formula.expert

Constants library

2 values, each with its units, its uncertainty, and where it came from.

Electromagnetic 2

Characteristic impedance of vacuum measured

Z0=376.730313412 ΩZ_{0} = 376.730313412\ \text{Ω}

ΩThe ratio of electric to magnetic field strength in a plane wave in free space — the 377 ohms every antenna engineer matches to.

Relative permittivity of PTFE measured

εr,PTFE=2.1 —\varepsilon_{r,\mathrm{PTFE}} = 2.1\ \text{—}

—Typical dielectric constant of PTFE (Teflon), about 2.1 and almost flat from DC to tens of gigahertz — the benchmark low-loss RF insulator.