## 3 Sinusoidal Vibration Test of the Deployable Reflector Antenna in STM Phase
Because the interface forces calculated from the original specification exceed the maximum allowable measuring force, the test specification for in-plane direction is reduced as the notched specification as shown in Table 1. For the out-of-plane direction, the interface load is not exceeding the calibrated range of the loadcell. The reason why the z-directional interface load is relatively small is that the CoG of STM is located near the center. In the sinusoidal vibration test performed by the acceleration input profile of the notched specification, the interface load measured by the loadcell falls within the calibrated range. LLSST was performed before and after the intermediate level vibration test to evaluate the frequency and amplitude shift. LLSST, so-called modal searching, is a test that excites a wide frequency band at a relatively low and constant level to identify the vibration mode. Conventional LLSST has been performed in the frequency range of \(5\) to \(2000\) Hz. However, since the vibration modes for the in-plane and out-of-plane directions are \(121.1\) and \(24.5\) Hz, respectively, the frequency range of the LLSST performed in the sinusoidal test is the relatively narrow frequency range from \(5\) to \(200\) Hz. As shown in Figure 5c,d, the responses of the control accelerometer for the full level test show that the sinusoidal vibration test was performed satisfying the specifications defined in Table 1. In addition, Figure 5e and f show the comparison of the \(1\)st to \(4\)th LLSS results. The in-plane and out-of-plane modes calculated in Figure 4 show a frequency shift of less than \(5\%\) and  
Figure 4: Modal analysis of the deployable reflector antenna under the stowed condition; (**a**) analysis configuration; analysis results of mode shapes, frequencies, and effective modal mass along (**b**) x-, (**c**) y-, and (**d**) z-axes, respectively. an amplitude shift of less than 10% [15]. These values of two shift mean that there was any misassemble or mechanical defect during the sinusoidal vibration test. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multicolumn{2}{c}{**In-Plane Specification**} & \multicolumn{4}{c}{**Out-of-Plane Specification**} \\ \hline
**Frequency** & **Acceleration** & **Tolerance** & **Frequency** & **Acceleration** & **Tolerance** \\ \hline
5–8 Hz & \(\pm\)0.00 mm & \(\pm\)3 dB & 5–12 Hz & \(\pm\)0.00 mm & \(\pm\)3 dB \\
8–30 Hz & 0.00 g & \(\pm\)3 dB & 12–70 Hz & 0.00 g & \(\pm\)3 dB \\
30–55 Hz & 0.00 g & \(\pm\)3 dB & 70–110 Hz & 0.00 g & \(\pm\)3 dB \\
55–80 Hz & 0.00 g & \(\pm\)3 dB & & & \\
80–110 Hz & 0.00 g & \(\pm\)3 dB & & & \\ \hline \multicolumn{2}{c}{Maximum acceleration: 9 g or more} & \multicolumn{4}{c}{Maximum acceleration: 4 g or more} \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Required specification of sinusoidal vibration test. Figure 5: Sinusoidal vibration test: (**a**) test setup for the inplane direction; (**b**) required environmental test specification; the test specifications for (**c**) inplane and (**d**) out-of-plane directions; the result of the low-level sine sweep (L LSS) for (**e**) inplane and (**f**) out-of-plane directions; The frequency and amplitude at the peak frequency of dashed circle in (**e,f**) are used for the reference of the modal survey.