On the fundamental and harmonic components of low-frequency Type III solar radio bursts

Using published data on low-frequency Type III bursts, it is demonstrated that the identification of the emission as fundamental or harmonic depends upon the visibility of the fundamental component. The viewing angle of the F components were calculated to find its distribution and frequency dependence. The shape of the Type III trajectory, position of the fundamental source at each frequency of observation, and the position of the satellite were obtained. The analysis shows that the directivity of the fundamental emission changes from a cone of some + or - 65 deg at 80 MHz to about + or - 15 deg at 100 kHz.