Long-Period Pulsations at Short Dm Wavelength

A great solar radio burst was observated at Yunnan Observatory on July 30,1990.In this burst,the long periodic(several tens of second)pulsatons were found at 1420MHz and 2000MHz.It is found that: 1 The bandwidth of the pulsations is larger than 600MHz. 2 The periods of the pulses at 1420MHz are larger than ones at 2000MHz. 3 The period of the pulse rises when the relative amplitude increases, and theyave an approximately linear relationship.