An active integrated antenna (AIA), which consists of a T-shaped microstrip-line-fed slot antenna, is proposed Since the designed antenna has an electromagnetically coupled feedback loop, it can easily solve the problem of DC isolation between ports of the amplifier. The fabricated parallel feedback antenna oscillator shows stable oscillation at a frequency of 10.05 GHz. The measured EIRP is 37.79 mW, and the cross-polarization levels are at least -15-dB lower than those of co-polarization for all directions. (C) 2005 Wiley Periodicals, Inc.