Plasma Frequency of Wire Medium Revisited

This paper revisits a model for the plasma frequency of a simple wire medium formed by a rectangular lattice of parallel metallic wires. We provide a comparative analysis of existing formulae for estimating the plasma frequency and derive a new expression. The proposed formula demonstrates superior accuracy for a square lattice of thin wires, with a relative error of less than $0.16\mathrm{\%}$ for the ratio of wires radii to period smaller than $0.13$, significantly outperforming previously known results in this range. For rectangular lattices with the periods ratio from $2$ to $10$ the new formula provides estimations with a relative error less than $2.7\mathrm{\%}$ for the ratio of wires radii to the smaller period less than $0.4$.