Frequency-Reconfigurable Self-Oscillating Active Antenna With Gap-loaded Ring Radiator

We investigate a new topology for realizing a compact frequency-reconfigurable self-oscillating active integrated antenna. The new design consists of a passive ring radiator, an unstable transistor, and two p-i-n diodes. Two gaps are etched across the radiator, with the diodes bridging the gaps to switch the antenna topology. By properly selecting the location of the gap with respect to the gate/drain terminals, the oscillation can be stabilized at two distinct frequencies, each associated with a resonance mode of the ring radiator. The simulated methods and experimental results are introduced in this letter, along with the discussion of design principles and considerations.