Rim-Mounted Reconfigurable Surfaces for Interference Nulling in Focus-Fed Axisymmetric Reflector Antenna Systems

This thesis addresses the use of an electronic reconfigurable surface (ERS) attached to an axisymmetric paraboloidal reflector antenna to mitigate interference through nulling for radio astronomy applications. The ERS is a reflectarray that consists of multiple elements, which can be electronically controlled to modify the reflected field. Previous research focused on a "conformal" system with elements placed on a parabololoidal surface extending beyond the unmodified reflector. These studies concluded that nulling could be achieved without compromising the gain and shape of the main lobe. This thesis builds on previous research by addressing two topics. The first topic is minimization of the ERS rim width. A closed form expression for the minimum width required for effective nulling in the close-in sidelobes is derived in this thesis. The second topic addressed in this thesis is ERS configurations comprised of flat panels as an alternative to the conformal ERS implementation. Flat panels may be easier to manufacture compared to their conformal counterpart. Flat panel ERS implementations are evaluated, and it is concluded that they are a suitable alternative to conformal ERS implementation.