Self-Oscillating/Amplifying Electrically Small Antenna With 10:1 Bandwidth

An electrically small self-oscillating/amplifying antenna with a 10:1 bandwidth (0.09 < ka < 0.9) is presented. It consists of a pair of electric and a pair of magnetic dipole elements, one of each in a Huygens dipole configuration, followed by a negative impedance converter (NIC) configured for operation in either its unstable or stable mode. The system supports self-oscillations in the unstable mode that yield a very wide tunability range. An external transmitter in the stable mode drives the NIC so that it operates as an injection-locked reflection amplifier, which enables boosting the radiated power. Both modes were optimized with full-wave/circuit-theory co-simulations. Their performance characteristics were confirmed with measurements of a prototype antenna that operates in the 10−100 MHz RF band.