What is an advantage of foam-dielectric versus solid-dielectric coaxial cable?
It is more resistant to moisture contamination
It has higher voltage breakdown
It has less loss per foot✓Correct answer
It has a better impedance match to 50 ohms
Explanation
Foam dielectric is largely air, which has lower dielectric losses than solid polyethylene, so a foam cable of the same size has lower loss per foot. That comes with trade-offs in the other directions, since foam has lower voltage breakdown and is more prone to absorbing and wicking moisture.