Sparse stepped-frequency waveform design for through-the-wall radar imaging

Wideband beamformers for applications such as through-the-wall imaging can exploit the efficiency and flexibility offered by aperture synthesis schemes and by stepped-frequency implementations. Aperture synthesis allows large imaging apertures to be realized using simple subarray components, whereas stepped-frequency use allows easy synthesis of different types of imaging waveforms. This paper shows how stepped frequency implementation in this setting can be tailored to reduce data acquisition time and hardware complexity. The idea of randomly selecting sparse subsets of the full-bandwidth frequency set leads to specific schemes including pseudo-uniform and tapered-density selection of retained frequencies. Both simulation and experimental results illustrate the potential of these approaches.