Squint-free beamforming in series-fed antenna arrays using synthesized non-foster elements

A method for squint-free arbitrary-angle broadband beamforming in series-fed antenna arrays is introduced. This method originates from the idea of loading a feedline with non-Foster elements. This type of loading reduces the per unit length inductance and capacitance of the transmission line and a fast-wave non-dispersive propagation, required for squint-free beamforming in series-fed antenna arrays, is obtained. Importantly, the challenges associated with traditional implementations of non-Foster reactive elements (e.g. stability) are circumvented by introducing a new methodology using negative-group-delay (NGD) networks. This method is established by showing that non-Foster reactive elements and NGD networks influence propagating waves in a similar manner. Subsequently, a series feeding network for linear antenna arrays is designed by loading a host transmission line with loss-compensated NGD networks. In summary, this paper introduces a new method for synthesizing stable non-Foster reactances, using NGD networks, which is utilized to present a solution to the beam squinting problem in series-fed antenna arrays.