Optimum Mitigation of distortion induced by Rayleigh Backscattering in Radio-over-Fiber links for the Square Kilometer Array Radio-Telescope

This paper presents the theoretical and experimental study of unexpected distortions induced by the Rayleigh backscattering phenomenon in Radio-over-Fiber (RoF) links within the Square Kilometer Array (SKA) project. For this system, the radio frequency (RF) signals coming from the sky and celestial sources are received by more than 130k antennas individually and then transmitted to the signal processing room through an analogue RoF link. The low frequency band considered (from 50MHz to 350MHz) and the relatively low levels of the power of such RF signals are identified as the cause of these distortion effects which can decrease drastically the receiver dynamic range. An analysis of the phenomenon is presented in this work, together with an efficient solution optimized for the considered applicative case.