Challenges Due to Rayleigh Backscattering in Radio over Fibre Links for the Square Kilometre Array Radio-Telescope

Abstract

In the realization of the Low Frequency Aperture Array (LFAA) within the Square Kilometre Array (SKA) project, the radiofrequency (RF) signals coming from sky and celestial sources, and received by each of the 130k+ antennas, are transmitted to the signal processing unit through analogue Radio over Fibre links. Within this low frequency band, the relatively low levels of the power of such RF signals may give rise to unexpected distortion effects. The present works highlights the physical origin of such undesired spurious frequencies generation, which can be also found in other applicative telecommunications scenarios. The details of a possible solution able to keep the above mentioned distortion terms at acceptably low levels are finally illustrated.