distinguish the fake targets with the accurate echo signs obtained from the efficient SEPA-CBoR method.

It is instructive to exploit the coupling effect between the chaff clouds and the sea surface so that the scattering mechanism of chaff clouds above the surface can be better understood. An EM model for low-altitude chaff clouds above the sea surface is proposed to analyze the scattering contributions of the EM waves between the chaff clouds and the surface. For high-density chaff elements, their scattering properties can be calculated quickly and accurately by the vector radiative transfer. During the process, Monte Carlo solver is used to simulate the energy change of photons and the coupling effect among chaffs. Meanwhile, the Advanced Integral Equation Model is applied to calculate the electromagnetic scattering energy of the sea. Moreover, the coupling effect between the chaff clouds and the sea is taken into account by the four-path method. Numerical results indicate that the validity of the VRT method can be verified by the FEKO. In addition, the dynamic coupling of RCS variation is simulated and the scattering characteristics of chaff clouds under different sea states and heights are analyzed to predict the scattering coefficients. Moreover, for chaff clouds with different spatial distributions, the scattering characteristics are analyzed to provide an effective strategy for practical applications.

In this article, we propose a multifunctional time-modulated metasurface-enabled electromagnetic (EM) tag as a low-complexity, low-cost, and effective alternative for cooperative target recognition. The novel metasurface can execute reflection, absorption, and detection functions within a singular structure, capable of switching among the three impedance states of p-i-n diode. Following the cooperative target identification mechanism, the metasurface tag applies time-modulated sequences to the cooperative radar signals. The realized different discrete frequency components give distinguishable coding signatures to it. While for non-cooperative radar signals, the tag operates in an absorbing state to achieve EM stealth. A prototype working within Ka-band is fabricated and tested, revealing features like a wideband, dual-polarization amplitude modulation, and detection functionality. These outcomes align with simulation expectations and validate the functionalities of the metasurface tag. Further, the anechoic and real scenario experiments demonstrate that the metasurface tag offers the ability to assist in target recognition with reading stability and coding extensions.

This paper proposes a low-profile metasurface antenna capable of beam direction manipulation that operates within the millimeter-wave frequency spectrum. The design encompasses a non-offset substrate-integrated waveguide (SIW) slot array antenna and a near-field Huygens metasurface. The SIW slot array antenna functions as a source, providing spherical wave excitation, whereas the near-field Huygens metasurface enable precise tailoring of the phase distribution above the SIW slot array antenna. The Huygens response of the meta-atom and the suppression of the open stopband (OSB) in the non-offset SIW slot array antenna are comprehensively illustrated. A simulation model that integrates the functionalities of both wave port and Floquet port is introduced to achieve more accurate electromagnetic responses from the near-field Huygens meta-atom; thereby facilitating enhanced control over electromagnetic wave propagation. To validate the aforementioned benefits, three prototype antennas with varying pointing angles were meticulously designed, fabricated, and experimentally evaluated. The results exhibit good concordance between the simulations and measurements across several key parameters, including the reflection coefficient and radiation pattern.