A near field spherical wave inverse synthetic aperture radar technique

Abstract

The authors present an imaging near-field spherical wave inverse synthetic aperture radar (SWISAR) algorithm based on a focusing operator of the scattered fields on the target surface. A spherical wave can be easily generated in an anechoic chamber using electrically small and low-cost horn antennas; no reflectors are used, avoiding surface tolerance problems, and diffraction can be minimized with an appropriate horn design. An additional advantage of this algorithm is its ability to account for bistatic measurement geometries and lateral tapers in the spherical wave illumination. A 2-D formulation has been used which is strictly valid for bodies which satisfy far-field conditions in the height dimension, as easily occurs with aircraft. The reconstruction of numerically simulated five point-like objects placed on a radial line for a frequency range of 18 to 26 GHz and an angular scan of 360 degrees is shown.