Measured back scattering cross section of thin wires

Prof. Ralph E. Hiatt was instrumental in designing the first anechoic chamber at the Radiation Laboratory Willow Run Facility of the University of Michigan. During the nineteen sixties it was one of the largest such facilities in the world. It is therefore appropriate to describe some of the basic RCS measurements, such as these wires, carried out in this chamber. A set of back scattering patterns was measured for a thin (metallic) wire (a//spl lambda/=6.27/spl times/10-3) for l//spl lambda/=0.3(0.25)0.5(0.5)1.60(0.10)5.42, where a is the radius of the wire, l is the wire length, and /spl lambda/ is the wavelength. From the set of patterns a number of curves were extracted showing the amplitude and phase of each back scattering lobe as a function of the wire length. These curves provide a convenient means of cross section estimation and may be used to reconstruct with reasonable accuracy the back scattering pattern for any value of l//spl lambda/, l//spl lambda//spl les/5.42. These data have been found useful in studies dealing with scattering form composite geometrical shapes where it is often found useful to compare the back scattering patterns with those of a thin wire, especially in the resonance region. A block diagram of a CW system used for the measurement is shown.