Characteristic impedance of a rectangular coaxial cone transmission line with an offset inner conductor

After the electromagnetic fields in a line are discussed, conformal mapping and the singular integral-equation technique are used to derive the expression for the characteristic impedance of a rectangular coaxial cone transmission line with an offset inner conductor (RCCTLO). Simple and very accurate formulas, based on only the spherical TEM mode propagating, for the capacitance and characteristic impedance are found in terms of complete elliptic integrals. The method enables the characteristic impedance of a GTEM cell to be evaluated accurately and easily.