Observations of Microwave Ultra-Fast Absorption Phenomena Above Solar Active Region

While we process observational data of the Flares 22, two rare phenomena of microwave ultra-fast absorption (MUFA)are found for the first time.They occurred at 3.67 GHz and 4.00GHz in the atmospheric layers above both active regions of NOAA/ USAF 4808 and 5060 in the interval 05^h50^m17^s～05^h50^m25^s UT on May 19, 1987 and 07^h38^m50^s～07^h38^m58^s UT on June 29, 1988, respectively.These absorption phenomena were observed with Phoenix Ⅱ Micowave Spectrometer at three frequencies (1.42, 2.84 and 3.67 GHz)and (1.42, 2.84 and 4.00 GHz)at Yunnan observatory.Spike emissions appeared at both 2.84 GHz and 1.42 GHz.The notable observational characteristics of both absorption phenomena are given.A possible abso rption mechanism of MUFA is discussed.