SCATTER MEASURED FROM IMPEDANCE DISCONTINUITIES

The vertically-polarized (electric vector in the plane of incidence) r adar cross sections of four-square doped silicon samples that were ins erted in a diamond-shaped aluminum fixture have been measured at eleva tion angles of both 5.5 degrees and 18 degrees (near grazing incidence ) at an azimuth angle normal to the edge of the samples. The measured scatter matches predictions for samples inserted in an infinite conduc tive plane that were made using two different two-dimensional models a t 18 degrees, but was 2-6 dB below predictions at 5.5 degrees in all c ases, A comparison between predictions made with and without a Leontov ich impedance-boundary-condition (IBC) approximation demonstrates that the discrepancy between theory and measurement at 5.5 degrees is not caused by the use of this approximation in the predictions. The most l ikely source of the discrepancy is the finite extent of the diamond-sh aped fixture used in the measurements.