The experiments on 3mm radiowave propagatin attenuation induced by sea fog were carried out. The results show that dense fog induces 7.55dB/km attenuation at 3mm. The sea fog characteristic parameters were calculated. The measured attenuation was compared with that calculated by ITU model at different visibility. Signal scintillation characteristics were analyzed. Key words 3mm communication, attenuation, visibility, scintillation index.um 11211$$$$ YANG Cheng yongSchool of Life Sciences,Zhongshan University,Guangzhou 510275,China,ZHOU Shi ning,ZHOU Yi pin,LIN Yong cheng Abstract:Bacterium 11211 which produces chitinase was isolated from the South China Sea.The growth condition and chitinase production of bacteria were investigated.Na was necessary for bacterium 11211 growth.Colloid chiyin could induce bacteria to produce chitinase.The growth of bacteria was slow in the medium containing colloid chitin as main carbon source,and the enzyme activity reached maximum on 7 d of incubation.Following the purification,the enzyme was characterized and its molecular weight was estimated by SDS PAGE.