Novel Closed-Form Expressions for Effective Electromagnetic Parameters of Honeycomb Radar-Absorbing Structure

Novel closed-form expressions for effective material properties of honeycomb radar-absorbing structure (RAS) are proposed. These expressions, which are derived from strong fluctuation theory with anisotropic correlation function, consist of two parts: 1) the initial value part and 2) the dispersion characteristic part. Compared with the classical closed-form formulas, the novel expressions provide for a better formulation of the effective electromagnetic parameters of honeycomb RAS, which are characterized by well-behaved increase in wide frequency band. The good agreement between the theoretical results and the existing experimental data confirms the validity of the proposed expressions. Furthermore, a linear monomial dispersion characteristic function, which argues not for the absolute frequency value, but the relative frequency displacement of a frequency point relative to the frequency of initial value, is introduced to replace the polynomial expansion of the unknown correlation part in strong fluctuation theory. Such replacement reveals the near-linear relationship between the undetermined coefficients of monomial function and the coating thickness of honeycomb RAS. Compared with polynomial fitting method, which is based on polynomial expansion, this technique can further support the prediction of undetermined coefficients, when simulation results or measurement data are not available.