Bistatic clutter measurements

Empirical data have been obtained from which estimates of the bistatic reflection coefficient \sigma_{0} have been determined. Measurements were made on two terrain types (grassy terrain and an area of tall weeds and rough ground) at low grazing bistatic angles of 70\deg, 75\deg, 80\deg , and 85\deg , and 0\deg to 180\deg azimuth angle. The terrain was illuminated at wavelengths of 3 cm and 23 cm, with horizontal polarization. Both like and orthogonal polarizations were received at each wavelength; four channels of data were recorded. The measurement technique utilized an aircraft with the 3-cm and 23-cm transmitters on board; receivers were mounted on a tower. The transmissions were pulsed, and coherent signals were recorded by utilizing a separate air-to-ground link for the receiver local oscillator signal.