In this paper, a novel synthetic aperture imaging method based on compressed sensing (CS) is presented. The method, employing a novel sampling matrix, provides a new sampling scheme to prevent from azimuth ambiguity in wider imaging swath observation. With fewer azimuth observations, the method provides acceptable imaging results and solves the ambiguity problem successfully. The novel method requires no modification to the hardware of contemporary imaging devices but lower pulse repetition frequency. It shares the advantages of reduced data amount, and no side lobe distort as well. Experiments are conducted to show the robustness of the method under a wide range of SNRs.