Radar and communication systems greatly benefit from having a highly directive antenna, with a narrow beamwidth. Previous studies have been performed on multiple techniques to obtain a reduced beamwidth, and the aim of this present work will be placed on exploring two of them. The first one is dielectric lenses, which consists of a dielectric structure placed outside of the antenna, which collimates the trasmitted radiation forward, as a planar wave. The second technique is virtual arrays, which allows a radiation pattern with a reduced beamwidth to be obtained by modifying the spacing between the elements in the transmission and reception arrays. Work on dielectric lenses has been widely reported, ranging from the use of metamaterials that allow to achieve a dielectric constant close to zero, to the use of additive manufacturing with artificially engineered dielectrics to achieve the desired beamwidth reduction. However, a clear procedure to design lenses based on certain radiation parameters has not been explored yet. Furthermore, research performed on the optimization of antenna elements in arrays to reduce the beamwidth has also been done. Multiple techniques such as numerical optimizations and compressive sensing have been used, and a reduction between 20% and 40% have been obtained. Nonetheless, these techniques do not account for electronical beam steering, which is a main feature of antenna arrays. With that in mind, the objective of this thesis is to develop a methodical design procedure for both dielectric lenses and virtual arrays. In the case of lenses, the aim is to derive equations that allow for estimating their size and obtain a dielectric constant profile regardless of the desired shape. As for the virtual arrays they are explored in order to obtain the minimum achievable beamwidth with a certain number of elements, without compromising both the beam steering capabilities and amplitude tapering.