又，S= L =10log 1-S=1oog1-C夏7 =101ogl-rf)-161o81-T <0 可见，插人损耗可能为负。置又， * 22 L S = G ( ) 0 1 1 10log 1 10log 1 1 10log 1 10log 2 2 2 2 2 2 21 2 22 < - G = - G = - - G - G = - G = L L L L L i S S L 可见，插入损耗可能为负