Stability Analysis of Non-Foster-Circuit-Loaded Artificial Magnetic Conductors

Stability analysis of the mushroom-type artificial magnetic conductors (AMCs), periodically loaded with negative inductor non-Foster circuits (NFCs), is investigated. A transmission line model, with unit cell parameters extracted from a full-wave analysis, is employed. Simply loading a Sievenpiper surface with NFCs is unstable, but stability is achieved if the via inductance is reduced below a critical value. For a stable NFC-loaded AMC, there are no growing waves in the dispersion diagram in the entire frequency range.