For example, the dielectric spacer separating the conductors in a coaxial cable might be treated as lossless (\(\sigma=0\)) for short lengths at low frequencies; whereas the loss of the cable for long...For example, the dielectric spacer separating the conductors in a coaxial cable might be treated as lossless (\(\sigma=0\)) for short lengths at low frequencies; whereas the loss of the cable for long lengths and higher frequencies is typically significant, and must be taken into account. In the latter case, the material is said to be a poor conductor because the loss is significant yet the material can still be treated in most other respects as an ideal dielectric.
