A circularly polarized, electrically small antenna augmented with non-Foster elements

A circularly polarized, electrically small antenna (ka=0.64) was presented. To improve its impedance bandwidth, two non-Foster circuits designed with the same configuration were, respectively, inserted into two Near-Field Resonant Parasitic (NFRP) elements of the antenna. Simulation results show that the antenna´s impedance and axial ratio (AR) bandwidth are both expanded due to the introduction of the non-Foster elements, and its gain maintains relatively stable and high values over its operating bandwidth (1.41-1.62 GHz).