In this paper, all active integrated antenna using a T-shaped microstrip coupled patch antenna, which acts as DC isolation the RF path, is proposed. The designed feedback-antenna oscillator has stable oscillation and a clear spectrum at the frequency of 5.813 GHz, which is only, a 0.2% deviation from the design,frequency. The measured EIRP is 19.2 mW, and the cross-polarization levels are at least - 13 dB lower than the co-polarization ones for all directions. (C) 2005 Wiley Periodicals, Inc.