Microwave Radar Signature Acquisition of Urban Structures

Abstract

Global and reliable reconnaissance using remote sensing techniques requires a weather and time independent detection, recognition, and identification capability for objects of interest. A space-borne high resolution SAR system in a spotlight mode can be an appropriate instrument. In the design phase of such a mission the availability of representative radar data from ground measurements is important for the analysis, the understanding simulation of complex target signatures, and for reference signatures used in automatic target recognition (ATR). Inverse SAR (ISAR) imaging allows the collection of very precise two-dimensional high-resolution radar signatures from objects. For a space-borne radar system, the imaging geometry is similar and differs only by a geometrical transformation. With ISAR high resolution images in the decimetre range are accomplished by rotating an object on a turntable with respect to a spatially fixed broadband radar system, and by recording a sequence of corresponding radar range returns within a specific azimuth angle area. Especially target recognition by radar in urban environment is challenging due to several image confusing effects like multi-path reflections, overlay, and shadowing. In order to support SAR simulation tools with measured data of urban elements, tower-turntable ISAR experiments have been performed on walls of miscellaneous building materials. Following an introduction of the measurement setup and the image processing, this paper shows some first results.