Stray signal source location in antenna/RCS ranges

A wide variety of antenna/RCS ranges are being used throughout the world for radiation and scattering measurements. In the case of far field ranges, once a range is completely operational, the quiet zone (where the antenna under test or target under test is normally mounted) is probed using a widebeam antenna. Invariably, the field probe data has some ripple indicating that there are stray (undesired) signals present in the range. One is interested in locating the sources of stray signals in order to modify the range to minimize the stray signals and/or design the measurement procedure to minimize the effect of stray signals on real scattering and/or radiation measurements. A variety of methods have been developed for determining the stray signal sources from the probe data. A brief summary of these methods is presented. We look at near field focusing, beam forming technique and time and direction of arrival estimation.