The characteristics of meteor trails observed at a frequency of 300 Mc/s

摘要: Abstract Some observations of radar echoes from meteor trails at frequencies 300 Mc/s and 32 Mc/s, carried out using transmitters installed in the 25 m radio telescopes Royal Radar Establishment, Malvern, are described. The have been used to assist interpretation occurring simultaneously higher frequency, it is shown that intensities observed order 80 dB below values predicted by simple theory. theoretical limiting sensitivity equipment was such a trail electron line density α = 2 × 10 8 cm −1 would give detectable echo. In fact all were with > 12 , giving rise “long duration” Mc/s. Doppler measurements show majority still behave as specular reflectors within ± 0.6° this showing effective scattering length usually about 50 m. explain low echo high necessary postulate ionised columns formed initially radii 1.5 m, so volume always less than critical It deduced overall for meteors 13 only 3 km.