In this chapter our main objective is to review our previous and current research efforts in this promising area of directive NP -based NAs. Focus will be placed on both symmetric and asymmetric two-dimensional (2D) and three-dimensional (3D) passive and active (with constant gain model) cylindrical NPs with appropriate layer designs, perforations or eccentricities. We will illustrate how perforations essentially only enhance the near-field radiation properties, while asymmetries introduced through the layer eccentricities also enhance the far-field radiation behaviors. We will also describe how symmetric multilayered cylindrical NPs with tailored scattering coefficients lead to super-directive and needle -like radiation patterns in forward as well as backward directions. Our results will be illustrated by various near-and far-field distribution results obtained either analytically and/or numerically with full-wave commercial packages. The canonical problem solutions prove not only to be essential reference results to build intuition and knowledge, but also to guide and verify more complex numerical simulations.
|Series||Nanoantennas and Plasmonics Modelling, Design and Fabrication|