Rigorous Analysis of Energy Flow in Non-Foster Matching
Silvio Hrabar · 2024
The basic idea of non-Foster matching of small highly reactive antennas was introduced more than 50 years ago (A. D. Harris and G. A. Myers, “An Investigation of Broadband Miniature Antennas” Tech. Rep., Naval Postgraduate School. Monterey, 1968). Despite this very extensive research history, non-Foster matching is not yet widely used in commercial applications. The main reasons lie in inherent stability problems (S.D. Stearns, Non-Foster Circuits and Stability Theory, Proc. on IEEE APS/URSI 2011) as well as the difficulties in dealing with high voltage levels that occur in the case of transmitting antennas. There is also an additional problem of achieving high efficiency, which is very rarely addressed in the current literature (T. Rowe, T.-Y. Shih and N. Behdad, “Power-Handling Capabilities of Non-Foster Impedance-Matching Networks: Using Gridded Vacuum Tubes and Power Transistors,” in IEEE Ant. and Prop. Mag., vol. 60, no. 4, pp. 60–69, Aug. 2018). All the above problems are related to the unusual interaction between active and reactive energy flows, which we analyze in this contribution.