Development of the miloSAR Testbed for the One Kilogramme radioCamera SAR for Small Drones

The radioCamera is a fully polarimetric, C-Band imaging radar (SAR) for sub 20 kg drones, under development by droneSAR (Pty) Ltd. While designing this 1 kg system, a number of unconventional FMCW architectures had to be explored in simulation and practice before committing to expensive RF and digital boards. The miloSAR is a low-cost and rapidly reconfigurable testbed radar, built from commercial off-the-shelf components in the 2400MHz band, developed to aid with refining the architecture for the radioCamera. The system differs from traditional homodyne FMCW radars which perform direct downconversion using a copy of the transmit waveform as the local oscillator (LO) for analogue dechirp. Heterodyne architectures inherently avoid the known issues of direct down-conversion receivers, namely, DC offset, LO self-mixing, and flicker noise. This paper provides an overview of the miloSAR and reports on initial SAR results achieving more than 500m range with 10mW radiated power.