Non-foster broadband matching networks for electrically-small antennas

Design of non-Foster matching networks for monopole and loop printed antennas operating much lower their resonance frequencies are presented. Both matching networks consist of a non-Foster element (negative capacitance or negative inductance) to compensate partly the antenna reactance and a lumped-element transformer to convert the real part of the antenna impedance to 50 Ohm. The non-Foster elements are realized as transistor-based negative impedance converters. Advantages in the antenna matching bandwidth over conventional matching networks are demonstrated. Operational bandwidth of the transformer is shown to be one the main factors limiting the antenna matching bandwidth when using the non Foster matching networks under consideration.