## 1 Introduction
They can be printed, even for high-frequency applications, but using most complex and costly devices (BJ, DMLS, and others that can easily cost thousands of times more than common FFF or SLA/DLP ones). Conversely, the most affordable AM technologies for 3D printing are FFF and Vat-polymerization which, however, only allow users to print polymeric materials. Moreover, most of these commercially available materials exhibit a relatively low dielectric constant (in the range of 2-3). This last factor could be a drawback if it is needed to realize some miniaturized structures or antennas. To overcome this limit, some research on composite materials obtained by combining polymers with some ceramic powders with a high dielectric constant have been carried out. For example, as reported in [12], 3D printing has been used to develop unconventionally shaped molds filled with a flexible silicone rubber/barium titanate (BaTiO\({}_{3}\)) compound, or in [13; 14], where 3D-printable filaments  
Figure 1: Trend of the term “3D printed antennas” of the last ten years in the Google Scholar database. composed of ABS or PLA and barium titanate have been realized, tested, and used to develop electromagnetic applications. The possibility of easily developing printable high-dielectric-constant devices with unconventional shapes paves the way for the use of 3D printing in developing one specific kind of antenna, which is the dielectric resonator antenna (DRA). These last started to be studied during the early 1980s, when the first paper about a new \"Resonant Cylindrical Dielectric Cavity Antenna\" was published by [PERSON], [PERSON], and [PERSON] [15]. DRAs are particularly suitable for mobile applications due to their small size (depending on the dielectric constant), high efficiency (due to the small amount of metal needed), and, with some shrewdness, wide band. Nevertheless, they are not so common if compared to microstrip antennas because the optimization of the planar manufacturing process better fostered the diffusion of the latter. Conversely, DRAs are traditionally manufactured using subtractive methods and their layouts and costs are particularly influenced by the rigidity of commonly acquirable ceramic parts that are very difficult to be postprocessed. In this regard, these antennas could highly benefit from a production process based on AM. In fact, it could improve their performance, due to the possibility of easily realizing complex shapes, while reducing the costs, which grow with the shape complexity. The impact of these potential advantages on the use of DRAs for a wider and wider range of applications can be summarized by citing [PERSON] himself, who recently wrote in one of his last papers [16]: _\"The dielectric resonator antenna has to date not seen as many applications as the microstrip antenna; the main obstacle seems to be the higher cost of its more complicated fabrication. However, once new manufacturing techniques such as 3-D printing are further established, and reduced size versions of these radiators for use at very high frequency operations become available, their use is likely to become much more pervasive.\"_  
In the following sections, the main working principles of DRAs will be summarized and the role of AM in overcoming their limits will be discussed. Then, as a proof of concept, a novel design for a compact 3D-printed wideband DRA, operating both in ISM 2.45 GHz and in the 5G-NR band, first proposed in [17], will be realized and tested. The proposed design differs from the previously proposed ones because it aims to exploit multiple aspects at once, as such taking the highest advantage of them.