Flexible Liquid Metal Frequency Selective Surface With Tunable Second-Order Bandpass Response

A flexible, fluidically tunable, second-order bandpass frequency selective surface (FSS) operating in the X-band is presented in this paper. The proposed multilayer structure utilizes elastomeric microfluidic channels to enclose and allow precise movement of gallium-based liquid metal slugs, while preserving its mechanically flexible nature. The liquid metal slug tuning elements are integrated into two periodic Jerusalem cross layers, which are coupled together through a periodic square aperture layer. By pneumatically shifting the position of the liquid metal slugs, the capacitance between adjacent Jerusalem cross elements can be linearly tuned, with high precision, to shift the operating frequency range of the filter in real time. Full-wave simulation of the bandpass FSS is performed for three different liquid metal slug orientations to demonstrate the tunability of the design.