Sidelobe Modification for Reflector Antennas by Electronically-Reconfigurable Rim Scattering

TL;DR

This paper introduces a passive, electronically reconfigurable rim on reflector antennas to modify sidelobes and cancel interference, enabling flexible sidelobe control with minimal impact on main lobe characteristics.

Contribution

It presents a novel passive reconfigurable rim technique for reflector antennas that achieves sidelobe cancellation using a small, frequency-independent surface area.

Findings

Reconfigurable rim covers about 11% of the reflector surface.

Effective sidelobe nulling achieved from any direction outside the main lobe.

1-bit phase control suffices for similar performance with an additional 6% surface area.

Abstract

Dynamic modification of the pattern of a reflector antenna system traditionally requires an array of feeds. This paper presents an alternative approach in which the scattering from a fraction of the reflector around the rim is passively modified using, for example, an electronically-reconfigurable reflectarray. This facilitates flexible sidelobe modification, including sidelobe canceling, for systems employing a single feed. Applications for such a system include radio astronomy, where deleterious levels of interference from satellites enter through sidelobes. We show that an efficient reconfigurable surface occupying about 11% of the area of an axisymmetric circular paraboloidal reflector antenna fed from the prime focus is sufficient to null interference arriving from any direction outside the main lobe with little change in the main lobe characteristics. We further show that the required surface area is independent of frequency and that the same performance can be obtained using 1-bit phase control of the constituent unit cells for a reconfigurable surface occupying an additional 6% of the reflector surface.