The ionospheric propagation of low- and very-low-frequency radio waves over distances less than 1000 km

Ionospheric Reflections from Heights Below the E Region

“…The same method at oblique incidence has been used by Naismith and Bramley (1951), while Weekes (1952,1955) have used a frequency modulation method. In most of these investigations, the frequencies used have been in the range [1][2][3][4][5] Mc/s, and the reflections from below the E region have nearly always Bracewell et al (1951); and later results have been reported by Watts (1952) and by Hopkins and Reynolds (1954).…”

LXXXV. The reflection of very low frequency radio waves at the surface of a sharply bounded ionosphere with superimposed magnetic field

“…A. Ratcliffe, F.R.S. Downloaded by [New York University] at 04:34 27 May 2015 K. G. Budden on the frequency radio waves (Bracewell et al 1951). It is concluded that the theory will account for the general form of some of the experimental results for frequencies of 16 kc./s, and above.…”

“…A CONSIDERABLE amount of information now exists on the nature of the reflection of very low frequency radio waves from the ionosphere (Budden, Ratcliffe and Wilkes 1936, Bracewell et al 1951. By " very low " we mean frequencies from about 10 kc./s, to 100 kc./s.…”

The correlation of VLF propagation variations with atmospheric planetary-scale waves

“…Deland and Cavalieri (1973) have further shown the electron density heights determined by Brown and Williams to be well correlated with planetary-ecale fluctuations of f-min (the minimum frequency a t which reflection from the ionosphere is recorded by an ionoeonde). Deland and Friedman (1972) have shown these same f-min variations to be correlated directly with atmospheric pressure fields for the stratosphere.Long distance VLF (3-30kHz) tranemissions have been used for many years to study a variety of ionospheric disturbances related to solar x-rays, solar energetic particles, trapped energetic particles, aurora, and magnetic storms (e. g. Bracewell et a:., 1951; Crombie, 1965; Belrose and Thomae, 1968;Westerlund et al , 1969;Zmuda and Potemra, 1972;Potemra and Rosenberg, 1973). The longest t h e scale of these disturbances is about 10 days and is only observed duriag severe polar cap absorption events with trans-polar VLF transmiasions o r following large geomagnetic storms with midlatitude transmissions.…”

“…Long distance VLF (3-30kHz) tranemissions have been used for many years to study a variety of ionospheric disturbances related to solar x-rays, solar energetic particles, trapped energetic particles, aurora, and magnetic storms (e. g. Bracewell et a:., 1951;Crombie, 1965;Belrose and Thomae, 1968;Westerlund et al , 1969;Zmuda and Potemra, 1972;Potemra and Rosenberg, 1973). The longest t h e scale of these disturbances is about 10 days and is only observed duriag severe polar cap absorption events with trans-polar VLF transmiasions o r following large geomagnetic storms with midlatitude transmissions.…”