An accurate quasi-optical S-parameter measurement method implemented in the normalized frequency bands Ka, W and J is presented in this paper. Permittivity extraction of various solid or non-solid dielectric materials is performed using the 4 S-parameters without time domain gating nor filtering. The procedure is validated through the comparison between the simulated and measured 4 S-parameters in magnitude and phase. Results are given for the Rexolite over a wide frequency span from the Ka to J band while some non-solid materials were characterized in the W band. Moreover, effects of rain flow on a dielectric slab were investigated for automotive radar applications in the W band and preliminary results are given.