We can write the above equation as k = ± ± ω ω ( L − − j R ω ω ) ( C − − j G ω ω ) = ± ± ω ω L C ( 1 − − j R ω ω L ) ( 1 − − j G ω ω C ) which is correct for any transmission line in general. And for typical transmission lines, that are carefully built from wire with low loss resistance R and small insulation leakage conductance G ; further, used for high frequencies, the inductive reactance ω ω L and the capacitive admittance ω ω C will both be large, so the constant k is very close to being a real number: k ≈ ≈ ± ± ω ω L C .