Precursors for synthetic aperture radar

Abstract

In this paper we study waveform design for synthetic-aperture radar (SAR) imaging through dispersive media. Under the assumptions of scalar wave propagation through a causal dielectric medium and single-scattering from an isotropic point scatterer, we use asymptotic analysis to derive the asymptotic approximation to the scattered electric field. From this asymptotic approximation, we define a sensing precursor that we propose for the transmit waveform for SAR imaging through dispersive material. We compare our sensing precursor with previously defined optimal waveforms (Varslot, Morales, and Cheney, Waveform design for synthetic-aperture radar imaging through dispersive media, SIAM J. Appl. Math., 71 (2011), pp. 1780 - 1800) in terms of both propagation and scattering capabilities, as well as imaging performance. With the filtered back-projection imaging algorithm that we use, we find that for high levels of signal-to-noise ratio (SNR), the optimal waveforms contain higher frequencies and thus produce better images. For low levels of SNR, the transmitted optimal waveforms and the sensing precursors are similar, thus giving comparable images.

Exact solution of the propagation of ON-OFF signals by dispersive waves

“…Their calculation was later corrected and modified [14], and precursors consistent with the theory were experimentally observed [15]. The Brillouin precursor, containing low-frequency wave components, exhibits power-law decay with propagation distance [16] and is expected to be applied to communication [17] and radar [18].…”