A Stretchable Liquid Metal Coaxial Phase Shifter

Abstract

Presented is a stretchable liquid metal coaxial phase shifter constructed of a liquid metal center conductor, a liquid metal shield in the shape of a hollow cylinder, and a stretchable rubber-based polymer (Ecoflex™00-30) which encases and insulates the liquid metal. The design builds on and enhances previous research consisting of the same liquid metal phase shifter but with the shield consisting of five hand-woven liquid metal strands. By modifying the design of the shield to consist of a hollow cylinder rather than woven strands, TEM breakdown at high frequencies is decreased, and the phase shifter improves its transmission and reflection coefficients at higher frequencies. Prototype results show a transmission coefficient (S21) better than -1.8 dB and a reflection coefficient (S11) better than -10 dB with a 40 mm stretch (62%) and a frequency band of 1 GHz to 4 GHz.