Pencil Beam Patterns Obtained by Planar Arrays of Parasitic Dipoles Fed by Only One Active Element

In this paper, an innovative method for obtaining a pencil beam pattern is presented. Planar arrays of parasitic dipoles are used to modify the pattern of an active dipole above a ground plane, in order to obtain a pencil beam of moderate gain and bandwidth. Only one feed point and one active element provide a very simple feeding network that reduces the complexity of the antenna. The correct configuration of the elements of the parasitic arrays allows to obtain the desired pencil beam pattern. Three designs that use parasitic arrays fed by a /2-dipole and synthesize pencil beam patterns are shown: 1) an antenna designed at 1.645 GHz and composed by one layer of 49 parasitic elements; 2) an antenna designed at the same frequency but composed by two layers of 49 parasitic elements; 3) an antenna designed at 5 GHz, composed by one layer of 49 parasitic elements, and taking into account the dielectric substrate and teflon screws.