In some configurations, such as in receiving systems, the noise generated by the added non-Foster element, due to the active devices that comprise them (i.e. diodes of transistors), is a key factor to be accounted for, that is intimately linked with the global system performance. Even when such non-Foster element is embedded into a distributed elements circuit or in a radiating structure, making impossible the access to its input-output ports, the noise characterization of the added noise is welcome. In this paper, the added noise due to a conventional transistor-based negative impedance converter (NIC), in an unbalanced configuration, and embedded in an Electrically Small Antenna (ESA) is measured by following the three-antenna method.