目的 归纳总结碳纤维长度和含量对碳纤维复合吸波材料（CFCAM）频散特性的影响规律。方法 以水性聚氨酯（PR）为基体树脂，碳纤维（CF）为填料，制备了不同长度和含量的CFCAM，采用扫描电镜和X射线衍射仪对CF改性前后的微观形貌和物质结构进行表征，用矢量网络分析仪测试CFCAM介电常数（ε），归纳总结出CF长度、含量对CFCAM的频散特性的影响规律。结果 随着CF长度的增大，CFCAM的ε先增大后减小，当CF长度为3 mm时，CFCAM不仅具有较好的频散特性，实部（ε′）和虚部（ε′′）都较大；随着CF含量增大，CFCAM的 增大，当CF质量分数为0.9%时，ε′达到18左右，ε′′达到9左右，预示着该含量下CFCAM有较大的储存能量的能力，并且对电磁波有较强的电损耗能力。结论 3 mm碳纤维在质量分数为0.9%时具有较好的频散特性，适宜用来制备吸波性能强、频带宽的雷达吸波涂层材料。

The work aims to summarize law of influence of carbon fiber content and length on frequency dispersion characteristics of carbon fiber composite absorbing materials. Carbon fiber composite absorbing materials (CFCAM) of different length and content were prepared with carbon fiber (CF) with filler and water-based polyurethane resin (PR) as matrix basin. Microstructure and material structure of unmodified and modified CFCAM were characterized by means of scanning electron microscopy and X-ray diffraction analyzer. Dielectric constant of CFCAM was tested with vector network analyzer. The law of influence of CF length and content on frequency dispersion characteristics of CFCAM was summarized. ε of CFCAM first increased and then decreased as CF length increased. CFCAM with 3 mm CF not only had good frequency dispersion characteristics, but also had larger real (ε′) and imaginary (ε′′) part of dielectric constant. ε of CFCAM increased as the content of CF increased. ε′ of CFCAM was nearly 18 and imaginary part 9 at the CF mass fraction of 0.9wt.%, indicating that CFCAM had greater capability in storing energy, and had strong capability of electric loss on electromagnetic wave. 3 mm carbon fiber at the mass fraction of 0.9wt.% exhibits better frequency dispersion characteristic, hence it can be used to prepare radar absorbing materials of good absorbing property and wide frequency band.