## 6 Results and Discussion  
In order to assess the practical utility of our equipment, the device was employed in the characterization of a 3D-printed metalens, fabricated with thermoplastic polylactic acid (PLA). The PLA plastic microwave permittivity was extracted according to the methods used in [25]. The results obtained from the instrument were then compared to those obtained from computer simulations. The metalens design used a hyperbolic phase profile with a 20 cm focal length, adjusted to operate at 30 GHz [26]. It has a square area with sides measuring 15 cm. The phase control is made with 3D printed prisms with varying side lengths, which act as truncated waveguides [7; 27]. The unit cell size is 6 mm, and the posts are 18 mm tall. The phase profile was sampled using eight phase levels, which required the same amount of different  
Figure 12: Schematic with step-by-step illustrations showing how the instrument works: (**a**) the entire schematic; (**b**) loop part only. structures in the design. More details can be found in [7]. Figure 13 illustrates the fabrication processes involved in metalens manufacturing. First, we simulated the metalens transmitted fields using the scalar angular spectrum formalism method [28] and using the local post approximation [29]. Figure 14 shows the normalized intensity distribution when increasing the distances from the metalens by 2 cm of increment, starting at 12 cm (Figure 14a) and finishing at 28 cm (Figure 14i). The intensity normalization in these reconstructions was performed considering the maximum and the minimum intensity of each distance matrix separately. Figure 14: _Cont._  
Figure 13: Step-by-step illustrations describing metalens fabrication. Figure 15 shows the normalized measured intensity distribution transmitted by the metalens, where (a-i) shows the intensity field at 12 cm to 28 cm, respectively, with steps of 2 cm. The intensity normalization was performed similar to the metalens simulation to maintain consistency in the comparison. These reconstructions provide a comprehensive view of the intensity distribution transmitted by the metalens at various distances from the receiving antenna, and they match quite well with the simulated intensity profiles shown in Figure 14. The instrument GUI was configured with the following parameters to obtain the fields depicted in Figure 15: a resolution of 3 steps per measurement and 50 measurements (accuracy) at each point. These settings resulted in the production of images with a size of 400 by 400 pixels. The good agreement between the simulation and the measurements highlights the high accuracy of the instrument and the quality of the fabricated metalens. This validation is crucial to ensure the accuracy and reliability of the results obtained from the use of the instrument for other future purposes. Figure 14: Simulated and normalized intensity profiles on planes placed at different distances subsequent to the metalens obtained with simulations; (**a-i**) show the results on planes that are 1 cm, 14 cm,..., 26 cm, and 28 cm away, respectively. The operating frequency is 30 GHz. Figure 15: Measured and normalized intensity profiles on planes placed at different distances subsequent to the metalens; (**a–i**) show the results on planes that are 12 cm, 14 cm,..., 26 cm, and 28 cm away, respectively. The operating frequency is 30 GHz. Upon analysis of Figures 14 and 15, a definitive determination of the actual focal length, previously stated as 20 cm, cannot be achieved. Thus, to establish the correspondence of the metalens behavior with the intended design, Figure 16 exhibits the intensity fields, encompassing all the extracted measurements, where (a-i) shows the intensity field at a distance of 12 cm to 28 cm, respectively, with steps of 2 cm, similar to the images shown in Figures 14 and 15. Figure 16 exhibits conspicuously more intense measurements than the other figures, reaching a maximum intensity of 6.25 V\({}^{2}\), attesting to the consistency of the focal length with the originally intended specifications.