A dipole with active metasurface reflector for polarization reconfigurability

Dissertation (MEng (Electronic Engineering))--University of Pretoria, 2022.In recent years reconfigurable antennas have gained a lot of attention for the advantages they present for diversifying the capabilities of communication systems. Many types of reconfigurable antennas exist that have pattern, frequency, and polarization diversity. These antennas are reconfigured either by mechanical rotating surfaces or by enabling specific sections of a structure with electrical switches. The use of an active reflective metasurface to design an antenna system with reconfigurable polarization was particularly interesting as little research have been done on the topic and presented an interesting concept to expand upon. This study focusses on the concept of a reconfigurable antenna based on an active reflective metasurface with reconfigurable polarization. Subsequently, an antenna system based on an active reflective metasurface combined with a planar dipole is proposed to achieve reconfigurable polarization. The aim of this antenna is achieve reconfigurable polarization through electrical switches positioned on the reflective metasurface. The polarization of the designed antenna can be switched between linear and circular polarization states through the use of positive-intrinsic-negative (PIN) diodes on the reflective metasurface. The designed antenna was manufactured and tested and functioned as expected. The measured results correlated well with the simulated results. The antenna has a physical size of 308 x 162 x 35 mm3 with an impedance bandwidth of 4.5% in the linear state, and 7% in the circular state, as well as an axial ratio bandwidth of 8.3%. This gives the antenna an effective bandwidth of 4.5% in the linear state and 7% in the circular state. The final measured results were degraded due to unexpected interference from the biasing network used to control the PIN diodes. However, even with the interference, the concept of a reconfigurable antenna based on an active reflective metasurface was proven. This research contributed to the field of antenna engineering with the focus on expanding the field of reconfigurable antennas.Electrical, Electronic and Computer EngineeringMEng (Electronic Engineering)Unrestricte