Measurements of low gain antennas at VHF frequencies for space-based AIS applications

Measurement of the radiation properties of low gain antennas at VHF frequency is in many cases a challenging task. Measurements performed in shielded anechoic chambers are usually preferred to outdoor ranges because they are not subject to the electromagnetic pollution and less affected by the scattering of the environment. However, different source of errors, such as truncation of the scanning surface and the presence of echoes caused by a poor reflectivity of the anechoic chamber, could affect the measurement results. In such cases, advanced post-processing techniques must be involved. In this paper, the results of two Engineering Models of a low gain VHF space antenna are reported. The first one has been tested in a multi-probe automotive hemispherical range and applying an advanced processing, in order to mitigate the truncation errors. The second has been measured in a spherical multi-probe system with smaller truncated area applying the standard data processing.