A microstrip antenna is proposed, which is with a thin-substrate and light-weight but considerable bandwidth and good directional radiation properties. This antenna works at 5.8 GHz and is printed on a thin substrate with a height of 0.5 mm, corresponding to 0.01λ0, where λ0 is the working wavelength of the antenna. To overcome the narrow bandwidth problem owing to the thin substrate, three parasitic patches of different sizes and with metalized conductive vias are placed close to the rectangular radiating patch. A prototype with 5×5 radiating elements is designed, fabricated and tested. Measurement results show that the proposed antenna possesses a |S11|<-10 dB impedance bandwidth up to 2.2%(from 5.866 GHz to 5.74GHz) and a gain of 8.2 dBi. The prototype is with a size of 164.5 mm×179 mm and a weight of 130.1 g, including the weight of 25 SMA connectors, 70.8 g, corresponding to 4.4 kg/m2.