## 3 Fabrication and Integration
### Telecommunications  
The different modulation schemes, emission patterns, data rates, the dynamics of the satellite and other minor parameters have an effect on the probability of completing the communications link between the CubeSat and the ground station. The link budget for the SE01's mission is summarized in Table 3.  
The SE01 CubeSat was equipped with a rigid canted turnstile antenna, as shown in Figures 5 and 6. Such antenna was tuned to the UHF frequency band, particularly to 435.8 MHz. The stiffness of such kind of antennas provides a very stable omnidirectional radiation pattern. However, rigid antennas occupy a significant space on the side panels of the satellite when they are stowed. The performance of such antennas is significantly reduced if the radiating elements have to be shortened from its tuned length. Therefore, such antennas are not suitable for CubeSats smaller than 2U; otherwise, the antennas would trespass the limits of the allowed envelope in its optimal length. For the VHF frequency band, the required space for the antenna should be even larger. Other kinds of antennas are also common for CubeSat missions. For example, \({}^{3}\)Cat-1 was equipped with two bi-stable metal dipoles [17]. This kind of antenna can be quite simple and reliable, and operate in either VHF or UHF bands. However, such antennas are usually coiled around the satellite in the stowed position, taking space from the CubeSat's side panels. Another example of antennas for CubeSats which can operate in the VHF and UHF bands are flexible coiled metal antennas, such as those used in Swisscube [24]. They take minimal space within the satellite structure while stowed, but once deployed they may not keep the optimal shape. New missions with ambitious imaging objectives require higher data rates that neither VHF nor UHF bands can provide. The current trend in CubeSats is moving toward S-band frequencies, around 2.3 GHz. Operating in the S-band requires antenna topologies with directional radiation patterns. This can be provided by patch antennas, such as the one used for INSPIRESAT-1 [50]. Patch antennas are monolithic, taking small space fitting in a flat surface of \(10\times 10\) cm\({}^{2}\), and may provide a gain of 6 dBi and an opening angle of 85\({}^{\circ}\). \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline  & **Peak** & **Nominal** & **Critical** & **Safe** & **Low Power** & **Control** & **Science** & **Science** \\  & **Power** & **Power** & **Mode** & **Mode** & **Mode** (Duty** & **Mode** & **Mode 1** & **Mode 2** \\  & **(mW)** & **(mW)** & **Cycle \%** & **Cycle \%** & **Cycle \%** & **Cycle \%** & **Cycle \%** & **Cycle \%** \\ \hline EPS & 120 & 120 & 100.00 & 100.00 & 100.00 & 100.00 & 100.00 & 100.00 \\ \hline OBC & 400 & 130 & 0.00 & 100.00 & 100.00 & 100.00 & 100.00 & 100.00 \\ \hline DCU & 20 & 20 & 0.00 & 100.00 & 100.00 & 100.00 & 100.00 & 100.00 \\ \hline RX & 400 & 180 & 0.00 & 100.00 & 100.00 & 100.00 & 100.00 & 100.00 \\ \hline TX & 5000 & 2800 & 0.00 & 0.00 & 0.33 & 0.33 & 0.33 & 0.33 \\ \hline ADCS & 1640 & 640 & 0.00 & 0.00 & 0.00 & 100.00 & 100.00 & 100.00 \\ \hline PL 1 (FIPEX) & 3100 & 2000 & 0.00 & 0.00 & 0.00 & 0.00 & 20.00 & 0.00 \\ \hline PL 2 (OC-OBC) & 180 & 150 & 0.00 & 0.00 & 0.00 & 0.00 & 0.00 & 100.00 \\ \hline TOTAL [mW] & & & 120 & 450 & 459 & 1099 & 1499 & 1249 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: SE01’s power budget. Currently, most common onboard radio systems are hardware-defined. However, the trend is moving toward software-defined radio (SDR), as it is the case for the SE01's mission [51]. The SDR equipment has the benefit of being able to develop different radio designs with a single hardware implementation, hence not compromising the design of the telecommunications subsystem at the early stages of the project. Further, SDR also has the advantage of allowing the developer to bypass certain processing blocks, in order to simulate the signal at different stages.