Leveraging the use of Liquid Metal Channels to Reconfigure Antennas’ Impedance and Radiation Performance

Abstract

The advent of liquid metals in the domain of RF system has opened new avenues for the researchers in smart antenna designs. Reconfigurability of antenna’s characteristics has been a keen topic of interest for the past several decades. Under this umbrella, various techniques have been employed by the designers to achieve the desired tunability. These include but are not limited to, use of varactor and p-i-n diodes, magnetic materials, ferroelectric materials, MEMS. Alongside these, embedding of metallic microfluidic channels within the antenna substrate has emerged as the most recent and novel technique. Metallic fluids, with their high conductivity and fluid nature, provide unique ideas to the designer. This thesis explores two different antenna designs that rely on EGaIn channels, a non-toxic metallic fluid, to achieve frequency switching and polarization reconfigurability. A circular patch antenna is designed at 2.5 GHz on a Rogers 5880 substrate with an integrated artificial magnetic conductor layer to boost its gain. Acrylic substrates have been used to realize EGaIn channels between the antenna and the ground plane. By optimizing the AMC for both the vacuum and metal-filled states, the design achieves efficient frequency switching from 2.5 GHz to 1.6 GHz with stable gain performance. This provides a proof-of-concept for how a switchable artificial magnetic conductor can be designed using such a technique. On the other hand, the second design validates polarization diversity with the application of EGaIn channels within the antenna substrate. A single patch antenna is shown to operate both with linear and circular polarizations using this concept at 2.5 GHz. Both the designs, i.e., polarization reconfigurable and frequency switchable, rely on microfluidic channels integrated into the acrylic substrates, allowing the antennas to switch between two or more operational states. The research thus highlights the potential of microfluidic channels to achieve reconfigurability in modern antenna systems.