Fully Printed Flexible and Reconfigurable Antenna With Novel Phase Change VO2 Ink Based Switch

Abstract

Vanadium dioxide (VO2) is identified as an attractive phase change material which can be used for switchable or reconfigurable RF components. At present, VO2 is deposited by expensive and complex thin film micro-fabrication techniques. With the surge in low cost, additively manufactured or printed components, it will be beneficial to print phase change materials or switches as well. However, these kinds of functional inks are not available commercially. In this work, we present, for the first time VO2 based ink that changes its conductive properties based on temperature. Precisely, it displays insulating properties at room temperature (resistance of ~1.2KΩ in the off-state), but becomes conductive when heated around 70°C (resistance of <10Ω in the on-state). Here, we demonstrate a fully printed thermally controlled reconfigurable antenna based on VO2 ink and a custom silver-organo-complex (SOC) ink supported on flexible kapton substrate. In a planar inversed F antenna (PIFA) configuration, when the switch is in the OFF state, the antenna operates at 3.5 GHz band for 5G communications, and when it is in the ON state, it operates at 2.4 GHz band suitable for WiFi, Bluetooth or Zigbee applications. The antenna performance is assessed in different bending conditions where it achieved a maximum gain of ~2 dBi at 3.2GHz with concave bending position.