Negative impedance converters for broadband antenna matching

The need for small antennas with wide instantaneous bandwidth is well established in mobile Cognitive radio nodes or transceivers. The fundamental limit of small antennas is a problem which passive matching cannot solve. However, non-Foster matching provides a means of getting around this problem. In this paper, we show a negative impedance converter that provides a negative capacitor up to 1.5GHz and we show how it can be used to match a small chassis antenna. This improves the instantaneous bandwidth of the antenna beyond what is achievable with passive matching.