Long range meteoric echoes via F-layer reflections

This note reports HF observations of meteoric back-scatter echoes at ranges greatly exceeding radio line-of-sight. The observations were part of a program of measurements on backscatter using COZI equipment, Examples are given of observations at South Dartmouth, Massachusetts in 1949 on 16 mc and of more recent observations in 1954 on 12 and 16 mc using improved equipment. Short duration echoes are observed in advance at ranges shorter than those of the ground backscatter. No such meteoric echoes are observed when the ground backscatter disappears. The meteoric echo ranges move with time of day just as the range to the ground backscatter moves. A plausible explanation for the observed meteoric echo ranges exceeding 1,000 miles is that they are due to backscatter from the trail, ionospherically propagated to and fro via the F region, just as the ground backscatter. Other possible ionospheric propagation modes are discussed