An Evaluation of HF Ionospheric Backscatter Echoes

Abstract : The characteristics of HF radar echoes reflected from ionization irregularities aligned along the lines of force of the earth's magnetic field are discussed. The spatial-geographical extent of ionospheric backscatter echoes is estimated for an HF radar located in the midlatitudes with the antenna beam oriented toward the polar region. Utilizing experimental radar-ionospheric data acquired at frequencies between HF and UHF, an analysis is made of the amplitude and the cross-sectional area statistics of HF field-aligned echoes. The Doppler frequency variation, the frequency of occurrence and the diurnal and seasonal variation of ionospheric backscatter echoes and their correlation with solar geophysical conditions are also discussed.