Design of Broadband Dielectric Collimators With the Phase-Field Design Method for Applications in the X-Band Range

Abstract

An electromagnetic (EM) collimator is a device to narrow EM wave propagation in a desired way. Recalling the device has been widely used in several EM applications such as radar detectors, it is encouraged to maximize its beam-focusing capacity over a wide operating band. This study aims to design mono-scale all-dielectric collimators, which exhibit a broadband functionality in the X-band range. The phase-field design method is employed to systematically derive topological configurations of the broadband collimators. Two types of collimators for steering beams into different focusing zones are under consideration. In order to iteratively improve the frequency response characteristics during design update process, the statistical moments of the frequency response representing the collimator performance are directly incorporated into a multiobjective optimization formulation. All-dielectric prototypes were fabricated by additive manufacturing, accommodating complicated geometrical entities. The improvement over frequency dependence is validated through numerical simulations and experimental confirmation with the printed structures.