Based on observations of the extraordinary behind-limb flare on February 16, 1984 the radio-flux time profiles at different
dm-wavelengths and dynamic spectrum corresponding
to a source height z > 200000 km above the photosphere are
compared with hard X-ray observations reported by Kane et al.
(1987). The nature of the dm-emission and implications on the
flare process are discussed. Dependíng on the emission
process estimations of relevant plasma parameters (electron
density, magnetic field) are given.
Part I of this review considers the outcome of different methods of observation of active regions at mm- and cm-v/aves exploring the source structures and parameters in the chromosphere and corona. Calculations of emission models invoking bremsstrahlung and gyromagnetic radiation are summarlzed applying for a great
variety of physical conditions. Diagnostic capacities of different kinds of microwave burst emission are briefly taken into account.
Part II of the review considers the dm- and m-radio spectral observations as diagnostic tool for the determination of plasma parameters in the coronal parts of solar active regions. The main attention is devoted to the radio diagnoetics of solar flares. The most important types of dm- and m-radio bursts are presented.
the latest theoretical and observational results summarized and their diagnostic aapects briefly discussed.