Lossless dielectric material

Questions
1. When we are talking about lossless dielectric, does it mean only the material's conductivity equal to zero, and does it mean anything to its relative permeability and permittivity?

2. Does lossless dielectric mean a vaccum?


Thanks in advance.

Think of the loss as an eddy current phase of a wave in a dielectric, not the leakage resistance. ( not technically correct but analogy)

So it impedes flow with a loss factor. It is indicated by the tangent of the loss contant for the material in dB and is a function of material type, thickness, and of course frequency. A vaccum removes the air dielectric. Epoxy/fiberglass in FR4 is ok to VHF but for microwave low loss FR4 is better then, Polyamide then you start getting into temperature sensitive materials like polyurethane, PTFE etc..

see Wiki for details