We report a multifunctional metamaterial composite structure that not only provides the broadband radar and thermal infrared bi-stealth function but also possesses an in-band microwave transmission window and high optical transparency. It is composed of four metasurface layers made of indium tin oxide (ITO) films with different surface resistances, which are specifically designed to sequentially control the infrared emission, microwave absorption and transmission. The fabricated sample exhibits a low reflectivity less than 10% in 1.5-9 GHz and a transmission peak of 50% around 3.8 GHz up to the incident angle of 30 degrees. In the infrared atmosphere window, a low thermal emissivity of about 0.52 is achieved. Meanwhile, it keeps good optical transparency by the use of the ITO films. The optically transparent, low-infrared-emissivity, radar-reflectionless and frequency-selective-transmission properties will enable the promising application of communication-compatible multispectral stealth technology.

No abstract

No abstract

In the past years, wireless communications based on digital coding metasurfaces have gained research interests owing to the simplified architectures and low costs. However, in most of the metasurface-based wireless systems, single-polarization scenario is used, limiting the channel capacities. To solve the problem, multiplexing methods have been adopted, but the system complexity is inevitably increased. Here, a space-frequency-polarization-division multiplexed wireless communication system is proposed using an anisotropic space-time-coding (STC) digital metasurface. By separately designing time-varying control voltage sequences for differently oriented varactor diodes integrated on the metasurface, we achieve frequency-polarization-division multiplexed modulations. By further introducing different time-delay gradients to the control voltage sequences in two polarization directions, we successfully obtain space-frequency-polarization-division multiplexed modulations to realize a new-architecture wireless communication system. The new communication system is designed with compact dual-polarized meta-elements, and can improve the channel capacity and space utilization. Experimental results demonstrate high-performance and real-time transmission capability of the proposed communication system, confirming the potential applications in multiple-user collaborative wireless communications.

No abstract