## 2 Materials and Methods  
The objects under investigation are aluminum-covered models created in order to evaluate their reflection properties in different attitude positions and over a wide range of frequencies. In this case, the attitude is the orientation of the object with respect to its hypothetical orbit. The test campaign, thus, aims to correlate the real experimental measures with the reflection properties of hypothetical orbiting objects. This aim is carried out considering a reference radar working at 400 MHz, with a wavelength of 75 cm. The experimental frequency range for measurements was set to 12-18 GHz with wavelengths of a maximum of 2.5 cm and a minimum of 1.7 cm. The relation between the real experimental data and the predicted reflection properties is thus given by a simple proportion between the samples' size, the experimental wavelength, and the reference radar wavelength: a given experimental frequency (12 GHz as an example) corresponds to a given wavelength (2.5 cm), with a precise ratio to the sample size. The same ratio is considered when a 400 MHz, 75 cm wavelength is applied, finding the hypothetical real object size, which is different for every frequency in the 12-18 GHz span. In other words, as the frequency of the reference radar is 400 MHz, with a wavelength of 75 cm, the scaling process of the samples, as a first approximation (i.e., considering only geometry and shape, without considering the effects of the atmosphere such as reflection, refraction, diffraction and interference that are anyway present in a ground tracking), allows to correlate the reflection properties of tested objects, shown in Table 1, to real size objects. In Figure 1, the experimental setup is shown. The choice of an experimental campaign based on a frequency span measure method and not on a single frequency can be explained with the flexibility of such a methodology, which allows a wider relation between samples and hypothetical real objects. Moreover, the size of the samples was chosen considering the incident wavelength: in real tracking, at 400 MHz, the wavelength is approximately of the same order of magnitude of the satellite; thus, the same relation was considered for the samples. The shape of the samples was chosen considering the most common shapes of satellites. In future works, a complete satellite model will be manufactured, with more complex geometries, such as parabolic antennas. The NRL arch method was chosen for the experimental campaign for its capability to perform free space measures: the incident signal wavelength is extremely lower than the distance between antennas and the target, simulating the real signal transmission in the best possible way. \begin{table}
\begin{tabular}{c c} \hline \hline
**Specimen** & **Dimensions** \\ \hline  & \multicolumn{1}{c}{Cubesat Characteristics} \\  & Dimensions of 0.1 m per side, \\  & attributable respectively to a satellite of 3 m per side at \\  & 12 GHz and to one of 4.4 m at 18 GHz. \\ \hline  & \multicolumn{1}{c}{Cylinder Characteristics} \\  & Dimensions: \\  & Height: 0.075 m, Diameter: 0.065 m \\  & attributable respectively to a satellite of 2.25 m in height \\  & at 12 GHz and to one of 3.3 m at 18 GHz. \\ \hline  & \multicolumn{1}{c}{Parallelepiped Characteristics} \\  & Dimensions: \\  & Height: 0.08 m, Width: 0.06 m, Thickness: 0.04 m \\  & attributable respectively to a satellite 2.4 m high at 12 \\  & \multicolumn{1}{c}{GHz and one of 3.5 high at 18 GHz.} \\ \hline  & \multicolumn{1}{c}{Parallelepiped Characteristics} \\  & plus \\  & Appendices size: \\  & 0.12 \(\times\) 0.02 each, the whole object corresponding to \\  & satellites with a body 2.4 m high at 12 GHz and a body \\  & 3.5 m high at 18 GHz, with appendices spanning 3.6 m \\  & and 5.3 m, respectively. \\ \hline  & \multicolumn{1}{c}{} \\ \end{tabular}
\end{table} 
Table 1: Pictures and characteristics of the samples under investigation, having a different geometry in order to evaluate different hypothetical orbiting objects.