Passive imaging using multiple navigation satellites as illuminator of opportunity

According to the Fourier transform relationship between target scattering function in the space domain and the echoes in the wavenumber domain, the distribution of echoes in the wavenumber domain is inherently linked to both the bandwidth of transmitted signal and the configuration of the illuminators and receivers. Therefore, a multi-aperture passive radar imaging system, which consists of multiple GNSS illuminators and a few stationary ground-based receivers, or even a single one, is proposed in this paper. It is possible to achieve a high resolution image using narrow-band GNSS illuminators by more apertures constructed from the different satellite orbits. Due to practical limitations, the echoes constitute a non-uniform and discontinuous coverage in wavenumber domain, which directly leads to poor inversion performance, so the scatter-by-scatter matched filtering method is utilized to reconstruct the images for its good robustness. Simulation results are provided to demonstrate the performance improvement of the proposed method.