Towards Broadband Tunable non-Foster Radiating Systems

It is shown that inherent instability of the non-Foster reactance (usually considered as a serious drawback of broadband active metamaterials) becomes a very useful feature in the case of selfoscillating radiating structures. Briefly, if a negative resistance is added to a non-Foster reactance, the whole circuit behaves as Thevenin’s source (an oscillator) that can be perfectly matched. Such a system delivers maximal power to ordinary passive load (for instance to an antenna), within a very broad (theoretically infinite) bandwidth.