FM passive bistatic radar imaging of airplanes in a real configuration

Passive bistatic radar (PBR) is a well-known topic but research is mainly focused on detection and estimation, and relatively little work has been done on PBR imaging. This paper studies the feasibility of using existing signals for imaging airborne aircraft. The use of the FM band for that purpose is motivated by the geographic prevalence of radio broadcasting and the large size of an FM cell. For the construction of radar images, tomography principles are applied. It centered around a Fourier transform of the radar cross-section (RCS) of airplanes acquired at different frequencies, incident angles and scattered angles in order to form a radar image. However, a sufficiently large part of the Fourier space must be filled to form an interpretable image, and this depends on the available frequencies, bistatic angles and aspect angles. Those parameters are constrained by the bistatic configuration considered and the trajectory of the observed airplanes. The relationships between these parameters and PBR imaging performance are analyzed and discussed in this paper. The main contribution is the successful construction of interpretable PBR images given a realistic configuration and limited trajectories for the airplanes. We discuss the use of these images for applications such as automatic target recognition.