A planar near-field scanning technique for bistatic radar cross-section measurements

Original publisher: Columbus, Ohio : Ohio State University, ElectroScience Laboratary ; [Cleveland, Ohio : National Aeronautics and Space Administration, Lewis Research Center ; Springfield, Va. : National Technical Information Service, distributor, 1990] OCLC Number: (OCoLC)62205458 Subject: Bistatic radar. Excerpt: ... algorithm on the area outside the scan plane. Since the fields outside the scan plane axe not known, the error is estimated as the " a priori " knowledge of the energy not received by the scan plane. This criterion is frequently used to require retaining 80 to 85 % of the radiated energy within the scan surface and limit test targets to ones that radiate directively. In this work, the array size and spatial windowing designs will be cho-sen to mimic the behavior of a compact range reflector. The array size requirement is thus the same as for a compact range reflector: the plane wave region must cover the test target entirely. For identicM target ( quiet ) zones, the necessary scan plane size is expected to be comparable with a compact reflector surface ( including rolled edges ). The size of the plane wave region in the target zone is proportional to the size of the scan plane. A useful plane wave region is often characterized by a 1 dB amplitude ripple and 10 degree phase ripple. In the literature, Johnson et.al. [ 1 ] quotes Woonton as having a minimum scan-plane to target-zone size ratio of 2.0, Chapman 2.3, and Georgia Tech 1.9. Joy and Rowland [ 3 ] used a minimum scan-plane to target-zone ratio of 1.7 for a highly directive parabolic dish target. Thus, as a general rule of thumb, the scan-plane must be twice the size of the largest target to be measured_ 2.3 Probe Measurement Spacing The planar scanner receives the incident scattered fields at discrete sample points. To satisfy the Nyquist sampling criterion, samples should be taken at intervals which are equal to or less than one half the wavelength. Cown 7