Noise measurements of a non-Foster circuit for matching of a receiver antenna

A non-Foster circuit has been designed for broadband matching of antenna impedance. This matching network is used to achieve bandwidths for electrically small antenna (ESA) that exceed Chu´s limit for passive antennas. The study of noise in non-Foster matching circuits is critical because of the effects of active components on the signal to noise ratio (SNR). This is specifically important for receive-type antennas. The non-Foster circuit discussed here is a floating open circuit stable (OCS) negative impedance converter (NIC) with a capacitive load. The noise figure of the non-Foster circuit is measured (9dB-14dB) in the frequency range of 100 MHz to 500 MHz and compared with simulation data. SNR analysis of the receiver antenna has been performed, and improvement of the SNR using non-Foster matching has been achieved.