A ground-folded slot antenna (GFSA) is presented. The antenna geometry is formed by folding the ground of a slot antenna along the slot length to enhance the gain and reduce the backward radiation. Two feeding methods are investigated for use with the GFSA: center feeding and edge feeding. The backward radiation is further reduced by placing a microwave absorber in the backside. The antennas are implemented and measured to show that the antennas operate over a wide bandwidth and have a higher gain and lower backward radiation than a conventional slot antenna. The performance of the proposed antenna as a sensor for an imaging radar is then investigated through a synthetic aperture radar experiment.