The angular distribution of spread F returns from an artificially modified ionosphere

Allen, E. M. ; Thome, G. D. ; Rao, P. B. ; Germain, R. L. St. (1974) The angular distribution of spread F returns from an artificially modified ionosphere Journal of Geophysical Research, 79 (22). pp. 3161-3169. ISSN 0148-0227

Full text not available from this repository.

Official URL:

Related URL:


A 32-element HF-phased array has been used to study the angular spectrum of spread F returns from an ionosphere modified by the powerful radio frequency heater transmitter at Platteville, Colorado. The diagnostic radar is a coherent pulse system that provides an angular resolution of 2.7° at the midband frequency of 7.5 MHz, a range resolution of 30 km, and a Doppler resolution of 0.08 Hz. The results are presented in the form of sky maps (brightness versus azimuth and elevation) of the returns as a function of group delay, Doppler shift, polarization, and sounding frequency. The principal result is that the returns that suffer the greatest group delay at a given sounding frequency come from a direction looking up the earth's magnetic field and exhibit negative Doppler shift. Ray-tracing simulation of the observed dependence of the range and the Doppler on the angle of arrival of the returns supports the view that the heater-generated spread F is caused by field-aligned ducts produced within the heated volume. A simulation run for Arecibo, Puerto Rico, in comparison with that for Platteville, reveals that the group delay spread is about the same and the angular spread is approximately in the same ratio as the heater beam widths at the two locations.

Item Type:Article
Source:Copyright of this article belongs to American Geophysical Union.
ID Code:40601
Deposited On:24 May 2011 14:36
Last Modified:24 May 2011 14:36

Repository Staff Only: item control page