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The experiment samples of La_ 1-xSr_xMn_ 1-yFe_yO_3(x=0.15, 0.20, 0.23; y=0.10, 0.12, 0.14, 0.16) were prepared by sol-gel process, and the loss tangent and absorption coefficient in the range of 2～18 GHz were measured by HP8722 net analyzing apparatus. It is found that changing the content of Sr or Fe would effect the microwave absorbing. When the thickness of La_ 1-xSr_xMn_ 1-yFe_yO_3 is 2 mm and x=0.20, y=0.14, the capability of microwave absorbing is the best one. There are two absorption peaks; the maximum is 34 dB and effective band width with 10 dB and more reaches 6.2 GHz. When the frequency between 2～12.5 GHz dielectric loss is considered as the major loss from the loss angle picture. When the frequency gets to near 12.5 GHz the loss angle tangent increases or decreases suddenly. When the frequency between 12.5～18 GHz magnetic loss is be considered as the major loss. The resistivity of La_ 0.8Sr_ 0.2Mn_ 0.86Fe_ 0.14O_3 at room temperature presents its semiconductor character, which is more beneficial to absorbing microwave.
The experimental samples of La 1-x Sr x Mn 1-y Fe_yO_3 (x = 0.15, 0.20, 0.23; y = 0.10, 0.12, 0.14, 0.16) were prepared by sol- gel process, and the loss tangent and absorption coefficient in the range of 2 When the thickness of La_1-xSr_xMn_1-yFe_yO_3 is 2 mm and x = 0.20, y = 0.14 There are two absorption peaks; the maximum is 34 dB and effective band width with 10 dB and more reaches 6.2 GHz. When the frequency between 2 ~ 12.5 GHz dielectric loss is considered as the major Loss from the loss angle picture. When the frequency gets toward 12.5 GHz the loss angle tangent increases or decreases suddenly. When the frequency between 12.5 and 18 GHz is considered as the major loss. The resistivity of La_0.8Sr_0.2Mn_ 0.86Fe 0.14O_3 at room temperature presents its semiconductor chara cter, which is more beneficial to absorbing microwave.