The realization of an active antenna composed of a reflection amplifie
r and a notch patch radiating surface, which also acts as the resonant
load, is discussed. Free oscillations are obtained by only one packag
ed microwave bipolar transistor directly integrated onto the radiating
surface Different configurations of the transistor assembly are studi
ed to satisfy the oscillation conditions and frequency stability. An o
utput power of 9 mW is measured at a frequency of 1.77 GHz.