Enhancing the directivity of a radiating array element for an optical true-time-delay network

Abstract

Abstract The directivity of a horn antenna as a true-time-delay array element of an optical beam-forming network is enhanced by using a graded index dielectric lens. The proposed refractive index distribution of the lens is designed to mitigate the phase error at the antenna aperture while keeping the antenna reflectionless. Ray-tracing-based optimization is carried out to achieve the best design parameters and modify the horn’s body. Realization of the lens is also demonstrated by discretizing the refractive index of the lens into several layers. The half-power beamwidth value of an example horn antenna is divided by four using the proposed lens. The functionality of the proposed lens is verified by conducting ray-tracing and full-wave simulations using COMSOL.