Electrical Length and Mechanial Length

hi,
electrical length is the length (in degrees or rad) "seen" by a wave at a given frequency (then it depends onf the frequency and the medium where the wave propagates) and mechanical length is the length we can measure and it doesn't depend on frequency.
For example, a coaxial cable with Er=3 and mechanical lenght 1 m:
- has an electrical length of 1875.6o, at 900 MHz but
- has an electricla lenght of 3750o at 1800 MHz.

Notice that the mechanical lenght is the same for both cases but the electrical length increases as the frequency increases and viceversa

regards