# Enhancement of Feed Source through Three Dimensional Printing
## 2 Generation of Wide Band Prototype  
The realized WBP was placed at a defined h1 = 12.5 mm (\(\lambda/2\)) distance from the base antenna as shown in Figure 1. We considered an aperture dimension of the horn of 4\(\lambda\times 4\lambda\) (\(\lambda\) = 25 mm at 12 GHz). The variation in the phase of 163.65\({}^{\circ}\) was noted above the feed horn source, which was decreased to 19.68\({}^{\circ}\) after the placement of the WBP at h2 = 6.25 mm (\(\lambda/4\)) above the top face of the WBP. The proposed WBP prototype, along with the unit cell arrangement, are shown in Figure 2. The cubes arranged in five layers are shown in Figure 2a, where the variation in cube dimension in each respective layer generates a corresponding change in the transmission magnitude and phase values. We set the cubes' dimensions as x1, x2, x3, x2, x1, and arranged them from Port 2 to Port 1. The variation in cube size was from a minimum of 0.5 mm (0.02\(\lambda\)) to a maximum of 7.5 mm (0.3\(\lambda\)). The proposed WBP perspective view is depicted in Figure 2b. The various cube dimensions, as arranged in five layers, are shown in Figure 3. The respective rounds were maintained from a central position of WBP across the end aperture dimension, where Round 1 lies in a central position, whereas Round 7 appears towards the end portion. The higher transmission magnitude (\(|\)S21\(|\)\(>\) 0.8) was maintained to provide an enhanced gain improvement. Round 1, Round 2, Round 3, Round 4, Round 5, Round 6, and Round 7 varied from 3.75 mm, 11.25 mm, 18.75 mm, 26.25 mm, 33.75 mm,41.25 mm, to 48.75 mm across the aperture dimension. Overall, we had 196 unit cells that were accompanied in the WBP structure. The relative dimensions of the cubes were noted from normalized phase values that were calculated in the h1 position. Synthesis algorithms prepared for generation of proposed prototype are highlighted in the below steps. 1. Calculate the required phase value at a 0.5\(\lambda\) distance above the defined aperture of the horn feed source. Phase values obtained in aperture positions of 3.75 mm, 11.25 mm, 18.75 mm, 26.25 mm, 33.75 mm, 41.25 mm, and 48.75 mm from the center of the aperture are 61.98\({}^{\circ}\), 51.16\({}^{\circ}\), 44.13\({}^{\circ}\), 44.51\({}^{\circ}\), 38.92\({}^{\circ}\), 8.53\({}^{\circ}\), and \(-\)55.92\({}^{\circ}\). 2. Normalize these noted phase values by considering higher phase values above the highest value. Here, we considered 240\({}^{\circ}\) and the normalized values obtained were 180\({}^{\circ}\), 190\({}^{\circ}\), 195\({}^{\circ}\), 195\({}^{\circ}\), 200\({}^{\circ}\), 230\({}^{\circ}\), and 295\({}^{\circ}\) for defined aperture positions of 3.75 mm, 11.25 mm, 18.75 mm, 26.25 mm, 33.75 mm, 41.25 mm, and 48.75 mm. 3. These normalized phase values are correlated to respective cube sizes from a database prepared with an arrangement of five layers of cubes. The respective cube sizes are 3, 7.5, 7.5 mm\({}^{3}\) in 3.75 mm; 1.5, 7.5, 7.5 mm\({}^{3}\) in 11.25 mm; 3.5, 7.5, 7 mm\({}^{3}\) in 18.75; 3.5, 7.5, 7 mm\({}^{3}\) in 26.25 mm; 2.5, 7.5, 7 mm\({}^{3}\) in 33.75 mm; 1.5, 7.5, 6 mm\({}^{3}\) in 41.25 mm; and 1.5, 7, 2.5 mm\({}^{3}\) in 48.75 mm. 4. Furthermore, cube sizes are tuned to appropriate values to maintain uniformity in the phase distribution at 6.25 mm (\(\lambda/4\)) above the top face of the WBP, which is based on the prepared five-layer cubes database. Thus, the obtained respective cube sizes are 3, 7.5, 5 mm\({}^{3}\) in 3.75 mm; 5.5, 7.5, 3 mm\({}^{3}\) in 11.25 mm; 5.5, 7.5, 1.5 mm\({}^{3}\) in 18.75; 5.5, 7.5, 1.5 mm\({}^{3}\) in 26.25 mm; 2, 7.5, 6.5 mm\({}^{3}\) in 33.75 mm; 5.5, 7, 3 mm\({}^{3}\) in 41.25 mm; and 3.5, 5.5, 6 mm\({}^{3}\) in 48.75 mm. These cubes are arranged for seven different rounds as Round 1, Round 2, Round 3, Round 4, Round 5, Round 6, and Round 7. Figure 1: System overview with proposed WBP. Figure 3: Building block of cubes in (**a**) Round 1 (**b**) Round 2 (**c**) Rounds 3 and 4 (**d**) Round 5 (**e**) Round 6 (**f**) Round 7. Figure 2: (**a**) Building block.