A novel L/C dual-band dual-polarized shared-aperture antenna with a single-layer perforated structure is proposed for synthetic aperture radar (SAR) applications. The aim is to broaden the impedance bandwidth in the lower L-band of the L/C shared-aperture SAR antenna. The antenna element has been simulated, fabricated and measured. The measurements show that the bandwidths, defined as reflection coefficient being less than or equal to -10 dB, is increased to 13.7% in the lower L-band, while that of the higher C-band reaches 17.0%. Experimental results have verified this design.