Method for controlling gas pressure sealed in coaxial communication cable

摘要

A method and apparatus for controlling the pressure of gas sealed in a coaxial communication cable so as to maintain the dielectric constant and hence electrical length thereof constant independent of temperature or the leakage of insulating gas sealed therein. Electrical signals are produced representing the temperatures of the gas sealed in the cable and the temperature of a reference gas sealed in a closed container as well as signals representing the pressures thereof. The two temperature signals are compared and the temperature of the reference gas adjusted in accordance therewith by a constant temperature bath. The two pressure signals are compared and gas is fed into the cable in accordance therewith. The temperatures of the cable and the reference gas are maintained at the same values as are the pressures thereby maintaining the density and hence dielectric constant of the gas sealed in the coaxial cable constant at all times.