Conclusions
The emission physics is generally still unclear for coherent radio
bursts in the decimeter range.
Even type III bursts are quantitatively not understood:
  - very high frequency emissions
  - even before flare
  - not related to electron acceleration rate
Narrowband spikes and pulsations are not understood even
qualitatively
The plausible causes are a small number (electron beams, flare
waves, trapped electrons and a few more).
Eidgenössische Technische Hochschule Zürich
Swiss Federal Institute of Technology,  Zürich