Directional Characteristics of Meteor Propagation Derived from Radar Measurements

Abstract

The directivity of radio reflections from meteor trails and the distribution of trail orientations (radiants) control the directional properties of meteor propagation. Because of the geometrical correspondence between radar and oblique path detection of meteors, the directional properties of meteor propagation can be determined from the range and azimuth distributions of the echoes detected by a radar system. The gross features of these directional properties for an east-west path in northern temperate latitudes are such that-for maximum circuit duty cycle (product of number of echoes and their average duration)-the antenna beams at the transmitter and receiver should be pointed north of the great circle bearing during the morning hours and south of this bearing during the evening. The optimum off-path angle may vary from a few degrees to greater than 20°. For a north-south path, the beams should be pointed west of the path at night and east of the path during the day, for maximum duty cycle. These gross features appear to repeat each day. In addition, short-term fluctuations in the radiant distribution have been noted, some of these fluctuations presumably being due to heretofore undetected meteor showers of very short duration. It appears that the information capacity of meteor burst and ionospheric scatter communication systems could be markedly increased by varying the bearings of the antenna beams according to the known diurnal variations in meteor radiants.