# Generation of Beam Tilt through Three-Dimensional Printed Surface
## 1 Introduction  
Beam tilting antennas play a significant role in modern wireless communication systems with their application in radar and satellite technologies [1, 2]. In 5G communication, the radiated beam could be directed to a specific location. Several designs have been presented in the literature for beam tilting [3, 4, 5, 6]. A clover antenna is demonstrated in [3], which shows a high gain and wideband operation to prove the beam-forming capability for 5G beam tilting applications. Similarly, the use of active devices such as PIN diodes is utilized to reconfigure the radiation patterns in a frequency selective surface [4]. The analysis performed for the phase-shifting surface principle is detailed in [5], where the beam tilting is attained by transforming the phase distribution of Fabry Perot cavity antenna (FPCA) in the near-field region with the use of surfaces such as wedge-shaped dielectric lens (WSDL), discrete multi-level grating dielectric (DMGD), printed gradient surface (PGS), and perforated dielectric gradient surface (PDGS). Additionally, phased array antennas are used in a wide range of applications such as satellite communications and radars, owing to their flexible control of beam direction. However, they require higher costs because of complex feeding and phase-shifting arrangements [6]. Several studies have been conducted, describing various methods adopted for tilting the beam direction as highlighted in [7]. Most of the systems are tall, bulky and have complex geometrical configurations. Examples include, transformation optics lens [8, 9], flat Luneburg lens [10, 11, 12], transmitarray prototypes [13; 14; 15] and reflect arrays [16; 17; 18]. In order to have a reduced antenna profile for tilting the beam direction, the research is growing in the field of metasurface design. The design of those novel metasurfaces has been of prime interest, such as in [19], where the idea of a radially gradient metasurface in addition to partial superstrate is chosen. These metasurfaces could also be designed through the use of 3D printing technology to realize the switchable phase, the so-called programmable metasurfaces [20]. The use of 3D printing technology has made high-quality mechanical prototyping fast and easy, where we can propose a novel approach for the fabrication of devices [21; 22]. The approach could be useful not only for ultra-high frequency systems but also for other classes of nanosystems such as those that are introduced in the microfluidics area [23]. A pair of 3D printed stepped dielectric (SD) and dielectric wedges (DW) were fabricated by using fused deposition modeling technology, where the former can focus on the broadside beam at an offset angle of 20\({}^{\circ}\), and the latter could be used to scan the antenna beam in both azimuth and elevation planes [24]. Furthermore, a pair of metasurfaces is designed to study the tilting effect of the beam for the resonant cavity antenna that is operating at a single frequency. These metasurfaces are fabricated with the particular arrangement of rectangular patches that enable the beam tilting method using near-field phase transformation [25]. Similarly, a computer numerical control (CNC) machine is used to realize phase correcting stepped dielectric phase transformers (PCSPT) and stepped dielectric phase transformers (SPT), which shows the improved antenna system that has a tilting and impedance matching bandwidth of 40.6% from 26.5 to 40 GHz [26]. This system does not require expensive phase-shifters and distribution networks, which shows advantages in terms of tilting bandwidth, aperture efficiency and gap between the source antenna and first beam tilting surface. Additionally, a full transmission phase range of 360\({}^{\circ}\) with high transmission magnitude is obtained by rotating the cross slot on all metal transmit array lenses along the same axis, which added the beneficial points such as compactness, low-cost and easy to control features for changing the beam direction along the azimuth and elevation planes [27].