# Analysis and Design of an X-Band Reflectarray Antenna for Remote Sensing Satellite System
## 7 Results and Discussion  
In this section, the above analyses for the required phase distributions and the reflecting element are combined to introduce the complete design of the proposed reflectarray antennas. Three designs are presented. The first has a pencil beam with a broadside radiation based on the phase distribution in Figure 4a; the simulation layout of the reflecting elements in this case is shown in Figure 13. It should be noted that directly allocating the dimensions for all these elements in this configuration on a simulation tool such as HFSS is complicated. However, this problem is simplified by generating a lookup table to convert the phase at each point on the reflectarray plane to the corresponding radii for the upper and lower circular patches of the corresponding element. Then, these radii with the corresponding centers are formatted as a Visual Basic Script (VBS), which is loaded directly by HFSS to draw the reflecting elements. This procedure introduces a significant improvement in developing the simulations. Figure 14 shows the simulated 3D radiation pattern of a broadside pencil beam with peak gain around 22 dBi. In Figure 15, the simulation layout of the reflecting elements for the tilted beam radiation pattern based on the phase distribution in Figure 4b is shown. The simulated 3D radiation pattern in this case is presented in Figure 16 and the peak gain is found to be nearly 21 dBi. Figure 17a shows the simulated layout of the reflecting elements for the flat-top pattern. This configuration  
Figure 11: Geometry of the proposed unit cell.  
Figure 12: Reflection phase response of the unit cell.  
was fabricated and measured to validate the flat-top pattern obtained by GA and that obtained by numerical calculation. Figure 17b-d shows the fabricated layers of the flat-top reflectarray antenna.  
Figure 14: 3D radiation pattern of the simulated broadside pencil beam reflectarray antenna.  
Figure 13: Simulation layout of the reflecting elements for the broadside pencil beam pattern.  
Moreover, a Yagi-Uda antenna was fabricated, as shown in Figure 18a, to complete the structure of the reflectarray. The frequency response of the reflection coefficient magnitude of the fabricated Yagi-Uda antenna was measured using a vector network analyzer (VNA; Rhode and Schwartz model ZVA67), as shown in Figure 18b. The excellent matching of the fabricated antenna at the operating frequency of 8.5 GHz can be noted in Figure 18c.  
Figure 16: 3D radiation pattern of the simulated tilted beam reflectarray antenna.  
Figure 15: Simulation layout of the reflecting elements for the tilted beam pattern.  
Figure 19 shows the complete reflectarray antenna with its feeding antenna. The radiation patterns of the fabricated antenna were measured inside as anechoic chamber, as shown in Figure 20. Figure 21 shows the measured normalized radiation pattern of this reflectarray antenna compared to the radiation pattern obtained by GA for the required phase distribution. It can be noted that the obtained radiation pattern satisfies the required mask to a good extent. The slight differences in the obtained radiation pattern can be explained due to the alignment and the fabrication accuracy. In addition, Figure 22 shows the 3D radiation pattern of the flat-top beam with peak gain of around 8 dBi.  
Figure 17: Reflecting elements for the flat-top pattern: (**a**) simulated layout, (**b**) fabricated upper layer, (**c**) fabricated bottom layer, and (**d**) fabricated ground plane.  
Figure 18: Measurement of the reflection coefficient of the fabricated Yagi–Uda antenna: (**a**) the fabricated Yagi–Uda antenna, (**b**) Yagi–Uda antenna connected to the Rhode and Schwartz model ZVA67 VNA, and (**c**) simulated and measured magnitude of the reflection coefficient.  
Figure 19: Fabricated prototype of the proposed reflectarray antenna.  
Figure 20: Fabricated antenna inside the anechoic chamber for the radiation pattern measurement.