Unilateral non-Foster elements using loss-compensated negative-group-delay networks for guided-wave applications

An analogy is demonstrated between negative group delay (NGD) networks and non-Foster reactive elements. It is shown that non-Foster elements and NGD networks influence a propagating wave in an equivalent manner. Based on this analogy, a novel method for the design of non-Foster elements using loss-compensated NGD networks is proposed. This method introduces a new perspective in realizing non-Foster elements based on wave propagation theory and dispersion engineering, as opposed to the traditional methods which are based on network theory. This method provides a way around the challenging stability problems of the traditional designs. Subsequently, a loss compensation method for NGD networks using regular unilateral amplifiers is presented that can be employed to design unilateral non-Foster elements. Such non-Foster elements can prove useful for guided-wave applications where a traveling wave is required to propagate in a certain direction. One design of a representative unilateral non-Foster element is presented using simulations and experiments.