Optically transparent microwave metamaterial absorbers

Abstract Optically transparent microwave absorbers based on metamaterials demonstrate exceptional microwave absorption performance while maintaining high optical transmittance, showcasing significant potential for applications in modern communication, defense, and architectural fields. Transparency in the visible light spectrum is primarily achieved through material selection and structural optimization. The artificially designed metamaterials based on transparent resistive films can be used to achieve devices with excellent wave absorption characteristics in the microwave frequency band. In this paper, we systematically review the research progress in the domain of optically transparent microwave metamaterial absorbers. We first introduce the implementation principles of optically transparent microwave metamaterial absorbers from the perspectives of transparency and wave absorption, laying the foundation for the in-depth discussions in subsequent sections. Subsequently, we focus on the research progress of optically transparent microwave metamaterial absorbers. In this paper, microwave metamaterial absorbers are classified into three types: passive absorbers, tunable absorbers and adaptive absorbers. Passive and tunable absorbers are further discussed based on their structural classifications. This paper summarizes the current research status and technical bottlenecks of optically transparent microwave absorbers while envisioning their extensive applications in stealth technology, wireless communication, and multifunctional devices. While challenges persist in balancing thickness, bandwidth and transmittance, future advancements in novel material, innovative structural designs, and manufacturing processes are expected to enable the realization of efficient, intelligent, multifunctional absorbers.