Non-Foster Circuit Adaptation for Stable Broadband Operation

A non-Foster circuit adaptation algorithm has been developed and demonstrated in a printed circuit board by using commercial off-the-shelf components. This algorithm enables adaptive stabilization of non-Foster circuits (NFCs) to achieve broadband operation, such as matching of electrically small receive antennas, hence avoiding potential oscillation and undesirable signal emission. The demonstrated system has been fabricated in a 6.4 ×8.9 cm² 4 layer FR4 PCB. Together with a fabricated NFC board, it achieves stable wideband matching for a 15 cm long monopole antenna under different environment conditions, such as an additional loading of a Cu metallic sheet in a proximate location to the antenna. The demonstration indicates the effectiveness of the proposed NFC adaptation algorithm and paves the way for broad applications of NFCs without stability concerns.