Abstract: Firstly,the double-T printed antenna was introduced.Then in terms of the advantage of dual-band and broadband,the antenna was optimized and fabricated in FR_4 substrate.The size of ground,inductance and the Polarization-Diversity's degree which influence the aotennae's performance were analyzed and designed.Finally,the polarization-diversity 45 degree Antennae which satisfied 802.11a/g's protocol were developed,the tested results meet requirements.