Multi-Stability Reconfigurable Deployable Quadrifilar Helix Antenna for Disaster Struck and Infrastrure-less Areas

Abstract

Communication needs in devastated areas that lack any supporting infrastructure necessitate lightweitght antenna systems that are better suited for emergency personnel. Furthermore, ensuring communication to satellite and terrestrial nodes is a crucial factor in areas with diminished infrastructure or under emergency conditions. This thesis has two main objectives. The first objective is to design a bistable deployable antenna structures such as the Quadrifilar Helix Antenna (QHA) for deployment in disaster-stricken areas. The design process involves combining reconfigurable and deployable elements to create light-weight designs that can be activated as needed, thereby restoring communication in areas with limited infrastructure. At first, this thesis presents a bi-stable deployable QHA that passively reconfigures its polarization and radiation pattern. The proposed structure is composed of counter-rotating helical strips, connected by rotational joints to allow a change in the helix height and radius. Each helical strip is composed of a fiber-reinforced composite material to achieve two stable deployed states. The antenna is suitable for terrestrial and satellite communication since it has an almost omnidirectional pattern for one stable state and a circularly polarized directive pattern for another stable in the L-band. Hence, this thesis introduces an antenna solution for infrastructure-less areas that is portable, agile, and passively reconfigured. The thesis then leverages bistability to propose a Reconfigurable Intelligent Surface (RIS). RISs have garnered significant interests for their potential to develop advanced wireless communications environments. Consequently, RISs can substantially enhance the capacity and coverage of wireless networks. They play a vital role in creating the intelligent propagation environments necessary for next-generation communication systems expected to roll out around 2030, including 5G and 6G technologies. Bistable RIS structures prepare for a generation of communication systems that can be deployed and reconfigured on demand with minimum power requirements to ensure communication needs are met. The presented RIS operates at a frequency of 1.7 GHz and presents seven reconfigurable radiation states. By changing the states of the unit cells, the RIS can redirect its radiation pattern.