| the magneto-ionic component which, at vertical incidence, is reflected at the height at which the electron density and the Earth's magnetic field are such that:|
fp2 = f 2 -f f B
where fp is the plasma frequency, f is the wave frequency, and f B is the electron gyro frequency
NOTE 1 – This component has left-handed or right-handed elliptical polarization depending on whether the direction of propagation is at an obtuse or acute angle to the Earth's magnetic field vector.
NOTE 2 – When the direction of propagation is perpendicular to the Earth's magnetic field this component has linear polarization with the electric flux density vector perpendicular to the plane defined by the direction of propagation and the magnetic field.