Radar forward-looking imaging based on modulated beam with linear phase front

The challenge of forward-looking imaging has persisted in the field of radar remote sensing. Owing to the unique imaging geometry, the commonly employed synthetic aperture radar (SAR) cannot synthesize a wide effective aperture for targets in front of the radar. In this paper, we introduce a novel imaging method that eliminates the need for relative motion between the radar and the target to tackle this issue. This method falls under the category of phase-front-modulation-based imaging technologies. Firstly, an azimuthal phase front control technique utilizing a uniform linear array (ULA) is introduced. This approach enables the generation of antenna beams with linearly varying phases. Secondly, the radar response is constructed from multi-time measurements using different modulated beams. An imaging model is established, and a target reconstruction method based on the fast Fourier transform (FFT) is proposed. Subsequently, the proposed method is validated via simulations, and its resolution capabilities are assessed. Finally, the autoregressive (AR) model is employed to extrapolate the radar response, achieving superresolution imaging outcomes. The work can benefit the development of novel information-rich radar based on phase front modulation.