Wave characteristics of tweek atmospherics deduced from the direction-finding measurement and theoretical interpretation

Abstract

Detailed wave characteristics (incident and azimuthal angles, wave polarization, and their frequency dependences) of tweek atmospherics have been elucidated on the basis of the application of our field-analysis direction finding to the VLF data observed in southern China. It is then found that the wave polarization of the first-order mode at the frequency above its cutoff frequency (f1c = 1.7 - 1.8 kHz) is always left handed and it becomes exactly left-handed circular when the wave frequency decreases down to the f1c, together with the fact the incident angle becomes zero (vertical) when the frequency approaches f1c. -from Authors