REPEATED ACTIVITY OF THE 0.8-1.2 GHZ RADIO-SOURCE OF MARCH 20, 1993

During March 20, 1993, from 12:00 to 16:00 UT, repeated radio burst ac tivity was observed in the 0.8-1.2 GHz frequency range. 'Periods' in i ntervals 0.1-0.5, 0.7-1.0, 2.8-3.9, 75-170 s, and 15-25 min were recog nized. This long-lasting narrowband activity consisted mainly of pulsa tions and continua. In some intervals it was accompanied not only by s pikes, broadband pulsations, and fibers in the 1-2 GHz frequency range , but also by type III and U burst activity at lower frequencies as we ll as by hard X-ray bursts. From several radio bursts, two characteriz ed by different fine structures were selected and compared. The observ ed differences are explained by different distribution functions of su perthermal electrons. The position of the 0.8-1.2 GHz radio source abo ve the photosphere and the magnetic field in the fiber burst source we re estimated to be 66 000-75 000 km and 120-135 G, respectively.