Hybrid Active and Microfluidic Modulated Reconfigurable Frequency Selective Surface

In this paper, a reconfigurable frequency selective surface (FSS) is presented for integrating rapid switching and wideband tuning functions into a single design. The proposed design mainly consists of two layers. Metallic patterns, integrated with two PIN diodes, are embedded on the F4B substrate on the top layer. A microfluidic channel layer, incorporating two coarse-tuning channels and one fine-tuning channel, is set at the bottom. This design facilitates fast switching between reflection and transmission states by actively controlling the PIN diodes. Meanwhile, liquid metals (LMs) are employed in the microfluidic channels for the frequency tuning function. In the transmission state, the design enables wideband and discrete frequency tuning from 7.36 GHz to 8.76 GHz by injecting or discharging LMs in the coarse-tuning channels. In addition, it can realize high-precision and continuous frequency tuning by adjusting the relative position of the LM segments in the fine-tuning channels.