Range requirements in radar cross-section measurements

The conditions for radar cross-section measurement are given in terms of permissible variations in the amplitude and phase of the incident field at the target. A number of minimum range conditions are listed and discussed. The minimum range associated with the uniform square aperture antenna is analyzed and its relationship to the sensitivity of measurement is determined. Measurements of small targets in the near zones of focused and unfocused apertures are examined. The substantial range reduction possible with the use of a suitable microwave lens, when measuring large and medium size targets, is indicated.