Abstract: For studying the electrical and mechanical properties of 3D composites, three kinds of 3D composites were prepared via vacuum assistant resin infusion process (VARI). Their permittivity (ε_r) and loss angle tangent (tanδ) were tested by resonance cavity perturbation method. In addition, their transmission coefficient, flatwise tension strength and flatwise compression properties were investigated. The results of experiments have shown that with the increase of thickness, the ε_r and tanδ decrease. The permittivity of 5 mm, 6 mm and 8 mm are 1.93, 1.77 and 1.62, and the loss angle tangent of 5 mm, 6 mm and 8 mm are 0.0083, 0.0078 and 0.0065. Besides, their transmission coefficients are all below 0.2 dB between 1 GHz and 12 GHz. What′s more, the results indicate that the compression strengths of the 5 mm, 6 mm and 8 mm are 5.8 MPa, 4.6 MPa and 3.8 MPa, respectively. The flatwise tension strengths of the 5 mm, 6 mm and 8 mm are 7.8 MPa, 6.4 MPa and 5.2 MPa, respectively, which indicates that the 3D composites have excellent mechanical properties.

Key words: 3D composite, permittivity, loss angle tangent, compression strength, flatwise tension strength