A novel technique for the measurement of the noise figure is proposed
for an amplifier embedded in a receiving active microstrip antenna, wh
ere direct measurement is impossible. The proposed technique is a comb
ination of the transducer power gain measurement of the amplifier and
the absolute noise power measurement of the active antenna. The measur
ed results of a receiving active microstrip antenna show the validity
of the measurement technique. This enables the characterisation of the
noise performance of active antennas.