Sidelobe Modification for Reflector Antennas by Electronically Reconfigurable Rim Scattering

Weight Selection for Pattern Control of Paraboloidal Reflector Antennas with Reconfigurable Rim Scattering

“…However, there may be multiple angles that we wish to null. Further, as we will show later, nulling a particular angle may cause small changes to the main lobe gain (this was also shown in [5]). This variation may be tolerable in some applications, but in radio astronomy it can be a significant problem [2].…”

“…The antenna system assumed in this paper is presented in Figure 1. Following the development in [5] we assume the equivalence of transmit and receive patterns and calculate the transmit patterns using physical optics (PO). The total electric field intensity E s scattered by the reflector in the far-field direction ψ is given by 2…”

“…Recently, another approach for cancelling (or generally modifying) the sidelobe(s) of a reflector antenna pattern has been proposed that uses reconfigurable rim scattering [5]. In that work it was shown that by using reconfigurable segments along the rim of a refletor antenna that introduce phase shifts to the reflected signal, sidelobe patterns can be altered and even cancelled.…”

“…That work examined prime focus-fed circular axisymmetric paraboloidal reflectors, although the concept is not limited to that type of system. Specifically, it was shown in [5] that as long as sufficient surface area along the rim is reconfigurable, sidelobe cancellation is possible. Additionally, the work showed that cancellation did not require continuously variable phase, but was in fact possible using quantized phase shifts (viz., binary or quaternary).…”

“…In the current work we build on the idea proposed in [5] by describing algorithms for determining the weights needed to cancel sidelobes at specific angles from the reflector axis in an open-loop fashion. More specifically, we first derive the optimal weights needed to cancel sidelobes at an arbitrary angle ψ.…”