Non-Foster networks for improvement of radiation efficiency and effective diversity gain of a multi-port antenna

The use of non-Foster components in wideband matching networks for improvement of effective diversity gain and total radiation efficiency of a multi-port antenna is studied. The frequency response of an optimized wideband matching network is first derived, and afterwards synthesized with real circuit components. As the required reactance slope of the realized components often turns out to be negative for both single and multi-port wideband antennas, the possibility to use negative capacitors and inductors (i.e. non-Foster components) is investigated. To exemplify this, two inverted L-antennas (bended monopoles) on a mobile phone sized ground plane is studied.