# Analysis of 3D Printed Dielectric Resonator Antenna Arrays for Millimeter-Wave 5G Applications
## 1 Introduction  
The advent of 5G technology has created a pressing need for advanced antenna systems capable of supporting higher frequencies and larger bandwidths. Dielectric resonator antennas (DRAs) have emerged as a promising solution due to their low-loss characteristics, high radiation efficiency, and ability to operate at millimeter-wave frequencies [1]. Since their introduction in 1983 [2], DRAs have been extensively researched in the fields of antennas and propagation, leveraging various materials and manufacturing techniques to optimize performance. Traditional methods using ceramic rods could typically offer high permittivity, ranging over 20, but it is less likely to achieve designs with permittivity below 20 [3, 4]. This would lead to limited choices in materials as well as design freedom. Other methods apply compound dielectric materials, such as printable dielectric ink [5], flexible magnetic polymer composite substrates with equal permittivity and permeability [6], and mixtures of silicone rubber and barium strontium titanate nanoparticles [7]. However, most compound dielectric materials need to be synthesized through complex processes, which increase the complexity and cost of the overall design. Additive manufacturing (AM), also known as 3D printing, is an emerging technology that has attracted significant attention from both the academic community and industry over the past few decades [8, 9, 10, 11, 12, 13, 14, 15, 16]. It offers advantages such as low cost, high design flexibility, rapid prototyping, reduced material waste, etc., and has been applied exclusivelyin manufacturing different components across various fields. Recent advancements in AM technologies have significantly expanded its applications and capabilities. Techniques such as stereolithography (SLA), selective laser sintering (SLS), fused deposition modeling (FDM), and direct metal laser sintering (DMLS) have evolved, offering enhanced precision, material diversity, and functional properties [17; 18; 19; 20; 21; 22]. The development of multi-material printing has further pushed the boundaries, allowing the creation of complex structures with varying mechanical properties within a single build [23; 24; 25; 26]. AM techniques have recently been applied to RF designs, including antennas, for various purposes across different applications [27; 28; 29; 30; 31; 32]. The integration of AM techniques into DRA manufacturing represents a significant advancement, enabling the production of complex geometries and customized designs previously unattainable with conventional methods. AM offers the capability to rapidly prototype and test various DRA designs, significantly reducing the time and cost associated with traditional manufacturing processes. Recent progress in using AM techniques to produce DRAs has been reported [33; 34; 35]. Five DRA samples were fabricated using two AM technologies, namely FDM and SLA, for 5G applications [33]. The FDM technique and the spatial variant lattices (SVL) synthesis algorithm were combined to design two inhomogeneous DRAs with linearly varying permittivity profiles along their radial and vertical axes [34]. Super-shaped DRAs were manufactured using inverted micro-SLA. DRA prototypes with basic cross-star shape geometries were manufactured by considering different twist angles along the vertical axis [35]. In general, different AM techniques have been applied to manufacture DRAs in recent years, while more details, such as surface profile, manufacturing resolution, and practical applications, remain to be explored. Although other commonly used AM techniques are rarely applied to DRA manufacturing, they have proven feasible for manufacturing other RF devices and show great potential for DRA fabrication. Examples include flat panel antennas using SLS [36], waveguide antennas using DMLS [37] or binder jetting [38], and rectangular cavity resonators using material jetting [39]. This paper discusses the feasibility of using off-the-shelf FDM technology to manufacture low-cost DRA arrays.