A series of radar measurements on the penetration of foliage has been made at 9.4, 16.2, 35, and 95 GHz. Measurements were made for both the one-way and two-way cases at 9.4 and 16.4 GHz at similar foliage areas for comparison. Most of the measurements were made at depression angles below 3 degrees, although a set of one-way measurements was made at 9.4 and 16.2 GHz for a depression angle of 29 degrees. Attenuation properties, polarization ratios, and noncoherent spectral correlation properties were investigated as a function of frequency, polarization, depth of foliage and wind speed. Limited comparisons are made with data previously available at lower frequencies.