Active antenna phase modulator performance

This paper demonstrates experimental and simulated evidence on the extent to which an active microstrip antenna consisting of a rectangular patch radiator peripherally loaded with a GaAs MESFET can be operated as a phase modulator. The results given illustrate that phase modulation can be obtained by applying a variable DC bias to the active antenna in the presence of an injection locking signal. It is shown that the injection locking signal can be applied at the fundamental, second harmonic or at subharmonic frequencies. The pushing characteristics of the active antenna module, together with phase modulation plots and circuit/device sensitivity to injection locking signal magnitude are presented.