A highly controllable MESFET active patch antenna/oscillator

This paper reports a new MESFET active patch antenna suitable for active radiator applications. Active radiator applications include spatial power combining, coded reradiation identification tagging, beacons, etc. The element reported here employs the MESFET with source and drain connected to matched patch antennas with the gate providing feedback for oscillation. The gate feedback is coupled through a microstrip stub, thereby providing a means for a variety of control functions. Specifically, the stub length is trimmable, electrically adjustable (through insertion of a varactor diode), and provides a vehicle for injection locking through aperture coupling to the stub.