We studied the transmission characteristics of a one-dimensional metamaterial slab operating at the millimeter-wave regime. The double-negative nature was proven by using a normal incidence transmission study. A split-ring resonator based metamaterial flat lens with five layers at the propagation direction was constructed and illuminated with oblique incidence. From the scanning experiments, the shifting of the beam to the negative side was observed. The experimental results are in agreement with the Drude-Lorentz model based simulations. Two-dimensional field maps that were obtained from these simulations demonstrated negative refraction, negative phase velocity, and the reflected beam properties at 99 GHz.