Abstract: A broadband circularly-polarized (CP) H-shaped aperture-coupled microstrip antenna is presented in this paperwith low back-to-front radiation level. A pair of parastic microstrip branch is added at the feeding line of the presented antenna forenhancing the impedance bandwidth. H-sharped apeture-coupled feeding is used in this antenna for reducing the back radiationand enhancing the radiational efficiency. Wilkinson power divider with 90°phase difference is used for pahse shifting of the twoperpendicularity electric field, which CP wave is radiated. After simulation and optimization, relative impedance bandwidth of42.8 percent is achieved of VSWR less than 2, and the axis ratio (AR) bandwidth is above 30 percent of AR less than 2dB. Espectially in 1200MHz~1540MHz, best performances is achieved for gain larger than 6dBi, back-to-front radiation level andcross polarization level less than -20dB.