The application of the extra element theorem to the optimal design of impedance-loaded, electrically-small antennas

The extra element theorem is applied to the optimal design of impedance loaded electrically-small antennas. The applicability of the extra element theorem includes active and non-Foster loading. A key component of the framework of the extra element theorem termed null-double injection is shown to provide a direct and quantitative determination of the efficacy of a particular loading point.