DME and the transponder are in the 960MHz to 1215MHz range. At 1GHz,
RG58 has 17.5dB/100ft., RG142 has 13.0dB/100ft., and FSJ1-50A has
6.0dB/100ft. If I was operating under extreme conditions, I would want
the best performing equipment available to me. Sometimes 1dB can make
the difference between getting a signal or not! Ask the guys talking to
the spacecraft out among the planets.