Electrically small antenna has attracted much attention because of its potential application in compact wireless communication and sensing systems. Matching is needed before any practical application for an electrically small antenna (ka < 1, k - wavelength number, a - radius of the smallest sphere that can surround the antenna) because it has an input impedance consisting of large reactance and small radiation resistance. An electrically small antenna matched by a lossless passive matching network, according to the Bode-Fano limit, has a narrow bandwidth limitation determined by the high-Q-factor property. A non-Foster element provides a negative reactance slope versus frequency which can cancel the corresponding positive reactance slope of the input impedance of an electrically small antenna. Thus by adding an active matching circuit properly designed with non-Foster element, the electrically small antenna may have a larger impedance bandwidth. Other than the antenna bandwidth, the power efficiency involving DC power dissipation of the antenna system can also be important.