Measurements of the dielectric properties of explosives and inert materials at millimeter wave frequencies (V-band and above) using free space reflection methods

We present a free space material measurement system operating in the E band (60-90 GHz) frequency range that uses calibration standards placed at the sample location to define the measurement reference plane directly at the sample surface. Measurement signal to noise is improved by using an aperture in radar absorbing material (RAM) to simplify the RF measurement environment. Measurements are provided that extend earlier work done in the 18-40 GHz frequency range. Data is extracted using numerical fitting of reflection-only data to a theoretical model based on geometric optics. System calibration, and results are presented.