Measurements of ionospheric reflectivity from 6 to 35 kHz

Very low frequency pulses, less than 140 μsec in duration, were transmitted from a 1.5-km balloon-supported antenna wire. At receiving sites about 170 km away the direct and ionospherically reflected waves arrived completely separated in time and were analyzed individually. Amplitudes of the plane wave reflection coefficients ∥R∥ and ∥R⊥ are given for 7 of the 60 or more available spectral lines between 6 and 35 kHz. Phase and group delays are given in terms of equivalent mirror heights of reflection. Diurnal, seasonal, and geomagnetic azimuth effects are described.