Side lobe level reduction in horn antennas using graphene

This paper proposes a novel method to suppress the side-lobe level of pyramidal horn antennas using graphene sheets. Using numerical full wave simulation, it is shown that loading graphene sheet inside the horn antenna leads to a tapered aperture field distribution, resulting in side-lobe level reduction. Graphene length and surface impedance are optimized with the purpose of achieving a low side-lobe level of -31dB while keeping the antenna gain as high as possible. In comparison to traditional metallic horn antennas (Metal-based horn), hybrid graphene-metal horn (Graphene-based horn) presents a truly smooth radiation pattern and improves the side-lobe by 17.6dB. In essence, graphene sheet acts as a high impedance surface (HIS) and hinders electromagnetic energy from reaching to horn aperture edges, so diffraction phenomenon is drastically diminished. Consequently, ripples and minor lobes are excluded from the radiation pattern of the proposed antenna.