In this study, glass fiber composite prepreg is manufactured with multi-walled carbon nanotube (MWNT) added epoxy using two different methods. Because MWNT agglomeration occurs, the calendering dispersion method is used to resolve this problem. The tensile and shear tests of glass/MWNT 1.8wt % added epoxy composite (CNT18) are conducted and the results are compared with the properties of a commercial glass/epoxy composite (GEP 118). The complex permittivity is measured using a network analyzer and a waveguide in the Ku-band. A single slab radar absorbing structure (RAS) is also designed and verified. It is found that the tensile and shear properties of CNT18 are sufficient to replace GEP 118 as a structural material. Furthermore, the10 dB bandwidth and reflection loss of the RAS using CNT18 is 12.87 to 17.78 GHz (4.91 GHz) and29.2 dB at 14.95 GHz, respectively. The measurement results align well with the simulation results. (c) 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42019.