In this paper, an effective T-gate with Drain-Field-Plate (TGDFP) technology is used in GaN-based HEMT for high breakdown voltage of 500 V and drain current of 540 mA/mm. Silvaco TCAD simulation showed that normally-off TGDFP HEMT with recessed gate length of 0.5 μm exhibited high threshold voltage up to +1 V and transconductance of 140 mS/mm along with frequency operation in S-band (∼3 GHz). The proposed lateral TGDFP HEMT provides desirable features for both Power and RF applications.