Passive synthetic aperture radar (SAR) has attracted research in recent years because of its advantages in exploiting opportunistic signals for imaging. Hence, it minimizes the need for active radar transmitters, significantly reducing system costs. In addition, the massive proliferation of telecommunication satellites in recent years motivates the idea of using the signal for the integrated sensing and communication (ISAC) concept. This paper explores the feasibility and opportunity of exploiting communication signals, specifically the common waveform of orthogonal frequency division multiplexing (OFDM), as a source of SAR illumination. The reflected signal is captured using a flying uncrewed aerial vehicle (UAV) at a much lower altitude than the satellite. To perform this evaluation, we developed an extensive signal-level emulator that considers many realistic aspects, such as orbital parameters, pulse repetition frequency (PRF), RF radio bandwidth, and antenna beamwidth. Point targets were placed within the imaging swath using regular spacing, and then the backscattered signal was collected using the UAV. Accordingly, the SAR image was formed using the range-Doppler (RDA) processing algorithm. The integrated sidelobe ratio (ISLR) was evaluated for ground reference point (GRP) cross-sections in order to provide a numerical assessment for performance. The results indicate the feasibility of exploring the direction of ISAC in passive SAR image formation.
