Non-Foster matching network design for VLF receive loop antenna

A non-Foster matching network of the receive loop antenna is applied to VLF (very low frequency) band in this paper. Based on an open stable negative impedance converter (NIC) by Linvill, a 1 * 1m rectangular loop antenna is equivalent as a two-port network, and the non-Foster matching and optimization are realized by a series tunable negative capacitance and negative inductance. The stability of the non-Foster matching network is analyzed and verified also. The results show that compared with the traditional passive matching network from 15 to 30 kHz, by using the non-Foster matching technique, the receive antenna's input reactance is sufficiently canceled by the negative elements, the -10 dB S-11 fractional bandwidth is improved by 64.9%, the total network's efficiency is improved over most frequency bands.