Variation of the electrical length of coaxial transmission lines with temperature

In a system where a number of transmission lines are fed from a common source, the phase relationship at the far end of the lines is determined by the electrical length of the transmission lines. This length is a function of the physical length and the dielectric constant of the line. Any variation in the dielectric constant or the physical length of the transmission line will cause a change in the electrical length and result in changed phase relationship at the far end of the line. This paper investigates the variation in the electrical length with temperature of several coaxial transmission lines.