A Backpropagation Imaging Technique for Subsampled Synthetic Apertures

Synthetic aperture radar (SAR)-based microwave imaging systems have been widely used in a great variety of application areas, ranging from Earth monitoring to nondestructive testing. The scanning speed is one of the key performance indicators of SAR-based imaging systems. One possibility to increase it is by widening the distance between measurements. However, this results in the presence of grating lobes which degrade the recovered microwave SAR images. To overcome this issue, this contribution presents a novel methodology that introduces the amplitude and phase of the field radiated by the transmitting (Tx) and receiving (Rx) antennas of the SAR system in the backpropagation imaging algorithm. The method takes advantage of the directive pattern of the Tx/Rx antennas to reduce the level of the grating lobes appearing in the SAR image. Results presented in this contribution confirm the effectiveness of the proposed methodology to work with subsampled apertures while minimizing the impact of the grating lobes in the SAR images. Subsampling rates of, at least, one wavelength, have been achieved while keeping the quality of the recovered SAR images similar to the ones retrieved when the Nyquist sampling rate is fulfilled.