## 1 Introduction
Different feeding techniques have been analyzed by describing how to obtain linear or circular polarization. Hybrid structures, which are obtained using DRAs to enhance the performance of other types of antennas (e.g., patch antennas), have been explored as well. Eventually, broadband DRAs have been developed, introducing staked or modified geometries--building them with different dielectric constant layers or altering their normal structure by drilling holes on them. Nevertheless, the starting point of all these improvements has always been a common and simple geometry. In this scenario, the use of AM technologies for the production process represents one of the most promising future research branches, while these kinds of antennas are usually realized by subtractive methods or by simply composing elementary dielectric shapes realized with high-pressure injection or made by firing a green ceramic part. This innovation would lead to more affordable and easily realizable DRAs, making their whole cost comparable with those of planar antennas. Moreover, if the geometric complexity does not influence the production costs anymore, more intricate and unconventional design possibilities, otherwise unrealizable with traditional manufacturing techniques, could be explored to obtain improved results in terms of gain, bandwidth, or radiation pattern. Obviously, it could be more difficult to handle with arbitrarily complex shapes, at least from a strictly theoretical point of view. Indeed, the analytical approximated formulas that allow for the prediction of working frequency or propagating mode equations are only available for the most common and simple DRA shapes. However, an interesting approach to the problem of analysis and synthesis of unconventional DRAs could be the use of genetic algorithms used to optimize some target functions that can be set up to achieve specific goals. For example, in [20], an interesting approach that exploits a shape generation technique called surface contour shape generation (SCSG), has been described and used to simulate different unconventionally shaped DRAs, comparing their performance. In [21], the so called [PERSON] \"superformula\" has been used as starting point to develop and realize a sub-6 GHz 5G DRA using stereolithography with a common commercial resin; eventually, in [22], [PERSON] himself, together with the other authors, explained how a 3D extension of the superformula could allow researchers to design a very wide range of shapes in an analytical way, and how this capability could be really useful to easily and quickly generate and simulate dielectric lens antennas that fulfill certain constraints. Once the synthesis of a new DRA shape is completed with one of the previously mentioned methods, the only remaining problem is the individuation of a proper coupling of material and technology suitable for manufacturing the antenna while guaranteeing the dielectric characteristics, in terms of dielectric constant and losses considered during the simulations. Indeed, as stated before, one of the main drawbacks of the polymer-based AM technologies is related to the extremely low dielectric constant that those materials exhibit, which usually ranges between 2 and 3. With this limitation in mind, and with the support from the colleagues of material engineering of the University of Salento, the authors are developing and characterizing different compound materials, suitable for both FFF and Vat Polymerization, respectively, in the form of ceramic-loaded 3D-printable filaments, and ceramic-loaded photosensitive resins. The goal is to obtain sufficiently low losses, as well as dielectric constant values of around 10, thus filling the last gap that prevents the wider use of the DRA technology empowered by AM. This is a realistic goal, considering that compound materials have dielectric properties that are a compromise between those of their two phases.