Design expressions for overhead quasi-coaxial transmission lines are developed and presented in a simplified form, suitable for engineering purposes. The electrostatic logarithmic potential method is used for low-, medium-, and high-frequency applications, where the line dimensions in wavelengths are quite low, so it is not necessary to take into account the retarded potential. This kind of transmission line is very useful and convenient for high-power broadcast transmissions, due to the high power capacity and very low attenuation of the line. This is especially important when the distance between the transmitting building and the radiating system is quite large.