Equivalent coaxial transmission lines

An equivalent coaxial line structure is proposed for a family of coaxial transmission lines that uses combinations of circular and noncircular coaxial components. The author further develops the approximate graphical method used and presents two novel types of equivalent coaxial lines whose eccentricities vary with the ratio of inner and outer conductors, for general coaxial systems. The proposed equivalent lines give a smooth transition between extremes of a small wire and a wire near contact. The results obtained are simple analytical expressions that are useful for fast computation of the characteristic impedance or for the CAD (computer-aided design) of coaxial components.<>