In modern military strategic and tactical operations, achieving low detectability of targets has become a critical requirement. With the continuous enhancements in battlefield intelligence and reconnaissance capabilities, as well as the steady improvements in sensor technology, traditional single-band stealth techniques are no longer sufficient to address the complexities of modern warfare. Consequently, the ability to counter multispectral sensing systems is crucial for ensuring the survival and operational effectiveness of military units. In this study, we propose and successfully fabricate a novel, high-integrity, ultra-wideband multispectral stealth material. This material is primarily composed of two functional layers: an absorbing layer specifically designed for radar frequencies and a shielding layer for the infrared spectrum. This configuration allows the material to manage electromagnetic waves over a broad bandwidth, effectively achieving signal shielding and a significant reduction in radar cross section (RCS) during radar detection. Simultaneously, the infrared shielding layer has a very low emissivity, thus reducing detectability in the infrared spectrum. To validate the material’s effectiveness, systematic experimental fabrication and testing are conducted on material samples. The results demonstrate that the material exhibits excellent stealth characteristics within the specified frequency ranges, with experimental outcomes consistent with simulation predictions.

A key challenge in designing multifunctional devices integrated with multi-layer metasurfaces is eliminating interference among various functionalities. In our structural design process, we employ joint simulations using MATLAB and CST to optimize the geometric parameters of the structure. The MATLAB Optimization Toolbox is used to refine the post-processing outputs from CST, ensuring an optimal design structure. For the simulations, unit cell boundary conditions are applied along the X and Y axes to simulate a periodic array model, while an open boundary is set along Z-axis. Radar stealth performance is measured using the arch method for reflectivity testing, where two double-ridged horn antennas are positioned on a rotating arch bracket—one as the transmitter and the other as the receiver—connected to an N5247A vector network analyzer through low-loss test cables. To minimize surrounding scattering and unwanted reflections, wedge-shaped foam absorbers are placed around the sample. Calibration is performed using a metal plate matching the size of the test sample. For infrared stealth measurements, the FIRE ONE PRO infrared thermal imager is used. A layer of non-woven fabric is placed on a heating stage to ensure uniform temperature distribution. Once the stage is preheated and stabilized at 100 ℃, the metasurface and a similarly sized piece of PET material are placed on the stage, and data are collected using the infrared thermal imager for both the control and experimental samples.

The metasurface demonstrates wave absorptivity greater than 90% in the frequency range of 4.16‒23.15 GHz, with an RCS reduction exceeding -10 dB (Fig. 3). It achieves good impedance matching with free space within its operational bandwidth, resulting in excellent wave absorption (Fig. 4). Analysis of the contributions of different structural layers to the wave absorption performance reveals that radar stealth is primarily due to electromagnetic interactions between the resonators in the radar absorbing layer (RAL) and the electromagnetic waves (Fig. 5). The distribution of surface currents and losses at resonance frequencies indicates the resonant modes and loss mechanisms (Fig. 6). An equivalent circuit model of the metasurface is developed, and simulations are verified using circuit simulation software (Fig. 7). Analysis of the metasurface’s structural parameters defines a tolerance range suitable for practical applications (Fig. 8). The metasurface shows stability with respect to both polarization angle and incident angle of the incident electromagnetic waves, maintaining absorptivity above 80% for incident angles from 0° to 50° (Fig. 9). A sample consisting of 25×25 units is fabricated and tested using both the arch method and infrared imaging. The test results for radar and infrared stealth closely match the simulated predictions Figs.10 and 11.

In this study, we present the design and fabrication of a highly integrated ultra-wideband multispectral stealth metasurface, which effectively combines an RAL with an infrared-shielding layer, achieving stealth performance across both radar and infrared bands. The material exhibits over 90% absorptivity in the radar frequency range of 4.16‒23.15 GHz, with an RCS reduction of at least -10 dB. In the infrared range of 3‒14 μm, the emissivity remains below 0.23. By analyzing the equivalent current distribution, loss distribution, and the equivalent circuit model, we elucidate the metasurface’s working principles and discuss its angular stability. A sample metasurface is fabricated and tested for radar and infrared stealth capabilities, showing excellent agreement between experimental and simulated outcomes.