A multifunctional terahertz metamaterial based on VO 2 with tunable phase transition is proposed, integrating narrowband absorption and polarization conversion. The device features a multilayer VO 2 /SiO 2 structure that exhibits excellent phase-transition responsiveness. In the metallic state, the device exhibits absorption exceeding 99% at 0.40, 1.15, 1.37, and 1.75 THz. In the insulating state, it serves as a polarization converter, realizing linear-to-cross polarization at 0.49-0.57, 1.06, and 1.52 THz, linear-to- left-hand circular polarization (LHCP) at 0.37-0.44, 0.68-1.04, and 1.20-1.49 THz, and linear-to- right-hand circular polarization (RHCP) at 1.08 and 1.57 THz, with normalized ellipticity approaching ±1. The device exhibits stable performance under varying polarization and incident angles, offering promising applications in spectral sensing, polarization control, and adaptive stealth.

This paper presents a highly frequency-selective polarization converter (FSPC) operating in the X-band. The proposed structure comprises three metallic patch layers, enabling efficient polarization conversion within the operating band while exhibiting strong reflection characteristics outside the band, accompanied by an extremely narrow transition region. The underlying polarization conversion mechanism is systematically elucidated through an analysis of the induced surface current distributions. Simulation results demonstrate that the proposed FSPC achieves a polarization conversion efficiency exceeding 90% over the frequency range of 8.08-11.94 GHz, while maintaining stable performance for incident angles up to 60°. To further validate its applicability in stealth-related scenarios, a 6×6 chessboard-configured FSPC array is investigated. The results indicate that a monostatic radar cross-section (RCS) reduction exceeding 10 dB can be achieved across the X-band, highlighting the proposed design as a promising candidate for polarization manipulation, radar stealth, and related electromagnetic applications.

This paper presents a transparent dual-polarized sound-insulating and thermal-insulating electromagnetic absorber based on indium tin oxide (ITO) films and polymethyl methacrylate (PMMA). Simulation results demonstrate that the absorber achieves broadband absorption over the 0.87-6.7 GHz range, with a relative bandwidth of 154%. The absorption mechanism is further clarified through analysis of surface current distributions and equivalent circuit model (ECM). Experimental measurements show good agreement with the simulation results. Compared with conventional absorbers, the proposed structure not only effectively absorbs electromagnetic waves but also integrates multiple functions, including optical transparency, sound insulation, and thermal insulation. It is highly suitable for multifunctional electromagnetic stealth applications requiring the integration of transparency, acoustic isolation, and thermal isolation, and shows broad prospects for window-integrated applications, particularly in the area of electromagnetic stealth for windows of military assets, such as military vehicle windows and aircraft pods.

A broadband frequency selective rasorber (FSR) of transmission-absorption-transmission (T-A-T) type is proposed. The lossy layer is composed of a split square ring integrated with four resistors, while the lossless layer consists of a square ring combined with a square patch that is perforated with sector-shaped apertures. Full-wave simulation results indicate that the proposed FSR achieves two wide passbands covering 3.34 – 11.43 GHz and 16.06 – 20.93 GHz, with peak insertion losses of −0.96 dB and −0.53 dB, respectively. Between the two transmission bands, an absorption band is formed in the frequency range of 12 – 13.4 GHz, where the absorptivity exceeds 80%. Furthermore, a 10×10 array sample is simulated and analyzed, and the results demonstrate that the proposed design realizes a minimum radar cross section (RCS) reduction of 8 dB within the frequency range of 4.92 – 19.63 GHz.

This paper presents an II-shaped polarization conversion metasurface (PCM) for radome applications, aiming to reduce the backward radar cross-section (RCS) of antennas while enhancing their radiation performance. The proposed II-shaped unit structure achieves a polarization conversion ratio (PCR) exceeding 90% across two independent frequency bands (5.4-7.92 GHz and 11.43-17.55 GHz), enabling effective manipulation of the polarization state of incident electromagnetic waves. The core innovation of the proposed design lies in its single-layer structure enabling dual-band polarization conversion, where the lower frequency band is primarily generated by the outer rectangular metal patch, while the higher frequency band is produced by the central I-shaped metal strip, with independent tunability for each operating band. Furthermore, by arranging the PCM units in a checkerboard configuration, a 180 degrees reflection phase difference between adjacent units is introduced, leading to significant suppression of co-polarized backward scattering. Simulation results demonstrate considerable reduction in the monostatic RCS within the target frequency bands. This work provides a practical solution for the design of radomes that combine low observability with improved antenna performance.

A broadband tunable dielectric flexible substrate electromagnetic (EM) absorber/reflector is designed and fabricated. The structure consists of upper, middle and lower layers. The upper layer features a copper foil etched with a center symmetrical subwavelength cell structure on a dielectric substrate. The middle layer is composed of PMI foam, metal aluminum foil, and a PIN diode. The lower layer consists of a conductive metal layer. The absorption $/$ reflection state of the structure is achieved by the on/off state of the PIN diode. The design integrates the structural elements with the feeding network, which effectively reduces the coupling effect of additional bias lines. The structure unit consists of two symmetrically designed diodes to guarantee dual polarization. In contrast to similar switchable absorbers/reflectors, its absorption depth can be dynamically adjusted by an external bias current. Meanwhile, it features low weight and low power consumption, with an energy consumption of only 0.096 W per square decimeter. The working mechanism of the EM absorber/reflector is explained through the distribution of electric field and surface current, and its working principle is analyzed using the equivalent circuit model (ECM). Finally, the design is fabricated and functionally measured. The measurement results agree well with the simulations.

An efficient method for electromagnetic (EM)-thermal field analysis of a frequency selective absorber (FSA) based on the finite-difference time-domain (FDTD) algorithm is proposed. Firstly, the EM process of the FSA under normal incidence are simulated and analyzed using traditional FDTD algorithm. Secondly, the EM losses mainly caused by the lossy resistors are obtained and used as heat source terms to analyze thermal process. To accelerate the thermal simulation process, the alternating direction implicit (ADI) FDTD method is adopted to efficiently solve the thermal effects of the whole structure. The method is proved by comparing with commercial software. After that, the EM-thermal field coupling process is analyzed and the efficiency of the method is compared.

This paper proposes a single-layer, single-port beam reconfigurable metasurface antenna based on characteristic mode analysis (CMA). Simulation results show that the antenna can provide four directional beams pointing in different directions and one omnidirectional beam at the Wi-Fi band (5GHz), which can flexibly respond to user needs in various scenarios. To maintain the structure’s simplicity, the mode behavior of the 3*3 circular metasurface structure is analyzed. After that, the structure is optimized using the CMA to gain desired characteristic mode currents and far-field radiation distributions. The final design shows both thin and light volume, thus making it easier to integrate into wireless communication systems.

An active frequency selective surface (FSS) system is designed, in which the working states are wirelessly controlled by the amplitude of the incoming electromagnetic wave. A sensing module is designed to detect the incident EM wave amplitude with an adjustable threshold, capable of providing a controllable output voltage of up to 36 V. This voltage is then utilized to control the active FSS, enabling transmission or reflection functions in 2.28-2.48 GHz. The sensing module and the FSS are fully integrated, simulated, and experimentally validated. The final measurement results agree well with the simulations, thus proving the effectiveness of the proposed technique.

This paper investigates temperature variations of a water-based absorber under the incidence of high-power transient electromagnetic (EM) waves using a nonuniform HIE/ADI FDTD Method. The hybrid implicit-explicit (HIE) method is adopted for the EM process, while the alternating direction implicit (ADI) method and fitting extrapolation method are used in the heat conduction process to improve calculation efficiency. EM-thermal coupling is achieved via transient power density, which is caused by the water dispersion simulated using the Debye model. The effectiveness of the method is validated through comparisons with the conventional FDTD method and the CST software.

The design of artificial electromagnetic materials (AEMMs) depends highly on full-wave numerical simulations or equivalent circuit model (ECM)-assisted analysis. This work proposes an intelligent design method using a deep learning (DL) technique based on the residual neural network (ResNet) to improve its efficiency. Firstly, adopting pixeled matrix modelling methods enhances the freedom of design. Next, the staircase approximation is utilised for the S-parameter curve, which also describes the required electromagnetic (EM) property to be used in the training process. These processed samples, along with their corresponding labels, are transformed and fed into ResNet for training. After these procedures, the structural matrix of the desired curve can be predicted through well-trained networks. To validate the effectiveness of the method, typical notched-band frequency selective absorbers (FSAs) are designed, while the reflective band can easily be adjusted. Compared with conventional methods and other deep neural network (DNN)-based methods, this method performs more efficiently and accurately. Finally, an illustrative sample is fabricated to validate the prediction result.

A multifunctional transmissive metasurface polarizer operating in the S-band is proposed. The structure adopts a sandwich-style design: the top and bottom layers consist of metal grating structures integrated with diodes to achieve polarization selection, while the intermediate layer incorporates a 45°-tilted metal strip array for cross-polarization conversion. Dynamic switching between polarization separation/conversion modes can be realized by controlling the biasing states of the diodes. Simulation results demonstrate that in polarization separation mode, the operating bandwidth fully covers the S-band. In polarization conversion mode, the polarization conversion rate (PCR) is greater than 80% across 1.8–4.5GHz (relative bandwidth of 85.7%), while maintaining stable performance under oblique incidence angles within 40°.

A deep-learning-based antenna inverse design method is proposed, which utilizes a residual neural network (ResNet) to construct an inverse model to directly predict the antenna structure from the target’s scattering parameters. The one-to-many problem can be solved to some extent by introducing a pre-trained forward model. The simulation results show that the method can effectively predict a reasonable antenna structure and ensure its physical feasibility, providing an efficient way for smart antenna design.

A dual-band Cassegrain antenna with a designed FSS as a sub-reflector is designed. The sub-reflector transmits S/C-band EM waves and reflects Ka-band, thus realizing dual-band working for the reflector antenna. The simulation results showed that the achieved Cassegrain antenna has a gain of 30.78dBi in the C-band and 27.88dBi in the Ka-band. Therefore, the efficiency is significantly improved due to reuse of the dual-band sub-reflector.

This paper mainly studies the changes in physical properties and the impact on transmission characteristics of an antenna radome with a high-temperature ceramic substrate Pyroceram 9606 under high-power microwave radiation. We conducted an electromagnetic, thermal bidirectional coupling simulation to obtain the optimal performance of the radome based on the relationship between antenna size, input power, and coverage distance with environmental temperature changes. Then, the electrical performance of the panel radome under steady-state temperature is studied. In a high-power environment, the antenna's beamwidth, aiming error, and insertion loss increased by about 0.2 degrees, 0.5 degrees, and 0.5dB compared to a normal temperature environment. The simulated anti high power electrical design provides applicable reference models and rules for the anti-electrical design of radomes.

A dual-band active frequency selective surface (AFSS) with switchable frequency response between the C-band and X-band is proposed. The unit of the AFSS structure consists of a reconfigurable layer, a thin dielectric substrate, and a feeding network layer from top to bottom. The interdigital resonator is introduced in the top layer to generate a bandpass response. By controlling the states of the PIN diodes welded in the middle of the interdigital resonator, the resonant frequency of the designed structure can be reconfigured. Full-wave simulation results show that the dual-band AFSS can operate at 5.12 GHz (OFF state) or 8.77 GHz (ON state), with dual-polarization stability and high angular stability up to 60 degrees. Additional an equivalent circuit model is used to analyze the working mechanism of the AFSS structure.

This paper proposes a 2.5-dimensional (2.5D) frequency-selective absorber (FSA) with two absorption bands on either side of the transmission window, which is realized using a bandpass FSS with two transmitting poles and two transmitting zeros. A wider transmission passband with good frequency steep- drop characteristic is achieved by printing two layers of metal rings and circular combined plates to form two LC resonance circuits and a loaded metal via in the middle. The results indicate that the FSA possesses frequency-selective characteristics and has the potential to integrate radiation properties.

In this paper, the influence of geometric parameters of seeker radome on the electrical performance of ballistic missile are simulated and analyzed. By establishing an overall model of the seeker antenna and radome, and using full-wave simulation software, the influence of geometric parameters such as order of radome curve, half cone angle, and the size of ball head radius on the transmission rate and boresight error of radome are compared and analyzed. Through a series of simulation analysis, the research results can provide strong data support for the selection of missile radome shape and the prediction of the influence degree of ablation amount on the electrical performance of radome.

A dual-band Fabry-Perot (FP) antenna structure loaded with an energy selective surface (ESS) is proposed to adapt to a complex electromagnetic environment. A patch antenna is first designed and incorporated into an FP structure to increase performance. After that, the upper surface is designed to achieve the ESS function by loading Schottky diodes symmetrically around the center of the unit's surface structure. The performance of the whole structure is analyzed. The final design presents a working bandwidth in the 6.25-7.45GHz and is capable of energy selection to outcoming incident waves while the antenna's performance remains.

This letter proposes a frequency selective surface (FSS) inverse design method based on a residual learning framework. Traditional FSS designs that meet industrial demands depend on designers' experience and repeated simulation iterations. The proposed method, however, can automatically design the FSS structure parameters that meet specific frequency response requirements. The residual-learning-based method is not only validated by two passband FSS design examples but has shown advantages over the commonly used convoluted neural network-based methods.