Highly Scalable, Flexible, and Frequency Reconfigurable Millimeter-Wave Absorber by Screen Printing VO2 Switch Array onto Large Area Metasurfaces

Abstract

Flexible and reconfigurable (FAR) electronics are in high demand for emerging applications, including wearable, bioelectronics, and internet of things. Highly scalable antenna arrays or periodic surfaces are required for high directivity or electromagnetic wave path control, particularly for 5G millimeter-wave (mm-wave) due to high path losses. Conventional lumped tuning components have limitations related to scalable FAR electronics and hence highly scalable and flexible vanadium dioxides (VO2) switch array is proposed for mm-wave applications. A frequency reconfigurable mm-wave absorber is designed by screen printing the VO2 switch array to demonstrate the proposed approach feasibility for large scale electronics, achieving high scalability, tunability, and flexibility because the 40 µm thick VO2 switch array satisfies radio frequency switch requirement. Flexibility and repeatability are tested up to 2000 bending cycles with 25 mm bending radius, and tunability and scalability are demonstrated with 300 ON/OFF ratio, and 98% product yield for 400 switches printed on 144 × 144 mm2 polyethylene terephthalate substrates. Absorption frequency is switchable from 14 to 28 GHz at 150 mm bend radius while retaining better than 90% absorptivity as a frequency reconfigurable mm-wave absorber. Therefore, the proposed VO2 switch array would be suitable for scalable 5G and 6G FAR electronics.