THREE model radar ranges have been constructed to measure the scattering cross-section of models. The first of these is a 10-mmusec pulse radar operating at a frequency of 35 kmc. The second, operating at the same frequency, is a CW balanced hybridTsystem. The third, at 8.75 kmc, has two modes of operation. In one it operates as a simple CW balanced hybridTsystem and in the other, which is inherently more stable, it uses low frequency modulation to achieve a range resolution of about 7 feet. As a combined facility, with various sizes of model, we can study the back-scatter cross-section of simple models, for any polarization, over an effective wavelength range of at least 40 to 1. The minimum detectable cross-section is about 45 db below a square wavelength. Back-scatter measurements have been made on a variety of simple shapes, Results were presented on metal cones and toroids.