# An Optimized Planning Tool for Microwave Terrestrial and Satellite Link Design
## 5 Tool Optimization  
In a combined effort with the Portuguese Army Directorate of Communications and Information Systems (DCSI), usability tests were performed in order to evaluate the developed tool's user-friendliness and to define the additional features that were found \begin{table}
\begin{tabular}{c c} \hline \hline Longitude of ascending node (\({}^{\circ}\)) & 231,55 \\ \hline Orbit inclination (\({}^{\circ}\)) & 32,14 \\ \hline Argument of perigee(\({}^{\circ}\)) & 137,36 \\ \hline Ellipse semi-major axis (km) & 9166,05744 \\ \hline Eccentricity & 0,0012574 \\ \hline \hline \end{tabular}
\end{table} 
Table 10: Main Keplerian elements of used satellite orbit for the simulated satellite project. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline  & **Frequency (GHz)** & **2** & **4** & **6** & **8** & **10** \\ \hline \multirow{3}{*}{Uplink} & Free-space attenuation (dB) & 169.2 & 175.2 & 178.7 & 181.2 & 183.1 \\ \cline{2-6}  & Atmospheric attenuation (dB) & 0.1 & 0.2 & 0.3 & 0.5 & 0.7 \\ \cline{2-6}  & Rain attenuation (dB) & 0.04 & 0.3 & 1.4 & 3.5 & 6.1 \\ \hline \multirow{3}{*}{Downlink} & Free-space attenuation (dB) & 169.9 & 175.9 & 179.4 & 181.9 & 183.9 \\ \cline{2-6}  & Atmospheric attenuation (dB) & 0.2 & 0.4 & 0.7 & 1.1 & 1.6 \\ \cline{2-6}  & Rain attenuation (dB) & 0.06 & 0.4 & 1.9 & 4.8 & 8.6 \\ \hline \hline \end{tabular}
\end{table} 
Table 11: Path attenuations for the simulated satellite system. Figure 14: Antennas and satellite positions for the simulated satellite project. \begin{table}
\begin{tabular}{c c c} \hline \hline  & Diameter (m) & 1.41 \\ \cline{2-4}  & Radiation efficiency (\%) & 50 \\ \cline{2-4}  & Minimum gain (dB) & 40.4 \\ \cline{2-4}  & Minimum emission power (W) & 61.57 \\ \hline \multirow{3}{*}{Receiving antenna} & Diameter (m) & 1.41 \\ \cline{2-4}  & Radiation efficiency (\%) & 50 \\ \cline{1-1} \cline{2-4}  & Minimum gain (dB) & 40.37 \\ \hline \hline \end{tabular}
\end{table} 
Table 12: Simulated satellite project link budget elements. useful for using the tool in professional practice. This process granted further professional value to the developed tool through the addition of the suggested features, as well as assuring that the tool is easy to use for the professional user. During several meetings, the following problems were brought up:  
1. The process of adding antennas and passive repeaters in terrestrial projects was found to be difficult since in the first iteration, these elements were added not by using different buttons but by using the right and left click of a mouse; the transmission and receiving antennas were added by order (i.e., first the transmission was added and then the receiving antenna, looping this order to change antenna positions), using the left mouse click, and the passive repeater was added by using the right mouse click. To facilitate this process, the buttons presented at the bottom of Figure 3 were created. 2. Users found it difficult to differentiate an input element from an output element. Therefore, the layout of the different elements was changed; input elements had a white outline, and output elements had a black outline. 3. It was requested to add a numerical element for each step window, allowing the user to understand the project progress made. This feature was added in the title of each step window. 4. The software allowed the user to input the elements without verification. The input of negative values and different decimal separation elements (. or,) led to inputs that were not valuable and displayed errors to the user, as presented in Figure 15.  
5. A step-by-step layout was suggested in order to visualize each step independently of the remaining steps, verifying whether all the inputs of a given step were correctly defined before moving to the next step. This created a methodical process to define the project elements, in contrast to defining different parts of a given step without particular order.