Antenna applications of non-Foster elements

Three different antenna applications of non-Foster elements in resonant antennas, leaky-wave antennas and series-fed antenna arrays, are investigated. A resonant antenna is presented in which an internal tuning element is replaced with a combination of non-Foster elements in order to make the antenna wideband. Moreover, a non-dispersive fast-wave transmission line, which can be obtained by loading a host transmission line with non-Foster reactive elements, is introduced. Subsequently, the applications of such an artificial transmission line in making squint-free leaky-wave antennas is presented. Finally, the requirements of true time-delay lines for applications in series-fed antenna arrays is discussed and it is shown that the non-Foster fast-wave transmission line can meet these requirements.