This paper presents two circuits for a high power GaN/AlGaN HEMT based self oscillating Active Integrated Antenna (AIA) using feedback topology. The first circuit, a fixed frequency high power source, is designed using a two-port T-coupled patch antenna in parallel feedback of a device. This circuit radiates 41 dBm power at 2.34 GHz frequency when being biased at Vgs = -2.1 V and Vds = 25 V. The second circuit, a frequency reconfigurable high power source, is designed using a frequency reconfigurable T-coupled two-port patch antenna in parallel feedback of a device. Frequency reconfigurability is achieved in the second circuit by adding one more strip and two pin diodes at both sides of centre patch of the two-port patch antenna. Change of biasing voltage of pin diodes changes the frequency of oscillation of the circuit. This circuit radiates 32.4 dBm power at 2.1 GHz when pin diodes are off and radiates 32 dBm power at 2.7 GHz when pin diode is on. To the best of our knowledge, the first circuit implemented radiates the highest power using single device whereas the second circuit is the first implementation of reconfigurable oscillating AIA in GaN and also delivers the same power in both states. Each circuit measures 80 mm x 80 mm.